tag:theconversation.com,2011:/fr/topics/snake-bites-23866/articlessnake bites – The Conversation2024-03-17T08:37:05Ztag:theconversation.com,2011:article/2244112024-03-17T08:37:05Z2024-03-17T08:37:05ZSnakebites: we thought we’d created a winning new antivenom but then it flopped. Why that turned out to be a good thing<figure><img src="https://images.theconversation.com/files/579144/original/file-20240301-30-2x5qov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A _Bothrops asper_ is prepared for its venom to be milked to use in making antivenom.</span> <span class="attribution"><span class="source">Jon G. Fuller/VWPics/Universal Images Group</span></span></figcaption></figure><p>Snakebites kill <a href="https://www.nature.com/articles/nrdp201763">over 100,000 people each year</a>, and hundreds of thousands of survivors are left with long-term disabilities such as amputations.</p>
<p>Africa, Asia and Latin America are <a href="https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0009073">the regions most heavily affected</a>. The most venomous snakes in Africa are the <a href="https://theconversation.com/why-knowing-what-black-mamba-venom-does-to-the-human-body-is-crucial-121386">black mamba</a>, cobras and saw-scaled and carpet vipers. In Asia, the Indian cobra, Russel’s viper, saw-scaled viper and common krait are the most venomous.</p>
<p>In the Central America and northern South America regions, the <a href="https://www.britannica.com/animal/viper-snake">venomous pit viper</a> <em>Bothrops asper</em> <a href="https://pubmed.ncbi.nlm.nih.gov/22146491/">is responsible for most of the fatal and harmful bites</a>.</p>
<p>We are venom and antivenom specialists who spent four years developing a therapeutic antibody to mitigate the effects of the pit viper’s bites. We were certain that we’d met all the standards for an effective, safe and efficacious antivenom. But, at the last hurdle, <a href="https://www.nature.com/articles/s41467-023-42624-5">we realised</a> the antibody didn’t neutralise the snake’s toxins: it enhanced them, worsening the venom’s effects.</p>
<p>Initially this was, of course, very disappointing. But it was also a valuable lesson. By reporting this new way that future antivenoms can fail, we have highlighted a problem with the <a href="https://iris.who.int/bitstream/handle/10665/255657/9789241210133-eng.pdf#page=217">current recommendations for testing antivenoms</a> that was hidden until now.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mozambique-had-no-data-about-snakebites-our-new-study-filled-the-gap-and-the-results-are-scary-192106">Mozambique had no data about snakebites. Our new study filled the gap -- and the results are scary</a>
</strong>
</em>
</p>
<hr>
<p>Our lesson is likely to have a much larger impact on the development of snakebite treatments than if the antibody had been a success, because the discovery will help antivenom researchers focus their efforts so they don’t fail at the last hurdle as we did. </p>
<h2>Developing our antivenom</h2>
<p>A large percentage of <em>B. asper’s</em> venom consists of potent muscle-damaging molecules called phospholipases A₂ (PLA₂s) and PLA₂-like toxins. These have <a href="https://pubmed.ncbi.nlm.nih.gov/36632869/">severe effects</a>, often leading to irreversible damage and disability. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/finally-snakebite-is-getting-more-attention-as-a-tropical-health-issue-131016">Finally, snakebite is getting more attention as a tropical health issue</a>
</strong>
</em>
</p>
<hr>
<p>Myotoxin II, a formidable PLA₂-like toxin within <em>B. asper’s</em> arsenal, is particularly significant. The precise mechanisms that underlie myotoxin II’s action aren’t fully understood. It is known to exert its effects locally, binding to muscle fibres and triggering muscle damage. This localised action poses a challenge for traditional antivenom treatments.</p>
<p>We have attempted to develop human monoclonal antibodies that target and neutralise this membrane-disrupting myotoxin II. For the first four years of our research project, the antibodies we discovered kept showing impressive effects in neutralising myotoxin II. </p>
<p>Even when tested in living mice, using the current gold standard for antivenom testing, the antibodies continuously showed impressive neutralisation. However, for our most promising antibody, we wanted to go a step further and carry out an experiment that more closely resembled a human envenoming, in which the antibody is injected after injection of the venom. </p>
<p>The results of this additional experiment were equal parts disappointing and surprising. Our most promising antibody in this last experiment changed its toxin-neutralising effect to toxin-enhancing instead, as we’ve <a href="https://www.nature.com/articles/s41467-023-42624-5">documented in a research paper</a>. </p>
<p>The results were so surprising that we decided to immediately repeat the experiment. We thought something must’ve gone wrong, like the antibody or other materials having gone bad. However, the results remained the same.</p>
<p>This curious phenomenon, which we termed “antibody-dependent enhancement of toxicity”, represents a novel discovery in toxin immunology. Similar phenomena have been observed in other contexts, such as with <a href="https://pubmed.ncbi.nlm.nih.gov/19307220/">poisonous mushrooms</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/3188055/">bacterial toxins</a>, but never before with toxins from the animal kingdom. </p>
<p>Additional studies will be needed to fully understand what causes antibody-dependent enhancement of toxicity. </p>
<h2>Reassessing preclinical models</h2>
<p>There’s good news about this failure. It’s a chance for antivenom researchers all over the world, no matter what snake species they’re working with, to reassess their preclinical models (like the <a href="https://iris.who.int/bitstream/handle/10665/255657/9789241210133-eng.pdf#page=217">current gold standard model</a>).</p>
<p>We also think antivenom researchers should consider incorporating more sophisticated experiments like the ones used in our study, which more closely resemble a real-life envenoming case. By doing so, the antivenom research community can streamline the drug discovery process. This will expedite the identification and development of safer and more effective snakebite treatments.</p><img src="https://counter.theconversation.com/content/224411/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andreas Hougaard Laustsen receives funding from Wellcome, the European Research Council, the Villum Foundation, and Innovation Fund Denmark. </span></em></p><p class="fine-print"><em><span>Bruno Lomonte receives funding from Vicerrectoría de Investigación, Universidad de Costa Rica, Costa Rica.</span></em></p><p class="fine-print"><em><span>Julián Fernández receives funding from Vicerrectoría de Investigación, Universidad de Costa Rica, Costa Rica. </span></em></p><p class="fine-print"><em><span>Christoffer Vinther Sørensen 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>By reporting this new way that future antivenoms can fail, the research has highlighted a problem with current antivenom testing recommendations.Christoffer Vinther Sørensen, Postdoctoral researcher, Department of Biotechnology and Biomedicine, Center for Antibody Technologies, Technical University of DenmarkAndreas Hougaard Laustsen, Professor & Center Director at the Department of Biotechnology and Biomedicine, Technical University of DenmarkBruno Lomonte, Emeritus Professor, Instituto Clodomiro Picado, Universidad de Costa RicaJulián Fernández, Researcher at Instituto Clodomiro Picado, Universidad de Costa RicaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2221422024-01-29T19:05:19Z2024-01-29T19:05:19ZStop killing brown snakes – they could be a farmer’s best friend<figure><img src="https://images.theconversation.com/files/571808/original/file-20240129-27-4fxoz7.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4245%2C2819&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>Many Australians who work outdoors – especially farmers and graziers – attempt to kill every snake they encounter, especially those thought to be venomous. In fact, <a href="https://www.jstor.org/stable/1565247">research</a> in one part of rural Australia found 38% of respondents tried to kill snakes wherever possible.</p>
<p>This attitude is misguided and dangerous. Despite their fearsome reputation, venomous Australian snakes pose little risk to human health. And snakes are hugely beneficial on farms by consuming pests such as rodents. </p>
<p><a href="https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1111/acv.12925">New research</a> by myself and colleagues estimated the magnitude of that benefit. We found adult eastern brown snakes can collectively remove thousands of mice per square kilometre of farmland each year, which substantially increases farm productivity. </p>
<p>Our study suggests the benefits of snake populations on agricultural land far outweigh the potential costs, and farmers should tolerate rather than kill them.</p>
<h2>A persecuted serpent</h2>
<p>Brown snakes are the most common deadly snake species found in disturbed agricultural habitats in the southern half of Australia. </p>
<p>The snakes are fast-moving and active during the day. Brown snakes are generally persecuted in rural areas because the danger of fatal snake bites is seen to outweigh their benefits as pest controllers.</p>
<p>It’s true that brown snakes are the <a href="https://www.researchgate.net/publication/320947425_Australia%27s_Dangerous_Snakes_Identification_Biology_and_Envenoming">most common</a> <a href="https://www.9news.com.au/national/eastern-brown-snakes-expert-reveals-what-makes-australias-deadliest-snake-so-lethal-what-to-do-if-bitten/9b454663-011e-4fa5-85a2-9d92888d0b30#:%7E:text=However%20according%20to%20statistics%20released,across%20most%20of%20eastern%20Australia.">cause</a> of fatal snake bite in Australia. But the bites are rarely fatal. Statistics show snakes of any species kill <a href="https://www.museum.qld.gov.au/learn-and-discover/animals-of-queensland/snakes#:%7E:text=Even%20dangerously%20venomous%20species%20pose,three%20snakebite%20deaths%20a%20year.">fewer than three</a> people per year in Australia, on average.</p>
<p><a href="https://www.flyingdoctor.org.au/qld/news/outback-survival-snakes-and-snakebites/">Around 3,000</a> snake bite cases are reported annually – a high proportion of which occur when a snake <a href="https://www.mja.com.au/journal/2017/207/3/australian-snakebite-project-2005-2015-asp-20">retaliates</a> to being attacked by a person.</p>
<p>Australian snakes, including brown snakes, <a href="https://researchers.mq.edu.au/en/publications/responses-of-free-ranging-brownsnakes-ipseudonaja-textilisi-elapi">generally retreat</a> rather than attack, even when provoked. Eastern brown snakes, in particular, tend to dwell in places where they are unlikely to be encountered by people. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/good-luck-fella-stay-safe-a-snake-catcher-explains-why-our-fear-of-brown-snakes-is-misplaced-150783">'Good luck fella, stay safe': a snake catcher explains why our fear of brown snakes is misplaced</a>
</strong>
</em>
</p>
<hr>
<h2>An upside to venomous snakes</h2>
<p>The most obvious benefit of maintaining brown snake populations is to reduce rodent numbers. Introduced species of rats and mice are a <a href="https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1005&context=nwrchumanconflicts">major cost</a> to Australian agriculture. In extreme cases, mice can destroy most or all of a crop.</p>
<p>We wanted to calculate the number of rodents removed from Australian farmland by brown snakes. </p>
<p>First, we drew on <a href="https://www.jstor.org/stable/3892162">work</a> I had done in the 1980s, which involved dissecting museum specimens to find out what proportion of brown snake diets consisted of rodents.</p>
<p>We then estimated the number of prey consumed each year by brown snakes. This was based on the feeding rates of captive snakes, data from commercially farmed pythons in farms in Thailand and Vietnam, and studies on a species of North American snake which is similar to brown snakes.</p>
<p>To estimate the abundance of brown snakes on farms, we consulted previous research on brown snake abundance, and rates of capture from fieldwork involving red-bellied black snakes. We also obtained data from the Atlas of Living Australia, an online compendium of information about the continent’s plants and animals.</p>
<p>Based on the combined data, we found a square kilometre of farmland can contain 100 adult eastern brown snakes, even where rates of encounters between people and those snakes are low. If each adult brown snake consumes around 100 wild mice each year – which is likely an underestimate – together this must equate to about 10,000 mice per square kilometre. Each mouse removed by a brown snake may eat several kilograms of grain crops over its life. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/4ITgdgPUMuY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>Give snakes a chance</h2>
<p>Agricultural productivity gains are not the only benefits of tolerating brown snakes on farmland.</p>
<p>It would also allow a reduction in the use of chemical methods for rodent control, which can be expensive and ineffective. The chemicals can also threaten the <a href="https://escholarship.org/uc/item/8044n35x">health</a> of <a href="https://pubmed.ncbi.nlm.nih.gov/9759690/">humans</a>, livestock, scavenging wildlife and pets.</p>
<p>Tolerating brown snakes might also reduce the incidence of snake bite. <a href="https://www.qld.gov.au/environment/plants-animals/animals/living-with/snakes#:%7E:text=Snakes%20usually%20prefer%20to%20retreat,the%20snake%20to%20move%20away.">Most snake bites</a> are inflicted when people are trying to catch or kill the reptile.</p>
<p>What’s more, one study <a href="https://www.researchgate.net/publication/320947425_Australia%27s_Dangerous_Snakes_Identification_Biology_and_Envenoming">suggests</a> snakes that are long-term residents of an area are less agitated by close encounters with people and know the location of nearby safe havens, and so pose relatively little threat. Culling snakes may create an influx of new animals unfamiliar with the location and not used to humans.</p>
<p>The obvious rebuttal is that killing snakes reduces the incidence of future snake bite, by reducing overall snake numbers. However, data suggests this is not necessarily the case. For example, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158397">one study</a> in Indonesia showed reticulated pythons remained abundant despite millions of individuals being removed over decades.</p>
<p>Maintaining viable populations of snakes has an ecological benefit. Removing high-level predators destabilises food webs and disrupts the way ecosystems function.</p>
<p>Finally, conserving snakes has merit in its own right. Many species of snakes are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3001371/#:%7E:text=Although%20there%20is%20little%20evidence,(Mullin%20%26%20Seigel%202009).">in decline</a>, including in Australia, and should be protected.</p>
<p>Our findings suggest the need for a more balanced view of the costs and benefits of snakes, including brown snakes. Tolerating them may bring benefits that outweigh the already low chance of life-threatening snake bite. </p>
<p><em>The author would like to acknowledge the contribution of Peter Mirtschin, Nathan Dunstan and Jeff Abraham to the research underpinning this article.</em></p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-research-reveals-these-20-australian-reptiles-are-set-to-disappear-by-2040-145385">New research reveals these 20 Australian reptiles are set to disappear by 2040</a>
</strong>
</em>
</p>
<hr>
<p><em>Correction: A figure relating to mice per square kilometre has been amended from 1,000 to 10,000.</em></p><img src="https://counter.theconversation.com/content/222142/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rick Shine receives funding from the Australian Research Council. </span></em></p>The benefits of snake populations on agricultural land far outweigh the potential costs, and farmers should tolerate rather than kill them.Rick Shine, Professor in Evolutionary Biology, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151022023-10-16T15:36:34Z2023-10-16T15:36:34ZAncient Egypt had far more venomous snakes than the country today, according to our new study of a scroll<p>How much can the written records of ancient civilisations tell us about the animals they lived alongside? <a href="https://www.tandfonline.com/doi/full/10.1080/14614103.2023.2266631">Our latest research</a>, based on the venomous snakes described in an ancient Egyptian papyrus, suggests more than you might think. A much more diverse range of snakes than we’d imagined lived in the land of the pharaohs – which also explains why these Egyptian authors were so preoccupied with treating snakebites!</p>
<p>Like cave paintings, texts from early in recorded history often describe wild animals the writers knew. They can provide some remarkable details, but identifying the species involved can still be hard. For instance, the ancient Egyptian document called the <a href="https://www.brooklynmuseum.org/opencollection/objects/60690">Brooklyn Papyrus</a>, dating back to around 660-330BC but likely a copy of a much older document, lists different kinds of snake known at the time, the effects of their bites, and their treatment. </p>
<p>As well as the symptoms of the bite, the papyrus also describes the deity associated with the snake, or whose intervention might save the patient. The bite of the “<a href="https://www.britannica.com/topic/Apopis-Egyptian-god">great snake of Apophis</a>” (a god who took the form of a snake), for example, was described as causing rapid death. Readers were also warned that this snake had not the usual two fangs but four, still a rare feature for a snake today. </p>
<p>The venomous snakes described in the Brooklyn Papyrus are diverse: 37 species are listed, of which the descriptions for 13 have been lost. Today, the area of ancient Egypt is home to far fewer species. This has led to <a href="https://core.ac.uk/download/pdf/339159652.pdf">much speculation</a> among researchers as to which species are being described. </p>
<h2>The four-fanged snake</h2>
<p>For the great snake of Apophis, no reasonable contender currently lives within ancient Egypt’s borders. Like most of the venomous snakes that cause the majority of the world’s snakebite deaths, the vipers and cobras now found in Egypt have just two fangs, one in each upper jaw bone. In snakes, the jaw bones on the two sides are separated and move independently, unlike in mammals. </p>
<p>The nearest modern snake that <a href="https://www.mdpi.com/2072-6651/9/5/171">often has four fangs</a> is the boomslang (<em>Disopholidus typus</em>) from the sub-Saharan African savannas, now only found more than 400 miles (650km) south of present-day Egypt. Its venom can make the victim bleed from every orifice and cause a lethal brain haemorrhage. Could the snake of Apophis be an early, detailed description of a boomslang? And if so, how did the ancient Egyptians encounter a snake that now lives so far south of their borders? </p>
<figure class="align-right ">
<img alt="Ancient Egyptian art depicting a hare-like creature battling a snake." src="https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=616&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=616&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=616&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=774&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=774&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553356/original/file-20231011-17-79rkof.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=774&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Representation of Apep (Apophis) in Ancient Egyptian wall painting. Note resemblance to boomslang (above).</span>
</figcaption>
</figure>
<p>To find out, our masters student Elysha McBride used a statistical model called <a href="https://www.mdpi.com/journal/climate/special_issues/Niche_Models">climate niche modelling</a> to explore how the ranges of various African and Levantine (eastern Mediterranean) snakes have changed through time.</p>
<p>Niche modelling reconstructs the conditions in which a species lives, and identifies parts of the planet that offer similar conditions. Once the model has been taught to recognise places that are suitable today, we can add in maps of past climate conditions. It then produces a map showing all the places where that species might have been able to live in the past.</p>
<h2>On the trail of ancient snakes</h2>
<p>Our study shows the much more humid climates of early ancient Egypt would have supported many snakes that don’t live there today. We focused on ten species from the African tropics, the <a href="https://www.britannica.com/place/Maghreb">Maghreb region</a> of north Africa and the Middle East that might match the papyrus’s descriptions. These include some of Africa’s most notorious venomous snakes such as the black mamba, puff adder and boomslang.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/vHtm5wAZgL0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>We found that nine of our ten species could probably once have lived in ancient Egypt. Many could have occupied the southern and southeastern parts of the country as it then was – modern northern Sudan and the Red Sea coast. Others might have lived in the fertile, vegetated Nile valley or along the northern coast. For instance, boomslangs might have lived along the Red Sea coast in places that 4,000 years ago would have been part of Egypt. </p>
<p>Similarly, one entry of the Brooklyn Papyrus describes a snake “patterned like a quail” that “hisses like a goldsmith’s bellows”. The puff adder (<em>Bitis arietans</em>) would fit this description, but currently lives only south of Khartoum in Sudan and in northern Eritrea. Again, our models suggest that this species’ range would once have extended much further north.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wildlife-wonders-of-britain-and-ireland-before-the-industrial-revolution-my-research-reveals-all-the-biodiversity-weve-lost-208721">Wildlife wonders of Britain and Ireland before the industrial revolution – my research reveals all the biodiversity we've lost</a>
</strong>
</em>
</p>
<hr>
<p>Since the period we modelled, a lot has changed. Drying of the climate and desertification had set in about <a href="https://doi.org/10.1007/s10437-022-09487-5">4,200 years ago</a>, but perhaps not uniformly. In the Nile valley and along the coast, for instance, farming and irrigation might have slowed the drying and allowed many species to persist into historical times. This implies that many more venomous snakes we only know from elsewhere might have been in Egypt at the time of the pharaohs.</p>
<p>Our study shows how enlightening it can be when we combine ancient texts with modern technology. Even a fanciful or imprecise ancient description can be highly informative. Modelling modern species’ ancient ranges can teach us a lot about how our ancestors’ ecosystems changed as a result of environmental change. We can use this information to understand the impact of their interactions with the wildlife around them.</p><img src="https://counter.theconversation.com/content/215102/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wolfgang Wüster receives funding from the Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Isabelle Catherine Winder 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>Ancient texts are still teaching us new things about the prevalence of wildlife.Isabelle Catherine Winder, Senior Lecturer in Zoology, Bangor UniversityWolfgang Wüster, Professor of Zoology, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1926192022-11-08T09:04:59Z2022-11-08T09:04:59ZA dumpsite is no place for a child: study shows Nigeria’s young waste pickers are at risk<figure><img src="https://images.theconversation.com/files/491263/original/file-20221024-1609-y8vdtg.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C2588%2C1715&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Children are among waste pickers exposed to hazards while working at the Olusosun landfill. Photo by: Lionel Healing/AFP.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-sift-through-rubbish-at-a-dump-17-april-2007-in-news-photo/73905533?phrase=olusosun%20dumpsite%20Lagos&adppopup=true">from www,gettyimages.com</a></span></figcaption></figure><p>The Olusosun landfill sprawls across 100 acres (40ha) in Nigeria’s largest city, Lagos. Initially situated at the outskirts of the city, it is now at the city’s centre due to urban encroachment. Olusosun is often described as <a href="https://link.springer.com/article/10.1007/s12011-021-02758-3">Nigeria’s biggest landfill</a>; it receives over one million tonnes of <a href="https://owlcation.com/stem/15-of-the-Worlds-Largest-Landfills">waste</a> annually. Most of this is electronic waste (such as lamps, televisions and laptops), municipal solid waste and construction waste.</p>
<p>Access to the dumpsite is not restricted. Waste pickers can go in and look for recyclable materials that can be resold. In most Nigerian cities, waste picking represents a vital survival strategy for the <a href="https://www.ijern.com/journal/March-2014/26.pdf">poor</a>.</p>
<p>It’s not only adults who operate as waste pickers. As we outline in our recent <a href="https://thescipub.com/abstract/10.3844/ajessp.2022.69.80">study</a>, children are also working at Olusosun. </p>
<p>We surveyed 150 of these child waste pickers; most were boys aged between 13 and 17. More than half (58.7%) of the children were not attending school. They worked at the dumpsite daily for social and economic reasons and their labour was physically taxing. They reported being bitten by insects and snakes. They slipped and sometimes fell. Many suffered from chronic headaches. For this they earned between N500 (US$1.20) and N1,600 (US$3.85) a day. </p>
<p>The use of a child for forced or <a href="https://www.scirp.org/journal/paperinformation.aspx?paperid=64999">exploitative labour</a> under section 28 (1) (a) of the Child’s Rights Act is an offence punishable with a fine or imprisonment. But in the informal sector of urban areas, Nigeria’s government has not made serious efforts to enforce this law to protect children.</p>
<p>A concerted effort is needed by government, civil society, and international organisations to eradicate waste picking by children. Financial aid could be offered to the children’s families so that they don’t feel they have no option but to let children work. And free, compulsory primary and secondary education is key to keeping children in the classroom rather than working.</p>
<h2>Huge health and safety risks</h2>
<p>Access to Olusosun landfill is unregulated, but there are informal systems in place to manage who can and cannot engage in waste picking. Our <a href="https://doi.org/10.3844/ajessp.2022.69.80">survey</a> confirmed that before any person could pick waste on this site, they had to register with an association. Unregistered people were not allowed to work on the site and if they did without permission, there would be a quarrel. </p>
<p>An informal association formed by the operators oversees the registration process. It is funded by membership fees and only registers adults. But once they are registered, those adults can hire children to do the work for them. They do this, we were told, to keep their costs low because they could pay children less than they would pay adults.</p>
<p>Information we obtained showed that child waste pickers’ minimum daily income was N500 (US$1.20); the maximum was N1,600 (US$3.85). The average daily revenue was N1,180 (US$2.84) – more than N30,000 (about US$72.20) per month. Although this amount is higher than the <a href="https://doi.org/10.3844/ajessp.2022.69.80">national minimum monthly wage</a> (N30,000) in the public sector, the work and the environment are hazardous and detrimental to the children’s health.</p>
<p>Children usually sorted the waste manually, with no protective equipment like gloves and face masks. They operated in an unsheltered environment regardless of conditions like rain, hot sun and cold weather. These conditions had resulted in gastrointestinal illnesses, skin diseases, stings and bites from insects. Many talked about suffering regular headaches.</p>
<p>Child waste pickers were also at risk of being pricked by sharp objects such as syringes, needles, surgical blades and broken bottles.</p>
<p>Despite all these hazards, the children continued working at the landfill because of chronic poverty. Some of the children’s parents were waste
pickers themselves. Many came from areas without <a href="https://www.premiumtimesng.com/news/more-news/469581-less-than-40-of-lagos-residents-have-access-to-water-governor.html">potable water</a>, sanitation facilities or basic healthcare services. </p>
<h1>Recommendations</h1>
<p>In addressing the use of children for forced or exploitative labour, integrated approaches have
<a href="https://assets.publishing.service.gov.uk/media/5984577fe5274a1707000067/105-Interventions-on-Child-Labour-in-South-Asia.pdf">demonstrated</a> the most success in South Asian countries. (Afghanistan is an important exception.) These approaches can include, for example, conditional cash transfers combined with interventions such as providing education and healthcare services. </p>
<p>Thus, a pragmatic regulatory framework should be developed whereby different actors (government, civil society and international organisations) focus on eliminating the practice of waste picking by children. Such efforts require strong political backing and financial support. </p>
<p>Such a regulatory framework should also make provision for financial aid to the children’s parents through a direct assistance programme. </p>
<p>There is a need for a well-thought-out plan by the government to introduce free and compulsory primary and secondary education for every child. Making education compulsory, especially at the secondary level, is a way to keep children learning and, ideally, setting themselves up for safe, decently-paid future work.</p><img src="https://counter.theconversation.com/content/192619/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amos Oluwole Taiwo 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>Employing children as waste pickers lowers costs but exposes them to hazards.Amos Oluwole Taiwo, Lecturer, Department of Urban and Regional Planning, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria, Olabisi Onabanjo UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/836582017-10-30T12:22:56Z2017-10-30T12:22:56ZUnsuitable antivenoms are being sold in Africa, costing lives<figure><img src="https://images.theconversation.com/files/192005/original/file-20171026-13309-musqyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_Echis_, also known as the saw-scaled viper, dominates snakebite statistics and kills more people annually than any other.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Snakes bite more than <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0050218">5 million people every year</a>. Of these, around 1.8 million people are envenomated and over <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0050218">94,000 are killed</a>. These statistics suggest that snakebite is one of the most <a href="http://www.who.int/snakebites/news/Snakebite_under_spotlight_in_Oxford/en/">neglected tropical diseases</a>. </p>
<p>But getting accurate statistics is incredibly difficult. Many bites go unreported, with as few as 8.5% of snakebite victims <a href="http://www.tandfonline.com/doi/abs/10.1080/00034983.1980.11687380">seeking medical treatment</a>. In Africa snakebite probably kills over <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0050218">30 000 people per year</a>. This is <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0000851">proportionally more</a> than in most other regions around the world. A large percentage of these deaths can be attributed to one genus of snake, <em>Echis</em>. </p>
<p>Also known as the saw-scaled viper, <em>Echis</em> can <a href="http://www.megasphera.cz/africanvenomoussnakes/images/Echis/Mapa_Efy_V.jpg">be found</a> throughout sub-Saharan Africa north of the equator and in parts of Asia and the Middle East. This small viper dominates snakebite statistics and kills more people annually than any other. For example, <em>Echis ocellatus</em> is responsible for as many as <a href="https://www.ncbi.nlm.nih.gov/pubmed/9129531">95% of snake bites in northern Nigeria</a>.</p>
<p>Many of the toxins in their venom target the blood to induce clotting. For humans, this causes a potentially lethal condition called <a href="http://www.sciencedirect.com/science/article/pii/S0887796314000972#bb0010">“venom-induced consumption coagulopathy”</a>, more commonly called VICC. This disrupts the body’s ability to regulate blood flow and results in severe internal bleeding. Haemorrhage, stroke, and shock are typically the cause of death following VICC. Antivenom is the only effective antidote.</p>
<p>But the continent is experiencing an <a href="http://www.nature.com/news/africa-braced-for-snakebite-crisis-1.18357">antivenom crisis</a>. This crisis is a result of the <a href="https://theconversation.com/the-african-snakebite-crisis-is-nothing-new-weve-been-worried-about-antivenom-for-decades-47293">discontinuation of a key antivenom</a> in Africa, <a href="http://www.toxinfo.org/antivenoms/productinfo/FAV-AFRIQUE.html">Fav-Afrique</a>. Fav-Afrique was very effective at treating snakebites in Africa. Some clinics reported a <a href="https://www.ncbi.nlm.nih.gov/pubmed/10674688">100%</a> success rate when using this antivenom. But the antivenom’s manufacturers, Sanofi-Pasteur, stopped production of Fav-Afrique after claiming they were <a href="http://www.bbc.com/news/health-34176581">priced out of the market</a>.</p>
<p>The disappearance of Fav-Afrique from African clinics partly explains the exceptionally high rates of snakebite death on the continent. It has seen an increase in the use of cheaper, Indian-produced antivenoms - many of which appear to be <a href="http://www.sciencedirect.com/science/article/pii/S0041010113000147">largely ineffective</a>. </p>
<p>To investigate the issue further, <a href="http://www.sciencedirect.com/science/article/pii/S0378427417312675">we conducted a comparison of four antivenoms</a> that are commonly used to treat <em>Echis</em> bites on the continent. Two were made using Indian <em>Echis</em> venoms and two made using African <em>Echis</em> venoms. We tested these antivenoms against venom samples from ten different populations of <em>Echis</em> across their distribution, from Africa to Asia. </p>
<h2>Comparing antivenoms</h2>
<p>We first added the venom to human <a href="http://www.redcrossblood.org/learn-about-blood/blood-components/plasma">blood plasma</a> and measured the rate at which each venom induced a blood clot. We then repeated the experiment, but with an additional step. Before adding the venom to the plasma, we mixed the venom and antivenom. This step was to give the antivenom a chance to bind with the venom toxins and neutralise their harmful activity on the blood. We assessed the effectiveness of the antivenoms by looking at how well they were able to slow the clotting caused by the venom when compared to our first experiment. </p>
<p>What we found was alarming. Despite the antivenoms being marketed as species-specific (that is, able to treat the bite of a given species), we found extreme region-specific variability in their effectiveness. This means that the performance of the antivenoms varied based on the geographical origin of the venoms, even within a single species. </p>
<p>The Indian-made antivenoms, common throughout Africa because they are affordable, showed little-to-no neutralisation of the African <em>Echis</em> venoms. Even the venoms of some Indian <em>Echis</em> populations showed limited response to the Indian antivenoms. </p>
<p>Clinical case statistics support our findings. After switching to an Indian-produced antivenom following the discontinuation of Fav-Afrique, some African clinics have recorded a horrific <a href="https://academic.oup.com/trstmh/article/102/5/445/1921278/Failure-of-a-new-antivenom-to-treat-Echis">7</a> to <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0003896">20-fold</a> increase in case death rates.</p>
<h2>Why such variability in the antivenoms?</h2>
<p>Antivenoms are developed by injecting a small amount of venom from either one or from multiple species (to produce “monovalent” or “polyvalent” antivenom, respectively) into a host animal, such as a horse. The animal’s immune system responds by producing antibodies that recognise and fight those venom toxins, much like what happens in our bodies when we get a vaccine. These antibodies are extracted and purified. The resulting antivenom is then marketed as being able to treat a bite by the species whose venom was used during its production. </p>
<p>This process is effective and reliable when venom composition does not differ much between individual snakes. Antivenoms may even be effective in treating the bite of a <a href="http://www.sciencedirect.com/science/article/pii/S0041010109002141">closely related snake species</a>. Unfortunately, this is not the case for <em>Echis</em> as their venom composition varies between populations. </p>
<p>This is partly thought to be an <a href="http://pages.bangor.ac.uk/%7Ebss166/Publications/2009_Barlow_Echis_scorpions_FirstCite.pdf">evolutionary adaptation linked to diet</a>. A key function of snake venom is to assist in prey capture. The toxins in venom do this by targeting specific parts of the prey’s physiology, such as the blood or the nerves, to disrupt normal body function and immobilise the animal. </p>
<p>Different <em>Echis</em> populations feed on different prey types. For example, some feed mostly on vertebrates such as rodents or lizards, while others prefer invertebrates such as scorpions. The physiology of these prey animals differs, and this dictates what makes a toxin effective for predation. This could be why some populations have evolved <a href="http://www.pnas.org/content/111/25/9205.full.pdf">different sets of toxins</a>.</p>
<p>From a medical perspective, this means that the antibodies in an antivenom may not be able to adequately recognise and fight all the harmful toxins in the venom. The outcome for patients and clinicians is variable or reduced antivenom effectiveness between regions. </p>
<p>Our results show the failings that come from using a geographically restricted range of antivenoms and marketing them inappropriately. Given the seriousness of snakebite in Africa and around the world, this puts the pressure firmly on antivenom manufacturers to develop, market, and distribute their antivenoms responsibly.</p><img src="https://counter.theconversation.com/content/83658/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bianca op den Brouw 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>Indian-made antivenoms, common throughout Africa because they are affordable, showed little-to-no neutralisation of the African Echis venoms.Bianca op den Brouw, PhD Candidate in Toxinology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/809822017-07-20T17:58:12Z2017-07-20T17:58:12ZSnakebites still exact a high toll in Africa. A shortage of antivenoms is to blame<figure><img src="https://images.theconversation.com/files/178650/original/file-20170718-10334-1b8s0tu.jpg?ixlib=rb-1.1.0&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>A snakebite is one of the most excruciating experiences a person can go through. Depending on how venomous the snake is, it can cause morbidity, pain, and death. Snakebite envenoming can lead to paralysis of the nerves and muscles, local tissue damage and the death of cells in an organ, haemorrhaging, and it may interfere with the blood’s ability to coagulate.</p>
<p>Snakebites are a major public health issue in most tropical parts of the world, where <a href="http://www.who.int/mediacentre/factsheets/fs337/en/">more than 5 million bites occur each year</a>. This leads to more than 150,000 deaths and about three times as many amputations. Poor people living in snake infested areas are the worst affected. But in sub-Saharan Africa, victims not only suffer from the snakebite, but also from a lack of effective treatment options. Only <a href="http://www.sciencedirect.com/science/article/pii/S1874391911002181?via%3Dihub">about 2% of victims receive antivenom</a>.</p>
<p>Antivenoms that are made from serum from large mammals, immunised with snake venom are the mainstay of treating snakebites. But they are in short supply in sub-Saharan Africa, as they are costly to manufacture, and limited financial incentive holds the development of new antivenoms.</p>
<p>In an effort to overcome the shortage of antivenoms, the global snakebite community has declared <a href="http://www.nature.com/news/africa-braced-for-snakebite-crisis-1.18357">an antivenom crisis</a>. These efforts have brought international attention from both private foundations, researchers, and the World Health Organisation to this neglected tropical disease.</p>
<h2>Africa’s venomous snakes</h2>
<p>Two main snake families that cause the most dangerous snakebites in sub-Saharan Africa are – <a href="https://www.livescience.com/54023-vipers.html">vipers</a> and <a href="https://www.britannica.com/animal/elapid">elapids</a>. The viper family has a number of species, like the gaboon viper (<em>Bitis gabonica</em>), which holds the world record for the largest fangs. The carpet viper (<em>Echis ocellatus</em>) has the highest death toll of any snake. The elapid snake family includes neurotoxic cobras, spitting cobras, and mambas. It also holds the most notorious snake of them all, <a href="http://www.nationalgeographic.com/animals/reptiles/b/black-mamba/">the black mamba (<em>Dendroaspis polylepis</em>)</a>. </p>
<p>The venoms of these two snake families are fundamentally different. The venom of elapid snakes cause toxicity to the entire body. The primary clinical symptoms include paralysis caused by neurotoxins that stops muscles receiving signals from the nerves.</p>
<p>In contrast, viper venoms hold a large arsenal of toxins that destroy tissue and interfere with the bloods ability to clot.</p>
<p>For their part, spitting cobra venoms produce both effects. This includes paralysis as well as cell destruction (or cytotoxicity), which can lead to significant tissue damage in eyes or bitten limbs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178651/original/file-20170718-10341-1o8n8eh.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">The black mamba is part of the elapid snake family.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Antivenom – the only effective therapy</h2>
<p>The severe effects of bites by both vipers and elapids need to be treated with antivenom. But a scarcity of antivenoms in Africa has had a devastating impact on thousands of victims. Factors leading to this shortage include low profitability for manufacturers (due to high cost of production and low purchasing power of most victims and health care systems affected by snakebite), lack of advocacy, and simply that many researchers and politicians are not aware that snakebites are a pressing issue.</p>
<p>Unfortunately, this isn’t likely to change immediately. </p>
<p>One silver lining is that the World Health Organisation has recently reintroduced snakebite on the <a href="http://www.who.int/neglected_diseases/diseases/en/">list of neglected tropical diseases.</a> This may help create awareness as well as incentives to get <a href="https://theconversation.com/how-biotechnology-could-offer-hope-for-snakebite-victims-68244">antivenoms to the clinic</a>.</p>
<p>There are two types of antivenoms available. </p>
<ol>
<li><p>Those that can neutralise the venom of a single snake species and sometimes closely related ones too. These are known as monovalent antivenoms.</p></li>
<li><p>Antivenoms that neutralise a wider range of snake venoms, these are known as polyvalent antivenoms. </p></li>
</ol>
<p>The benefit of using monovalent antivenoms is that they may have a higher efficacy against bites from the specific species they are raised against. For their part, polyvalent antivenoms are useful because they can be used against a range of different bites. This is particularly helpful when the perpetrating snake hasn’t been identified. </p>
<p>In Africa, only polyvalent antivenoms are on the market due to the existence of many different snake species, difficulties in distinguishing them from each other, and since administration of an incorrect antivenom in a given case is avoided by having only one alternative (for the given geographical region) to choose from. Typically these antivenoms are manufactured to be effective against the venom from several vipers, selected cobras, and <a href="https://www.ncbi.nlm.nih.gov/pubmed/27339430">one to three mamba species.</a>.</p>
<h2>What to do, and not to do</h2>
<p>Symptoms and clinical presentation in patients bitten by a snake can be affected by a number of factors. These include: the snake species, the precondition of the patient, the dose of venom injected, and the availability of treatment options. Symptoms can develop quicker in children. </p>
<p>What’s important is that people, in the first instance, try to identify the snake. Proper identification – like a photo – is highly valuable.</p>
<p>Efforts should be made to ensure that the bitten section is immobilised or kept below the heart to reduce the spread of the venom. The patient should be kept still until help arrives or until safe transport is arranged to a health care facility. Patients bitten by a venomous viper or elapid species should be admitted for at least 12 hours. </p>
<p>If someone’s eyes are exposed to venom they should be washed thoroughly. But no other specific home treatment should be initiated. It’s a really bad idea to cut, suck or wash the bite site. </p>
<p>The numbers of deaths from snakebites won’t be reduced unless more, and preferably less expensive, antivenom is made available. This will require a joint effort between researchers, policymakers, and funding bodies.</p>
<p>Snakebites still claim the lives of many causing much morbidity to humans each year, but recent <a href="http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0005361">technological developments</a>, <a href="http://www.mdpi.com/2072-6651/8/12/351">rising awareness</a>, and <a href="https://www.statnews.com/2017/06/12/snakebite-who-priority/">increasing political focus</a> may hold the promise for a brighter future for snakebite victims.</p><img src="https://counter.theconversation.com/content/80982/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andreas Hougaard Laustsen receives funding from the Novo Nordisk Foundation and the Hørslev Foundation. </span></em></p><p class="fine-print"><em><span>Lotte Høgberg 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 best cure against a snakebite is to avoid being bitten at all. Here is what you need to know about snakebites, antivenom, and what you need to do if bitten.Andreas Hougaard Laustsen, Associate Professor at the Department of Biotechnology and Biomedicine, Technical University of DenmarkLotte Høgberg, Pharmacist, PhD, at the Danish Poisons Information Center (GIFTLINJEN), Department of Anaesthesiology, Copenhagen University HospitalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/728112017-02-27T15:26:48Z2017-02-27T15:26:48ZNew puff adder behaviour uncovered: it uses two ways to entice its prey<figure><img src="https://images.theconversation.com/files/157684/original/image-20170221-18624-sjmga1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Puff adders display diverse predatory strategies. This shows they have higher cognitive abilities than previously thought.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Predators use a variety of strategies to increase the odds of capturing prey. An amazing example involves the use of luring behaviours, which are aimed at increasing a predator’s foraging success by attracting potential prey to within striking range.</p>
<p>Luring behaviours result from an evolutionary adaptation referred to as <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev.es.13.110182.001125?journalCode=ecolsys.1">aggressive mimicry</a>. This typically includes a predator (the mimic), a model organism (the model), and a potential prey (the dupe). A classic example, the <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0310.1979.tb01022.x/full">North American alligator snapping turtle</a> wriggles a pink, fleshy structure located on the floor of its mouth, which presumably resembles a worm (the model) to deceive fish (the dupes). This attracts fish and facilitates their capture by the turtle.</p>
<p>Luring also takes place on land as we found in a recent study examining the foraging behaviour of free-ranging snakes. Our <a href="http://link.springer.com/article/10.1007/s00265-016-2244-6">study</a> on the foraging in puff adders – one of Africa’s most widespread, iconic, and medically important snake species – is unique in several ways. But more of it later.</p>
<p>As part of our study we used radiotelemetry in conjunction with <a href="https://www.jstor.org/stable/4098590?seq=1#page_scan_tab_contents">fixed videography</a> to study foraging in puff adders. Fixed videography is a technique that involves continuously recording behaviours of subjects for later analysis.</p>
<p>Puff adders are ideal subjects for such studies because they use specific ambush sites where they lie in wait <a href="http://rspb.royalsocietypublishing.org/content/282/1821/20152182">for prey for extended periods</a> (sometimes days or weeks). This allowed us to setup tripod-mounted surveillance videocameras to record foraging of wild puff adders in their natural environment so that we could record natural predator-prey interactions.</p>
<p>We recorded nearly 5,000 hours of puff adder foraging behaviour in the <a href="http://www.dinokengreserve.co.za/">Dinokeng Game Reserve</a> in South Africa’s Gauteng province. It showed that to attract prey to within striking range puff adders used two techniques: they extended their tongues (lingual luring) and also waved their tails (caudal luring), apparently to mimic an invertebrate model such as a worm or caterpillar. </p>
<p>Lingual luring happened solely in response to the presence of frogs indicating that this behaviour is a frog-specific hunting technique. This suggests that puff adders can visually discriminate amphibians from small mammals, lizard, and birds – even at night when most of the hunting takes place.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157680/original/image-20170221-18646-12z8xvo.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">Luring is a technique adopted by puff adders to draw prey withing striking range.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Luring behaviours</h2>
<p>Luring behaviours have been reported previously in other animals. For example, in addition to the alligator snapping turtle, the <a href="http://www.jstor.org/stable/pdf/20065809.pdf">snowy egret</a> and <a href="https://www.jstor.org/stable/1565240?seq=1#page_scan_tab_contents">four</a> <a href="http://www.jstor.org/stable/1562808?seq=1#page_scan_tab_contents">species</a> of <a href="http://www.bioone.org/doi/abs/10.1670/06-016.1">semi-aquatic snakes</a> from North America are known to use their tongues to lure fish. </p>
<p>Caudal luring has also been observed in many species of <a href="http://booksandjournals.brillonline.com/content/journals/10.1163/15685381-00002997">snakes</a>, in some species of <a href="http://0-www.jstor.org.innopac.wits.ac.za/stable/1446599?seq=1#page_scan_tab_contents">lizards</a>, and the aquatic larvae of <a href="http://www.bioone.org/doi/full/10.1093/jisesa/ieu008">some dragonflies</a>.</p>
<p>But our study is the first report two lures in the same organism. It is also the first to report lingual luring in a predator foraging for terrestrial prey – all other cases involved fish as prey. And this is the first record ever of puff adders luring. </p>
<p>We are not sure what puff adders were trying to attract with their caudal-luring since there was never any potential prey in the camera’s field of view. Although we can’t provide conclusive evidence, we believe the reason for this behaviour is to lure prey because it’s been recorded in other <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8312.2008.01016.x/full">snakes</a> species.</p>
<p>Our study shows that puff adders display diverse predatory strategies and complex decision-making process to catch prey. This demonstrates that they have higher cognitive abilities than most people would expect of a snake. </p>
<p>Second, the puff adder is commonly kept in captivity for antivenin and for public display. Yet neither lingual nor caudal luring has previously been reported for the species. This shows that that even common species of snakes are often not as well-known as commonly assumed. </p>
<p>Clearly, more field studies are needed to unravel the complexity of snake behaviour. Our study illustrates the power of the radiotelemetry-videography combination as a tool for the study of snake behaviour in a natural setting.</p><img src="https://counter.theconversation.com/content/72811/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Xavier Glaudas receives funding from National Geographic. </span></em></p><p class="fine-print"><em><span>Graham Alexander receives funding from the National Research Foundation and National Geographic.</span></em></p>New research shows that puff adders use two luring techniques to attract prey within striking range.Xavier Glaudas, Post-Doctoral Fellow School of Animal, Plant and Environmental Sciences, University of the WitwatersrandGraham Alexander, Professor of Herpetology, Environmental Physiology and Physiology, Ecology and Evolution, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/714082017-02-05T19:00:37Z2017-02-05T19:00:37ZHissstory: how the science of snake bite treatments has changed<figure><img src="https://images.theconversation.com/files/154019/original/image-20170124-8057-1s3soio.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gone are the days when we were told to suck out a snake's venom. So what's the current treatment and how have treatments changed over time?</span> <span class="attribution"><span class="source">State Library of NSW/Hood</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Summer is traditionally Australia’s snake bite season, when both snakes and people become more active. The human death toll is now admirably low, but it wasn’t always so.</p>
<p>Although colonial statistics are highly unreliable, in 1882-1892 about 11 people died from snake bites across Australia a year. Since then, the <a href="http://www.abs.gov.au/ausstats/abs@.nsf/0/1647509ef7e25faaca2568a900154b63?OpenDocument">continent’s population</a> has grown from 2.2 million to 24.3 million, yet on average just two people died from snake bites a year <a href="https://theconversation.com/welcome-to-australia-a-land-of-creatures-out-to-kill-you-maybe-71490">in 2001–2013</a>. While improved transport, communications and ambulance services have all contributed, so have the first aid and medical measures used to counteract snake venom.</p>
<h2>Complex colonial remedies</h2>
<p>A typical case from 1868 suggests the complexity – and desperation – of colonial remedies. When Victorian railway workers killed a brown snake at Elsternwick Station, they threw its body to stationmaster John Brown. Either the serpent was still alive, or Brown brushed its fangs, when he struck it “with an angry gesture”. The usual signs of envenomation (venom injected into the skin) soon appeared: vomiting, physical weakness then creeping paralysis followed by “coma”. Death, seemingly, was inevitable.</p>
<p>The stationmaster was rushed to nearby Balaclava, where surgeon George Arnold tied a ligature (tourniquet) around Brown’s arm before slicing out the bite site, hoping to remove the venom. He then poured ammonia (a hazardous chemical used today in cleaning) onto the wound to neutralise any remaining venom before urging Brown to drink six ounces (175mL) of brandy to stimulate his circulation.</p>
<p>He waved pungent smelling salts under Brown’s nose then applied a paste-like poultice of mustard to his patient’s hands, feet and abdomen to alleviate internal congestion. Further stimulation followed via electric shocks before the staggering, semi-conscious stationmaster was marched up and down to keep him awake – and alive. Brown, nevertheless, kept deteriorating.</p>
<p>Arnold urgently summoned the colony’s only medical professor, <a href="http://adb.anu.edu.au/biography/halford-george-britton-3693">George Halford at Melbourne University</a>, who reluctantly agreed to apply his new snake bite remedy. He opened a vein in Brown’s arm and injected ammonia directly into the bloodstream. The stationmaster revived almost immediately, leading another doctor to assert “the injection of Ammonia saved the man’s life” (do not try this at home).</p>
<h2>Name your poison</h2>
<p>John Brown’s treatment followed a pattern familiar across Australia from 1800 into the 1960s. While many of the 1868 interventions now seem bizarre – or downright dangerous – they <a href="http://medicalhistorymuseum.mdhs.unimelb.edu.au/__data/assets/pdf_file/0018/1942002/Spectacular-Serpents-Snakebite-in-colonial-Australia.pdf">made sense in historical context</a>. Until well into the 20th century, snake bite treatments alternated between three fundamental approaches.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=910&fit=crop&dpr=1 600w, https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=910&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=910&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1144&fit=crop&dpr=1 754w, https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1144&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/154020/original/image-20170124-8067-n1jkov.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1144&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Self-experimentation has been a common danger among snake bite investigators.</span>
<span class="attribution"><span class="source">State Library of NSW</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In common with today’s understanding, most European settlers, and many Indigenous cultures, considered venom to be <a href="http://www.manchesteruniversitypress.co.uk/articles/snakebite-science-suffering/">an external “poison” that moved through the body</a>. Physical measures such as ligature or suction were thus common to expel venom or limit its circulation. </p>
<p>A second strand of remedies, from mustard poultices to injected ammonia, sought to counteract its ill effects in the body, often by stimulating heart function and blood flow.</p>
<p>The third approach was to directly neutralise venom itself, for instance, pouring ammonia onto the bite.</p>
<p>Until the 1850s, physical measures dominated, while the next 50 years were the heyday of opposing-action treatments. When Halford’s intravenous ammonia fell from favour (as it didn’t seem to work), it was replaced in the 1890s by injections of another notorious poison: strychnine. At first even more popular than ammonia, this highly toxic plant-based poison was blamed for killing more patients than it saved. Yet by far the most popular colonial remedy, both with practitioners and patients, was drinking copious quantities of alcohol, especially brandy.</p>
<h2>The slow premiere of antivenoms</h2>
<p>The third approach, directly neutralising venom, underlay both Australia’s hugely popular folk “cures” and the novel “antivenene” technology developed in the 1890s. Now they are known as antivenoms and are created by injecting venom into (generally) horses, prompting an immune response, then purifying antibodies from their blood to inject into snake-bitten patients.</p>
<p>But antivenenes suffered a slow gestation in Australia. The first, targeting black snake venom, was developed in 1897; experimental tiger snake antivenene followed in 1902. But antivenenes are tricky to produce, distribute and store. They also proved difficult to administer, sometimes provoking life-threatening anaphylactic reactions (a severe allergic response).</p>
<p>It wasn’t until 1930 that <a href="https://discovery.wehi.edu.au/timeline/snakebite-antivenom">commercial tiger snake antivenene</a> came onto the Australian market.</p>
<p>Other injections targeting a wider range of serpents. “Polyvalent” antivenene, which is effective against multiple venoms, <a href="http://www.venomsupplies.com/assets/Pioneers-published-paper.pdf">only emerged from the mid-1950s</a>. Meanwhile, patients continued to undergo various first-aid measures, particularly ligatures and Condy’s crystals (<a href="https://en.wikipedia.org/wiki/Potassium_permanganate">potassium permanganate</a>, used to clean wounds) applied to the bite in the hope of inactivating venom.</p>
<h2>Two eternal questions</h2>
<p>Current snake bite management only stabilised in the 1980s. Two developments were key: rapid tests to identify the injected venom and a new first-aid strategy.</p>
<p>Scientist <a href="https://www.mja.com.au/journal/2002/177/3/struan-keith-sutherlandao-mb-bs-md-dsc-fracp-frcpa">Struan Sutherland</a> pioneered the “<a href="http://stjohn.org.au/assets/uploads/fact%20sheets/english/FS_snakebite.pdf">pressure immobilisation technique</a>”. This recommends tightly wrapping a bandage around the bitten region, adding a splint and minimising movement to slow venom spread.</p>
<p>Not washing or cutting the bite site leaves a venom sample to aid identification and so choose the most appropriate antivenom.</p>
<p>But today’s management is still being evaluated because both venoms and treatments still <a href="https://www.mja.com.au/journal/2013/199/11/snakebite-australia-practical-approach-diagnosis-and-treatment">pose clinical challenges</a>, including severe reactions and long-term damage.</p>
<p>And just as in 1868, two eternal questions remain critical: was it truly a deadly serpent, and did it inject enough venom to kill?</p><img src="https://counter.theconversation.com/content/71408/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Hobbins received an Australian Postgraduate Award to undertake his PhD on the subject of snakebite in colonial Australia, and is the 2016 Merewether Fellow at the State Library of New South Wales, which entails research on a similar topic.</span></em></p>Snake bite treatments have changed remarkably over the past 200 years. But most, if not all, made sense in their historical context.Peter Hobbins, ARC DECRA Fellow, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/518092016-01-11T19:20:56Z2016-01-11T19:20:56ZYes, Australian snakes will definitely kill you – if you’re a mouse<figure><img src="https://images.theconversation.com/files/107709/original/image-20160111-16066-c9mq0k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Australian snakes can kill the most mice with the smallest amount of venom.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/michaelsale/5305780693/">Michael Sale/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The idea that Australia is home to many of the most deadly snakes in the world is based on <a href="http://www.ncbi.nlm.nih.gov/pubmed/?term=Broad+A+and+1979">animal research from the 1970s</a> that looked at the effect of 25 venoms on mice. While not entirely untrue, the claim is also not quite right.</p>
<p>A more accurate statement might be that Australian snakes are the best mouse killers in the world: they’re able to kill the most mice with the smallest amount of venom. While that’s clearly bad news for mice, how does it translate into human risk? </p>
<p>The occurrence and severity of a snake bite depends on a complex interaction between snake behaviour, venom toxicity and human behaviour. Significant factors include how toxic the venom is; how much of it is injected by the snake; and how humans encounter and interact with snakes. </p>
<h2>Toothless tigers?</h2>
<p>Australian snakes have very toxic venoms but inject tiny amounts at a time because most have short fangs. The only evidence of a brown snake bite may be a small scratch, for instance, but the venom is so toxic that it quickly results in the person’s blood failing to clot, which puts them at risk of bleeding to death.</p>
<p>Mulga snakes (King Brown) can deliver larger amounts of venom, but have one of the less toxic venoms of dangerous Australian snakes. </p>
<p>Historically, tiger snakes and death adders were <a href="https://en.wikipedia.org/wiki/List_of_fatal_snake_bites_in_Australia#Before_1900">responsible for most deaths</a>. They’re widely distributed throughout Australia and their bites cause paralysis. </p>
<p>Before the advent of modern intensive care, paralysis was – more often than not – fatal. But with the development of antivenom in the 1930s and 1950s, and machines that can breathe for people, paralysis from snakebite has become uncommon.</p>
<p>Taipans also cause paralysis, but are a rare cause of snakebite in Australia (in contrast to Papua New Guinea where they cause much havoc). </p>
<p>In modern times, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0053188">brown snake bites</a> have become more common and now cause the majority of such deaths in Australia. This group of snakes appears to have thrived despite human invasion and the destruction of natural habitats. Brown snakes are now the most common cause of severe snake envenoming in Australia, according to the <a href="http://wikitoxin.toxicology.wikispaces.net/Australian+Snakebite+Project">Australian Snakebite Project</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/107710/original/image-20160111-16054-n3f329.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">Eastern Brown Snake (<em>Pseudonaja textilis</em>) is one of the group of snakes that cause the most severe envenomings in Australia.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/kookr/2943122737/">David Cook/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>They cause the majority of the one to five deaths from snakebites each year, usually from early collapse and cardiac arrest. Unfortunately, antivenom is unlikely to help these people because cardiac arrest happens within 30 minutes of the bite. Early basic life support from bystanders is most important for snake bites because this can keep someone alive until they’re transported to hospital. </p>
<h2>Treating bites</h2>
<p>Severe snake envenoming is actually quite rare in Australia, with only about <a href="http://www.newcastle.edu.au/research-and-innovation/centre/health-medicine/clinical-toxicology/research/australian-snakebite-project">100 cases each year</a>. After brown snakes, red-bellied black snake bites are the next most common, but they rarely cause severe envenoming and occur only in eastern Australia. </p>
<p><a href="https://www.mja.com.au/journal/2012/197/3/tiger-snake-notechis-spp-envenoming-australian-snakebite-project-asp-13?0=ip_login_no_cache%3Dd1b8938253cd24d4615a174a91fe452b">Tiger snakes</a>, which continue to account for a significant number of bites in southern Australia, are one of three snakes found in Tasmania and account for almost all serious snake bites in Victoria. They cause all three major types of toxicity: coagulopathy (making a person’s blood unable to clot), neurotoxicity (paralysis) and myotoxicity (muscle damage). </p>
<p>Snake bites are treated with antivenom, which needs to be given as soon as possible after a bite to be effective. The <a href="http://www.newcastle.edu.au/research-and-innovation/centre/health-medicine/clinical-toxicology/research/australian-snakebite-project">Australian Snakebite Project</a> has demonstrated that only one vial of antivenom is required to treat all cases of snake envenoming.</p>
<p>But many of the effects of snake envenoming are irreversible in the short term (muscle damage, for instance, and paralysis), so antivenom won’t help for these. Instead, treatment in intensive care will support the patient while the body repairs. This is why antivenom needs to be given early. </p>
<p>Using antivenom comes with the risk of an allergic reaction, so it’s important that only people with envenoming be treated. <a href="http://www.nature.com/articles/srep04827">Recent research</a> measuring snake venom enzymes in blood appears to identify envenoming early. It is hoped that development of bedside testing of these enzymes will improve early recognition.</p>
<p>Although the effects of venom are reasonably well understood, why they cause severe toxicity in humans remains unclear. After all, we are not prey for snakes; small reptiles (such as skinks) or small mammals (such as marsupial rats) are their primary targets. </p>
<p>The toxicity we see in humans, such as venom’s clotting effects that commonly occur with brown snake, tiger snake and taipan bites, is most likely a chance occurrence. This idea is supported by <a href="http://www.sciencedirect.com/science/article/pii/S0049384815302152">recent research</a> that shows many animals, including rodents and skinks, are highly resistant to the clotting effect of snake venom. But they’re highly susceptible to the neurotoxic effects of snake venoms. </p>
<p>In most other parts of the world, vipers, which have much larger fangs, are much more common. They inject ten or more times as much venom as Australian snakes, but have less toxic venoms. The other major difference is that vipers can cause local skin and tissue damage and, in some cases, this can lead to amputation. Unlike the human impact of Australian snakes, viper envenoming is a <a href="http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0050218">huge public health issue worldwide</a>.</p>
<p><em>This article is part of our series <a href="https://theconversation.com/au/topics/deadly-australia">Deadly Australia</a>. Stay tuned for more pieces on the topic in the coming days.</em></p><img src="https://counter.theconversation.com/content/51809/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Geoff Isbister receives funding from the National Health and Medical Research Council - Senior Research Fellowship, Centre for Research Excellence in Translational Venom and Antivenom Research and a Program Grant.</span></em></p>Australian snakes are the best mouse killers in the whole world. And while that’s clearly bad news for mice, how does it translate into human risk?Geoff Isbister, Director, Clinical Toxicology Research Group, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.