tag:theconversation.com,2011:/au/topics/worms-2821/articles
Worms – The Conversation
2024-03-26T17:01:48Z
tag:theconversation.com,2011:article/226643
2024-03-26T17:01:48Z
2024-03-26T17:01:48Z
The ‘worm moon’ once marked the spring return of earthworms – until global warming kicked in
<figure><img src="https://images.theconversation.com/files/584414/original/file-20240326-16-7psmz6.jpg?ixlib=rb-1.1.0&rect=8%2C8%2C5982%2C3970&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Darkfoxelixir / shutterstock</span></span></figcaption></figure><p>The worm moon has risen. The final full moon of winter in the northern hemisphere appeared on <a href="https://www.theguardian.com/news/gallery/2024/mar/25/a-volcanic-eruption-and-a-worm-moon-photos-of-the-day">March 25</a> and owes its name to <a href="https://www.nationalgeographic.co.uk/2019/02/full-moon-names-explained">Native Americans</a> who noted winter’s end by the trails of earthworms it illuminated on the newly thawed soil. </p>
<p>Common names of full moons generally come from seasonal animals, colours or crops: wolf moon, pink moon, harvest moon. But the worm moon may be losing its significance, as climate change leads to wetter summers and milder winters in much of the world. I’ve been an earthworm scientist for more than three decades, and, of late, I’m seeing signs of worms at the surface in months when they used to be inactive.</p>
<p>To track how the worm moon might be changing we can look at a particular earthworm species (<em>Lumbricus terrestris</em>, aka the dew worm, nightcrawler or lob worm) which is unusually easy to track. Also sometimes called the common earthworm, if you see a big worm in the garden, it’s likely to be this species. </p>
<hr>
<p><em>Do the seasons feel increasingly weird to you? You’re not alone. Climate change is distorting nature’s calendar, causing plants to flower early and animals to emerge at the wrong time.</em></p>
<p><em>This article is part of a series, <a href="https://theconversation.com/uk/topics/wild-seasons-152175?utm_source=InArticleTop&utm_medium=TCUK&utm_campaign=WS">Wild Seasons</a>, on how the seasons are changing – and what they may eventually look like.</em></p>
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<p>Most worms spend most of their lives underground, but the dew worm almost completely leaves its deep burrow, with tail tip left in, as it ventures on to the soil surface every night to feed on dead leaves. These worms also mate on the soil surface. They may be hermaphrodite (both male and female) but still need to exchange sperm with a partner – each fertilising the other.</p>
<p>Such activities usually take place under the cover of darkness to avoid birds and other potential daytime predators. However, the worms are restricted by soil conditions at the top of the burrow. They cannot surface if the soil is baked dry (in summer) or frozen (in winter). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large worm in soil" src="https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584428/original/file-20240326-22-f8tpaz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Lumbricus terrestris</em> is a large earthworm found across the world.</span>
<span class="attribution"><span class="source">D. Kucharski K. Kucharska / shutterstock</span></span>
</figcaption>
</figure>
<p>In theory, the passing of winter would kickstart the surface activity (and therefore the worm moon). Yet if the winter isn’t that cold, we perhaps need to reconsider which moon should be termed the “worm moon”. Maybe a date earlier in the year would be better, or perhaps the term may cease to have any real meaning.</p>
<p>We can get a sense of how these earthworms can adapt to changing circumstances by looking at the northernmost populations, such as those in Finland, which are exposed to 24 hours of daylight in summer. These “white nights”, when the sky never gets dark, put additional stress on these worms as they cannot use darkness to hide from predators but must still feed and mate at the surface while conditions allow.</p>
<h2>Finland v Lancashire v Ohio</h2>
<p>A decade ago, colleagues and I set out to see if Finnish worms behaved any differently during the white night period to worms of the same species taken to Finland from lower latitudes. We <a href="https://www.sciencedirect.com/science/article/pii/S0038071714000248">compared native dew worms</a> from an area in south-west Finland at 60°N, with those from Lancashire in the UK (53°N) and Ohio in the US (40°N, more than 2,000km south of Finland), both of which have dark nights throughout the year.</p>
<p>We put these worms outdoors under ambient (white night) light in soil-filled drainpipes (1m deep) in a large, controlled temperature water bath (an old chest freezer with no lid). We looked at their feeding and mating, and, in parallel, repeated the experiment under darkened conditions at “night”. </p>
<p>In darkness, worms from all three origins were similarly very active in feeding and mating. </p>
<p>Under ambient conditions, the Finnish worms were generally the most active. They emerged earlier in the evening and ceased their activity later in the morning than those from the two more southerly populations. It seems the species had adapted to its conditions, with a normal reluctance to surface during daylight overtaken by a need to feed and mate.</p>
<p>Perhaps with warming soils, earthworms are becoming more active during traditionally colder or drier months. This will increase their effect on the soil – earthworms are ecosystem engineers and generally lead to increased soil fertility – which is generally positive, even if churning up the soil can lead to <a href="https://www.nature.com/articles/nclimate1692">further decomposition and greenhouse gas emissions</a>. </p>
<p>A worm moon and white nights would never normally appear in the same sentence. However, changes in the activities of worms as the global climate becomes less predictable means we may need to rethink at least one of our terms of reference that has marked time for hundreds or thousands of years. Enjoy the traditional worm moon while it lasts.</p><img src="https://counter.theconversation.com/content/226643/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Richard Butt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The last full moon of winter can illuminate earthworms in newly-thawed soil.
Kevin Richard Butt, Reader in Ecology, University of Central Lancashire
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/220828
2024-02-14T13:24:42Z
2024-02-14T13:24:42Z
We designed wormlike, limbless robots that navigate obstacle courses − they could be used for search and rescue one day
<figure><img src="https://images.theconversation.com/files/571646/original/file-20240126-17-1c52dw.JPG?ixlib=rb-1.1.0&rect=55%2C0%2C4024%2C1578&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Limbless robots may not need lots of complex algorithms when they have mechanical intelligence. </span> <span class="attribution"><span class="source">Tianyu Wang</span></span></figcaption></figure><p>Scientists have been trying to build <a href="https://en.wikipedia.org/wiki/Snakebot">snakelike, limbless robots</a> for decades. These robots could come in handy in <a href="https://www.science.org/content/article/searching-survivors-mexico-earthquake-snake-robots">search-and-rescue</a> situations, where they could navigate collapsed buildings to find and assist survivors. </p>
<p>With slender, flexible bodies, limbless robots could readily move through confined and cluttered spaces such as debris fields, where walking or wheeled robots and human rescuers tend to fail.</p>
<p>However, even the most advanced limbless robots have not come close to moving with the agility and versatility of worms and snakes in difficult terrain. Even the tiny nematode worm <em><a href="http://www.wormbook.org/">Caenorhabditis elegans</a></em>, which has a relatively simple nervous systems, can navigate through difficult physical environments. </p>
<p>As part of a team of <a href="https://www.lulab.gatech.edu/">engineers</a>, <a href="https://crablab.gatech.edu/">roboticists and physicists</a>, we wanted to explore this discrepancy in performance. But instead of looking to neuroscience for an answer, <a href="https://en.wikipedia.org/wiki/Biomechanics">we turned to biomechanics</a>. </p>
<p>We set out to build a robot model that drove its body using a mechanism similar to how worms and snakes power their movement. </p>
<h2>Undulators and mechanical intelligence</h2>
<p>Over thousands of years, organisms have evolved <a href="https://www.britannica.com/science/nervous-system">intricate nervous systems</a> that allow them to sense their physical surroundings, process this information and execute precise body movements to navigate around obstacles. </p>
<p>In robotics, engineers design algorithms that take in information from sensors on the robot’s body – a type of robotic nervous system – and use that information to decide how to move. These algorithms and systems are usually complex. </p>
<p>Our team wanted to figure out a way to simplify these systems by highlighting mechanically controlled approaches to dealing with obstacles that don’t require sensors or computation. To do that, we turned to examples from biology.</p>
<p>Animals don’t rely solely on their neurons – brain cells and <a href="https://my.clevelandclinic.org/health/body/23123-peripheral-nervous-system-pns">peripheral nerves</a> – to control movement. They also use the physical properties of their body – for example, the elasticity of their muscles – to help them react to their environment spontaneously, before their neurons even have a chance to respond.</p>
<p>While computational systems are governed by <a href="https://en.wikipedia.org/wiki/Computational_logic">the laws of mathematics</a>, mechanical systems are governed by physics. To achieve the same task, scientists can either design an algorithm or carefully design a physical system. </p>
<p>For example, limbless robots and animals move through the world by bending sections of their body left and right, <a href="https://en.wikipedia.org/wiki/Undulatory_locomotion">a type of movement called undulation</a>. If they collide with an obstacle, they have to turn away and go around it by bending more to one side than the other.</p>
<p>Scientists could achieve this with a robot by attaching sensors to its head or body. They could then design an algorithm that tells the robot to turn away or wind around the obstacle when it “feels” a large enough force on its head or body. </p>
<p>Alternatively, scientists could carefully select the robot’s materials and the arrangement and strength of its motors so that collisions would spontaneously produce a body shape that led to a turn. This robot would have what scientists call “mechanical intelligence.”</p>
<p>If scientists like us can understand how organisms’ bodies respond mechanically to contact with objects in their environment, we can design better robots that can deal with obstacles without having to program complex algorithms. </p>
<p>If you compare a diverse set of undulating organisms with the increasingly large zoo of <a href="https://en.wikipedia.org/wiki/Snakebot">robotic “snakes</a>,” one difference between the robots and biological undulators stands out. Nearly all undulatory robots bend their bodies using a series of connected segments with motors at each joint. But that’s not how living organisms bend.</p>
<p>In contrast, all limbless organisms, from large snakes to the lowly, microscopic nematode, achieve bends not from a single rotational joint-motor system but instead through <a href="http://www.wormbook.org/chapters/www_bodywallmuscle/bodywallmuscle.html">two bands of muscles</a> on either side of the body. To an engineer, this design seems counterintuitive. Why control something with two muscles or motors when one could do the job? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a gray worm with a window showing the inside of the worm's body, which has two bands of muscle on the left and right side, cuticle on the top and nerve cord on the bottom, top and sides." src="https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=283&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=283&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=283&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=355&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=355&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575078/original/file-20240212-26-it6ean.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=355&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nematodes have two bands of muscle on the sides of their bodies that control motion.</span>
<span class="attribution"><span class="source">Ralf J. Sommer and WormAtlas</span></span>
</figcaption>
</figure>
<p>To get to the bottom of this question, our team built a new robot called MILLR, for mechanically intelligent limbless robot, inspired by the two bands of muscle on snakes and worms. MILLR has two independently controlled cables that pull each joint left and right, bilaterally.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the design of MILLR, with servo motors on each body segment, and cables and pulleys connecting them." src="https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=275&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=275&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=275&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=345&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=345&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575079/original/file-20240212-20-gtf8t7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=345&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">MILLR’s design, inspired by nematode <em>C. elegans</em>.</span>
<span class="attribution"><span class="source">Tianyu Wang</span></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1126/scirobotics.adi2243">We found</a> this method allows the robot to spontaneously move around obstacles without having to sense its surroundings and actively change its body posture to comply to the environment.</p>
<h2>Building a mechanically intelligent robot</h2>
<p>Rather than mimicking the detailed muscular anatomy of a particular organism, MILLR applies forces to either side of the body by spooling and unspooling a cable. </p>
<p>This way, it mirrors the muscle activation methods that snakes and nematodes use, where the left and right sides take turns activating. This activation mode pulls the body toward one side or another by tightening on one side, while the other side relaxes and is pulled along passively. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="On the left, a photo showing a worm weaving between pegs. On the right, a photo showing a worm-like robot weaving between pegs." src="https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=122&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=122&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=122&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=153&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=153&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575081/original/file-20240212-26-bro51v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=153&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">MILLR’s design allows it to move through obstacles the same way worms do.</span>
<span class="attribution"><span class="source">Tianyu Wang and Christopher Pierce</span></span>
</figcaption>
</figure>
<p>By changing the amount of slack in the cables, <a href="https://doi.org/10.1126/scirobotics.adi2243">we can achieve</a> varying degrees of body stiffness. When the robot collides with an obstacle, depending on the cable tension, it selectively maintains its shape or bends under the force of the obstacle. </p>
<p><a href="https://doi.org/10.1126/scirobotics.adi2243">We found that</a> if the robot was actively bending to one side and it experienced a force in the same direction, the body complied to the force and bent further. If, alternatively, the robot experienced a force that opposed the bend, it would remain rigid and push itself off the obstacle. </p>
<p>Because of the pattern of the tension along the body, head-on collisions that would normally cause the robot to stop moving or jam itself instead naturally led to a redirection around the obstacle. The robot could push itself forward consistently. </p>
<h2>Testing MILLR</h2>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/21F7IOF9BMs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<p>To investigate the benefits of mechanical intelligence, we built tiny obstacle courses and sent nematode worms through them to see how well they performed. We sent MILLR through a similar course and compared the results.</p>
<p>MILLR moved through its course <a href="https://doi.org/10.1126/scirobotics.adi2243">about as effectively as the real worms</a>. We noticed that the worms made the same type of body movements when they collided with obstacles as MILLR did.</p>
<p>The principles of mechanical intelligence could extend beyond the realm of nematodes. Future research could look at designing robots based on a host of other types of organisms for applications ranging from search and rescue to <a href="https://youtu.be/e0D9IVo-E9M?si=d8jGaC5GDLaMbEeS">exploring other planets</a>.</p><img src="https://counter.theconversation.com/content/220828/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was supported by the National Science Foundation Physics of Living Systems Student Research Network, NSF-Simons Southeast Center for Mathematics and Biology, Army Research Office Grant, and the Dunn Family Professorship.</span></em></p>
Robots often have a hard time navigating through debris, but robots designed based on worms and snakes could move around obstacles faster, thanks to an idea called mechanical intelligence.
Tianyu Wang, Ph.D. Student in Robotics, Georgia Institute of Technology
Christopher Pierce, Postdoctoral Scholar in Physics, Georgia Institute of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/223461
2024-02-14T01:12:59Z
2024-02-14T01:12:59Z
A secret war between cane toads and parasitic lungworms is raging across Australia
<p>When the first cane toads were brought from South America to Queensland in 1935, many of the parasites that troubled them were left behind. But deep inside the lungs of at least one of those pioneer toads lurked small nematode lungworms.</p>
<p>Almost a century later, the toads are evolving and spreading across the Australian continent. In <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2023.2403">new research</a> published in Proceedings of the Royal Society B, we show that the lungworms too are evolving: for reasons we do not yet understand, worms taken from the toad invasion front in Western Australia are better at infecting toads than their Queensland cousins.</p>
<h2>An eternal arms race</h2>
<p>Nematode lungworms are tiny threadlike creatures that live in the lining of a toad’s lung, suck its blood, and release their eggs through the host’s digestive tract. The larva that hatch in the toad’s droppings lie in wait for a new host to pass by, then penetrate through its skin and migrate through the amphibian’s body to find the lungs and settle into a comfortable life, and begin the cycle anew.</p>
<p>Parasites and their hosts are locked into an eternal arms race. Any characteristic that makes a parasite better at finding a new host, setting up an infection, and defeating the host’s attempts to destroy it, will be favoured by natural selection. </p>
<p>Over generations, parasites get better and better at infecting their hosts. But at the same time, any new trick that enables a host to detect, avoid or repel the parasites is favoured as well. </p>
<p>So it’s a case of parasites evolving to infect, and hosts evolving to defeat that new tactic. Mostly, parasites win because they have so many offspring and each generation is very short. As a result, they can evolve new tricks faster than the host can evolve to fight them. </p>
<h2>The march of the toads</h2>
<p>The co-evolution between hosts and parasites is most in sync among the ones in the same location, because they encounter each other most regularly. A parasite is usually better able to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1461-0248.2007.01028.x">infect hosts from the local population</a> it encounters regularly than those from a distant population.</p>
<p>But when hosts invade new territory, it can play havoc with the evolutionary matching between local hosts and parasites. </p>
<p>Since cane toads were released into the fields around Cairns in 1935, the toxic amphibians have hopped some 2,500 kilometres westwards and are currently on the doorstep of Broome. And they have <a href="https://www.nature.com/articles/439803a">changed dramatically</a> along the way. </p>
<p>The Queensland toads are homebodies and spend their lives in a small area, often reusing the same shelter night after night. As a result, their populations can build up to high densities. </p>
<p>For a lungworm larva, having lots of toads in a small area, reusing and sharing shelter sites, makes it simple to find a new host. But at the invasion front (currently in Western Australia), <a href="https://www.publish.csiro.au/wr/WR08021">toads are highly mobile</a>, moving over a kilometre per night when conditions permit, and rarely spending two nights in the same place. </p>
<p>At the forefront of the invasion, toads are few and far between. A lungworm larva at the invasion front, waiting in the soil for a toad to pass by, will have <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/09-0530.1">few opportunities</a> to encounter and infect a new host. </p>
<h2>Lungworms from the invasion front</h2>
<p>When hosts are rare, we expect the parasite will evolve to get better at infecting the ones it does encounter, because it is unlikely to get a second chance.</p>
<p>To understand how this co-evolution is playing out between cane toads and their lungworms, we did some experiments pairing hosts and parasites from different locations in Australia. What would happen when toad and lungworm strains that had been separated by 90 years of invasion were reintroduced to each other?</p>
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Read more:
<a href="https://theconversation.com/is-toadzilla-a-sign-of-enormous-cane-toads-to-come-its-possible-toads-grow-as-large-as-their-environment-allows-195929">Is 'Toadzilla' a sign of enormous cane toads to come? It's possible – toads grow as large as their environment allows</a>
</strong>
</em>
</p>
<hr>
<p>To study this we collected toads from different locations, bred them in captivity and reared the offspring in the lab under common conditions. We then exposed them to 50 lungworm larvae from a different area of the range, waited four months for infections to develop, then killed the toads and counted how many adult worms had successfully established in their lungs.</p>
<p>As expected, worms from the invasion front were best at infecting toads, not just their local ones. Behind the invasion front, in intermediate and old populations we found that hosts were able to fight their local parasites better than those from distant populations. </p>
<p>While we saw dramatic differences in infection outcomes, we have yet to determine what biochemical mechanisms caused the differences and how changes in genetic variation of host and parasite populations might have shaped them. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/in-the-evolutionary-arms-race-between-cane-toads-and-lungworms-skin-secretions-play-a-surprising-role-163821">In the evolutionary arms race between cane toads and lungworms, skin secretions play a surprising role</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/223461/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee A Rollins receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Rick Shine receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Greg Brown does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Cane toads are evolving as they spread across Australia. Parasitic lungworms are becoming more infectious to keep up.
Greg Brown, Postdoctoral researcher, Macquarie University
Lee A Rollins, Scientia Associate Professor, UNSW Sydney
Rick Shine, Professor in Evolutionary Biology, Macquarie University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/217856
2023-11-21T21:53:50Z
2023-11-21T21:53:50Z
Oxygen in the St. Lawrence Estuary is decreasing – and having a major impact on small animals living there
<figure><img src="https://images.theconversation.com/files/559651/original/file-20231025-23-oo8vam.jpeg?ixlib=rb-1.1.0&rect=24%2C0%2C4001%2C2752&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The majestic St. Lawrence River, a jewel of economic, historical and environmental importance, reminds us of the need to preserve this essential ecosystem.</span> <span class="attribution"><span class="source">(Ludovic Pascal)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>The waters of the St. Lawrence Estuary are running out of breath. The lack of oxygen in deep waters is affecting the organisms that live on the bottom of the estuary.</p>
<p>How do deep ecosystems react to this deoxygenation?</p>
<p>In a previous article, we highlighted the <a href="https://theconversation.com/why-the-st-lawrence-estuary-is-running-out-of-breath-184626">causes of the decrease in the concentration of oxygen in the bottom waters of the estuary and Gulf of St. Lawrence</a>. This phenomenon, called hypoxia, is intensifying in this environment. In this article, we look at the impacts of low oxygen levels on the organisms that live at the bottom of the estuary and the Gulf of St. Lawrence, and on the overall functioning of this ecosystem.</p>
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<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<h2>The seabed, an environment teeming with life</h2>
<p>A large number of organisms live at the very bottom of the oceans. These are known as <a href="https://theconversation.com/discover-6-fascinating-animals-that-live-at-the-bottom-of-the-st-lawrence-river-215977">benthic organisms</a>. </p>
<p>This group of small animals includes starfish, worms, crustaceans and molluscs. They colonize the surface of the sediment (known as epifauna; “epi” for “on,” and “fauna” for “animal”) or burrow into the sediment (known as endofauna; “endo” for “inside”). </p>
<p>These organisms are not very mobile and cannot travel great distances.</p>
<h2>Bioturbation or the art of mixing sediment</h2>
<p>Benthic organisms don’t move around much, but they are far from being useless. On the contrary, they play a crucial role in the functioning of benthic ecosystems, through bioturbation. </p>
<p><a href="https://doi.org/10.3354/meps09506">Bioturbation</a> refers to all the activities that benthic organisms carry out, both on, and in sediments. Bioturbation can be compared to what earthworms do in our gardens: they dig burrows, mix grains of sediment and inject water containing oxygen into areas of the sediment that lack it. </p>
<p>Benthic organisms are therefore the “gardeners” of the ocean floor. And they help to maintain a healthy ecosystem. By bringing oxygen into the sediments, bioturbation allows many organisms to establish themselves there. It also increases biodiversity and promotes the decomposition of organic matter while <a href="https://doi.org/10.1007/s00227-019-3597-y">reducing the concentration of potentially toxic waste, such as hydrogen sulphide</a>.</p>
<h2>Oxygen and bioturbation: a not-so-simple relationship</h2>
<p>Twenty years ago, researchers used <a href="https://doi.org/10.4319/lo.2007.52.6.2555">models to try to predict the consequences of deoxygenation on the ecosystems of the bottom of the St. Lawrence</a>. Their work highlighted a critical element in anticipating future changes: how bioturbation responds to oxygen depletion.</p>
<p>Deoxygenation can lead to several types of responses in ecosystems. In a linear response scenario, the intensity of bioturbation decreases gradually and proportionally with the decrease in oxygen concentration. In such cases, it is relatively simple to predict the consequences, as the relationship is predictable. </p>
<p>However, there is another type of response that is non-linear and characterized by a threshold effect. This means that there is a certain critical point, a threshold, at which responses change abruptly. Before this threshold, the responses differ from those observed afterwards. These non-linear responses are associated with the development of resistance (or compensatory) mechanisms. These mechanisms operate at the level of the individual, the population (the set of individuals of the same species in a given location) and/or the community (the set of populations in a given location). They compensate for the effects of a disturbance until they are no longer sufficient. It is these compensatory mechanisms that make it difficult to predict the consequences of a disturbance.</p>
<h2>A non-linear relationship</h2>
<p>Our team has been studying the deoxygenation of the St. Lawrence for more than 20 years, but we had never before observed a clear relationship between the bioturbation of communities of benthic organisms and oxygen concentrations.</p>
<p>This raises an important question: does bioturbation respond in a linear or non-linear way to oxygen depletion? And is this a predictable relationship?</p>
<p><a href="https://doi.org/10.5194/bg-20-839-2023">The recent fall in oxygen concentrations in the bottom waters of the St. Lawrence</a> has enabled us to answer this question by observing a threshold effect for the first time. <a href="https://doi.org/10.1111/gcb.16994">We now know that the relationship between oxygen concentration and the functioning of benthic ecosystems is not linear</a>. </p>
<p>In other words, these ecosystems can resist deoxygenation up to a certain critical threshold, which is observed at an oxygen concentration of around 60 micromolar (i.e. approximately 20 per cent saturation, or 20 per cent of what the dissolved oxygen concentration should be if the water were in equilibrium with the atmosphere). This concentration is close to the value above which we speak of hypoxia. Below this threshold, communities of benthic organisms change, but surprisingly, without any significant loss of biodiversity. </p>
<p>However, the organisms that make up these communities are much less active. They are actually running out of air! They considerably reduce their movements, move towards the surface of the sediment and the intensity of bioturbation becomes practically zero. </p>
<p>In other words, in these conditions of severe hypoxia, the organisms no longer have enough energy to mix and irrigate the sediment.</p>
<h2>When bioturbation stops, what happens?</h2>
<p>These results have major implications for the role of sediments in the overall health of ecosystems in the estuary and Gulf of St. Lawrence. When bioturbation stops, the sediments are neither mixed nor irrigated efficiently, leading to the accumulation of toxic waste very close to the surface of the sediment. </p>
<p>As this waste accumulates, it could even spread into the water column, scaring away sensitive species and increasing deoxygenation. </p>
<p>When and under what conditions would this happen? This is the question we now need to answer. </p>
<p>Deoxygenation of the bottom waters of the St. Lawrence is of particular concern because it is likely to lead to changes in the abundance and distribution of fishery resources. Indirectly, therefore, it could have socio-economic effects that have yet to be fully assessed.</p><img src="https://counter.theconversation.com/content/217856/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ludovic Pascal is a member of the Québec Océan inter-institutional group and the Nereis Park scientific association. He has received funding from the FRQNT, the MEOPAR Network of Centres of Excellence, and the Québec government (Réseau Québec Maritime, MEIE, MELCCFP).</span></em></p><p class="fine-print"><em><span>Gwénaëlle Chaillou has received funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), Fonds de Recherche du Québec, Canada Research Chairs, and the Government of Québec (Réseau Québec Maritime, MEIE, MELCCFP). She is a member of the Québec Océan inter-institutional group, ACFAS, the Geochemical Society and the International Association of Hydrogeologists - Canadian National Committee (IAH-CNC).</span></em></p>
The waters of the St. Lawrence are running out of breath and bottom-dwelling organisms are already feeling the effects. Here’s how ecosystems are reacting.
Ludovic Pascal, Postdoctorant en biogéochimie marine, Université du Québec à Rimouski (UQAR)
Gwénaëlle Chaillou, Professeure de chimie marine à l'Institut des sciences de la mer de Rimouski (ISMER-UQAR), Université du Québec à Rimouski (UQAR)
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/217227
2023-11-13T16:25:47Z
2023-11-13T16:25:47Z
Earthworms are our friends – but they will make the climate crisis worse if we’re not careful
<figure><img src="https://images.theconversation.com/files/559077/original/file-20231113-22-x1gfqr.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6720%2C4476&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-earthworms-on-wet-soil-space-2331008495">New Africa/Shutterstock</a></span></figcaption></figure><p>Earthworms are revered for the way they nourish healthy soils, and scientific evidence validates the affection gardeners feel for these industrious invertebrates. Nevertheless, research has shown that our soil-dwelling friends may be less benevolent as the climate crisis escalates and grants them access to recently defrosted northern soils.</p>
<p>Historically, earthworms were viewed alongside slugs and snails as garden pests and thought to eat flower and vegetable roots from beneath the soil surface. They were killed and removed from gardens until more informed naturalists like Charles Darwin made observations that showed their worth. </p>
<p>Sometimes referred to as “Darwin’s plough”, earthworms naturally till the soil and increase its fertility by pulling leaves underground where they rot and enrich the soil. </p>
<p>Earthworms are considered ecosystem engineers too – species with an outsized influence on their environment. As such, they carry out numerous activities that are beneficial to us, including the formation, drainage and aeration of soils. They are also a protein-rich food source for birds and mammals. </p>
<figure class="align-center ">
<img alt="A bird with earthworms in its beak." src="https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559078/original/file-20231113-23-4d70qz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A firm favourite of feathered friends.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/a-bird-with-a-worm-in-its-mouth-standing-in-the-grass-FBWpkk20hoc">Jack Blueberry/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Unfortunately, they now have what may be perceived as a darker side.</p>
<h2>Globetrotters without feet</h2>
<p>European earthworms, such as the well-known lobworm (<em>Lumbricus terrestris</em>), the large and darkly pigmented worm you’ve probably seen writhing in a patch of upturned soil, are now found worldwide. Centuries ago they travelled in the soil of crop and fruit-bearing plants as they were taken by settlers to new lands. On newly ploughed farms this was seen as a bonus and these introduced worms bolstered food production. </p>
<p>More recently, these introduced earthworms have established themselves in more natural habitats, such as the temperate forests of North America. More often than not, their arrival in these forests has been as discarded fishing bait. There, the earthworm’s tendency to bury fallen leaves and till the soil has <a href="https://www.jstor.org/stable/3868431?searchText=&searchUri=&ab_segments=&searchKey=&refreqid=fastly-default%3A184c54dd2618c074f41c077ce668985c&seq=1">caused problems</a>, severely altering the nutrient status of the soil, exposing tree roots and reducing cover for ground nesting birds. </p>
<p>Earthworms are now viewed as invasive alien species in such ecosystems. Further north, in the boreal forests of Arctic and sub-Arctic Canada, an even greater problem is growing</p>
<p>Arctic soils are thought to store <a href="https://bg.copernicus.org/articles/11/6573/2014/bg-11-6573-2014.pdf">around half</a> of all the carbon locked up in soil globally. The greatest risk to the carbon storage of boreal forests was always assumed to be forest fires, which <a href="https://cdnsciencepub.com/doi/10.1139/er-2021-0074">may be increasing</a> as a result of rising global temperatures. </p>
<p>But earthworms may actually pose as great a threat. As land that was once covered with ice or in a semi-permanent frozen state thaws, the carbon-rich nutrients it held for thousands of years become accessible to microorganisms and soil-dwelling animals. </p>
<p>After the last ice age, no earthworms were present in northern soils. Since these creatures spread through the earth at a rate of only <a href="https://link.springer.com/article/10.1007/BF00317626">10 metres per year</a> under normal circumstances, even if they could survive, they wouldn’t be expected to reach such regions for centuries. </p>
<h2>Heading north</h2>
<p>But by building roads and pursuing recreational activities like freshwater angling, people are accidentally transporting ecosystem-engineering earthworms into areas where recently defrosted soil awaits. Again, it is abandoned, living fishing bait that creates a new invasion front.</p>
<p>By exercising their natural behaviour, earthworms are unlocking carbon from this soil and much of it is being released into the atmosphere as carbon dioxide. A study published in 2015 <a href="https://doi.org/10.1016/j.soilbio.2015.05.020">predicted</a> average losses of 10g of carbon per square metre of forest floor per year – a similar figure to that released by wildfires or the removal of trees for timber.</p>
<p>You might think earthworms would struggle to survive Arctic winters, but some, such as the octagonal worm (<em>Dendrobaena octaedra</em>) are relatively freeze-tolerant and their eggs can <a href="https://cdnsciencepub.com/doi/10.1139/er-2021-0074">survive temperatures of -35°C</a>. Others, such as the lobworm, can burrow deep to survive freezing temperatures above. Such species, once established, are not easily eradicated. </p>
<figure class="align-center ">
<img alt="A worm in soil." src="https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559120/original/file-20231113-15-e1twa2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The lobworm, once confined to western Europe, is now globally distributed.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/common-earthworm-lumbricus-terrestris-nightcrawler-1581313723">Liz Weber/Shutterstock</a></span>
</figcaption>
</figure>
<p>In these newly available soils, earthworms are interacting with a range of microorganisms and enabling them to more easily decompose plant matter which was <a href="https://pub.epsilon.slu.se/31133/1/blume-werry-g-et-al-20230619.pdf">previously locked up in ice</a>, generating large volumes of carbon dioxide, methane and other greenhouse gases in the process.</p>
<p>This creates a positive feedback loop as the further release of greenhouse gases accelerates temperature rise. This is probably an unstoppable process and the best action with respect to earthworms is to prevent their accidental introduction at further sites in the sub-Arctic through education and, potentially, the policing of recreational areas.</p>
<p>Earthworms are vital in most soils, but in extremely northern latitudes, a massive shift has occurred in our view of these exceptional animals. Globally, we – the general public, governments, industry and scientists – must begin to address the issues of the climate crisis that affect us, earthworms, and indeed all living things on Earth.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 20,000+ readers who’ve subscribed so far.</a></em></p>
<hr><img src="https://counter.theconversation.com/content/217227/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Richard Butt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Thawing permafrost in the far north is an inviting prospect for invertebrate burrowers.
Kevin Richard Butt, Reader in Ecology, University of Central Lancashire
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/215977
2023-10-26T22:16:17Z
2023-10-26T22:16:17Z
Discover 6 fascinating animals that live at the bottom of the St. Lawrence River
<figure><img src="https://images.theconversation.com/files/554598/original/file-20231016-24-cndzzv.jpg?ixlib=rb-1.1.0&rect=7%2C3%2C2537%2C1912&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Not only do corals inhabit the cold waters of the St. Lawrence, but the species that holds the title of largest marine invertebrate on the planet is present at the entrance to the Gulf.</span> <span class="attribution"><span class="source">(Fisheries and Oceans Canada)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>In the vast St. Lawrence River, an impressive variety of animals live on the seabed. This group of organisms is called benthos. </p>
<p>These organisms live either buried in the sediment (infaunas) or on the surface of the seabed (epibenthos). Benthic invertebrates have no backbone, are not very mobile and are generally small. </p>
<p>And they are far from being rare. As far back as 1988 <a href="https://books.google.ca/books?hl=fr&lr=&id=CoDHrKyVgscC">researchers</a> listed over 1,855 species of benthic invertebrates living in the estuary and gulf of the St. Lawrence River. These represent 84 per cent of all invertebrate species in the St. Lawrence waters. </p>
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<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
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<p>Needless to say, many new species have been identified since then, and our knowledge about them continues to grow.</p>
<p>As specialists in benthic ecology, we invite you to discover the benthos through six special features that are certain to pique your curiosity.</p>
<h2>Luminous worms</h2>
<p>Like earthworms in our gardens, marine worms inhabit the ocean floor. They come in all shapes and sizes, and some are even covered in scales. But their originality doesn’t stop there. Some of these worms are actually capable of <a href="https://doi.org/10.11646/ZOOSYMPOSIA.2.1.26">bioluminescence</a>. The production of light in the form of luminous flashes has three general functions: defensive (to escape predators), offensive (in support of predation) and communicative (for reproduction). </p>
<p>In the St. Lawrence River, the only scale worms with this ability are of the <em>Harmothoe</em> genus, of which there are five species. These species can be found on both clay and rocky bottoms in both coastal and deep-water areas.</p>
<h2>Are corals cold?</h2>
<p>For many, oceans bring to mind vacations, heat, diving and coral reefs. But does coral only grow in warm waters? Absolutely not. Some <a href="https://www.dfo-mpo.gc.ca/oceans/ceccsr-cerceef/corals-coraux-eng.html">20 species</a> live in the salty waters of the St. Lawrence ecosystems and this number <a href="https://research.library.mun.ca/12107/1/thesis.pdf">triples</a> if we include the East Coast of Canada. </p>
<p>But what is coral? Corals are actually marine <a href="https://oceanservice.noaa.gov/facts/coral.html">polyps</a>, cylindrical animals with a mouth surrounded by a ring of tentacles, that secrete a molecule called calcium carbonate to form a skeleton. </p>
<p>There are two types: soft corals, with an internal skeleton that reinforces the structure of the <a href="https://oceanservice.noaa.gov/facts/coral.html">colony</a> (a collection of cloned individuals) while ensuring its elasticity, and hard corals, where each polyp secretes a cup-shaped external skeleton, creating their characteristic rigidity. </p>
<p>Not only do corals inhabit the cold waters of the St. Lawrence, but the species that holds the title of largest marine invertebrate on the planet is present at the entrance to the Gulf, notably on the rocky slopes of the Scotian Shelf. This is the <a href="https://www.dfo-mpo.gc.ca/oceans/publications/cs-ce/index-eng.html"><em>Paragorgia arborea</em></a>, some colonies of which can reach six metres in height.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="corals on the seabed" src="https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554072/original/file-20231016-27-sgbiot.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Some colonies of Paragorgia arborea can reach six metres in height.</span>
<span class="attribution"><span class="source">(Fisheries and Oceans Canada)</span>, <span class="license">Fourni par l'auteur</span></span>
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<h2>Starfish: dreaded gourmets</h2>
<p>Starfish are so colourful and pretty you can find them in souvenir stores, but don’t be fooled by their appearance. They are actually <a href="https://www.thecanadianencyclopedia.ca/en/article/starfish">fearsome predators</a>, and understanding how they feed will likely change the way you see them. </p>
<p>Faced with the two greediest species in the St. Lawrence (<em>Asterias rubens</em> and <em>Leptasterias polaris</em>), mussels normally have nothing to fear. But thanks to dozens of ambulacral feet — little suckers on their underside — starfish can easily open mussels. As soon as the mussel shows a sign of weakness, the starfish is able to extract its own stomach from its body and insert it into the mussel, where on contact with the flesh, it begins digesting it. In this rather unusual situation the meal can last around 10 hours. Afterwards, the starfish swallows its stomach again and starts hunting for new prey.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="starfish" src="https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=643&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=643&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=643&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=808&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=808&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554073/original/file-20231016-27-9kcy6a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=808&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Starfish are formidable predators.</span>
<span class="attribution"><span class="source">(Cindy Grant)</span>, <span class="license">Fourni par l'auteur</span></span>
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<h2>You said centenarian?</h2>
<p>Present in the Gulf of St. Lawrence, particularly in the Magdalen Islands, the Northern quahog (<em>Arctica islandica</em>) is the world’s longest-living animal. It is a <a href="https://www.dfo-mpo.gc.ca/shellfish-mollusques/identification-eng.htm">bivalve mollusc</a> protected by a calcareous shell with two valves, like that of a mussel or oyster. The Northern quahog can easily live up to 200 years, but the oldest specimen, recorded in Iceland, <a href="https://www.nationalgeographic.com/animals/article/131116-oldest-clam-dead-ming-science-ocean-507">was 507 years old</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bivalve mollusc" src="https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=533&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=533&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=533&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=670&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=670&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554074/original/file-20231016-27-vxm7uh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=670&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Northern quahog is the world’s longest-living animal.</span>
<span class="attribution"><span class="source">(Lisa Treau De Coeli)</span>, <span class="license">Fourni par l'auteur</span></span>
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</figure>
<p>Other bivalves are known to live long lives. The age of these molluscs can be determined by the growth rings on their shells, rather like trees, but the technique here is called sclerochronology. It is even possible to <a href="https://www.frontiersin.org/articles/10.3389/fmars.2019.00483/full">read the history of the climate</a> on the shells of several bivalves and use this information to predict future conditions.</p>
<h2>Worms, medicine and the Olympics</h2>
<p>Arenicolous worms (<em>Arenicola marina</em>) can be identified by the typical shape of their burrows (a mound of small wiggles), which can be seen at low tide on the St. Lawrence coast.</p>
<p>Although seemingly trivial, these marine worms could enable major advances in medicine thanks to their <a href="https://pubmed.ncbi.nlm.nih.gov/34210070/">hemoglobin</a>, which is capable of transporting up to 50 times more oxygen than that of humans. This particular property enables the worms to store oxygen from seawater at high tide and use this reserve at low tide. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8304559/">In medicine</a>, the hemoglobin of the arenicolous worm could be used to improve organ preservation during transplants, to make oxygenating dressings or to develop a blood substitute for emergency transfusions. </p>
<p>Although this worm could revolutionize medicine, it could also pose problems for anti-doping agencies and athletes. Virtually undetectable and hyper-performing, the incredible oxygenating benefits of the arenicolous worm’s hemoglobin could undoubtedly boost athletes’ performance at the next Olympics.</p>
<h2>Natural “crazy glue”</h2>
<p>Although mussels are tossed about by breaking waves all day long, they still manage to hold tight to the rocks. Their secret? The <a href="https://www.nature.com/articles/ncomms14539">byssus</a>, a collection of hair-sized fibres that are both strong and elastic. </p>
<p>The proteins that make up byssus form natural ‘crazy glue’; this liquid glue hardens rapidly, enabling the mussel to adhere with unrivalled tenacity to virtually any surface, even wet ones. </p>
<p>The unusual properties of byssus have fascinated humans since ancient times. In days gone by, these filaments of “marine silk” were used to weave luxurious garments. More recently, the particular chemical composition of the sticky proteins derived from byssal threads has inspired the creation of <a href="https://news.northwestern.edu/stories/2022/03/mussels-synthetic-glue/">underwater adhesives and surgical glues</a>.</p>
<p>In conclusion, while the epifauna of the St. Lawrence is relatively well known, knowledge of the endofauna remains sparse and patchy, even in 2023. Initiatives are underway to discover and characterize this sediment-dwelling fauna. </p>
<p>These studies will undoubtedly lead to the discovery of other exciting facts about the benthos.</p><img src="https://counter.theconversation.com/content/215977/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Philippe Archambault is scientific co-director of the ArcticNet network of centers of excellence, and a member of the Québec Océan strategic cluster, the CNRS/Université Laval International Research Laboratory, Takuvik, and co-director of the 'Ecosystem Functioning and Environmental Protection' axis at the Institut Nordique du Québec.</span></em></p><p class="fine-print"><em><span>Cindy Grant is a member of the Québec-Océan strategic group and of the Unité Mixte Internationale Takuvik.</span></em></p><p class="fine-print"><em><span>Gabrièle Deslongchamps is a member of the Québec-Océan strategic group and of the Unité Mixte Internationale Takuvik.</span></em></p><p class="fine-print"><em><span>Lisa Treau De Coeli is a member of the Québec-Océan strategic group and of the Unité Mixte Internationale Takuvik.</span></em></p>
In the vast St. Lawrence River, an impressive variety of animals live on the seabed. This group of organisms is called benthos or benthic invertebrates.
Philippe Archambault, Professor & CoScientific Director of ArcticNet, Université Laval
Cindy Grant, Professionnelle de recherche, biologie marine & écologie benthique, Université Laval
Gabrièle Deslongchamps, Professionnelle de recherche, Université Laval
Lisa Treau De Coeli, Professionnelle de recherche en écologie benthique, Université Laval
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/209155
2023-10-18T14:18:15Z
2023-10-18T14:18:15Z
Tapeworm is spreading in Kenya – demand for meat brings parasite to new areas
<p><em>Echinococcus granulosus</em>, a type of tapeworm, is a harmful parasite that affects <a href="https://www.who.int/news-room/fact-sheets/detail/echinococcosis">1 million people</a> worldwide. </p>
<p>The parasite can grow slowly in people for years to form thick-walled cysts in vital organs, such as the liver and lungs. Known as cystic echinococcosis, or hydatid disease, it can cause abdominal pain, nausea and vomiting. And if not treated, it can be fatal.</p>
<p>It’s a zoonotic disease, meaning it spreads from animals to people, with a <a href="https://www.cdc.gov/dpdx/echinococcosis/index.html">life cycle</a> involving humans, dogs and ruminant livestock. It’s also considered a <a href="https://www.who.int/news-room/facts-in-pictures/detail/neglected-zoonotic-tropical-diseases">neglected disease</a> by the World Health Organization (WHO). It needs greater attention because of how dangerous it can be and because treatment can be invasive and expensive. It costs <a href="https://www.who.int/news-room/fact-sheets/detail/echinococcosis">US$3 billion a year</a> globally to treat cases and compensate for losses to the livestock industry. </p>
<p>In Kenya, the disease has <a href="https://doi.org/10.1080/00034983.1982.11687565">long been endemic</a> – meaning present over a long period of time at a relatively low level – in pastoralist communities who live and work closely with livestock, in north-western Kenya and Maasailand. </p>
<p>Traditional pastoralist livestock farming in Kenya’s north, for example in Turkana, has <a href="https://doi.org/10.1080/00034983.1985.11811888">concentrated</a> the risk of disease in communities there. But populations in other parts of Kenya <a href="https://www.nature.com/articles/s41598-021-98495-7">are increasing</a>, and thus so is the demand for meat. As a result, more animals are being driven south for slaughter, bringing tapeworm infections with them.</p>
<p>We’re part of a collaboration between the <a href="https://www.ilri.org">International Livestock Research Institute</a>, <a href="https://www.jkuat.ac.ke/">Jomo Kenyatta University of Science and Technology</a>, the <a href="https://www.liverpool.ac.uk/">University of Liverpool</a> and the <a href="http://www.kemri.go.ke">Kenya Medical Research Institute</a>. We’ve tracked the spread of <em>Echinococcus</em> tapeworm into populations in a non-endemic area for the first time. This work is important so that steps can be taken to prevent the spread of such diseases, particularly from animals to humans.</p>
<p>We conducted four pieces of research which covered how prevalent <em>Echinococcus</em> tapeworm was in livestock being brought for slaughter, how it spread to people and how great the human disease burden was. </p>
<p>We’ve found that the parasite is highly prevalent in livestock moving into these non-endemic areas and is now spreading, via dogs, into human populations.</p>
<p>Our findings highlight how important it is to carry out disease surveillance, particularly as populations grow and dynamics change. </p>
<h2>Mapping the spread</h2>
<p>Our studies focused on Busia and Bungoma counties, which border one another and which previously didn’t have the tapeworm disease, cystic echinococcosis, among humans and livestock. </p>
<p>For our <a href="https://www.nature.com/articles/s41598-021-98495-7">first study</a> we assessed how prevalent tapeworm was in livestock being brought for slaughter. Over two years, we collected over 16,000 reports in both counties and <a href="https://www.nature.com/articles/s41598-021-98495-7">found</a> a very high infection rate in the samples we collected – 32% of the livers of cattle and goats, 74% of lungs in cattle and 58% of lungs in goats.</p>
<p>Our <a href="https://onlinelibrary.wiley.com/doi/10.1002/ece3.7317">second</a> and <a href="https://www.sciencedirect.com/science/article/pii/S2405939022001459?via%3Dihub">third</a> studies sought to understand how <em>Echinococcus</em> tapeworm might spread to humans in the counties. We hypothesised that local dogs could be acting as the vector. </p>
<p>Dogs congregate at slaughter facilities and consume whatever is discarded. For instance, we saw that often lungs from slaughtered animals were being discarded because of hydatid cysts. Dogs could get tapeworms from eating meat like this.</p>
<p>We tracked the movements of 73 dogs using GPS collars over five days each and saw that they regularly visited slaughterhouses. Through examining their faecal samples, we saw that the parasite was present, and 16% were positive for <em>Echinococcus</em> antigens in faeces. This meant they could bring the disease to households and people. </p>
<p>The parasite matures in the dogs’ intestines, and the dog sheds eggs in faeces, contaminating the environment. People get infected when inadvertently parasite eggs from the environment are eaten, usually due to poor household hygiene.</p>
<p>Our <a href="https://journals.plos.org/globalpublichealth/article?id=10.1371/journal.pgph.0000235">final study</a> was to examine how great the human disease burden was in Bungoma county. Using ultrasound technology, we found cystic lesions which may indicate <em>Echinococcus</em> infection among a small number (around 1%) of the community members.</p>
<p>While we did not find the population extensively suffered from this disease, we detected early signs of the establishment of a local transmission cycle. This means that the parasite has been introduced and is spreading slowly in groups of people and dogs which have not been exposed before. This slow-moving outbreak could soon represent a much more significant public health problem if left unchecked.</p>
<p>Unfortunately, very few people in the area can access the tools necessary to diagnose and treat the condition. Ultrasound imaging is the most effective way to screen for and monitor infections, allowing healthcare providers to offer people the necessary treatment. By the time human infections are advanced, expensive operative procedures to remove hydatid cysts are the only treatment available.</p>
<p>Routine ultrasound imaging over time also helps monitor treatment and surgical outcome. However, many health facilities lack ultrasound services. </p>
<h2>A public health risk</h2>
<p>The intersection of infected livestock from endemic tapeworm regions and dogs scavenging for disposed animal by-products creates conditions under which it is more likely that humans become infected. </p>
<p>As Africa’s agricultural systems face increasing demands from population growth and demographic changes, rapid unplanned growth can have devastating unintended consequences. </p>
<p>To protect populations, systems of surveillance must keep up with the changing world. Tracking the spread of disease, as we have done with <em>Echinococcus granulosus</em> in a non-endemic region, is an essential step to prevent future outbreaks of public health concern.</p>
<p><em>Madison Spinelli, Princeton in Africa Fellow at the International Livestock Research Institute, contributed to the writing of this article.</em></p><img src="https://counter.theconversation.com/content/209155/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Fèvre receives funding from UKRI, the Wellcome Trust, US DTRA and the CGIAR.</span></em></p><p class="fine-print"><em><span>Laura Falzon and Titus Mutwiri do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The intersection of infected livestock from endemic tapeworm regions and dogs scavenging for disposed animal by-products creates the perfect storm to infect vulnerable human populations.
Titus Mutwiri, Lecturer, Kenya Methodist University
Eric Fèvre, Professor of Veterinary Infectious Diseases, University of Liverpool and International Livestock Research Institute, Kenya, University of Liverpool
Laura Falzon, Post-doctoral research associate, University of Liverpool
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/212437
2023-08-29T03:58:29Z
2023-08-29T03:58:29Z
Finding a live brain worm is rare. 4 ways to protect yourself from more common parasites
<p><a href="https://www.theguardian.com/australia-news/2023/aug/28/live-worm-living-womans-brain-australia-depression-forgetfulness">News reports</a> this morning describe how shocked doctors removed a live worm from a woman’s brain in a Canberra hospital last year. The woman had previously been admitted to hospital with stomach symptoms, dry cough and night sweats and months later experienced depression and forgetfulness that led to a brain scan. </p>
<p>In the <a href="https://wwwnc.cdc.gov/eid/article/29/9/23-0351_article">case study</a> published in Emerging Infectious Diseases journal, doctors describe removing the live 8cm-long nematode (roundworm) from the brain of the 64-year-old woman who was immunosuppressed. The worm was identified as <em>O. robertsi</em> which is native to Australia, where it lives on carpet pythons. The woman may have come into contact with worm eggs via snake faeces while foraging for Warrigal greens to eat.</p>
<p>It’s important to note this is an extremely rare event and headlines about brain worms can be alarming. But there are more common parasites which can infect your body and brain. And there are ways you can minimise your risks of being infected with one. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1696138859241787734"}"></div></p>
<h2>Common parasites and how they get in</h2>
<p>Parasitic infection is extremely common. Arguably the most widespread type is pinworm (<em>Enterobius vermicularis</em> also called threadworm), which is thought to be present in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522669/">over a billion people</a> worldwide, especially children. Pinworms grow to around 1cm in length and are specific to human hosts. They cause intense bottom itching and get passed from person-to-person. It’s a myth that you can get it from pets.</p>
<p><a href="https://www.cdc.gov/parasites/giardia/pathogen.html#:%7E:text=Giardia%20duodenalis%20is%20a%20protozoan,Giard%20of%20Paris%20and%20Dr.">Giardia</a> (<em>Giardia duodenalis</em>) is also very common and can contaminate food, water and surfaces. This water-borne parasite is associated with poor sanitation and causes stomach symptoms like diarrhoea, cramps, bloating, nausea and fatigue. Giardia cysts (little sacs of immature parasite) spread disease and are passed out in faeces, where they can remain viable in the environment for months before being consumed by someone else. They can also be ingested via foods (such as sheep meat) that is raw or undercooked.</p>
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Read more:
<a href="https://theconversation.com/health-check-the-low-down-on-worms-and-how-to-get-rid-of-them-36486">Health check: the low-down on 'worms' and how to get rid of them</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://www.cdc.gov/dpdx/hookworm/index.html">Two types</a> of hookworm – <em>Necator americanis</em> and <em>Ancylostoma duadonale</em> – are found in soil. Only <em>Ancylostoma duodenale</em> is an issue in Australia and is typically found in <a href="https://www.cdc.gov/dpdx/hookworm/index.html">remote communities</a>. </p>
<p>When a person is infected (usually via barefeet or contaminated footwear) these worms enter the bloodstream and then hit the lungs. From the bronchi in the upper lungs, they are swallowed with secretions. Once in the gut and small bowel they can <a href="https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections#:%7E:text=Transmission,these%20eggs%20contaminate%20the%20soil.">cause anaemia</a> (low iron). This is because they are consuming nutrients and affecting iron absorption. They also release an anticoagulant that stops the human host’s blood clotting and causes tiny amounts of blood loss. </p>
<p>Fortunately, these very common parasites do not infect the brain. </p>
<p>Across the world, it’s estimated <a href="https://pubmed.ncbi.nlm.nih.gov/22491772/">30–50% of people</a> are infected with <em>Toxoplasma</em>. Most people will be asymptomatic but many carry the <a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">signs of infection</a>. </p>
<p>The parasites can remain in the body for years as tiny tissue cysts. These cysts can be found in brain, heart and muscle. Infants can be born with serious eye or brain damage if their mothers are infected during pregnancy. People with compromised immunity – such as from AIDS or cancer treatment – are also at risk of illness from infection via pet cats or uncooked meat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person pats cat" src="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545183/original/file-20230829-21-sm0791.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Toxoplasmosis can be transmitted by cats.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hand-woman-petting-brown-cat-outside-1166422114">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">One in three people are infected with _Toxoplasma_ parasite – and the clue could be in our eyes</a>
</strong>
</em>
</p>
<hr>
<h2>Then there are tapeworms and amoebas</h2>
<p>Tapeworms can infect different parts of the body including the brain. This is called <a href="https://www.cdc.gov/parasites/resources/pdf/npis_in_us_neurocysticercosis.pdf">neurocysticercosis</a> and is the leading cause of epilepsy worldwide. Neurocysticercosis is uncommon in the Western world and infection is usually via eating pork that is uncooked or prepared by someone who is infected with tapeworm (<em>Taenia solium</em>). It is more likely in locations where pigs have contact with human faeces via sewerage or waterways. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brain scan" src="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=755&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=755&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=755&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=949&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=949&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545182/original/file-20230829-17-vqey6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=949&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A brain scan of someone infected with pork tapeworm.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/brain-ct-cysticercosis-larva-pork-tapeworm-1619246149">Shutterstock</a></span>
</figcaption>
</figure>
<p>Tapeworm larvae can infect muscle and soft tissue. Brain tissue can provide a home for larvae because it is soft and easy to get to via blood vessels. Brain infection can cause headaches, dizziness, seizures, cognitive impairment and even dementia, due to an increase in <a href="https://www.cdc.gov/parasites/cysticercosis/gen_info/faqs.html">cerebral spinal fluid pressure</a>.</p>
<p><em><a href="https://www.cdc.gov/parasites/naegleria/general.html">Naegleria fowleri</a></em> is an amoeba found in lakes, rivers and springs in warm climates including <a href="https://www.sahealth.sa.gov.au/wps/wcm/connect/public+content/sa+health+internet/public+health/water+quality/naegleria+fowleri#:%7E:text=How%20common%20are%20Naegleria%20fowleri,frequently%20found%20in%20the%20environment.">in Australia</a>. People swimming in infected waters can have the parasite enter their body through the nose. It then travels to the brain and destroys brain tissue. The condition is <a href="https://www.cdc.gov/parasites/naegleria/general.html#:%7E:text=Top%20of%20Page-,What%20is%20the%20death%20rate%20for%20an%20infected%20person%20who,States%20from%201962%20to%202022.">almost always fatal</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-parasites-and-how-do-they-make-us-sick-121489">What are parasites and how do they make us sick?</a>
</strong>
</em>
</p>
<hr>
<h2>Yikes! 4 ways to avoid parasitic infection</h2>
<p>That all sounds very scary. And we know being infected by a snake parasite is very rare – finding one alive in someone’s brain is even rarer. But parasites are all around us. To minimise your risk of infection you can:</p>
<p><strong>1.</strong> avoid undercooked or raw pork. Freezing meat first may reduce risks (though home freezers <a href="https://www.cdc.gov/parasites/trichinellosis/prevent.html">may not get cold enough</a>) and it must be cooked to a <a href="https://www.sciencedirect.com/science/article/pii/S0924224418301560#:%7E:text=and%20time%20conditions.-,Cooking%20at%20core%20temperature%2060%E2%80%9375%20%C2%B0C%20for%2015,relied%20upon%20in%20home%20situations.">high internal temperature</a>. Avoid pork if you are travelling in places with poor sanitation</p>
<p><strong>2.</strong> avoid jumping or diving into warm fresh bodies of water, especially if they are known to carry <em>Naegleria fowleri</em>. Although only a <a href="https://www.cdc.gov/parasites/naegleria/graphs.html">handful of cases</a> are reported each year, you should assume it’s present </p>
<p><strong>3.</strong> practise good <a href="https://www.cdc.gov/handwashing/when-how-handwashing.html#:%7E:text=Follow%20Five%20Steps%20to%20Wash%20Your%20Hands%20the%20Right%20Way&text=Wet%20your%20hands%20with%20clean,for%20at%20least%2020%20seconds.">hand hygiene</a> to reduce the risk of rare and common infections. That means washing hands thoroughly and often, using soap, scrubbing for at least 20 seconds, rinsing and drying well. Clip and clean under fingernails regularly</p>
<p><strong>4.</strong> to avoid soil-borne parasites wear shoes outside, especially in rural and remote regions, wash shoes and leave them outside.</p><img src="https://counter.theconversation.com/content/212437/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Headlines about brain worms can be alarming. There are much more common parasites which can infect your body and brain and ways you can minimise your risks of being infected with one.
Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/205065
2023-07-11T19:24:49Z
2023-07-11T19:24:49Z
Last seen 90 years ago, strange worm species is found crawling in Malaysia
<figure><img src="https://images.theconversation.com/files/536803/original/file-20230711-29-zqck7d.png?ixlib=rb-1.1.0&rect=152%2C54%2C1388%2C891&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The first specimen of _Bipalium admarginatum_ was found by George Verdon in the jungle of a tropical island.</span> <span class="attribution"><span class="source">George Verdon</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>George Verdon had a biological enigma on his hands. He’d stumbled across an animal while out for a run which was proving difficult to identify… In all fairness, this run had been through an island jungle on the Malay peninsula, so the chance of finding something weird was significantly higher than usual, but nevertheless this particular animal was resisting his attempts to work out what it was.</p>
<p>It was about 10 cm long and looked like a worm. It also had stark stripey warning colours and for a moment almost looked like a tiny juvenile snake. However, when looking at the head – hammerheaded and flattened and apparently eyeless – it was clearly something different.</p>
<p>As a professional wildlife filmmaker, George has seen a lot of strange animals, but was lost with this one. After some Internet research, he found that there were some scientists crazy enough (us…) to study these weird creatures.</p>
<p>For the last 10 years, we have undertaken to characterise the land flatworms which invade European countries, such as <a href="https://theconversation.com/obama-nungara-how-a-flatworm-from-argentina-jumped-the-atlantic-and-invaded-france-131186"><em>Obama nungara</em></a>, now found in more than 70 departments in France, or the giant species <a href="https://theconversation.com/yes-giant-predatory-worms-really-are-invading-france-97106"><em>Bipalium kewense</em></a>. George got in touch in August of 2019, sending us an e-mail with some photos and asking if we knew any more about it. </p>
<p>Upon comparison with the scientific literature, it turned out to be a species that hadn’t been seen in the 90 years since it was first discovered: <em>Bipalium admarginatum</em>. It hadn’t been recorded since it was first described in 1933 by de Beauchamp, on an island not far away from George’s sighting. Naturally, we were excited, and asked George if he had collected the specimen he had seen. For some reason we don’t understand, he had been out for a jog without a field kit, and had subsequently let the animal glide back into the leaf litter. We asked him if he could dive back into the jungle to find a few specimens, and gave instructions on how best to find and catch them.</p>
<h2>Macaques, and quadruple gin and tonic… without tonic</h2>
<p>Returning to the scene of the sighting armed with collecting vials, larval forceps, and the help of Liv Grant (a friend and colleague), George found more of the species. This was only half of the challenge, as they turned out to be in the territory of macaques, who were not feeling hospitable. Liv took up the task of fending off the marauders while George hastily collected, and the two quickly retreated.</p>
<p>So far so good, but how to preserve them? The instructions we gave were to put the animals in pure ethanol, but tropical islands are notoriously lacking when it comes to laboratory supplies. Or so we thought… George found a solution: a quadruple gin and tonic, minus the tonic, the lime, the ice, and the umbrella. After putting the specimens into a vial with the gin, George brought them to Michelle Soo, at the UCSI University of Kuala Lumpur, who took charge of verifying the discovery.</p>
<h2>Complete mitochondrial genome</h2>
<p>The next step was to attempt a molecular analysis of the animal. This is important for characterising it and understanding its relationship with other species of the genus <em>Bipalium</em>. Normally this is only done <a href="https://peerj.com/articles/4672/">on specimens well preserved in absolute ethanol</a>. Romain Gastineau, at the University of Szczecin in Poland, tried anyway… and thanks to next-generation sequencing techniques, we were able to characterise the complete mitochondrial genome of <em>Bipalium admarginatum</em>, despite the original harvest in the gin. </p>
<p>Only about 10 complete mitogenomes are known in this family, all the others having been obtained from specimens harvested under perfect conditions and <a href="https://peerj.com/articles/12725/">impeccable ethanol in a laboratory</a>. It deserved a <a href="https://doi.org/10.11646/zootaxa.5277.3.11">publication</a>, which we undertook. We were even able to convince the scientific journal <a href="https://doi.org/10.11646/zootaxa.5277.3.11">to add a summary in the Malay language</a>, in order to convince the country’s citizens to collect any bizarre worms they will encounter. Hopefully we will receive other specimens, there are so many extraordinary species to discover and rediscover.</p><img src="https://counter.theconversation.com/content/205065/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jean-Lou Justine a reçu des financements du Muséum National d'Histoire Naturelle, Paris.</span></em></p><p class="fine-print"><em><span>Leigh Winsor, Michelle Soo et Romain Gastineau ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur poste universitaire.</span></em></p>
A strange worm found in the jungle, then harvested and preserved in… gin, provides a better understanding of the evolution and genetics of flatworms.
Jean-Lou Justine, Professeur, UMR ISYEB (Institut de Systématique, Évolution, Biodiversité), Muséum national d’histoire naturelle (MNHN)
Leigh Winsor, Adjunct Senior Research Fellow, James Cook University
Michelle Soo, Assistant Professor, Deputy Dean of the Department of Biotechnology, UCSI University
Romain Gastineau, Professeur assistant (Institut des sciences de la mer et de l'environnement), University of Szczecin
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/199156
2023-02-02T22:18:37Z
2023-02-02T22:18:37Z
Guinea worm: A nasty parasite is nearly eradicated, but the push for zero cases will require patience
<figure><img src="https://images.theconversation.com/files/507952/original/file-20230202-14714-ndbz5k.jpg?ixlib=rb-1.1.0&rect=3%2C3%2C510%2C334&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Guinea worms are long, white parasites that emerge from the legs of infected people through painful blisters.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Dracunculus_medinensis.jpg#/media/File:Dracunculus_medinensis.jpg">CDC/Wikimedia Commons</a></span></figcaption></figure><p>A painful, parasitic disease that once infected 3.5 million people per year is tantalizingly close to being eradicated.</p>
<p>On Jan. 24, 2023, <a href="https://www.cartercenter.org">The Carter Center</a>, a nonprofit founded by former U.S. President Jimmy Carter, announced that “Guinea worm is poised to become the second human disease in history <a href="https://www.cartercenter.org/news/pr/2023/2022-guinea-worm-worldwide-cases-announcement.html">to be eradicated</a>,” having recorded just 12 cases worldwide in 2022. It represents the lowest annual figure since 1986, when the <a href="https://www.cartercenter.org">Carter Center</a> began leading global efforts to eradicate Guinea worm disease. </p>
<p>I have been <a href="https://scholar.google.com/citations?user=yb246-8AAAAJ&hl=en&oi=ao">working as a parasitologist</a> for over two decades. I know the suffering that parasitic diseases like Guinea worm infections inflict on humanity, especially on the world’s most vulnerable and poor communities. <a href="https://www.clemson.edu/science/academics/departments/genbio/about/profiles/kpaul">My own research</a> on African sleeping sickness – a deadly disease caused by a parasite carried by tsetse flies – has shown me how difficult it is to fight these diseases.</p>
<p>Thanks to a massive global effort, Guinea worm is now almost gone. However, humanity has been <a href="https://www.who.int/teams/control-of-neglected-tropical-diseases/dracunculiasis/dracunculiasis-eradication-portal">tantalizingly close to fully eradicating Guinea worm</a> for many years. To take the final step from almost gone to fully eradicated is not easy, but with patience and vigilance, it is possible.</p>
<h2>A painful and persistent parasite</h2>
<p>Guinea worms are parasitic nematodes that infect humans and a few other animals. They live in ponds, rivers and creeks all across Africa but are mostly endemic to sub-Saharan Africa. </p>
<p>A Guinea worm infection is a nasty experience. The worm mainly infects people after they drink water that is contaminated with tiny crustaceans called <a href="https://www.cdc.gov/parasites/guineaworm/biology.html">copepods that are infected with worm larvae</a>. Most people don’t realize they are infected for about a year – roughly the time it takes for the larvae to burrow their way out of the stomach and into the abdominal cavity, develop into adults and mate. Once the females mature into pregnant worms, the horror show begins. </p>
<p>The pregnant worms must get back to the water to give birth, so they crawl down to the lower leg or foot. Once there, they <a href="https://www.cartercenter.org/news/multimedia/slideshows/guinea-worm-photo-downloads.html">burrow out through an incredibly painful blister</a> in a process that can take weeks. The intense pain causes people to plunge their leg into water to get relief, and this is when the worm expels her larvae, starting the cycle anew. </p>
<p>There are no vaccines or drugs for Guinea worm. The current best treatment is very low-tech: treat the wound and <a href="https://www.cdc.gov/parasites/guineaworm/treatment.html">slowly extract the worm over several painful weeks</a>. Due to the intense pain, infected adults cannot work or provide for their families. Infected kids miss school and fall behind on their education. Though there are usually no long-term complications, infection confers no immunity, so people can get infected repeatedly over their lifetimes, too.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three children with black filtration straws." src="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507953/original/file-20230202-14479-wj9b1v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tools like filtration straws, the black tubes being held by these children in the north-central African country of Chad, can prevent Guinea worm infection.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Preventing_Guinea_worm_disease_in_Chad_(34173755220).jpg#/media/File:Preventing_Guinea_worm_disease_in_Chad_(34173755220).jpg">CDC Global/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Path to eradication</h2>
<p>Guinea worm is awful, so I welcome any news of removing it from the list of diseases that affect people. But alongside hope, a healthy dose of realism is needed: Eradicating any disease is difficult. So far, humanity has succeeded only with smallpox, which was <a href="https://www.who.int/news-room/feature-stories/detail/the-smallpox-eradication-programme---sep-(1966-1980)">eradicated with the help of vaccines in the late 1970s</a> after 200 years of effort.</p>
<p>A disease like Guinea worm is a distinctly different challenge. Eradication will not come from a medical solution like a pill or vaccine. Instead, people will have to change their behavior. The ideas are simple, but that does not mean this will be easy.</p>
<p>The Guinea worm eradication program has employed a two-part strategy to <a href="https://www.cartercenter.org/health/guinea_worm/index.html">interrupt the Guinea worm’s transmission cycle</a>. The first part was to prevent people from getting infected from contaminated water and food. The program launched educational campaigns, ran surveillance programs and distributed millions of tools – like filtration cloths, filters and chemical water treatments – for people to secure clean water.</p>
<p>The second part of the plan was aimed at preventing reintroduction of the parasite into the environment. Again, education programs were a key component, but so were Guinea worm treatment centers. These centers acted as places where infected people and their families could receive care, food and shelter during the long treatment process. By giving infected people a place to stay, treatment centers prevent a person from putting their leg into a body of water and inevitably releasing the larva.</p>
<p><iframe id="pyuwi" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/pyuwi/6/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>A difficult last step</h2>
<p>Since the eradication effort began in the mid-1980s, annual Guinea worm infections have fallen from the millions down to the dozens. But the final push to zero has been difficult and slow. In 2015, there were <a href="https://www.cartercenter.org/news/pr/guinea-worm-worldwide-cases-Jan2016.html">just 22 recorded cases</a>, but infections have stayed in the low double-digits since then.</p>
<p>The massive drop in Guinea worm cases showed that this strategy was working, but there was a complication. In 2020, researchers discovered that a Guinea worm outbreak in the Central African country of Chad was <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255611/">driven by infected dogs</a>, adding a new set of challenges to interrupting the transmission cycle. This led to public health officials returning to the field, increasing surveillance and urging people to <a href="https://doi.org/10.4269/ajtmh.20-1525">report and contain infected dogs</a>.</p>
<p>These many eradication efforts since 2015 have slowly brought case numbers down to the current record low of 12 total cases.</p>
<p>As the world approaches zero cases of Guinea worm disease, the laborious epidemiological detective work of chasing down infection reports and finding hidden water sources gets tougher. Some of the few remaining communities affected by Guinea worm are nomadic or very remote. And as Guinea worm infections grow rare, vigilance can wane and people revert to their old ways, opening the door for Guinea worm to reemerge.</p>
<p>The final push to full eradication will be a challenge that requires patience and faith on the part of institutions and governments supporting the effort. But it also requires that millions of people living in endemic areas do what they can to break the transmission cycle and kick Guinea worm out for good.</p><img src="https://counter.theconversation.com/content/199156/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kimberly Paul receives funding from the National Institutes of Health. </span></em></p>
After nearly 40 years of effort, Guinea worm disease is on the cusp of being the second human disease – after smallpox – to be eradicated on Earth.
Kimberly Paul, Associate Professor of Biochemistry, Clemson University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/187255
2022-08-15T02:57:13Z
2022-08-15T02:57:13Z
Why do my kids keep getting worms? And is that what is making them so cranky?
<figure><img src="https://images.theconversation.com/files/478227/original/file-20220809-18-soyxhr.jpg?ixlib=rb-1.1.0&rect=32%2C40%2C5431%2C3596&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>As a parent, it might feel like you are constantly giving your children worm treatments – usually in the form of chocolate or sweetened chewable tablets. </p>
<p>In fact, most kids in Australia (or any other rich country) get very few worms compared to kids in places where poor hygiene practices make all sorts of worms common. But there is one species of worm so common and so tied to humanity, it can defeat even our most comprehensive hygiene standards. </p>
<p>Young children are really good at transmitting infection with these tiny pests. And they can get really cranky in the process.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-parasites-and-how-do-they-make-us-sick-121489">What are parasites and how do they make us sick?</a>
</strong>
</em>
</p>
<hr>
<h2>An ancient species</h2>
<p>Pinworms are an ancient species and have been found in fossilised 230-million-year-old <a href="https://doi.org/10.1186/s13071-014-0486-6">proto mammalian poo</a>. The closest relatives of the pinworm humans get are found in our closest cousins, <a href="http://dx.doi.org/10.1051/parasite/1999063201">the apes</a>. Our pinworms are thought to have evolved with us. The oldest pinworm eggs from a human host were found in some <a href="https://www.science.org/doi/10.1126/science.166.3913.1620">10,000-year-old</a> dried human stools discovered in a Colorado cave. So, pinworms are very well adapted to living in and with humans.</p>
<p>Pinworm infection is present in <a href="https://www.aerzteblatt.de/int/archive/article/206305">between 5%</a> and <a href="https://www.cdc.gov/parasites/pinworm/epi.html">up to 50%</a> of primary school children, though easy access to good treatments and <a href="https://www.ajtmh.org/view/journals/tpmd/65/5/article-p558.xml">school education programs</a> have reduced levels over the last 20 to 30 years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="microscopic worm" src="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478220/original/file-20220809-24-4tu41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pinworm under the microscope.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/strongyloides-stercoralis-threadworm-stool-analyze-600w-508000876.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<p>These worms are white and thread-like with females <a href="https://www.cdc.gov/parasites/pinworm/">measuring up to 13 milimetres long</a>. Males are less than half that size. They live in humans worldwide, mostly in children between four and 11 years old. They can also <a href="https://www.aerzteblatt.de/int/archive/article/206305">infect adults</a> though usually with less negative effects. </p>
<p>Pinworms have been associated with some other conditions including types of <a href="https://doi.org/10.1371/journal.pone.0232143">appendicitis</a>, <a href="https://doi.org/10.1111/j.1365-4632.2004.02332.x">vaginitis and urethral infections</a> but these are not common outcomes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/love-the-parasite-youre-with-the-entertaining-life-of-unwelcome-guests-from-flea-circuses-to-aliens-137602">Love the parasite you're with - the entertaining life of unwelcome guests from flea circuses to Aliens</a>
</strong>
</em>
</p>
<hr>
<h2>The egg problem</h2>
<p>The problem isn’t usually the adult worms, which live in the caecum (a pouch where the small and large intestines meet) for up to two months. </p>
<p>When the female wriggles out of the gut to lay her eggs <a href="https://www.cdc.gov/parasites/pinworm/">around the anus</a> – usually early in the morning – it can cause irritation. But the biggest issue is caused by eggs that are stuck onto the perianal skin with an irritating glue. This is what causes even more irritation and itching. </p>
<p>The worm’s life cycle actually depends on the child or adult scratching their bum. When the eggs are scratched off onto the hands or under the nails they can be transferred to other children at home or at school, or to adults. Most often they go to the scratching child’s mouth where they can be swallowed and start another infection, known as an “auto infection”. </p>
<p>The eggs are so light they can infest pyjamas, bed clothes, the bedroom and in long term infections they are found in <a href="https://pubmed.ncbi.nlm.nih.gov/21286054/">house dust</a> (though studies suggest these eggs are <a href="https://www.aerzteblatt.de/int/archive/article/206305">not viable beyond one week</a>).</p>
<p>Pinworm eggs are literally a pain. They can make a child scratch so much they cause skin inflammation called <a href="https://journals.lww.com/jpgn/Fulltext/2009/05000.aspx">puritis</a>. This becomes very painful and can result in lost sleep and a <a href="https://www.cdc.gov/parasites/pinworm/">very tired and cranky child</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&rect=1190%2C23%2C3347%2C2875&q=45&auto=format&w=1000&fit=clip"><img alt="two kids in airport scratching bottoms" src="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&rect=1190%2C23%2C3347%2C2875&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=432&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=432&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478223/original/file-20220809-14-qqm53q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=432&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pinworm infection can cause intense itching.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/denver-colorado-9252021-woman-two-600w-2062641551.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-in-three-people-are-infected-with-toxoplasma-parasite-and-the-clue-could-be-in-our-eyes-182418">One in three people are infected with _Toxoplasma_ parasite – and the clue could be in our eyes</a>
</strong>
</em>
</p>
<hr>
<h2>So that’s what’s up with them …</h2>
<p>There are many reasons for a child to be tired and cranky. But if your primary school age child is behaving this way and has an itchy bum, pinworm may be the culprit. </p>
<p>Pinworm eggs are so small they can’t be seen individually but the females lay more than <a href="https://www.aerzteblatt.de/int/archive/article/206305">10,000 in creamy coloured clumps</a>, which may be visible around the anus. The female is also visible when laying eggs, which means a check of your child’s bottom when they are itching intensely may be revealing. Otherwise a sticky tape swab of the skin next to the anus can be analysed for eggs under a microscope. Your doctor can organise such a test. </p>
<p>Treatment is simple and easily obtained from the chemist. Most worming brands use the same drug, called <a href="https://search.informit.org/doi/10.3316/informit.464588837788277">mebendazole</a>. Medication should be taken by each member of the family and the dose should be repeated two weeks later to ensure control of pinworm in the home. Contaminated clothing and bedding should be washed in hot water. </p>
<p>Other methods of <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/pinworms">preventing infection</a> include regularly washing hands and scrubbing finger nails. A shower with a good bum wash is also a good idea, especially in the morning. Trying to stop children sucking their fingers and thumbs, sucking toys or other items that might carry eggs is also suggested, though not easily achieved.</p>
<p>Although we have better control of pinworms in the 21st century, they are still with us and we are very unlikely to be able to eradicate such a well-adapted and intimately entwined parasite.</p><img src="https://counter.theconversation.com/content/187255/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Sandeman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
A large proportion of primary school aged kids get infected with pinworm at some time – and yes, it can make them pretty moody.
Mark Sandeman, Honorary Professor, Federation University Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/182524
2022-05-19T13:08:09Z
2022-05-19T13:08:09Z
Banana paper could save East Africa’s potatoes from devastating worms
<figure><img src="https://images.theconversation.com/files/462000/original/file-20220509-17-vv5kwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Potatoes grown in the Kibirichia area of Mount Kenya.</span> <span class="attribution"><span class="source">© 2010 CIAT Neil Palmer/Flickr</span></span></figcaption></figure><p>Potatoes originated in South America, where they were domesticated about <a href="https://www.cambridge.org/core/books/feeding-the-people/AB26809BD10BBD77659D7618A46DB454">8,000</a> years ago. The plants were eventually brought to Europe in the mid-1500s, from where they spread to the rest of the world. </p>
<p>They have become a very important crop in East Africa, both as a food and economically. In Kenya alone, potatoes contribute <a href="https://cipotato.org/media/farming-success-potatoes-kenya/2019">over US$500 million</a> to the economy annually, employing around 2.5 million people.</p>
<p>However, although the potato-growing area is increasing, productivity is <a href="https://www.fao.org/faostat/en/#home">steadily declining</a>. This is due to various reasons including potato cyst nematodes, a microscopic type of roundworm that feeds on potato roots and lives in the soil. They’re causing substantial losses to potato production in Kenya, and likely the region. Current estimates show that approximately <a href="https://doi.org/10.3389/fpls.2020.00670">US$127 million</a> worth of losses are attributed to the nematodes in Kenya every year.</p>
<p>Potato cyst nematodes followed the potatoes from South America and have become established in most potato growing regions of the world. In East Africa, prevailing conditions, like the tropical climate which allows for all-year-round potato production, has led to the build-up and manifestation of the pest. </p>
<p>The population of nematodes in Kenya is quite remarkable. They can be up to <a href="https://doi.org/10.3389/fpls.2020.00670">15-fold higher</a> than the levels recorded in Europe, where 10 eggs per gram of soil is <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1744-7348.2002.tb00172.x">commonplace</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=346&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=346&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=346&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=435&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=435&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461999/original/file-20220509-16-xkdinz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=435&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Potato cyst nematode.</span>
<span class="attribution"><span class="source">US Department of Agriculture/Flickr</span></span>
</figcaption>
</figure>
<p>Due to the magnitude of the damage that the nematodes cause to potato production, <a href="http://dx.doi.org/10.1111/mpp.13047">strict quarantine regulations</a> have been implemented across many parts of the world to contain and restrict their further spread.</p>
<p>But we may have <a href="https://www.nature.com/articles/s41893-022-00852-5">found a solution</a>: banana paper. Potatoes can be wrapped in a “banana paper”, that we devised, at planting to protect it from the worms. The paper is made from fibre waste from harvested bananas which would otherwise have been discarded. In East Africa, bananas are plentiful – and therefore so will the fibre waste. </p>
<h2>Potato root signals</h2>
<p>Potato cyst nematodes are soil dwelling and seek out plant roots to feed on once potatoes are planted. They are so-called because the female becomes filled with her brood of eggs inside her body which, upon maturity, is referred to as a cyst. </p>
<p>As she matures the female becomes balloon shaped, her cuticle hardens, forming a toughened cyst wall. When the female dies the cyst becomes a protective casing for the eggs which will hatch only in response to chemical signals received from growing potato roots. Otherwise, the eggs can remain in a dormant state within the protective cyst for many years. This means that they are very difficult to manage and almost impossible to eradicate.</p>
<p>Once hatched the juvenile nematodes locate potatoes using chemical signals that are released from the roots. They then burrow into the root and establish a feeding site where they then suck out the contents of the cells. This damages the potato roots and reduces their growth and potato yields. In severe infestations the plant may die.</p>
<p>To combat these nematodes, we tested a paper made from banana fibre in Kenya, and it works. Potatoes are enclosed or wrapped in the “banana paper” at planting which protected the plant from the nematodes.</p>
<p>The special combination of the substances that make up the “banana paper” (the “lignin” and the “cellulose”) which allows us to apply tiny amounts of chemical nematicides, a type of chemical pesticide used to kill nematodes. These are slowly released as the paper naturally deteriorates. The potato seed tuber, enclosed in the treated banana paper, is protected by the pesticidal activity over time, but with minimal dosages that reduce environmental contamination. </p>
<p>The idea is that the nematodes are killed by the pesticide before they infect the potato roots. However, by chance, the same ligno-cellulose make-up also adsorbs the chemical signals from the potato roots that the nematodes require to hatch from the egg and locate roots. If the juvenile nematodes are unable to find their host roots their energy reserves quickly deplete and they die. This means that even without any treatment, the paper is still very effective.</p>
<p>And it means that the combination of interference in the signalling between the potato roots and nematodes, along with a low nematicide dosage makes for a very effective nematode management option.</p>
<p>In tests conducted in Kenya, potato yields were up to five-fold higher than normal farmer practice with nematode densities significantly suppressed. </p>
<p>There is much anticipation that the banana paper technology can provide a vehicle for the delivery of pesticides, all at ultra-low dosages, towards their more effective and efficient use and at more environmentally acceptable levels. Research is currently underway to assess the use of the paper on other crops, such as yam, cassava and sweet potato and against other nematode pests, such as root knot nematodes and lesion nematodes.</p>
<h2>Way forward</h2>
<p>To make this a reality there is need to demonstrate the local production of banana paper in East Africa. We’re encouraged that a local paper manufacturer has indicated that this is viable.</p>
<p>Meanwhile, a more extensive assessment of the paper is necessary to ensure that it is equally effective across variable climatic, ecological and soil conditions, as well as on various crops.</p>
<p>It is also necessary to expose the technology to farmers, to create awareness of this potential product. Farmers and agricultural staff and researchers first need to be cognisant of the potato cyst nematode pests themselves and why they need to be controlled. Farmers are aware of declining and poor yields but do not understand the reasons behind this and that a tiny worm that is almost invisible can be responsible for such dramatic losses.</p>
<p>It’s been a very exciting find as banana paper could offer a realistic mechanism for managing nematode pests, and potentially other difficult-to-manage diseases and disease complexes of crops.</p><img src="https://counter.theconversation.com/content/182524/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Potato productivity in Kenya is declining, this is partly due to potato cyst nematodes - a microscopic type of roundworm that feeds on potato roots.
Danny Coyne, Soil Health Scientist, International Institute of Tropical Agriculture (IITA)
Solveig Haukeland, General nematologist, International Centre of Insect Physiology and Ecology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/177191
2022-02-16T22:53:00Z
2022-02-16T22:53:00Z
A new species of flatworm in our gardens that comes from Asia: Humbertium covidum
<figure><img src="https://images.theconversation.com/files/446553/original/file-20220215-21-1d169v2.png?ixlib=rb-1.1.0&rect=0%2C19%2C3199%2C1681&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The new species _Humbertium covidum_.</span> <span class="attribution"><a class="source" href="http://dx.doi.org/10.7717/peerj.12725">Pierre Gros</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>A hundred animal or plant new species are described each year in metropolitan France. In most cases, these are native species, present here for a long time, but which had so far escaped the attention of scientists. In a very different way, <a href="https://peerj.com/articles/12725/">we are now reporting</a> the existence of a new species found in France, but which has been introduced, and which is even potentially capable of invading our gardens.</p>
<p>This species is a flatworm, the size of one knuckle of your little finger. The species is elongated, with a broader head, like all hammer-headed flatworms. Its colour is quite extraordinary: totally black, it is reminiscent of “liquid metal”. Its name: <em>Humbertium covidum</em> – we will come back to this name later.</p>
<h2>How to tell the species apart?</h2>
<p>For about ten years, we have known that flatworms have invaded the gardens of France. Our team thus reported and mapped the invasion by several species: <a href="https://peerj.com/articles/1037/">the New Guinea flatworm</a> (<em>Platydemus manokwari</em>), the <a href="https://peerj.com/articles/4672/">giant hammerhead worms</a> (especially <em>Bipalium kewense</em>) and the oddly named <em>Obama nungara</em>, which alone has invaded <a href="https://peerj.com/articles/8385/">more than 70 departments in France</a>. We have also reported recent invasions <a href="https://doi.org/10.11646/zootaxa.4951.2.11">overseas</a>.</p>
<p>To give a <a href="https://en.wikipedia.org/wiki/International_Code_of_Zoological_Nomenclature">name to a species</a>, scientists must be convinced that the species is new, and therefore explain how it is different from already known species. In all cases, the shape and colour of the organism must be accurately described. Very often, it is also necessary to precisely describe the sexual organs of the species, which are characteristic and different from other species. This is where a problem arises for flatworms: some species only reproduce asexually, and therefore simply do not have sex organs. One can imagine the problem of how then to differentiate them. This is why we used modern molecular biology techniques to characterise the mitochondrial genomes of these species.</p>
<h2>The mitochondrial genome</h2>
<p>The <a href="https://en.wikipedia.org/wiki/Mitochondrial_DNA">mitochondrial genome</a>, abbreviated as mitogenome, is the genetic code that makes the mitochondria work, small organelles that are in their thousands and are the energy powerhouses in all cells. As this mitochondrial genome is present in millions of copies in an animal, it is therefore technically easier – and less expensive – to obtain it than the genome of the nucleus. The mitochondrial genome is circular DNA, about 15,000 nucleotide base pairs long: long enough to give a lot of information, and short enough to be easily obtained.</p>
<p>We therefore obtained the mitochondrial genome of several species of invasive flatworms, such as that of the <a href="https://doi.org/10.1080/23802359.2020.1748532">New Guinea flatworm</a> and <a href="https://doi.org/10.1080/23802359.2019.1596768">hammerhead worms</a>. We used the characteristics of these genomes to differentiate the species found, even if they had no visible sexual characteristics.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=594&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=594&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=594&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=747&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=747&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442105/original/file-20220123-25-xyqe5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=747&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The mitochondrial genome of the new species <em>Humbertium covidum</em>.</span>
<span class="attribution"><span class="source">Justine et al., 2022</span></span>
</figcaption>
</figure>
<h2>The new species in France</h2>
<p><a href="https://peerj.com/articles/12725/">We found the new “metallic black” species</a> in two gardens in France, both in the department of <a href="https://en.wikipedia.org/wiki/Pyr%C3%A9n%C3%A9es-Atlantiques">Pyrénées-Atlantiques</a>, in communes separated by a hundred kilometres. It is now well known that the department of Pyrénées-Atlantiques is a <a href="https://peerj.com/articles/4672/">small paradise for flatworms</a> introduced from all over the world, mainly because of its mild and always somewhat humid climate. In both cases, there were only a few individuals of the black species. </p>
<p>At the beginning of our study, we even wondered if they were not simple black variants of a larger species, <em>Bipalium kewense</em>, also found in these gardens. But close examination of the specimen morphology and genome, and comparison of these with other species, there was no doubt that the black species was different. We then looked in the scientific literature if the species had been described elsewhere, and especially in tropical Asia, which is the main continent of origin of these hammerhead worms. We did find a few reports of animals that look like it, but nothing more.</p>
<h2>Also in Italy</h2>
<p>Toward the end of 2019, we were warned that a black species was proliferating in a field in <a href="https://en.wikipedia.org/wiki/Veneto">Veneto</a>. Hundreds of black worms, very active early in the morning, and very mobile. <a href="https://doi.org/10.1007/s10530-021-02638-w">Other reports</a> were then made of this black worm near Rome. We compared the mitochondrial genome of individuals found in France with that of individuals found in Italy: they were very little different, which shows that they are the same species, which was therefore already present in two countries in Europe.</p>
<p>And so, it was necessary to describe the species, that is to say, to give it a <a href="https://en.wikipedia.org/wiki/International_Code_of_Zoological_Nomenclature">Latin name</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/PwXlwyXAiIU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The new species <em>Humbertium covidum</em>, filmed in Italy.</span></figcaption>
</figure>
<h2>The name of the new species</h2>
<p>Assigning a name to a species is an essential and essential key step for any subsequent study. When dealing with potentially invasive species, and which therefore may attract the attention of the legislator, it is even more essential to be able to name them: the laws and decrees use Latin names, because these names guarantee that we correctly designate the right species.</p>
<p>Each Latin species name is binomial, with a genus name and a species name. For the genus name, it is “Humbertium”, simply because the animal has the characters of <a href="https://biblio.naturalsciences.be/associated_publications/bjz/bibliographic-references/ISI_000170313800034">this genus described in 2001</a>. For the name of the new species, we have chosen “<em>covidum</em>”, a name obviously based on “Covid”, the virus. Why? First, because we started this work in 2020, when our laboratories were in the <a href="https://en.wikipedia.org/wiki/COVID-19_lockdowns">Covid pandemic regulatory lockdown</a>. Then, as the pandemic progressed, we wanted to name the species to honour of all the victims. And finally, it seemed to us that “<em>covidum</em>” was an appropriate name for an organism capable of invading the world and coming from Asia, like <a href="https://en.wikipedia.org/wiki/COVID-19_pandemic">the Covid-19 pandemic</a> itself.</p>
<h2>Invasive species</h2>
<p>Apart from <a href="https://peerj.com/articles/12725/">the description of this single species</a>, what does this discovery of a new species of flatworm in Europe tell us? Above all, that foreign species are constantly invading our regions (the same thing exists elsewhere in the world, with European species invading other continents). Should we blame them and hold them responsible? These species have nothing to do with it, of course. It is humanity that is responsible, and in particular the modern phenomenon of <a href="https://en.wikipedia.org/wiki/Globalization">globalisation</a>, by which goods are circulated at a breakneck pace in all directions. A few individuals of a flatworm, who do not realise anything, find themselves crossing the whole world in a few days, probably in the soil of a lot of plants. They arrive in a new environment where their natural enemies are absent, find abundant food, and proliferate. In the case of <em>Humbertium covidum</em>, by analysing the DNA of their prey, we were able to show that the species eats small snails, but it may also consume other prey.</p>
<p>How is this arrival of <em>Humbertium covidum</em> a problem? Because the animal species that live on and in the ground have been in balance with their European environment for a long time, and the arrival of an opportunistic predator can change this balance, and therefore alter the <a href="https://en.wikipedia.org/wiki/Biodiversity">biodiversity</a> of our soils. Altering biodiversity has an ecological cost, and even an economic cost. For example, we can calculate that invasive species reduce agricultural production. The cost of invasive alien species in France is enormous, in the order of <a href="https://doi.org/10.3897/neobiota.67.59134">hundreds of millions of euros</a> per year.</p>
<p><em>Humbertium covidum</em> is therefore <a href="https://peerj.com/articles/12725/">one more example of an introduced species</a>, which ultimately threatens biodiversity. Hopefully, unlike the virus that gave it its name, it doesn’t take over the world.</p><img src="https://counter.theconversation.com/content/177191/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jean-Lou Justine has received funding from the Muséum National d'Histoire Naturelle. He is one of the "Academic Editor" (volunteer) of the scientific journal PeerJ in which this research is published.</span></em></p><p class="fine-print"><em><span>Leigh Winsor ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>
A new species of flatworm is invading us. It is metallic black in color and its name is Humbertium covidum.
Jean-Lou Justine, Professeur, UMR ISYEB (Institut de Systématique, Évolution, Biodiversité), Muséum national d’histoire naturelle (MNHN)
Leigh Winsor, Adjunct Senior Research Fellow, James Cook University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/166777
2021-09-12T08:19:31Z
2021-09-12T08:19:31Z
Worms can affect vaccine efficacy: lessons for COVID-19?
<figure><img src="https://images.theconversation.com/files/419749/original/file-20210907-25-197nrh4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Schistosoma under the microscope.. </span> <span class="attribution"><span class="source">Getty Images</span></span></figcaption></figure><p>Over a year since the first case of the SARS-CoV-2 pandemic, fast advances in vaccine development have given the world a fighting chance against the coronavirus. <a href="https://www.nejm.org/doi/full/10.1056/nejmoa2035389">SARS-CoV-2</a> vaccines have become leading instruments against severe health effects associated with COVID-19 disease. </p>
<p>SARS-CoV-2 vaccines reduce severe disease and improve survival of infected patients. Their impact has been seen in <a href="https://doi.org/10.1016/S0140-6736(21)00677-2">developed countries</a> where mass vaccination has been most efficient. In developing regions, such as many African countries, SARS-CoV-2 vaccination campaigns have been relatively <a href="https://theconversation.com/interested-in-vaccine-rollouts-across-africa-heres-a-map-to-guide-you-156802">slow</a>. </p>
<p>The impact of COVID-19 has differed among <a href="https://dx.doi.org/10.1016%2FS0140-6736(20)32580-0">developing African countries</a>. In some, SARS-CoV-2 infections have been relatively low. Others have reported high numbers. Vaccine coverage of the continent is still <a href="https://www.afro.who.int/news/eight-10-african-countries-miss-crucial-covid-19-vaccination-goal">low</a> as countries await adequate supplies.</p>
<p>But there is an added worry: the effectiveness of vaccines in developing countries, particularly those with very high levels of <a href="https://www.sciencedirect.com/sdfe/pdf/download/eid/3-s2.0-B9780702040641000646/first-page-pdf">chronic parasitic infections</a>. These are a major cause of morbidity and mortality and are prominent among the so-called <a href="https://www.sciencedirect.com/sdfe/pdf/download/eid/3-s2.0-B9780702040641000646/first-page-pdf">neglected tropical diseases</a>. </p>
<p>One of these is schistosomiasis, also known as bilharzia. Symptoms of it present as a sudden onset of fever, dry cough, diarrhoea and abdominal pain. About <a href="https://www.sciencedirect.com/science/article/pii/S1413867015000264#:%7E:text=Schistosomiasis%20is%20the%20second%20most,207%20million%20cases%20of%20schistosomiasis.">90%</a> of the people requiring treatment for this debilitating parasite are sub-Saharan Africans. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8172021/">Research</a> – on both animal models and human studies – suggests that chronic schistosomiasis infection can result in decreased vaccine efficacy. </p>
<p>In a recent paper, we <a href="https://www.sciencedirect.com/science/article/pii/S1471492221001744?casa_token=SrJAN4GljBgAAAAA:5pniuFDMhIrOAeI2nRz4RSK4PV_8VcQlnDiSLTXWa0bDzGmKWxPUBVq3JiZKHq8TthNNd5YVuwaq">reviewed</a> evidence on the influence of infection with the parasitic worms causing schistosomiasis on host immune responses to vaccines. The vaccines we focused on were to prevent measles, hepatitis B, tetanus and tuberculosis.</p>
<p>We found that measles and hepatitis B vaccines were less effective in people who have schistosomiasis. </p>
<p>We also evaluated the potential of using medication designed to treat parasitic worm infections in restoring vaccine responses affected by schistosomiasis. We found that it can improve vaccination effectiveness. </p>
<p>We concluded that treatment for schistosomiasis should be considered an important part of SARS-CoV-2 vaccination campaigns where the parasite is commonly found.</p>
<h2>Impact of schistosomiasis on vaccination</h2>
<p><a href="https://www.who.int/news-room/fact-sheets/detail/schistosomiasis">Schistosomiasis</a> is a neglected tropical disease which affects more than 236 million people. Most live in Africa. </p>
<p>No direct evidence is available yet on whether SARS-CoV-2 vaccines can be affected by schistosomiasis. But <a href="https://doi.org/10.1016/j.pt.2021.07.009">evidence</a> shows that for viruses such as hepatitis B and measles, the parasite reduces the level of protection given by their specific vaccines. For example, if a person is infected by the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6189399/">schistosome parasite</a> some time after being vaccinated, they might rapidly lose the immunity provided by the vaccination.</p>
<p>In addition, schistosomiasis commonly causes enlarged liver and spleen, known as <a href="https://doi.org/10.1016/j.pt.2021.07.009">hepatosplenomegaly</a>. This condition is associated with weakened immune responses to vaccines in endemic areas. </p>
<p>The efficacy of SARS-CoV-2 virus vaccines might be affected too. If they were, the regions mostly likely to bear the impact would be in sub-Saharan Africa where schistosomiasis is endemic. </p>
<h2>Strategic efforts</h2>
<p>Our findings call for prompt evaluation of the potential impact of parasitic infections, such as schistosomiasis, on the efficacy of SARS-CoV-2 vaccines.</p>
<p>The World Health Organisation has endorsed only one drug, <a href="http://apps.who.int/iris/bitstream/handle/10665/152781/9789241564861_eng.pdf;jsessionid=BA0FA02F103B66A1C97491E0A7DEB1F9?sequence=1">praziquantel</a>, to treat and control schistosomiasis disease. In African regions where the disease is endemic, praziquantel is often given annually to vulnerable populations.</p>
<p><a href="https://doi.org/10.1016/j.pt.2021.07.009">Studies</a> have shown that praziquantel either has no effect on viral vaccine immunity or improves immunity by clearing worms from people with schistosomiasis. </p>
<p>Praziquantel treatment is safe and generally accessible. </p>
<p>Based on our findings we believe there’s a case to be made for offering the treatment along with mass SARS-CoV-2 vaccination campaigns where schistosomiasis is endemic. </p>
<p>The other intervention that’s needed is that <a href="https://doi.org/10.1093/trstmh/traa202">current disruptions</a> of mass praziquantel administration should be addressed.</p>
<p>Disruptions were understandable in the early stages of the pandemic. But it’s now critical to maintain past successes against the parasite. And it could be vital to the success of vaccination against the SARS-CoV-2 virus.</p><img src="https://counter.theconversation.com/content/166777/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Justin Komguep Nono receives funding from the EDCTP2 programme supported by the European Union and the Poliomyelitis research Foundation of South Africa. He is co-chair of the research working group of the Global Schistosomiasis Alliance (GSA) and a founding member of JRJ Health, a health-promoting association based in Cameroon. None of these entities had any role in the conceptualisation, design, analysis of data, decision to publish, and preparation of the present article. </span></em></p><p class="fine-print"><em><span>Fungai Musaigwa receives funding from National Research Foundation (South Africa), Polio Research Foundation (South Africa) and University of Cape Town. </span></em></p>
Although there is no evidence yet that it affects COVID-19 vaccines, schistosomiasis, a neglected tropical disease, has been associated with lower vaccine immunity for several vaccines.
Justin Komguep Nono, Research Officer, Institute of Medical Research and Medicinal Plant Studies (Cameroon) and Research fellow, University of Cape Town
Fungai Musaigwa, PhD candidate, University of Cape Town
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/163821
2021-07-18T20:03:14Z
2021-07-18T20:03:14Z
In the evolutionary arms race between cane toads and lungworms, skin secretions play a surprising role
<figure><img src="https://images.theconversation.com/files/409688/original/file-20210705-21-s23dlf.JPG?ixlib=rb-1.1.0&rect=23%2C7%2C5152%2C2894&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Martin Mayer</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Unlike many other species of amphibians, the cane toad is thriving. It was introduced to Australia (and other places, such as Hawaii) to get rid of pest insects in sugar cane plantations. It had no effect on the pest insects, but soon after its introduction in 1935 it began to spread over large parts of the country. </p>
<p>And it didn’t come alone. Cane toads brought with them a parasite from their native range in South America, the lungworm nematode <em>Rhabdias pseudosphaerocephala</em>. </p>
<p>This invasion provides an ideal model to study the evolutionary “arms race” by which hosts and parasites adjust to each other, as we showed in a recent <a href="https://academic.oup.com/biolinnean/article/132/4/861/6126939">study</a>.</p>
<h2>How parasites can drive evolution</h2>
<p>Parasites are the stuff of nightmares (just think of the <a href="https://theconversation.com/meet-phronima-the-barrel-riding-parasite-that-inspired-the-movie-alien-22555">creature</a> in the movie Alien). Most people don’t think about parasites too much, and one reason is that over the past two centuries we humans managed to rid ourselves of most parasites that used to pester us.</p>
<p>Nonetheless, parasites are an essential part of most ecosystems and important drivers of evolution. But for most kinds of parasites, we don’t really know fundamental facts such as how they find their hosts in the first place and conversely, how hosts protect themselves from getting infected. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-phronima-the-barrel-riding-parasite-that-inspired-the-movie-alien-22555">Meet Phronima, the barrel-riding parasite that inspired the movie Alien</a>
</strong>
</em>
</p>
<hr>
<p>The host and its parasites are locked in an “arms race” of adaptations and counter‐adaptations. Hosts evolve to detect and reject parasites; parasites evolve to deceive the host’s detection and suppression systems; then hosts evolve to defeat those new tricks, and so on. </p>
<p>This is why host–parasite interactions can be powerful drivers of evolution. Selection should favour hosts that can either reduce their chances of getting infected, which is called resistance, or limit the harm caused by a given parasite infection, which is called tolerance.</p>
<h2>Cane toads vs lungworms</h2>
<p>How does that arms race play out during a biological invasion, when both the host and the parasite are subject to powerful new evolutionary forces? </p>
<p>Using cane toads and their lungworm parasites, our <a href="https://onlinelibrary.wiley.com/doi/10.1111/ele.13832">new paper</a> shows that the skin secretions of the cane toad host play a surprisingly important role. </p>
<p>The secretions that coat an amphibian consists of two parts: substances produced by the amphibian itself plus skin microbiome, mostly bacteria. These secretions contain many antimicrobial properties, which might help to fight off pathogens (such as chytrid fungus, the cause of so many amphibian declines). </p>
<p>At the same time, parasites try to overcome those barriers. Lungworm larvae (which develop in the faeces of an infected toad and then wait for a new toad to pass by) might use the smell of skin secretions as a cue to find their host in the first place.</p>
<p>We reasoned that the infective larvae of lungworms might even use the toad’s skin secretions to cloak themselves from the amphibians’ immune system when trying to make their way to the lungs (which is where they need to settle, mature, and reproduce). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/409689/original/file-20210705-35922-1q2zn86.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The cane toads’ current distribution in Australia (a), a cane toad used for our experiments (b) and a lungworm parasite located in a toads’ lung (c).</span>
<span class="attribution"><span class="source">Mayer, Shine & Brown</span></span>
</figcaption>
</figure>
<h2>How the role of skin secretions changes</h2>
<p>If hosts and parasites are constantly adapting to each other, we expect to see different strategies in different places for infection avoidance (in hosts) and host detection (in parasites). These differences might arise very quickly, such as during a biological invasion. </p>
<p>To test this idea, we experimentally infected cane toads from different regions in Australia with lungworm parasites from different regions. Additionally, we reduced skin secretions in some of the toads to test how their presence or absence affected the infection success of the parasite. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/409687/original/file-20210705-35723-jaq4xj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A male cane toad in Northern Australia.</span>
<span class="attribution"><span class="source">Martin Mayer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that the role of skin secretions differed markedly between geographic regions. </p>
<p>In the toads’ core range (their main habitat) in tropical Queensland, toad skin secretions functioned as a cue for the parasite to find their host. But not only that, they also helped the parasites to infect the toads, meaning that more parasites managed to reach the toads’ lungs when skin secretions were intact. So it seems that these lungworms indeed cloak themselves from the host’s immune system. </p>
<p>But this was not the case at the toads’ invasion front (where toads are spreading into new territory) in Western Australia. Here, the skin secretions of cane toads appear to act as a <em>defence</em> against lungworms, reducing rather than enhancing their infection success. </p>
<p>Thus, although cane toads have been spreading through Australia for only 85 years, we see major divergences in the roles that their skin secretions play in host–parasite biology. </p>
<h2>The state of the arms race</h2>
<p>These geographical divergences fit well with the idea that cane toads in the core range have low resistance to parasite infection, because parasites are ubiquitous due to the nice warm and wet conditions year round. </p>
<p>Conversely, at the invasion‐front, where conditions are harsh and dry for most of the year, increased host resistance might be favoured – especially if parasite infection reduces the dispersal ability of a fast-moving invasion-front toad. </p>
<p>Thus, the cane toads on the invasion-front appear to be ahead in the arms race: they have adapted to the new conditions, while the lungworms are still catching up.</p><img src="https://counter.theconversation.com/content/163821/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rick Shine receives funding from the Australian Research Council. There is no conflict of interest.</span></em></p><p class="fine-print"><em><span>Martin Mayer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Australia’s invasive cane toads may be out-evolving their lungworm parasites.
Martin Mayer, Postdoctoral Research Associate in Animal Ecology, Aarhus University
Rick Shine, Professor in Evolutionary Biology, Macquarie University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/145920
2020-12-10T13:35:04Z
2020-12-10T13:35:04Z
Why do scientists care about worms?
<figure><img src="https://images.theconversation.com/files/374060/original/file-20201210-15-upgx8b.jpg?ixlib=rb-1.1.0&rect=110%2C0%2C6498%2C4476&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Whether in the wild or in the lab, worms have an interesting story to tell.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/ascariasis-is-a-disease-caused-by-the-parasitic-royalty-free-image/1045455096">Sinhyu/iStock via Getty Images</a></span></figcaption></figure><p>I traveled to a marine research station on a picturesque Swedish fjord many times over the four years I worked on my Ph.D. What brought me back again and again? Buried in the mud off the west coast of Sweden lives a small orangey brown worm, which, to the untrained eye, looks entirely insignificant.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="blobby brownish worm" src="https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=610&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=610&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=610&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=767&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=767&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374013/original/file-20201209-23-cs1eid.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=767&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author’s worm of choice, <em>Xenoturbella</em>.</span>
<span class="attribution"><span class="source">Fraser Simpson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The fact that I devoted so much study to this boring-looking worm was a source of great amusement to my friends. To them, and perhaps to most people, the word worm conjures up the idea of a fat pink earthworm. So why sift through tons of mud from a freezing Swedish fjord to find a handful of animals I could dig up in the garden?</p>
<p>Broadly defined, a worm is any relatively small soft-bodied animal, but there’s an amazing amount of diversity in this group. These animals live across the globe, and some of them are remarkably resilient; they can be found in habitats ranging from deep-sea hydrothermal vents to lakes that are three times saltier than the sea. “Worm” is really a catchall term for a huge variety of animals with different characteristics that span the tree of life.</p>
<p>This diversity means that scientists from many different disciplines are interested in lots of different species of worms. For instance, my worm from the fjord, called <em>Xenoturbella bocki</em>, holds a pivotal position for understanding animal evolution.</p>
<p>At first glance you might think that people and all these worms have very little in common. But really, many worm species provide opportunities for scientists to perform basic research on cells and systems that can be translated into information about our biological origins, and even relevant applications for human development and health.</p>
<h2>Regeneration</h2>
<p>If your head is chopped off, you won’t grow a new one. But if you were a planarian flatworm, you wouldn’t just grow a new head – your head would also grow a new body. Cut one of these inconspicuous worms into hundreds of tiny pieces, and you’ll end up with hundreds of new animals. Planaria are truly the masters of regeneration.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vXN_5SPBPtM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Watch Planaria regenerate before your eyes.</span></figcaption>
</figure>
<p>In order to achieve this feat, both the instructions and the materials for constructing a new body must be present in each of those fragments. These building blocks are called neoblasts: <a href="https://doi.org/10.1007/s00427-012-0426-4">stem cells distributed throughout the worm</a> that have the potential to become any adult cell type.</p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>.]</p>
<p>Planarian regeneration research has some surprising applications. Scientists can investigate which genes keep neoblasts in a flexible state, or direct them to become specific cell types during the regenerative process. This research won’t help researchers learn how to regenerate new human heads, but it can inform their <a href="https://doi.org/10.1101/gad.187377.112">understanding of wound healing</a> or suggest <a href="https://doi.org/10.1242/dmm.032573">new targets for cancer research</a>.</p>
<h2>Fossil record</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Adult priapulid worm." src="https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372847/original/file-20201203-23-11eukuz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An adult priapulid.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Adult_priapulid.jpg">Bruno C. Vellutini/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If there were a prize for the most unfortunate-looking worm, it might go to the name-says-it-all “penis worms,” formally known as the Priapulida. Their unlucky appearance actually makes priapulids very well adapted to burrowing into the soft sediment where they live.</p>
<p>This behavior leaves a valuable legacy. The <a href="https://doi.org/10.1098/rspb.2018.2505">fossilized traces of burrowing worms</a> represent some of the most important fossils recovered from the Cambrian era. The first early representatives of most of the major animal groups date to this geological period, which began around 540 million years ago. Evidence indicates that priapulid-like worms created these trace fossils as they burrowed into the soft substrate where they lived.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="rock fossil with outline of a worm creature" src="https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=883&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=883&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=883&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1110&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1110&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374055/original/file-20201210-20-1v6hozy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1110&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fossil evidence of an ancient priapulid.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/fossils-protostomia-priapulida-archaeopriapulida-ottoia-news-photo/122223615">DEA/G. Cigolini/De Agostini via Getty Images</a></span>
</figcaption>
</figure>
<p>These ancient ancestors mean that Priapulids have been described as “living fossils.” Studying their developmental genetics offers an insight into the ancient origins of the different cell types and organs we find in animals today.</p>
<p>For example, by understanding how modern priapulids make their guts, scientists can infer the developmental processes and genes that shaped the guts of animals living hundreds of millions of years ago. Then, researchers can better understand how different animals have refined and modified what their gut looks like and how it is patterned in response to their environment and diet.</p>
<h2>Where did eyes come from?</h2>
<p>Even to Charles Darwin, the <a href="https://www.newscientist.com/term/evolution-of-the-eye/">evolution of the eye</a> posed a conceptual problem. How could such a complex structure have arisen through natural selection? </p>
<p>A relative of the earthworm and the leech, an annelid called <em>Platynereis dumerilii</em>, turns out to be an important animal to help understand how it happened. <em>Platynereis</em> is particularly slowly evolving, and, similar to priapulids, provides a window into the <a href="https://doi.org/10.1038/eye.2017.226">features found in our very ancient ancestors</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Platynereis larvae in the lab at 48 hours of age" src="https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372850/original/file-20201203-15-1vhwh79.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two-day-old <em>Platynereis dumerilii</em> larvae with their DNA stained blue.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Hoechst_33342_Stain_-_Platynereis_dumerilii_larvae.jpg">7and/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><em>Platynereis</em> larvae have one of the simplest eyes in the animal kingdom: a two-cell structure comprised of a photoreceptor, capable of detecting light, and a pigment cell. But it has an additional type of photoreceptor in its larval brain – one that is also found in the vertebrate eye. This suggests that <a href="https://doi.org/10.1038/news041025-18">both of these photoreceptor types</a> were present in an ancestral animal. By investigating how <em>Platynereis</em> uses these cells, scientists can hypothesize the steps by which cell types and circuitry ultimately were integrated to create the vertebrate eye.</p>
<p>The world of worms extends far beyond the humble earthworm in your backyard: There are literally millions of different species living all across the world. The examples outlined here are just a small representation of that diversity and the unexpected reach that research on these critters can have.</p><img src="https://counter.theconversation.com/content/145920/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Robertson received PhD funding from the ERC </span></em></p>
‘Worm’ is really a catchall term for a huge variety of animals with different characteristics that span the tree of life. They hold clues about our own origins as well as hints about human health.
Helen Robertson, Postdoctoral Scholar of Organismal Biology and Anatomy, University of Chicago
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/151308
2020-12-03T14:45:59Z
2020-12-03T14:45:59Z
How a tiny worm is helping to find a cure for an extremely rare form of cancer
<figure><img src="https://images.theconversation.com/files/372823/original/file-20201203-17-1h4vco.png?ixlib=rb-1.1.0&rect=7%2C0%2C1294%2C504&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have recreated the mutant gene that causes a rare cancer called phaeochromocytoma in a millimetre-sized worm.</span> <span class="attribution"><span class="source">University of Dundee</span>, <span class="license">Author provided</span></span></figcaption></figure><p>When the Williamson family from Dundee <a href="https://www.thecourier.co.uk/fp/news/local/dundee/833499/tayside-dad-who-tragically-lost-his-wife-to-cancer-features-in-new-tv-campaign/">lost their mother Sue to a rare cancer</a> named <a href="https://www.nhs.uk/conditions/phaeochromocytoma/">phaeochromocytoma</a> in 2003, they didn’t realise that further devastation was to follow.</p>
<p>Of her four children, twins Jennie and James discovered that they also have the faulty gene that cut short their mother’s life. Both twins are affected with inoperable tumours wrapped around vital blood vessels and nerves in their necks. Father Jo decided to appear in a Cancer Research pledge video (below) in memory of his wife and to raise awareness of the important work that cancer researchers do for people like his children.</p>
<p>We have been working closely with the family to understand more about the gene mutation that causes this cancer. Along with a consortium of researchers from universities in Hungary and India, we have, for the first time, been able to recreate the Williamson defect in a tiny worm, just one millimetre long. This progress is vital to better understand the mutation, and it helps point to possible treatments for the cancer.</p>
<p>The cancer is called a <a href="https://www.facebook.com/PhaeoPara/">phaeo</a>. It pulses excessive adrenaline-like hormones into the circulation. Phaeo is hard to diagnose because it mimics conditions such as high blood pressure and can kill patients receiving routine anaesthesia.</p>
<p>When symptoms occur in the young, phaeo may be picked up on imaging (such as ultrasound and MRI/CAT scans) with a high chance of phaeo-causing genes in their DNA. This is the case in the Williamson family, where mum Sue was the index case, but died of malignant-phaeo, despite the removal of a tumour in her twenties.</p>
<p>And even though two of her children carry this defective gene, the first modicum of hope is now on the horizon in familial phaeo after the family decided to find an alternative approach to their DNA mutation. The new hope fuses science, serendipity and a minuscule worm that has been around for hundreds of millions of years.</p>
<h2>The Williamson worm</h2>
<p>The defective gene in the Williamson family altered the structure of a protein called <a href="https://dmm.biologists.org/content/13/10/dmm044925">SDHB</a>. SDHB has a very unusual function that needs an introductory explanation from science fiction. In the <a href="https://www.backtothefuture.com/movies/backtothefuture1">Back to the Future</a> films, Doc Brown’s time-travelling DeLorean sports car is powered by a water-fuelled “flux-capacitor” that can generate vast power. Now imagine that human life itself depends on the biological equivalent of such a device that fuels our internal power generation system. In biology, SDHB is like a flux capacitor that splits apart the sugar we eat into its constituent hydrogen and electricity.</p>
<figure class="align-right ">
<img alt="A poster of the original Back To The Future film showing the star Michael J Fox." src="https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=808&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=808&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=808&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1015&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1015&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372820/original/file-20201203-17-y7r183.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1015&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Human biology requires a similar kind of power-generating ‘flux capacitator’ that we see in Back To The Future.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Back_to_the_Future">Universal Pictures</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>So in the Williamsons, the puzzle lay in finding out how a tiny malfunction in one DNA instruction (mutant SDHB) could cause recurrent cancer in the family. In the past attempts by researchers to make a mouse phaeo model failed to yield insight because the mice looked healthy.</p>
<p>A new approach was needed. By genetic manipulation of DNA, our international group created a worm model of SDHB malfunction that has yielded some new data. We chose to model phaeo using worms because the worm equivalent of SDHB has remained substantially unchanged over hundreds of thousands of years.</p>
<p>So, despite the vast gulf of time that separates worms from modern humans, nature had not changed the DNA blueprint for this essential “flux-capacitor” that permits the energy generation needed for life. This power generator was perfected over 400 million years ago and still works unchanged in animal cells today.</p>
<h2>The results</h2>
<p>The results are revealing because it was immediately obvious that the Williamson mutant worms are sick, sterile, small and sickle shaped. Importantly, the changed appearance can be further investigated by mating them with other mutant worms with other cancer-causing genetic defects. This is underway. In the meantime, a few conclusions can be drawn.</p>
<p>First, the Williamson family mutation does not delete the whole SDHB gene in the affected DNA. This family has a differently folded three-dimensional “origami” structure to their SDHB protein driven by the wrong instructions from their mutant SDHB gene. The Williamson SDHB protein is misshapen, exactly where fuel metabolism occurs. These worms also make so much less of this mutant misshapen SDHB protein. So Williamson worms have contributed something new to nature.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rl7_4mBv30s?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Second, Williamson worm power stations – or <a href="http://www.mrc-mbu.cam.ac.uk/what-are-mitochondria">mitochondria</a>, the part of the cell that transforms what we eat (proteins, sugars, fats) into energy – use a very different fuel mix. Normal SDHB runs like a car that can seamlessly switch fuel sources when one fuel runs low. Williamson worms cannot do this and they can only partially burn fuels to release <a href="https://www.livescience.com/lactic-acid.html">lactic acid</a> as a “frustrated” end product of <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/glucose-metabolism">glucose metabolism</a>.</p>
<p>So when pushed to perform at their collective personal best, and despite plentiful oxygen trapped inside a tiny molecular cage or cavity made of iron and protein found inside all mitochondria, the Williamson mitochondria cannot effectively maximise their energy output.</p>
<p>Third, and rather excitingly, it is possible to kill Williamson worms with drugs that leave normal worms unscathed. This is where new hope arises because at the moment there is no cure for the Williamson cancer. The search is now on for useful drugs to test in animals, and the findings of this research mean they could now be developed.</p>
<p>Finally, SDHB has just been found to be abnormally controlled across a wide variety of common cancers which adds to the potential of this worm research. Which means that rare and common may well be different manifestations of the cancer process.</p><img src="https://counter.theconversation.com/content/151308/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anil Mehta has acted as a scientific advisor to the governments of Ireland and Finland, and to the Phaeo and Para charity. In the past he has received research support from many sources including the Wellcome Trust.</span></em></p><p class="fine-print"><em><span>Gordon Stewart has received grant funding form the Wellcome Trust and other charitable organisations. </span></em></p>
A new discovery fuses science, serendipity and a millimetre-sized worm that is hundreds of millions of years old to help develop a treatment for phaeochromocytoma.
Anil Mehta, Honorary Reader in Experimental Medicine, University of Dundee
Gordon Stewart, Emeritus Professor of Experimental Medicine, UCL
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/147578
2020-11-11T19:19:33Z
2020-11-11T19:19:33Z
Curious Kids: Do worms have blood? And if so, what colour is it?
<figure><img src="https://images.theconversation.com/files/368765/original/file-20201111-13-x5fk9i.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5742%2C3785&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock </span></span></figcaption></figure><blockquote>
<p><strong>Do worms have blood, and if they do, what colour is it? Momo Bice, aged 9, Carlton</strong></p>
</blockquote>
<p><a href="https://theconversation.com/au/topics/curious-kids-36782"><img src="https://images.theconversation.com/files/291898/original/file-20190911-190031-enlxbk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=90&fit=crop&dpr=1" width="100%"></a></p>
<p>Hi Momo. Well, the short answer to your question is: yes. Many worms do have blood, and it is either colourless or pink, or red, or even green! But to answer your question properly, first we need to decide what type of worm we are talking about. </p>
<p>There are lots of different sorts of worms. Generally, a worm is any long, thin animal that does not have a backbone, but scientifically we recognise three types of worms: flatworms, roundworms and segmented worms. Worms live in the sea, in sand and soil. Some live inside plants or animals, and we call them parasites.</p>
<p>So let’s look at what blood you might find inside these different types of worms. </p>
<figure class="align-center ">
<img alt="Segmented worm" src="https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368787/original/file-20201111-15-1jhwpuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Worms live in sea, sand soil, or – if we’re unlucky – even inside us.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>The three worm types</h2>
<p><strong>Flatworms:</strong> These include tapeworms, which are parasites (meaning they live on a host organism), and planaria, which live in ponds and lakes. These animals are so flat they don’t even need blood. They absorb oxygen through their skin and it spreads directly to every cell in their body. As a result they are pretty much colourless, or whitish.</p>
<p><strong>Roundworms:</strong> Also called nematodes, these worms are mainly found in soil. Roundworms can also live as parasites in humans, causing really <a href="https://theconversation.com/with-fewer-resources-were-finding-clever-ways-to-map-river-blindness-in-africa-32126">nasty</a> <a href="https://www.cdc.gov/parasites/toxocariasis/gen_info/faqs.htm">effects</a> such as blindness and brain defects. One large roundworm that lives in the intestines of humans can grow to more than <a href="https://www.cdc.gov/parasites/ascariasis/biology.html">35 centimetres</a> – that’s longer than a standard ruler!</p>
<p>As the name suggests, roundworms are tube-shaped. Their body cavity contains fluid that delivers oxygen to its organs. But this fluid is not called blood, because it does not circulate around the body.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-are-parasites-and-how-do-they-make-us-sick-121489">What are parasites and how do they make us sick?</a>
</strong>
</em>
</p>
<hr>
<p>Most roundworm species are very small, and so can diffuse oxygen through their skin to all parts of their body. But very large roundworms can’t do this as easily, especially when they live inside animals where there is not much oxygen. These large worms use an oxygen-carrying molecule called haemoglobin – more on that in a minute.</p>
<p><strong>Segmented worms:</strong> These worms include earthworms, leeches and marine worms. Also known as annelids, the bodies of segmented worms are divided by grooves into a series of segments. Most have circulatory systems – that is, blood vessels and a heart that pumps blood around the body. </p>
<figure class="align-center ">
<img alt="A flatworm" src="https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368777/original/file-20201111-19-u1jv20.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Flatworms have no body cavity.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>So what colour is the blood?</h2>
<p>The <a href="https://biomolecules101.wordpress.com/2020/01/17/oxygen-transport-proteins-the-colors-of-blood/">colour of blood</a> in any animal is determined by the molecule that carries oxygen and other gases in and out of the body. If the molecule uses iron to carry the oxygen, then the blood is usually red. If it uses copper, the blood is usually blue. But these molecules can also be green and pink. </p>
<p>All these colours except blue are found in worms. Haemoglobin is the most common oxygen-carrying molecule, including in worms. Haemoglobin contains iron, which means most worm blood – including that of earthworms and leeches – is red. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-leeches-suck-our-blood-117316">Curious Kids: why do leeches suck our blood?</a>
</strong>
</em>
</p>
<hr>
<p>Some segmented worms use a different oxygen-carrying molecule called <a href="https://doi.org/10.1098/rspb.1926.0008">chlorocruorin</a>. The blood of these worms can be either green or red.</p>
<p>One group of segmented marine worms has pink blood. This is because the molecule that carries the oxygen is a type of blood pigment, known as <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/hemerythrin">hemerythrin</a>, which is described as pink or purple.</p>
<p>A few species of segmented worms don’t have any oxygen-carrying molecules at all, so their blood is colourless.</p>
<p>So, the answer to your question is that all segmented worms have blood, while roundworms and flatworms do not. The blood colour depends on the molecule that carries oxygen in that worm. And most worms have red blood, just like us! </p>
<figure class="align-center ">
<img alt="Child's hands holding worms and soil" src="https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368776/original/file-20201111-21-1c1giiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There are three worm types, and not all have blood.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/147578/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Sandeman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Pink blood, green blood, or no blood at all – when it comes to what’s inside a worm’s body, the answer is more complicated – and fascinating – than you’d think.
Mark Sandeman, Honorary Professor, Federation University Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/149691
2020-11-09T18:30:09Z
2020-11-09T18:30:09Z
Land flatworms are invading the West Indies
<figure><img src="https://images.theconversation.com/files/368025/original/file-20201106-21-1ukfsjf.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C3109%2C1494&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Amaga expatria_, a spectacular species, has just been reported in Guadeloupe and Martinique.</span> <span class="attribution"><a class="source" href="http://dx.doi.org/10.7717/peerj.10098/fig-5">Pierre & Claude Guezennec</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>In 2013, an inhabitant of Cagnes-sur-Mer, France, found a <a href="https://en.wikipedia.org/wiki/Geoplanidae">land flatworm</a> in his garden and had the good idea to send the photograph to a network of naturalists. We then launched a <a href="https://sites.google.com/site/jljjustine/que-faire-si-je-trouve-un-plathelminthe?">citizen science survey</a> in France to learn more – and we were not disappointed. More than 10 species of land flatworms from elsewhere are now reported in metropolitan France, including a giant species 30 centimetres long and a species that is now found in more than 70% of France’s departments.</p>
<hr>
<p>
<em>
<strong>
À lire aussi :
<a href="https://theconversation.com/obama-nungara-how-a-flatworm-from-argentina-jumped-the-atlantic-and-invaded-france-131186">Obama nungara: how a flatworm from Argentina jumped the Atlantic and invaded France</a>
</strong>
</em>
</p>
<hr>
<p>An unexpected result was receiving photographs from the overseas French departments, particularly the West Indies. With a tropical climate, the West Indies can host species that could not survive in mainland France. We often receive new accounts of <a href="https://doi.org/10.20944/preprints202005.0023.v1">species found in the Antilles</a> and this is an initial report.</p>
<h2>The giant “hammerhead worm”, <em>Bipalium kewense</em></h2>
<p>Let’s start with the big one. The “hammerhead worm”, <em>Bipalium kewense</em>, is indeed a giant: 30 centimetres – longer than your shoe, even if you wear size 44. “<em>Kewense</em>” is a Latin term meaning “from Kew”, because it was first found in 1878 in the tropical greenhouse of Kew Gardens, London, home to plants from all over the world. It was determined much later that its area of origin is in Vietnam. This is one of the characteristics of many <a href="https://en.wikipedia.org/wiki/Geoplanidae">land flatworms</a>: they may have gone unnoticed in their country of origin, but are soon observed in the regions they have been introduced to and invaded.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bipalium kewense" src="https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367496/original/file-20201104-19-1jcecv3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ‘hammerhead worm’ <em>Bipalium kewense</em>, the longest of the invasive land flatworms of the West Indies, here killing an earthworm.</span>
<span class="attribution"><span class="source">Pierre Gros</span></span>
</figcaption>
</figure>
<p><em>Bipalium kewense</em> is present in Guadeloupe, Martinique, and in other Caribbean islands such as Cuba. It also found in <a href="http://dx.doi.org/10.7717/peerj.4672">South and North America, Southern Africa, Australia, New Zealand and Europe</a>.</p>
<hr>
<p>
<em>
<strong>
À lire aussi :
<a href="https://theconversation.com/yes-giant-predatory-worms-really-are-invading-france-97106">Yes, giant predatory worms really are invading France</a>
</strong>
</em>
</p>
<hr>
<p>Outside of its source region, the species also gave up… sexual reproduction. Those found in the West Indies do not have sex organs and reproduce through a phenomenon called <a href="https://en.wikipedia.org/wiki/Fission_(biology)">fission</a>. A piece of the tail breaks off and grows a head, producing a new individual. Each is therefore a clone of their parent, themselves a clone of their parent. This same individual has thus invaded several continents. <em>Bipalium kewense</em> is a predator of earthworms, which it kills with a deadly poison, <a href="https://en.wikipedia.org/wiki/Tetrodotoxin">tetrodotoxin</a>.</p>
<h2>The little “hammerhead worm”, <em>Bipalium vagum</em></h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bipalium vagum" src="https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367687/original/file-20201105-17-6pcck.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The little ‘hammerhead worm’ <em>Bipalium vagum</em>, present in Guadeloupe and Martinique, photographed here in French Guiana.</span>
<span class="attribution"><span class="source">Sébastien Sant</span></span>
</figcaption>
</figure>
<p><em>Bipalium vagum</em> has the same general shape as <em>Bipalium kewense</em>, with its elongated body and broad head, but it is much smaller, a few centimetres long, and the lines on its back are much more distinct. The species <a href="https://doi.org/10.11646/zootaxa.1001.1.3">was only described in 2005</a> and found in Bermuda. As with all <em>Bipalium</em> species, the region of origin is believed to be in Asia, but it is not known where exactly. In 2018 we showed that the species is also present in <a href="http://dx.doi.org/10.7717/peerj.4672">Martinique and Guadeloupe</a>. It has also been found in Florida, South America and various countries in Asia. In English, the species is called the “mollusc-eating hammerhead worm” although its diet has not been studied in any specific way.</p>
<h2>One of the “100 most harmful invasive species”, <em>Platydemus manokwari</em></h2>
<p>In 2000, scientists drew up a list of the <a href="http://www.issg.org/pdf/publications/worst_100/english_100_worst.pdf">“100 world’s worst invasive alien species”</a>. This includes the tiger mosquito, the Florida turtle and the black rat. One land flatworm was included: <em>Platydemus manokwari</em>, the New Guinea flatworm. It eats snails and was <a href="http://dx.doi.org/10.7717/peerj.1037">deliberately introduced to some Pacific islands</a> in an attempt to control giant African land snails, themselves introduced as potential food. Instead, they became a pest, attacking and exterminating many of the native snails and endangering island biodiversity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Platydemus manokwari" src="https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367501/original/file-20201104-23-1cfongx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The famous <em>Platydemus manokwari</em>, the New Guinea flatworm, has now invaded Guadeloupe as well.</span>
<span class="attribution"><span class="source">Pierre Gros</span></span>
</figcaption>
</figure>
<p>In 2019, we received some very bad news – reports indicated that <em>Platydemus manokwari</em> had arrived in <a href="https://doi.org/10.20944/preprints202005.0023.v1">Guadeloupe</a>. The species is already in other Caribbean islands such as <a href="http://dx.doi.org/10.7717/peerj.1037">Puerto Rico</a> and is on the way to invade Florida, Texas and Louisiana. No report has yet been received from Martinique, but unfortunately it is necessary to add “yet”. It has also been found in <a href="https://peerj.com/articles/297/">mainland France</a>.</p>
<h2>The one that looks a bit like a banana, <em>Amaga expatria</em></h2>
<p><em>Amaga expatria</em>, like <em>Bipalium vagum</em>, was also <a href="https://doi.org/10.11646/zootaxa.1001.1.3">described in 2005</a> from two specimens found in a botanical garden in Bermuda. No one has found this species for 15 years – one would think it is rare. And then, we received more than <a href="https://peerj.com/articles/10098/">20 reports from Martinique and Guadeloupe</a>, 10 times more than all those that were known. <em>Amaga expatria</em> is well established almost everywhere on the two islands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Amaga expatria, map" src="https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/368044/original/file-20201106-21-cm56e3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Places where the flatworm <em>Amaga expatria</em> was found in Guadeloupe and Martinique. The colours represent rainfall.</span>
<span class="attribution"><span class="source">Jessica Thévenot; background, Météo-France</span></span>
</figcaption>
</figure>
<p><em>Amaga expatria</em> is a large species, up to 15 cm long, with a broad and flat body. The colour is yellow-orange, with black dots. Yes, it looks a bit like, in colour and shape, a banana cut lengthwise.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Amaga expatria" src="https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/367505/original/file-20201104-17-t8a0u1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The flatworm <em>Amaga expatria</em>, living animals photographed in various places in Guadeloupe.</span>
<span class="attribution"><span class="source">Laurent Charles, Mathieu Coulis et Guy van Laere</span></span>
</figcaption>
</figure>
<p>Where does this species come from? The species name “<em>expatria</em>” had been chosen to indicate that it was not at home in Bermuda. The genus <em>Amaga</em> includes about 10 species from South America, and so the species probably comes from there – but the species <em>Amaga expatria</em> has not yet been found in its country of origin. Is the species in other islands in the West Indies? We do not know.</p>
<p>For <em>Amaga expatria</em>, we were able to use advanced molecular methods to analyse its <a href="https://en.wikipedia.org/wiki/Mitochondrial_DNA">mitochondrial genome</a>, as we had done for <a href="https://doi.org/10.1080/23802359.2019.1596768">other species</a>. As a further result, new sequencing methods make it possible to identify the DNA of the animals the worm has eaten. This is how we had proof that <em>Amaga expatria</em> eats a snail in Martinique, named <em>Subulina octona</em>. Local naturalists have also told us that <a href="https://peerj.com/articles/10098/">the species eats various snails and earthworms</a>.</p>
<h2>Where do these invasive worms come from?</h2>
<p>Each of these species has a different geographic origin: Continental Asia for <em>Bipalium kewense</em> and <em>Bipalium vagum</em>, New Guinea for <em>Platydemus manokwari</em>, and Central America for <em>Amaga expatria</em>. How did they get to the West Indies? The answer is the same for all: by transporting plants. A land flatworm in the soil of a flower pot, or even stuck between two leaves in a banana plant, is virtually invisible. These worms to not invade the world alone and certainly not on purpose – it was international and inter-island trade that enabled their spread. Once on an island, they will invade very slowly, garden by garden, or very quickly, if flower pots or plants are transported. When the invasion happened, we don’t know, but <em>Bipalium kewense</em>, for example, has been reported in <a href="http://dx.doi.org/10.7717/peerj.4672">dozens of countries for decades</a>.</p>
<h2>Why is this important for the ecology of the West Indies?</h2>
<p>All of these land flatworms are predators – they eat prey that they will capture on the ground. However, soil ecology is important, and depends on all those animals that live in the soil and on its surface. Adding new predators to the West Indian soil ecosystem, which will consume some species but not others, has the potential to upset ecological balances. It’s like putting a wolf in a field of sheep – it’s not hard to imagine that the number will decrease. But we do not yet have precise figures on the impact of these introduced species – what their prey is and how great the impact.</p>
<h2>What to do?</h2>
<p>We currently are in the early stages of scientific work to find out what the ecological impact of these invading animals is – this is currently unknown. Eventually we would like to find ways to remove them, but this is a distant goal. Right now, you can help by <a href="https://sites.google.com/site/jljjustine/que-faire-si-je-trouve-un-plathelminthe?">reporting land flatworms</a> found in your garden or on your walks. It’s simple: take a photo, note the location, and <a href="https://inpn.mnhn.fr/informations/inpn-especes">send the report</a>. Who knows, there are probably other species not yet spotted – unfortunately.</p><img src="https://counter.theconversation.com/content/149691/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jean-Lou Justine received grants from the Muséum National d'Histoire Naturelle, Paris. He is one of the Academic Editors of PeerJ (<a href="https://peerj.com/">https://peerj.com/</a>), the scientific journal in which several of the studies cited here were published.</span></em></p><p class="fine-print"><em><span>Hugh Jones ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>
Several species of flatworms have invaded the West Indies, and some are spectacular. We take stock of the situation with a study published at the same time as this article.
Jean-Lou Justine, Professeur, UMR ISYEB (Institut de Systématique, Évolution, Biodiversité), Muséum national d’histoire naturelle (MNHN)
Hugh Jones, Chercheur, Natural History Museum
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/147910
2020-10-15T19:09:14Z
2020-10-15T19:09:14Z
Cats carry diseases that can be deadly to humans, and it’s costing Australia $6 billion every year
<figure><img src="https://images.theconversation.com/files/363183/original/file-20201013-21-12l0k86.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4942%2C3275&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Rotiv Artic/Unsplash</span></span></figcaption></figure><p>Toxoplasmosis, cat roundworm and cat scratch disease are caused by pathogens that depend on cats — pets or feral — for part of their life cycle. But these diseases can be passed to humans, sometimes with severe health consequences. </p>
<p>In <a href="https://doi.org/10.1071/WR20089">our study</a> published today in the journal Wildlife Research, we looked at the rates of these diseases in Australia, their health effects, and the costs to our economy.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/P25VoNs-m1Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Professor Sarah Legge discusses the key findings of the study.</span></figcaption>
</figure>
<p>Based on findings from a large number of Australian and international studies, Australian hospital data and information from the Australian Bureau of Statistics, we estimate many thousands of people in Australia fall ill or sustain a minor injury as a result of cat-dependent diseases each year. </p>
<p>Our estimations suggest more than 8,500 Australians are hospitalised and about 550 die annually from causes linked to these diseases.</p>
<p>We calculated the <a href="https://www.nespthreatenedspecies.edu.au/media/mosiufqg/7-4-cat-dependent-disease-findings-factsheet_v13.pdf">economic cost</a> of these pathogens in Australia at more than A$6 billion per year based on the costs of medical care for affected people, lost income from time off work, and other related expenses.</p>
<p><iframe id="tc-infographic-533" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/533/7a45b270e1d0517b1ef18350eccefebc05937a1e/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<h2>Toxoplasmosis</h2>
<p>Toxoplasmosis is an illness caused by the parasite <em>Toxoplasma gondii</em>. It’s the most serious cat-dependent disease.</p>
<p>Newly infected cats shed millions of <em>T. gondii</em> oocysts (like tiny eggs) <a href="https://pubmed.ncbi.nlm.nih.gov/30945159/">in their poo</a> and these can <a href="https://www.taylorfrancis.com/books/9780429092954">survive many months</a> in the environment.</p>
<p>Humans become infected when they ingest these oocysts, which are in the soil and dust in <a href="https://pubmed.ncbi.nlm.nih.gov/23849140/">places where cats have defecated</a>, especially sandpits, vegetable gardens or kitty litter. </p>
<p>Humans can also become infected from eating undercooked meat, if those farm animals have come into contact with cat-shed oocysts. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-what-bugs-can-you-catch-from-your-pets-40954">Health Check: what bugs can you catch from your pets?</a>
</strong>
</em>
</p>
<hr>
<p>Up to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109627/">one-third</a> of people globally are infected with <em>T. gondii</em>, most without knowing it. Australian studies have reported infection rates between <a href="https://obgyn.onlinelibrary.wiley.com/doi/abs/10.1111/j.1479-828X.1986.tb01582.x">22% and 66%</a>.</p>
<p>Once infected, about <a href="https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(04)16412-X.pdf">10%</a> of people develop illness; the other 90% have no symptoms. </p>
<p>Based on overall infection rates and Australia’s population size, we estimate there are more than 125,000 new infections in Australia each year. </p>
<p>Of these, around 12,500 people get sick, mostly with non-specific, flu-like symptoms that resolve within a couple of weeks; 650 require hospitalisation, and 50 die, with these more serious cases often experiencing <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2011.0588">brain swelling and neurological symptoms</a>.</p>
<p>People with compromised immune systems, such as those with cancer or HIV, are at <a href="https://www.frontiersin.org/articles/10.3389/fmicb.2017.00389/full">highest risk</a>. </p>
<figure class="align-center ">
<img alt="The parasite _Toxoplasma gondii_" src="https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363186/original/file-20201013-15-8gyklm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Toxoplasmosis is caused by the parasite <em>Toxoplasma gondii</em>.</span>
<span class="attribution"><span class="source">Yale Rosen/Flickr</span></span>
</figcaption>
</figure>
<p>Pregnant women who become <a href="https://academic.oup.com/cid/article/18/6/853/309419">infected for the first time</a> can miscarry, or their babies may be born with <a href="https://link.springer.com/article/10.1007/s10393-019-01405-7?fbclid=IwAR0JVqIvlNW6auH1KM6se3baY0cvr2nhiGubjAUfpNvldaqW-pdD6u24T9I">congenital deformities</a>. </p>
<p>Based on <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1991.tb121307.x">reported</a> and estimated <em>T. gondii</em> <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1991.tb121307.x">infection rates in newborns</a>, about 240 infected babies are born in Australia each year. </p>
<p>More than <a href="https://www.taylorfrancis.com/books/9780429092954">20%</a>, or about 50 of these babies, will have symptoms that require life-long care, including impaired vision or hearing, and intellectual disabilities. Another 90 babies will develop symptoms, usually related to vision or hearing, later in life. </p>
<figure class="align-center ">
<img alt="A woman holds her pregnant belly." src="https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363188/original/file-20201013-13-1fieeac.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Toxoplasmosis carries unique risks for pregnant women.</span>
<span class="attribution"><span class="source">Freestocks/Unsplash</span></span>
</figcaption>
</figure>
<h2>Long-term impacts of latent infection</h2>
<p>Even if the initial infection causes little illness, the <em>T. gondii</em> parasite stays with us for life, encased in a cyst, often in the brain. These “latent” infections may <a href="https://www.scientificamerican.com/article/rage-disorder-linked-with-parasite-found-in-cat-feces/">affect our mental health</a> and behaviour, such as delaying our reaction times. </p>
<p>Many studies have found people with <em>T. gondii</em> infection are <a href="https://bmcinfectdis.biomedcentral.com/articles/10.1186/1471-2334-2-11">more likely to have a car accident</a>. A <a href="https://www.cambridge.org/core/journals/psychological-medicine/article/driving-us-mad-the-association-of-toxoplasma-gondii-with-suicide-attempts-and-traffic-accidents-a-systematic-review-and-metaanalysis/70570A7C590118DD547C6182802FF606">review of several studies</a> found if there were no <em>T. gondii</em> infections, car accident rates would theoretically be 17% lower.</p>
<p><em>T. gondii</em> infections also appear more common in people with mental health disorders such as schizophrenia, and in people who attempt suicide. Reviews across many studies suggest that without <em>T. gondii</em> infections, there could be 10% fewer <a href="https://doi.org/10.1017/S0033291719000813">suicides</a> and 21% fewer <a href="https://www.sciencedirect.com/science/article/pii/S016758771400347X?via%3Dihub">schizophrenia</a> diagnoses. </p>
<p>There’s still debate over whether the parasite <em>causes</em> car accidents and mental health disorders, or whether the association is explained by another shared factor. But it is possible <em>T. gondii</em> infection is a risk factor for these issues, in the same way <a href="https://www.heartfoundation.org.au/heart-health-education/are-you-at-risk-of-heart-disease?gclid=CjwKCAjww5r8BRB6EiwArcckC2IYHvDluDKoW6monTCdHehlqmDf09htTJTsFPu8SVqoX7d8GuhT6BoC25YQAvD_BwE">smoking is a risk factor for heart attacks</a>. </p>
<p>Scientists are still discovering how <em>T. gondii</em> influences the brain, but studies on rodents suggest it may involve <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0023866">changed brain chemistry</a> or <a href="https://theconversation.com/is-the-brain-parasite-toxoplasma-manipulating-your-behavior-or-is-your-immune-system-to-blame-116718">inflammation</a>. </p>
<h2>Putting it all together</h2>
<p>If we accept <em>T. gondii</em> infections do increase the risk of car accidents, suicides and schizophrenia, then considering the incidence of these accidents and health issues in Australia, without <em>T. gondii</em>, we estimate we could potentially avoid: </p>
<ul>
<li><p>200 deaths and 6,500 hospitalisations due to car accidents </p></li>
<li><p>300 suicides and 4,500 suicide attempts</p></li>
<li><p>800 schizophrenia diagnoses each year.</p></li>
</ul>
<p>Combining deaths from car accidents and suicide with the 50 deaths from acute toxoplasmosis, we reach a total of 550 deaths related to <em>T. gondii</em> infection per year. </p>
<p>The hospitalisation total for <em>T. gondii</em> includes 650 for acute toxoplasmosis, 50 for congenitally infected babies, 6,500 for car accidents, and 800 for schizophrenia. We didn’t include hospitalisations for suicide attempts, as we didn’t have statistics on that. So this could be a conservative estimate, notwithstanding the fact there are other factors involved in car accidents and mental health issues.</p>
<h2>Cat scratch and roundworm</h2>
<p><a href="https://wwwnc.cdc.gov/eid/article/12/3/05-0931_article">Cat scratch disease</a> is a bacterial infection (<em>Bartonella henselae</em>) that people can contract if bitten or scratched by an infected cat. </p>
<p>Typical symptoms include sores, fevers, aches and swollen glands. But <a href="http://www.ajtmh.org/content/journals/10.4269/ajtmh.20-0088">more serious symptoms</a>, such as inflammation of heart tissue, cysts in the organs and loss of vision, can also occur.</p>
<p>Prevalence figures are not available in Australia, but based on <a href="https://ajph.aphapublications.org/doi/10.2105/AJPH.83.12.1707">rates in the United States and Europe</a>, where cat ownership patterns and cat infection rates are similar, we estimate at least 2,700 Australians get sick annually from cat scratch disease, and 270 are hospitalised.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/your-cat-has-toxoplasmosis-and-youre-worried-join-the-club-9365">Your cat has toxoplasmosis and you're worried? Join the club</a>
</strong>
</em>
</p>
<hr>
<p>Cat roundworm is a parasitic infection (<em>Toxocara cati</em>) that people and other animals can contract by accidentally consuming the parasite’s egg, which infected cats shed in their poo.</p>
<p>Most cat roundworm infections <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304401711004869">cause mild symptoms</a>, but the migration of the larvae through the body can cause tissue damage, which can be serious if it occurs in a place like the eye or heart. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363194/original/file-20201013-15-17sdrvp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An adult cat round worm.</span>
<span class="attribution"><span class="source">Beentree/Wikimedia commons</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What can we do?</h2>
<p>Some <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320716309223">700,000</a> feral cats and another <a href="https://www.publish.csiro.au/wr/WR19174">2.7 million</a> pet cats roam our towns and suburbs acting as reservoirs of these diseases. </p>
<p>There are no human vaccines for these diseases. Treatment for <em>T. gondii</em> infection in cats isn’t <a href="http://www.abcdcatsvets.org/toxoplasma-gondii-infection-2/">considered useful</a> because cats usually shed the oocysts without the owner even realising the cat has the parasite. Cats can be treated to rid them of roundworm, but treatment for <em>B. henselae</em> (the bacteria that causes cat scratch) may not be <a href="http://www.abcdcatsvets.org/feline-bartonellosis/">effective</a>.</p>
<p>But if you’re a cat owner, there are some things you can do. Keeping pet cats indoors or in a securely contained outdoor area could reduce the chance your pet will contract or pass on a disease-causing pathogen. </p>
<figure class="align-center ">
<img alt="A cat sits on the windowsill, looking out onto the street." src="https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/363193/original/file-20201013-13-t9gsbu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">If cats are always kept indoors they have a low risk of catching and spreading the disease.</span>
<span class="attribution"><span class="source">Jaana Dielenberg</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Cats should be kept out of veggie gardens and children’s sandpits. Washing hands after handling kitty litter and gardening, and washing vegetables thoroughly, can also reduce the risk of transmission. </p>
<p>As <em>T. gondii</em> can be contracted from infected meat, cooking meat well before eating, and not feeding raw meat to pets, can also help. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-cat-one-year-110-native-animals-lock-up-your-pet-its-a-killing-machine-138412">One cat, one year, 110 native animals: lock up your pet, it's a killing machine</a>
</strong>
</em>
</p>
<hr>
<p>The urban feral cat resevoir could be reduced by preventing access to food sources such as farm sites, rubbish bins and tips. We could do this with improved waste management and fencing. </p>
<p>People <a href="https://theconversation.com/why-australia-needs-to-kill-cats-116654">shouldn’t feed feral cats</a>, as this can lead to cat colony formation, where infection rates are also higher. </p>
<p>Pet cats should also be <a href="https://theconversation.com/how-desexing-cats-saves-lives-19914">desexed</a> to prevent unwanted litters that end up as free-roaming ferals.</p>
<p>These steps would cost us and our pet cats little, but could prevent unnecessary impacts on our health and well-being.</p><img src="https://counter.theconversation.com/content/147910/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Legge receives funding from the Nationa Environmental Science Program's Threatened Species Recvery Hub.</span></em></p><p class="fine-print"><em><span>Chris Dickman receives funding from the National Environmental Science Program's Threatened Species Recovery Hub and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jaana Dielenberg receives funding from the Australian Government’s National Environmental Science Program through the Threatened Species Recovery Hub.</span></em></p><p class="fine-print"><em><span>John Read CEO and a shareholder in Thylation Operations <a href="http://www.thylation.com">www.thylation.com</a> that is developing Felixers .to control feral cats</span></em></p><p class="fine-print"><em><span>John Woinarski receives funding from the National Environmental Science Program through the Threatened Species Recovery Hub</span></em></p><p class="fine-print"><em><span>Pat Taggart is a Research Officer for the Vertebrate Pest Research Unit within the Department of Primary Industries NSW. </span></em></p><p class="fine-print"><em><span>Tida Nou receives funding from the Australian Government's National Environmental Science Program though the Threatened Species Recovery Hub.</span></em></p>
When cats were introduced to Australia, they brought several diseases with them. These diseases are taking a big toll on human health and the economy — but there are things we can do.
Sarah Legge, Professor, Australian National University
Chris Dickman, Professor in Terrestrial Ecology, University of Sydney
Jaana Dielenberg, University Fellow, Charles Darwin University. Science Communication Manager, The University of Queensland
John Read, Associate Lecturer, Ecology and Environmental Sciences, University of Adelaide
John Woinarski, Professor (conservation biology), Charles Darwin University
Pat Taggart, Adjunct Fellow, University of Adelaide
Tida Nou, Project officer, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/138405
2020-06-03T12:15:15Z
2020-06-03T12:15:15Z
Parasitic worms in your shellfish lead a creepy but popular lifestyle
<figure><img src="https://images.theconversation.com/files/336189/original/file-20200519-152344-gc94zt.jpg?ixlib=rb-1.1.0&rect=1%2C2%2C697%2C520&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Parasites do very well for themselves, which is why they are so common in the animal kingdom.</span> <span class="attribution"><a class="source" href="http://www.marinespecies.org/introduced/aphia.php?p=image&pic=99515">Geoffrey Read</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>If you’re an oyster lover, seeing a shaggy worm slither across your appetizer is revolting – even though such worms are harmless to people. An internet search using the keywords “oyster” and “worm” will bring up a large cache of images, each one less palatable than the next. </p>
<p>As a <a href="https://scholar.google.com/citations?user=DtgT_YIAAAAJ&hl=en">biologist</a>, I study invasive species including these mud blister worms. Despite their high gross-out factor, their parasitic lifestyles are fascinating. While parasites do cause harm to their hosts, they are also a crucial piece of the planet’s ecosystem.</p>
<h2>Shell-boring worms</h2>
<p>Mud blister worms belong to a larger group of segmented worms, collectively known as <a href="https://www.smithsonianmag.com/science-nature/14-fun-facts-about-marine-bristle-worms-180955773/">polychaetes</a>. “Poly” means many and “chaete” means bristles in ancient Greek. Mud blister worms are one of many species that burrow into the shells of animals like oysters, abalone and scallops, where they spend their entire adult life.</p>
<p>Considering the shells of oysters and scallops are made up of calcium carbonate, which has limited nutritional value, it might seem an odd location for a worm infestation. But rather than feeding on the shell itself, these worms create an amazing network of tunnels within the shell’s matrix, using it as a house rather than a food source. </p>
<figure>
<img src="https://cdn.theconversation.com/static_files/files/1045/vl6Q3M.gif?1589988051" width="100%">
<figcaption><span class="caption">This worm, <i>Polydora cornutanhas</i>, uses tentacles to snag passing algae and food particles, while its body remain safely ensconced in the shell of its host organism.</span></figcaption>
</figure>
<p>The worms feed by protruding their tentacles out of tiny openings in the shell, where they capture food particles from the surrounding seawater. Unlike other parasites, which feed directly on their hosts, mud blister worms invade their hosts’ outer covering and must have food delivered to them for survival.</p>
<p>How many worms can a single shell harbor? I once counted more than 120 worms emerging from the shell of a heavily infested Pacific oyster. The surface of the oyster looked like any other, but once it was immersed into a special irritating solution, a stunning number of worms began to rise up, just like a creature in a zombie film. </p>
<h2>Sibling cannibalism</h2>
<p>Adult worms are sedentary, meaning they remain within the tunnels they create and do not actively leave their quarters. The offspring of these worms, however, are free-swimming larvae, which are released into the water column after birth and <a href="https://doi.org/10.1007/s00227-013-2388-0">disperse the species throughout the ocean</a>. </p>
<p>After mating, females produce an egg case containing thousands of eggs, some of which hatch into larvae and some of which do not hatch at all. The latter become “nurse eggs,” or food that <a href="https://doi.org/10.1007/s00227-013-2388-0">nourish the developing offspring</a>. This is where things get interesting. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/zqXuh82_D6c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">It’s ‘eat or be eaten’ among larvae.</span></figcaption>
</figure>
<p>In one of my earliest <a href="http://hdl.handle.net/10019.1/96594">studies of these worms</a>, my colleagues and I found that in situations where nurse eggs were depleted, larger larvae often viciously attacked and cannibalized their siblings within the egg case. In other situations, the cannibalism occurred even in the presence of nurse eggs. </p>
<p>The mother is in charge of releasing the larvae, using a <a href="https://doi.org/10.1016/j.jembe.2014.07.012">pair of tentacles to rupture the egg</a> cases at a time of her choosing. Because she is solely responsible for liberating the offspring from the egg case, she has complete <a href="https://doi.org/10.1016/j.jembe.2014.07.012">control over which siblings live and which die</a>. </p>
<p>Sibling cannibalism, as brutal as it sounds, is actually quite common across the <a href="https://doi.org/10.1016/j.aaf.2016.12.001">animal</a> <a href="https://doi.org/10.1111/j.1439-0310.2010.01792.x">kingdom</a>. Sand tiger sharks, for example, exhibit a similar behavior where <a href="https://doi.org/10.1098/rsbl.2013.0003">siblings fight each other to the death</a> in the womb although, in this case, the mother shark does not exert as much control as a mud blister worm matriarch does. </p>
<p>The evolutionary significance of sibling cannibalism – and why it seems to have emerged in animals as far apart on the tree of life as worms and sharks – is still not fully known and remains an <a href="https://doi.org/10.1073/pnas.1911677117">active area of evolutionary biology research</a>. </p>
<h2>Threats to humans and the aquaculture industry</h2>
<p>Luckily, shell-boring worms pose no threat to humans. Aside from an unexpected protein boost, accidental consumption will not lead to any health problems. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/336513/original/file-20200520-152338-4ui98g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Oysters under siege.</span>
<span class="attribution"><a class="source" href="https://youtu.be/zqXuh82_D6c">Federal University of Recôncavo da Bahia and State University of Santa Cruz</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>However, these worms are <a href="https://www.adfg.alaska.gov/static/species/disease/pdfs/bivalvediseases/shellboring_polychaetes.pdf">notorious pests in the aquaculture industry</a>. Heavy infestations can cause reduced growth in shellfish, because the mollusk must <a href="https://www.int-res.com/abstracts/aei/v7/n2/p147-166/">divert energy from growth to shell repair</a>. In addition, the meat of infested oysters has been reported as having a <a href="http://masgc.org/projects/details/maximizing-the-return-on-investment-of-oyster-aquaculture-by-managing-mud-b">more “watery” consistency</a> than uninfested oysters. Together, these effects result in a commercial loss for aquaculture farms. </p>
<p>In past years, scientist have proposed the <a href="https://doi.org/10.1016/j.aquaculture.2010.10.031">use of chemical compounds</a> and the <a href="https://doi.org/10.1016/0044-8486(95)01212-5">heat-shocking of oysters</a> to control the worms, but there has yet to be a silver bullet for eradication. </p>
<p>Perhaps one of the most overlooked facts in zoology is that parasitism is the <a href="https://doi.org/10.1016/j.biocon.2010.10.025">most predominant lifestyle on Earth</a> and plays an important role in maintaining ecosystems by <a href="https://doi.org/10.1007/s10393-004-0028-3">stabilizing food webs and regulating population sizes</a>. Like many marine invertebrates, the larvae of these worms serve as planktonic food for animals higher up in the food chain, thereby <a href="https://doi.org/10.1093/icb/icq037">contributing to the overall structure of the marine community</a>. </p>
<p>So next time you are at a seafood restaurant and you order a couple of raw oysters, try breaking apart the shells – perhaps after you’ve finished eating. You might discover a few hidden freeloaders. </p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=youresmart">You can read us daily by subscribing to our newsletter</a>.]</p><img src="https://counter.theconversation.com/content/138405/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Davinack does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Mud blister worms make their homes in the shells of oysters and other shellfish, where they weaken their hosts.
Andrew Davinack, Assistant Professor of Biology, Clarkson University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/131186
2020-02-06T17:00:29Z
2020-02-06T17:00:29Z
Obama nungara: how a flatworm from Argentina jumped the Atlantic and invaded France
<figure><img src="https://images.theconversation.com/files/313665/original/file-20200205-149742-18ajp1o.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Obama nungara_ in a garden in France.</span> <span class="attribution"><a class="source" href="http://dx.doi.org/10.7717/peerj.8385/fig-3">Photo by Pierre Gros</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>An unfortunate consequence of globalisation is the introduction of exotic species into countries where they are not native. In some cases, such species can proliferate and become invasive. In France, the most noted invasions in recent years have been the <a href="https://theconversation.com/the-city-loving-devil-bug-lands-in-paris-and-continues-its-march-around-the-world-94145">devil bug</a> and the <a href="https://en.wikipedia.org/wiki/Asian_hornet">Asian hornet</a>. </p>
<p>While nonnative insects are quickly spotted because they fly during the day, less visible are invasive flatworms, also known as land planarians. They’re generally nocturnal, soil-dwelling creatures, and their presence is often discovered only when they’re well established in their host country.</p>
<p>In the UK, the <a href="https://en.wikipedia.org/wiki/New_Zealand_flatworm">New Zealand flatworm</a>, <em>Arthurdendyus triangulatus</em>, has invaded England, Scotland and Northern Ireland, and is highly abundant. This species is the only land planarian <a href="http://data.europa.eu/eli/reg_impl/2019/1262/oj">officially declared to be invasive</a> as invasive by the European Union. In the United States, <a href="https://peerj.com/articles/4672/">hammerhead flatworms are common</a> in the south and even in the north, with a <a href="http://dx.doi.org/10.11646/zootaxa.4656.3.13">first report in Canada</a>. In addition, the infamous New Guinea flatworm, <em>Platydemus manokwari</em> – the only one listed in the <a href="http://www.issg.org/pdf/publications/worst_100/english_100_worst.pdf">“100 world’s worst invasive alien species”</a> – is now <a href="https://peerj.com/articles/1037/">rapidly colonising Florida</a>. In Australia, many native flatworms are common, but the New Guinea flatworm <a href="https://peerj.com/articles/1037/">is also an invader</a>.</p>
<p>Several species of land planarians have <a href="https://peerj.com/articles/297/">invaded France and Europe</a> in recent decades. The most spectacular are the bipaliines, or <a href="https://peerj.com/articles/4672/">“hammerhead worms”</a>, which can reach 1 metre in length. In France, they mainly occur in the southernmost departments. However, other species of invasive terrestrial flatworms possibly pose a greater threat to the soil fauna.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=341&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=341&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=341&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=429&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=429&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313671/original/file-20200205-149747-1how2c6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=429&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Citizen science: photographs of <em>Obama nungara</em> sent by non-professionals from many places in France.</span>
<span class="attribution"><span class="source">Various authors, layout by Jean-Lou Justine</span></span>
</figcaption>
</figure>
<h2>More than 1,000 reports of land flatworms in France</h2>
<p>Our team has just <a href="https://peerj.com/articles/8385">published the results</a> of seven years of work on the occurrence of land flatworms in France, based on participatory science. Scientists cannot visit every garden, but citizens have made an extraordinary contribution by sending more than <a href="https://sites.google.com/site/jljjustine/que-faire-si-je-trouve-un-plathelminthe">1,000 reports</a>. Of these, the most striking result is that more than half of these reports, 530 exactly, concerned only one species of terrestrial flatworm.</p>
<p>This most abundant species is the land planarian <em>Obama nungara</em>. At the start of our study, it had no name… because it had never been described by scientists. In 2016, researchers from Brazil, Spain and the United Kingdom gave it its <a href="https://doi.org/10.1111/zoj.12358">full name</a>, <em>Obama nungara</em>. The <a href="https://doi.org/10.1111/zsc.12019">name of the genus</a>, <em>Obama</em>, had been created a few years earlier based on two words of Brazil’s Tupi language: <em>oba</em> – leaf, and <em>ma</em> – animal, alluding to the flattened leaf-like form of the animal. (That the genus shares the name of a former US president is pure coincidence.)</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313666/original/file-20200205-149789-14z5bzj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A map of France showing departments invaded by <em>Obama nungara</em>.</span>
<span class="attribution"><span class="source">Jessica Thévenot</span></span>
</figcaption>
</figure>
<p>Where can <em>Obama nungara</em> be found in France? Unfortunately, the simple answer is almost everywhere. The species is present in three-quarters of the French departments. We now have precise maps of the present distribution of the flatworm thanks to the numerous reports from citizen scientists. The most affected departments are those of the Atlantic border, while <em>Obama nungara</em> is less abundant in the northeast quarter of France and the mountainous regions. Why? Probably because land planarians do not flourish in climatic extremes – dry hot summers and freezing cold winters – whereas the mild, moist maritime climate of the country’s Atlantic coast suits them perfectly.</p>
<p>The species was first found in Brazil, and initially scientists thought that this was its country of origin. Researchers then turned to more sophisticated methods, using molecular markers – the famous “barcode” – to determine its geographic origin. From the results of these analyses, the population that has invaded France and the other countries of Europe was found to <a href="https://peerj.com/articles/8385">come from Argentina</a>, not from Brazil. In fact, the population of <em>Obama nungara</em> in Brazil has not left this country.</p>
<h2>How did <em>Obama nungara</em> get from Argentina to Europe?</h2>
<p><a href="https://en.wikipedia.org/wiki/Geoplanidae">Land flatworms</a> are rather fragile, soft-bodied soil animals with very limited mobility. However, humans have given them a great way to travel all over the planet – together with the soil in potted plants. Most likely, some <em>Obama nungara</em> travelled as stowaways in soil from a commercial nursery in Argentina, and subsequently carried by ship to a port in Europe. It reminds us of the famous <a href="https://en.wikipedia.org/wiki/Argentine_ant">Argentine ant</a>, which invaded the Mediterranean regions of Europe only a few decades ago.</p>
<hr>
<p>
<em>
<strong>
À lire aussi :
<a href="https://theconversation.com/yes-giant-predatory-worms-really-are-invading-france-97106">Yes, giant predatory worms really are invading France</a>
</strong>
</em>
</p>
<hr>
<p>The species is now well established in several countries, such as <a href="https://doi.org/10.1111/zoj.12358">Spain</a>, Portugal, Italy, <a href="https://doi.org/10.26496/bjz.2019.29">Belgium</a>, and the <a href="https://doi.org/10.1111/zoj.12358">United Kingdom</a>. Only in France has a <a href="https://peerj.com/articles/8385">detailed study of the distribution</a> of the species been made. How did this animal that has limited mobility disperse to all these countries? Again, via the international commercial plant trade exporting potted plants to garden centres in various countries. </p>
<p>Commercial garden centres and nurseries provide an ideal mechanism for <em>Obama nungara</em> to be inadvertently dispersed by garden enthusiasts when they unknowingly purchase potted plants containing egg cocoons or mature specimens of the land planarian. Once in an urban garden, the animal can thrive and proliferate, and over time can move into neighbouring gardens or adjoining farmland.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313667/original/file-20200205-149747-18d98j3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Proliferation of <em>Obama nungara</em> in a garden.</span>
<span class="attribution"><span class="source">by Sylvain Petiet</span></span>
</figcaption>
</figure>
<h2>Why did <em>Obama nungara</em> proliferate?</h2>
<p>Scientists have a <a href="https://doi.org/10.2307/2265769">general rule for invasions</a>: if species are moved to a new environment, 1 in 10 succeeds in establishing itself. Among those that do, only 1 in 10 will proliferate exponentially, often because it has no natural predators in its new country. <em>Obama nungara</em> is among the latter group and is therefore an <a href="https://en.wikipedia.org/wiki/Invasive_species">invasive alien species</a> (IAS). Being small, brown and mainly nocturnal, the species is unobtrusive and readily overlooked. It reproduces very quickly and makes “cocoons” – which are small, hardy black balls that are even more difficult to see – and each cocoon contains up to several embryos.</p>
<p>Importantly, <em>Obama nungara</em> has no natural enemies in Europe. While these soft-bodied terrestrial flatworms may seem to be fragile, they are protected by secretions containing a sophisticated chemical arsenal that generally makes them repugnant to potential predators such as birds.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313668/original/file-20200205-149802-592ytu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Adult <em>Obama nungara</em> and its cocoon, which is reddish at first then turns black.</span>
<span class="attribution"><span class="source">by Pierre Gros</span></span>
</figcaption>
</figure>
<p>Like other land planarians, <em>Obama nungara</em> is a top-level predator, and eats soil-dwelling animals such as earthworms and snails. Soil is a complex environment, with hundreds of species interacting. With <em>Obama nungara</em>, humans have inadvertently introduced a wolf into the flock of sheep. It is voracious and reproduces rapidly, and can swiftly increase in numbers.</p>
<p>Do we know what the impact of <em>Obama nungara</em> is in our gardens? Not yet. How many, and which prey species does an <em>Obama nungara</em> eat? We presently know very little. What we do know, however, is that the <a href="https://peerj.com/articles/8385">species is proliferating</a> and therefore most certainly consumes a lot of soil animals. Counts have allowed us to estimate the production of individuals, per reproduction, at 1,000 worms per hectare per day… at the end of the year, even allowing for natural mortality in the flatworm populations, a lot of land planarians survive to eat other soil animals.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=584&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=584&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=584&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=733&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=733&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313669/original/file-20200205-149747-afqtf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=733&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Obama nungara</em> killing and eating an earthworm.</span>
<span class="attribution"><span class="source">by Pierre Gros</span></span>
</figcaption>
</figure>
<h2>What can we do?</h2>
<p>Overseas experiences suggest that checking imported plants for the presence of land flatworms at the port of entry and in distribution centres is at present difficult, impracticable and costly, and so they have not been widely adopted. Unfortunately, there is little that can be done to limit the spread of such species once they have been established. Invasive land flatworms may take a decade or more before they become so numerous and widespread that they are noticed, by which time it is too late to adequately control them. Furthermore, there are no chemicals approved or authorised for combating them, and manually collecting and killing them found in gardens seems to be <a href="https://doi.org/10.7717/peerj.8385">ineffective</a>.</p>
<p>Scientists will continue to map the distribution of the flatworm, and the help of citizen scientists with this task is crucial. To better assess the ecological impact of <em>Obama nungara</em>, we will now try to determine the full spectrum of prey it consumes.</p><img src="https://counter.theconversation.com/content/131186/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jean-Lou Justine received grants from the Muséum National d'Histoire Naturelle, Paris. He is one of the Academic Editors of PeerJ (<a href="https://peerj.com/">https://peerj.com/</a>), the scientific journal in which several of the studies cited here were published.</span></em></p><p class="fine-print"><em><span>Leigh Winsor ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'a déclaré aucune autre affiliation que son organisme de recherche.</span></em></p>
The predatory flatworm Obama nungara travelled in potted plants from Argentina to Europe, where it’s distrupting soil ecosystems. Now, citizen-scientists are helping map their distribution.
Jean-Lou Justine, Professeur, Muséum national d’histoire naturelle (MNHN)
Leigh Winsor, Adjunct Senior Research Fellow, James Cook University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/121489
2019-11-18T03:27:08Z
2019-11-18T03:27:08Z
What are parasites and how do they make us sick?
<figure><img src="https://images.theconversation.com/files/302081/original/file-20191118-66917-1qcf7by.jpg?ixlib=rb-1.1.0&rect=53%2C26%2C6000%2C3961&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Giardia is an example of a parasite you don't want to catch. Symptoms can include diarrhoea, abdominal cramps, fatigue, weakness and weight loss.</span> <span class="attribution"><span class="source">From shutterstock.com</span></span></figcaption></figure><p>A <a href="https://www.cdc.gov/parasites/about.html">parasite</a> is an organism that lives in or on an organism of another species.</p>
<p><a href="https://www.cdc.gov/parasites/about.html">Three main classes</a> of parasites can cause disease in humans: protozoa, helminths, and ectoparasites. Protozoa and helminths largely affect the gut, while ectoparasites include lice and mites that can attach to or burrow into the skin, staying there for long periods of time.</p>
<p>The majority of protozoa and helminths tend to be non-pathogenic (meaning they don’t cause disease) or result in very mild illness. Some, however, can cause severe disease in humans. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-the-low-down-on-worms-and-how-to-get-rid-of-them-36486">Health check: the low-down on 'worms' and how to get rid of them</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://en.wikipedia.org/wiki/Fecal%E2%80%93oral_route">Faecal-oral transmission</a>, where parasites found in the stool of one person end up being swallowed by another person, is the most common mode of transmission of parasitic protozoa and helminths. </p>
<p>The initial symptoms tend to be gastrointestinal symptoms like diarrhoea. When parasites invade the red blood cells or organs, the consequences can become more serious. </p>
<h2>Protozoa</h2>
<p>Protozoa are tiny single-celled organisms that multiply inside the human body. </p>
<p>The protozoa giardia, for example, has a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC88984/">classic two-stage life cycle</a>. In the first stage, called trophozoite, the parasite swims around and consumes nutrients from the small bowel. In the second stage it develops into a non-moving cyst.</p>
<p>Cysts excreted in faeces can contaminate the water supply, and ingesting contaminated food or water results in transmission. Close human to human contact and unsanitary living conditions can promote transmission.</p>
<p>Symptoms of <a href="https://www1.health.gov.au/internet/publications/publishing.nsf/Content/ohp-enhealth-manual-atsi-cnt-l%7Eohp-enhealth-manual-atsi-cnt-l-ch1%7Eohp-enhealth-manual-atsi-cnt-l-ch1.5">giardia</a> can include severe or chronic diarrhoea, abdominal cramps, fatigue, weakness and weight loss.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302085/original/file-20191118-66945-12388mf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Once the parasite has been diagnosed, it can usually be treated effectively.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>Other important protozoa are the plasmodium species. Plasmodium develop in mosquitoes, and infected mosquitoes transmit the parasite to humans by biting them. Plasmodium destroys red blood cells which impacts organ function and causes a disease in humans known as malaria. </p>
<p>Malaria causes the most deaths of all parasitic diseases. In 2017 it was estimated malaria resulted in <a href="https://www.who.int/gho/malaria/epidemic/deaths/en/">435,000 deaths globally</a>, most of them young children in sub-Saharan Africa. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-our-red-blood-cells-keep-evolving-to-fight-malaria-96117">How our red blood cells keep evolving to fight malaria</a>
</strong>
</em>
</p>
<hr>
<h2>Helminths</h2>
<p>Helminths, often called worms, are large multicellular organisms usually visible to the naked eye in their adult stages. As a general rule, <a href="https://www.cdc.gov/parasites/about.html">helminths cannot multiply</a> inside the human body. </p>
<p>One major group of helminths are flatworms. Flatworms literally have <a href="https://www.britannica.com/animal/flatworm">flattened soft bodies</a>. Their digestive cavity has only one opening for both the ingestion and removal of food. It’s thought <a href="https://www.britannica.com/animal/flatworm">80% of flatworms</a> are parasitic.</p>
<p>Tapeworms are one type of flatworm. The <a href="https://www1.health.gov.au/internet/publications/publishing.nsf/Content/ohp-enhealth-manual-atsi-cnt-l%7Eohp-enhealth-manual-atsi-cnt-l-ch1%7Eohp-enhealth-manual-atsi-cnt-l-ch1.5">most common human tapeworm</a> in Australia is the dwarf tapeworm. The prevalence of dwarf tapeworm in isolated communities in northwest Australia is estimated to be <a href="https://irjponline.com/admin/php/uploads/1625_pdf.pdf">around 55%</a>. </p>
<p>Infestation in humans comes from ingesting dwarf tapeworm eggs. Transmission from <a href="https://www.cdc.gov/parasites/hymenolepis/faqs.html">person to person</a> occurs via the faecal-oral route. As with other parasites, the major risk factors are poor sanitation and shared living quarters. Symptoms include diarrhoea, abdominal pain, weight loss and weakness.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302102/original/file-20191118-66921-7ra1wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some parasites, like plasmodium, which causes malaria, are transmitted to humans via mosquito bites.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>Another major group of helminths are nematodes, commonly known as roundworms. Nematodes are the <a href="https://en.wikipedia.org/wiki/Nematode">most numerous</a> multicellular animals on earth and can be found in almost every environment. Unlike flatworms, they do have a digestive system that extends from the mouth to the anus. </p>
<p>More than <a href="https://www.sciencedirect.com/science/article/abs/pii/S1471492203002447">50% of the world’s population</a> are thought to be affected at one point during their life by at least <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517378/">one of six main classes</a> of nematodes. </p>
<p>The eggs or larvae of these nematodes usually develop in soil before being transmitted to the human host. For this reason these nematodes are often called soil-transmitted helminths. A good example are hookworms which <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517378/">infest humans</a> by penetrating the skin from contaminated soil. So wearing <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003285">appropriate footwear</a> is an important way to prevent hookworm transmission.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-parasite-attack-on-darwins-finches-means-theyre-losing-their-lovesong-118586">A parasite attack on Darwin's finches means they're losing their lovesong</a>
</strong>
</em>
</p>
<hr>
<p>The <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517378/">pinworm</a> Enterobius vermicularis has a different life cycle to the other nematodes. Pinworm larvae develop in eggs on the skin near the anus or under the fingernails.</p>
<p>Pinworm, also known as threadworm, is the <a href="https://www.healthdirect.gov.au/threadworms-pinworms">most common helminth parasite</a> in Australia. Itching around the anus is a major symptom of pinworm. Pinworms are easily passed from one person to another and it’s common for entire families to be infested.</p>
<h2>Ectoparasites</h2>
<p>The term <a href="https://www.cdc.gov/parasites/about.html">ectoparasites</a> generally refers to organisms such as ticks, fleas, lice and mites that can attach or burrow into the skin and remain there for long periods of time. </p>
<p><a href="https://www.healthdirect.gov.au/scabies">Scabies</a>, for example, a contagious skin disease marked by itching and small raised red spots, is caused by the human itch mite. Scabies usually is spread by direct, prolonged, skin-to-skin contact. </p>
<p><a href="https://www.healthdirect.gov.au/head-lice">Head lice</a> are small, wingless insects that live and breed in human hair and feed by sucking blood from the scalp. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302100/original/file-20191118-66917-h8c1hp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Head lice, a type of ectoparasite, are common in children.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<h2>Prevention and treatment</h2>
<p>Some parasites can lie dormant for extended periods of time. This can make the diagnosis of parasitic infestation challenging as there may be no symptoms, or symptoms can be vague and non-specific. </p>
<p>The good news is we have very good medications to treat many different kinds of parasites once they’ve been diagnosed. These medications do have side effects but on the whole are <a href="https://www.mayoclinicproceedings.org/article/S0025-6196(11)60055-4/fulltext">very effective</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/six-human-parasites-you-definitely-dont-want-to-host-17332">Six human parasites you definitely don't want to host</a>
</strong>
</em>
</p>
<hr>
<p>Treatment of parasites should be accompanied by preventative strategies such as improving sanitation and ensuring the availability of appropriate clothing and footwear in affected areas.</p>
<p>The <a href="https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections">World Health Organisation</a> has recommended periodic medical treatment (deworming) to all at-risk people living in endemic areas, but widespread implementation remains challenging.</p><img src="https://counter.theconversation.com/content/121489/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
There are three classes of parasites that can cause disease in humans. Here’s what you need to know.
Vincent Ho, Senior Lecturer and clinical academic gastroenterologist, Western Sydney University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/123905
2019-10-25T12:31:29Z
2019-10-25T12:31:29Z
Not all candy is candy – at least for tax purposes
<figure><img src="https://images.theconversation.com/files/296035/original/file-20191008-128686-3uwk8f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A convenience store worker hands out candy to trick-or-treaters on Halloween.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Halloween-New-York/eaed15e3d36e4f28878a4b2c17355787/2/0">AP Photo/Wong Maye-E</a></span></figcaption></figure><p>Halloween shoppers have many delicious decisions to make before trick-or-treaters show up at their doors. And in many states, those choices will change how much tax they pay.</p>
<p>In Illinois, for example, locals pay a higher state sales tax rate – <a href="http://www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=582&ChapterID=8">6.25% versus 1%</a> – on Reese’s, gummi worms and Hershey’s milk chocolate bars than on Twix, Twizzlers and Hershey’s Cookies ‘n’ Creme bars.</p>
<p>Trying to distinguish between these two groups may be devilishly hard for shoppers, but to the <a href="https://www2.illinois.gov/rev/research/taxinformation/sales/Pages/rot.aspx">Illinois Department of Revenue</a>, the difference is simple. The first three treats are candy, and <a href="https://www.illinoispolicy.org/candy-crush-illinois-slaps-sales-tax-on-snickers-but-not-twix/">the second three are not</a>.</p>
<p>I’m a <a href="https://papers.ssrn.com/sol3/cf_dev/AbsByAuth.cfm?per_id=1997162">taxation expert</a>, and I have studied many aspects of state sales taxes. I have found that sales taxes can affect taxpayers, retailers and states in <a href="https://scholarship.richmond.edu/law-faculty-publications/1436/">unexpected ways</a>. Halloween offers a perfect window into the surprising difficulty of getting sales taxes just right.</p>
<h2>Sales tax</h2>
<p>States <a href="https://taxfoundation.org/state-sales-tax-reliance-2019/">rely heavily on sales taxes</a> for revenue.</p>
<p>Nationwide, sales taxes represent <a href="https://www.census.gov/content/dam/Census/library/publications/2015/econ/g14-stc.pdf">about a third of state revenue intakes</a>. From the states’ perspectives, there is a lot to like about sales taxes.</p>
<p>States have a great deal of autonomy in crafting their sales tax codes, and <a href="https://scholarship.law.berkeley.edu/cgi/viewcontent.cgi?article=2323&context=facpubs">taxpayers seem not to pay all that much attention</a> to sales taxes, making sales taxes politically appealing sources of revenue.</p>
<p>Perhaps most importantly, <a href="https://www.gao.gov/assets/690/688437.pdf">vendors can be relied on to collect sales taxes</a>, <a href="https://perma.cc/UHQ4-TXK7">streamlining enforcement</a> of the taxes.</p>
<p>However, sales taxes do raise concerns. Namely, they burden low-income taxpayers <a href="https://itep.org/wp-content/uploads/whopaysreport.pdf">to a greater degree</a> than high-income taxpayers, since low-income taxpayers spend a higher percentage of their disposable income on the taxes than high-income taxpayers.</p>
<p>For example, US$30 or so of sales tax on $500 of groceries strains the budget of a couple with $2,000 of monthly income more than the budget of a couple with $12,000 of monthly income. The <a href="https://fns-prod.azureedge.net/sites/default/files/media/file/CostofFoodAug2019.pdf">estimated monthly grocery bill</a> for a young couple on a low-cost plan, meaning they <a href="https://www.fns.usda.gov/cnpp/usda-food-plans-cost-food-reports-monthly-reports">spend less on groceries than an average couple</a>, is $500.</p>
<p>People must buy food to survive, making it harder for low-income taxpayers to change their purchasing habits to avoid the sales tax burden. To address this concern, many state legislatures have chosen to reduce the sales tax rate that applies to sales of certain necessities such as groceries and medical supplies.</p>
<p><a href="http://www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=582&ChapterID=8">Illinois</a>, for instance, lowers its sales tax rate from 6.25% to 1% for grocery purchases. Other states, like <a href="https://www.cdtfa.ca.gov/lawguides/vol1/sutl/6359.html">California</a>, exempt groceries from their sales taxes all together.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296038/original/file-20191008-128668-1a5mtks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some of this candy, well, isn’t.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/alameda-ca-november-17-2016-many-517744681?src=zsYYrqyAtEvkfdtXPNte4Q-1-0">Sheila Fitzgerald/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>What is candy?</h2>
<p>Now, states like Illinois must figure out where to draw the line.</p>
<p>If “groceries” are <a href="https://www.cbpp.org/research/state-budget-and-tax/which-states-tax-the-sale-of-food-for-home-consumption-in-2017">eligible for lower sales tax rates</a>, the states must define what foods qualify. Some foods, like eggs, milk and bread, are easy to categorize as groceries. Others, like <a href="https://taxfoundation.org/how-high-are-taxes-distilled-spirits-your-state-2016/">alcohol</a> and <a href="https://taxfoundation.org/meals-taxes-major-us-cities-0/">prepared meals</a>, are easy to exclude – and often are subject to extra taxes beyond basic sales taxes.</p>
<p>But how does one deal with all the food in between those groups? For instance, is meat a necessity? If so, are steaks necessities?</p>
<p>One approach to this sorting problem is to list out in granular detail each food that counts as a grocery item, leaving the remaining foods to be taxed at the higher rate. Such a list would provide perfectly targeted tax relief, but would demand constant and costly updating as new products make their way into grocery stores.</p>
<p>Instead of a granular method, states often take a more generalized approach to drawing the line. Under that approach, groceries are defined as food for consumption off-premises – which essentially means the food is purchased to take home, not to be eaten on the spot – and everything else is not eligible for reduced sales tax rates.</p>
<p>Many states, like Illinois, go further and provide that certain categories of food, such as candy, also do not qualify as groceries.</p>
<p>These more generalized approaches sacrifice accuracy for ease of administration but ultimately demand further line drawing. When is food purchased for home consumption? What is candy?</p>
<p>States like New York sometimes look to preparation methods to determine when food is purchased for consumption at home or on the premises. Have your bagel from the local deli toasted, and the New York Department of Taxation and Finance concludes you will be dining in. Avoid the toaster, and you will be <a href="https://www.tax.ny.gov/pubs_and_bulls/tg_bulletins/st/food_sold_by_food_stores.htm">taking it to go</a> and paying less sales tax.</p>
<p>Illinois defines candy as sweets and confectioneries, <a href="http://www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=582&ChapterID=8">but not if flour is a listed ingredient</a>.</p>
<p>Therefore, in some states that cookie crunch in your Twix is doubly satisfying. It feeds your sweet tooth while also getting you a sales tax break. </p>
<p>And, yes, Twizzlers and Hershey’s Cookies and Cream both have flour in them, too.</p>
<p>[ <em>You respect facts and expertise. So do The Conversation’s authors and editors.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=yourespect">You can read us daily by subscribing to our newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/123905/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hayes Holderness does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Which candies count as candy in the eyes of the tax law? The answer often depends on one ingredient.
Hayes Holderness, Associate Professor of Law, University of Richmond
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/117316
2019-06-12T06:44:12Z
2019-06-12T06:44:12Z
Curious Kids: why do leeches suck our blood?
<figure><img src="https://images.theconversation.com/files/275582/original/file-20190521-23832-boh2uq.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1182%2C781&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Leeches suck blood because it is a very good food for them. Some leeches only need to feed once a year.
</span> <span class="attribution"><a class="source" href="https://pixabay.com/photos/leech-medical-leech-angler-bait-368345/">Pixabay</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast <a href="http://www.abc.net.au/kidslisten/imagine-this/">Imagine This</a>, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.</em> </p>
<hr>
<blockquote>
<p><strong>Why do leeches suck our blood? - Thomas, aged 6.</strong></p>
</blockquote>
<hr>
<p>The short answer is that leeches need blood to grow and reproduce (make baby leeches). </p>
<p>Leeches are worms that live in water or on land and feed by sucking blood from fish, frogs, lizards, birds or, if they get the chance, larger animals like humans. </p>
<p>They suck blood because it is a very good food source for them. Some leeches only need to feed once a year.</p>
<p>The only trouble with sucking blood is you have to do it very carefully, especially if the animal you are sucking it from is able to bite you or pull you off. So leeches, like all blood suckers, usually like to bite without causing too much pain. They like to bite in spots where they are hard to find. </p>
<h2>Blood clots but leeches have a solution</h2>
<p>The other thing leeches have to worry about is that blood clots. A blood clot forms whenever you get a cut which stops bleeding in a few minutes – eventually the blood clot forms a scab. </p>
<p>This happens when blood contacts the air. It clumps together and forms a solid lump. The leech cannot feed if the blood forms a lump and so it releases a chemical that prevents this clumping. </p>
<p>This keeps the blood flowing so the leech can suck for two or three hours without stopping. That way it collects enough food to last until it finds another animal to bite.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275545/original/file-20190521-69199-1t2g9st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leeches were once used in medicine.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/srinagarjkindia20190321-impure-blood-seen-coming-out-1345307573?src=UhbvFPzApGBrITkmYltWZA-1-69">Faizan Ahmad sheikh/shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-does-our-heart-beat-102609">Curious Kids: how does our heart beat?</a>
</strong>
</em>
</p>
<hr>
<p>Leeches are not the only animal that feeds on the blood of animals. Others include mosquitoes, ticks, vampire bats (yes they exist, but only in South America), bed bugs, lice, other insects and the lamprey fish. All these feed on larger animals – but don’t kill them, so they are all called parasites.</p>
<p>Parasites all live on or in other animals and many of them feed on blood. Blood is easy to collect whether you are inside or outside the body. It is highly nutritious and there is always lots of it, so the animal the parasite is feeding on can usually spare some. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275551/original/file-20190521-23841-19mao5h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Here are some leeches on the shoe of a hiker in the rainforest.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1198664179?src=kWC0p2JMgNHqYf8Lrkv6NA-1-43&size=huge_jpg">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Leeches and medicine</h2>
<p>Leeches can be annoying and their bites can make us itchy but they are not usually dangerous to humans. In fact, leeches have been used to treat human diseases for thousands of years. Their blood sucking ability was thought to be useful in sucking diseased or “bad” blood out of the body and so sick people had leeches applied regularly. </p>
<p>However, we now know that allowing leeches to suck blood does little to help in most cases. In fact, if too many leeches are applied, a sick person can get weak from loss of blood.</p>
<p>The one area of medicine where leeches are still helpful is using them to improve blood circulation in the skin. They also reduce the chances of blood clotting when that could be dangerous in some sick people. However, these days we can make an artificial version of the chemical leeches use to prevent blood clots, which is called “hirudin”.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/275585/original/file-20190521-23845-1dlua9w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Leeches need blood to grow and reproduce.</span>
<span class="attribution"><a class="source" href="https://pixabay.com/photos/leech-leech-therapy-medicinal-leech-1055446/">Pixabay</a></span>
</figcaption>
</figure>
<p>Leeches need blood to grow and reproduce, which they can do easily as all leeches are both male and female at the same time. They still have to mate with another leech but both partners can lay eggs after mating.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-do-ants-have-blood-108925">Curious Kids: do ants have blood?</a>
</strong>
</em>
</p>
<hr>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au</em></p>
<figure class="align-left ">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/117316/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Sandeman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The short answer is that leeches need blood to grow and reproduce. But it’s in their interests to do it carefully, without causing too much pain, and in spots that are hard to find.
Mark Sandeman, Honorary Professor, Federation University Australia
Licensed as Creative Commons – attribution, no derivatives.