tag:theconversation.com,2011:/uk/topics/tick-borne-disease-73182/articlesTick-borne disease – The Conversation2023-08-21T15:04:41Ztag:theconversation.com,2011:article/2117642023-08-21T15:04:41Z2023-08-21T15:04:41ZTicks are becoming a growing health risk in the UK – here’s why<figure><img src="https://images.theconversation.com/files/543744/original/file-20230821-17-xnnyki.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C5937%2C3961&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The castor bean tick is the most common species in the UK.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/encephalitis-tick-crawls-on-skin-harmful-2165382461">Aleksey Matrenin/ Shutterstock</a></span></figcaption></figure><p>Earlier this year, the UK Health Security Agency confirmed a case of <a href="https://www.gov.uk/government/news/tick-borne-encephalitis-detection-in-england">tick-borne encephalitis</a> – a potentially deadly virus carried by ticks that causes brain inflammation. A British man is also said to have contracted <a href="https://www.independent.co.uk/news/uk/home-news/tick-bite-alpha-gal-syndrome-lyme-disease-b2388148.html">alpha-gal syndrome</a> after being bitten by a tick. This condition can trigger a fatal allergy to red meat.</p>
<p>The ticks that carry these pathogens are already common in other parts of the world, including Europe and North America. But in light of these reports, many may be wondering whether ticks and tick-borne diseases are a growing risk in the UK.</p>
<h2>Are tick numbers increasing?</h2>
<p>It’s difficult to provide a straightforward answer as to whether tick populations are rising in the UK. This is because tick abundance surveys tend to be fairly localised and only done during short, sporadic time frames.</p>
<p>This is important, as the tick lifecycle typically spans around two years, but may last several years depending on whether or not it feeds. Tick populations will also vary depending on the local populations of the animals they use as hosts (such as rodents and birds).</p>
<p>So given the sporadic data we have on tick density, it’s difficult to estimate how much tick populations have really increased, and whether this is part of a long-term trend. But we are seeing both an upsurge of some species and the <a href="https://www.annualreviews.org/doi/10.1146/annurev-ento-052720-094533">establishment of new ticks</a> in the UK in recent years.</p>
<h2>Why are things changing?</h2>
<p>Climate change undoubtedly has had a huge impact on <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2648658/#:%7E:text=Although%20changes%20in%20climate%20and,in%20development%20rates%20will%20make">tick infestations</a>.</p>
<p>This has been particularly noticeable in <a href="https://www.niehs.nih.gov/research/programs/geh/geh_newsletter/2020/12/spotlight/climate_change_likely_to_influence_the_abundance_and_geographic_range_of_ticks_and_their_associated_diseases.cfm">colder regions</a>, such as in parts of Canada where ticks had not previously been recorded. In the UK, recent milder winters mean ticks are being sighted <a href="https://www.annualreviews.org/doi/10.1146/annurev-ento-052720-094533">earlier in the year</a> than normal.</p>
<p>A push to build parks and green spaces, particularly in <a href="https://www.sciencedirect.com/science/article/pii/S1877959X21002107?via%3Dihub">towns and cities</a>, is another factor which can influence tick abundance. While green spaces have many benefits to human health and the environment, these can also provide a <a href="https://www.sciencedirect.com/science/article/pii/S1877959X22002059">suitable habitat for ticks</a> – with a high risk of exposure to humans and their pets.</p>
<p>On farms, areas set aside to preserve wildlife also provide excellent tick habitats. These are often close to paths used by hikers.</p>
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<img alt="A tick crawls across a leaf." src="https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/543745/original/file-20230821-17-cw1568.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">
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<span class="caption">Green spaces create a suitable habitat for ticks.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/encephalitis-tick-insect-crawling-on-leaf-2290170043">nechaevkon/ Shutterstock</a></span>
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<p>Animals also drive up tick numbers. Deer, rodents and <a href="https://www.sciencedirect.com/science/article/pii/S1877959X22002059">ground-foraging birds</a> (such as blackbirds) are all important hosts. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142536/">Migratory birds</a> also aid in the spread of <a href="https://www.sciencedirect.com/science/article/pii/S1877959X2200214X">ticks in the UK</a> as they carry them from <a href="https://pubmed.ncbi.nlm.nih.gov/22300969/">other countries</a>. Pets travelling from outside the UK are also responsible for the importation of at least <a href="https://bvajournals.onlinelibrary.wiley.com/doi/full/10.1136/vr.104263">ten tick species</a>.</p>
<h2>What health risks do ticks carry?</h2>
<p>In the UK, the most common tick species is the castor bean tick (<em>Ixodes ricinus</em>). The red sheep tick (<em>Haemaphysalis punctata</em>) and the newly established ornate dog tick (<em>Dermacentor reticulatus</em>) are also becoming more common. </p>
<p>Ticks can carry harmful germs.</p>
<p>Lyme borreliosis (also known as Lyme disease) is one such example. In the UK, this is spread by the castor bean tick. Symptoms of <a href="https://www.nhs.uk/conditions/lyme-disease/">Lyme disease</a> include a circular or oval rash around the bite area, as well as fatigue and flu-like symptoms that can become chronic if untreated. </p>
<p>The incidence of Lyme disease is fairly low in the UK (just under <a href="https://www.gov.uk/government/publications/lyme-borreliosis-epidemiology/lyme-borreliosis-epidemiology-and-surveillance">3% of ticks</a> carry it). But in other parts of Europe, between <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514677/">9-22% of ticks</a> carry Lyme disease – and this number is rising.</p>
<p><a href="https://theconversation.com/tick-borne-encephalitis-virus-in-the-uk-what-it-is-and-how-to-protect-yourself-203619">Tick-borne encephalitis virus</a> has also now become established in the UK. This is also spread by the castor bean tick. It initially causes flu-like symptoms, but may lead to brain inflammation. Cases of tick-borne encephalitis virus are still rare in the UK. </p>
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Read more:
<a href="https://theconversation.com/tick-borne-encephalitis-virus-in-the-uk-what-it-is-and-how-to-protect-yourself-203619">Tick-borne encephalitis virus in the UK – what it is and how to protect yourself</a>
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<p>Ticks can also transmit a pathogen that causes babesiosis, which affects humans and animals. This illness attacks the red blood cells, leading to anaemia. </p>
<p>Recently, some fatal <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-018-2718-7">cases in dogs</a> were associated with the <em>Dermacentor reticulatus</em> tick. This tick isn’t native to England but has now become established in Essex and the south-east coast. </p>
<p>The red sheep tick has also been reported in <a href="https://www.sciencedirect.com/science/article/pii/S1877959X22000085">South Downs National Park</a>. This carries bacteria called <em>Borrelia miyamotoi</em>, which causes <a href="https://www.cdc.gov/relapsing-fever/index.html">tick-borne relapsing fever</a> – an infection characterised by recurrent bouts of chills, sweat, muscle aches and vomiting. </p>
<p>Public health officials are particularly concerned about the spread of the lethal viral infection Crimean-Congo haemorrhagic fever. This disease causes fever, muscle aches and dizziness, which can rapidly progress to kidney deterioration or sudden liver failure in just a few days. It has a 10-40% fatality rate.</p>
<p><a href="https://www.ecdc.europa.eu/en/crimean-congo-haemorrhagic-fever">Crimean-Congo haemorrhagic fever</a> is transmitted by Hyalomma ticks, which are most common in the Mediterranean basin. Although this tick hasn’t been detected in the UK, cases have been spreading <a href="https://www.ecdc.europa.eu/en/crimean-congo-haemorrhagic-fever/facts/factsheet">throughout Europe in recent years</a> – with recent cases <a href="https://www.independent.co.uk/news/health/crimean-congo-hemorrhagic-fever-uk-cchf-symptoms-b2377034.html">reported in Spain</a>.</p>
<h2>Protecting yourself</h2>
<p>The best way to prevent tick-borne diseases is by avoiding tick bites.</p>
<p>Avoid tall grasses and areas where ticks thrive (such as moorlands and woodlands), especially during the warmer months. If you planning on going outdoors, stay on marked paths and cover yourself with long clothing so ticks can’t bite you. Insect repellents can also help.</p>
<p>If you find you’ve been <a href="https://www.nhsinform.scot/illnesses-and-conditions/injuries/skin-injuries/tick-bites#:%7E:text=Using%20fine%2Dtoothed%20tweezers%2C%20gently,the%20skin%20around%20the%20bite.">bitten by a tick</a>, you should remove it as soon as possible to avoid risk of infection. If you become unwell after being bitten by a tick, it’s important to visit a GP as soon as possible.</p><img src="https://counter.theconversation.com/content/211764/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Cutler has previously received funding from ECDC and is currently a member of a COST-Action (PRAGMATICK) on tick-borne diseases. </span></em></p>Ticks can spread a range of disease – including Lyme disease and the fatal Crimean-Congo haemorrhagic fever.Sally Cutler, Professor, Medical Microbiology, University of East LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2079962023-06-20T16:28:16Z2023-06-20T16:28:16ZCrimean-Congo haemorrhagic fever – why this tick-borne virus could become more common in richer countries<figure><img src="https://images.theconversation.com/files/532913/original/file-20230620-19-rdo2o8.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C3238%2C2158&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/search/hyalomma-tick">Gertjan Hooijer/Shutterstock</a></span></figcaption></figure><p>Climate change is already having, and will continue to have, a significant effect on global health. This is likely to be <a href="https://www.thelancet.com/article/S0140-6736(21)01787-6/fulltext">greatest</a> in rural poorer populations in sub-Saharan Africa. However, <a href="https://www.nature.com/articles/s41558-022-01426-1">richer countries</a>, such as the UK, will also probably be on the receiving end of emerging infectious disease threats as the country warms.</p>
<p>Infections that are mainly found in the tropics are on the move to new locations. Dengue, a virus transmitted by mosquitoes, is becoming more <a href="https://theconversation.com/dengue-in-france-tropical-diseases-in-europe-may-not-be-that-rare-for-much-longer-191033">widely reported</a> in European countries, particularly in some parts of Italy and France. The West Nile virus, which is also spread by mosquitoes, has been <a href="https://www.cdc.gov/westnile/statsmaps/historic-data.html">common</a> across many states in the US, with typically more than 1,000 cases reported each year.</p>
<p>Another virus shifting to new locations is the Crimean-Congo haemorrhagic fever virus (CCHFV), which is transmitted by ticks. Most cases occur in Africa or Asia, but cases have been reported in several <a href="https://www.ecdc.europa.eu/en/crimean-congo-haemorrhagic-fever/facts/factsheet">European countries</a>, including Spain, Turkey, Greece, Russia and Ukraine, with recent <a href="https://www.mirror.co.uk/news/uk-news/new-deadly-virus-highly-likely-30236885">media reports</a> warning we might see the virus arrive in the UK.</p>
<p>So what is CCHFV, and should we be worried? Let’s take a look.</p>
<p>There are <a href="https://www.ecdc.europa.eu/en/crimean-congo-haemorrhagic-fever/facts/factsheet">approximately 15,000 cases</a> of CCHFV a year, globally. CCHFV is a serious pathogen – <a href="https://www.who.int/health-topics/crimean-congo-haemorrhagic-fever">typically between 10-40%</a> of people who contract the virus will die from it.</p>
<p>As the name suggests, CCHFV is part of a group of diseases known as viral haemorrhagic fevers. These are <a href="https://www.afro.who.int/health-topics/viral-haemorrhagic-fever">described</a> as causing “severe multi-system syndrome”, meaning multiple organ systems in the body are affected. These infections can also be accompanied by severe bleeding. Other viruses in this <a href="https://www.nature.com/articles/s41579-023-00871-9">group</a> include Ebola, Marburg, dengue, and Rift Valley fever virus.</p>
<p>CCHFV is transmitted by a tick species called the <a href="https://www.ecdc.europa.eu/en/disease-vectors/facts/tick-factsheets/hyalomma-marginatum">Hyalomma tick</a>. The virus was first identified in the Crimean Peninsula in 1944, with an outbreak in the Congo in 1956 resulting in the modern-day <a href="https://www.who.int/health-topics/crimean-congo-haemorrhagic-fever">name</a>. To avoid stigma, the linking of pathogen names to the site of the first known outbreaks is <a href="https://www.who.int/news/item/08-05-2015-who-issues-best-practices-for-naming-new-human-infectious-diseases">no longer</a> practised.</p>
<p>A tick bite is the most common way to contract CCHFV. Though transmission has also <a href="https://www.nature.com/articles/s41579-023-00871-9">occurred</a> after needlestick injuries or from infected blood, meaning there is some risk to healthcare workers. </p>
<p>But there is little sustained transmission between humans, with outbreaks typically relying on the presence of an infected tick. Hyalomma ticks can be found on a range of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4704823/">animals</a>, including livestock and rabbits. Most animals appear to be able to carry the tick and the virus <a href="https://www.nature.com/articles/s41579-023-00871-9">without</a> becoming unwell.</p>
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Read more:
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<p>In people infected with CCHFV, symptoms typically <a href="https://www.who.int/health-topics/crimean-congo-haemorrhagic-fever#tab=tab_2">start</a> with fever, muscle ache or dizziness, and can rapidly progress within a few days to kidney deterioration or sudden liver failure. </p>
<p>CCHFV is <a href="https://www.who.int/activities/prioritizing-diseases-for-research-and-development-in-emergency-contexts">recognised</a> by the World Health Organization (WHO) as a virus where there has been limited research but where the pathogen is considered to be a high threat. </p>
<p>There is no vaccine available, nor any established antiviral treatment. However, <a href="https://www.nature.com/articles/s41579-023-00871-9">ribavirin</a>, a medicine used to treat other viruses such as hepatitis C, has shown some promise.</p>
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<img alt="A herd of cattle." src="https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532917/original/file-20230620-15-gmkp0q.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">
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<span class="caption">Hyalomma ticks, which transmit HHCFV, can be found on a range of animals.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/herd-charolais-cross-brahman-cattle-charbray-1023813052">Jen Watson/Shutterstock</a></span>
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<h2>Should we be worried?</h2>
<p>Within the UK, there have so far only been small numbers of <a href="https://www.bbc.co.uk/news/health-60872683">imported cases</a>, where people have contracted the virus while travelling in high-risk areas. </p>
<p>There is ongoing research and surveillance in areas such as <a href="https://www.telegraph.co.uk/global-health/science-and-disease/why-official-mosquitoes-hunters-kent-fear-new-surge-malaria/">marshlands</a>, where ticks and mosquitoes are caught and studied to see if there are any new or evolving threats. The Hyalomma tick <a href="https://www.hps.scot.nhs.uk/publications/hps-weekly-report/volume-56/issue-13/cchf-confirmed-in-the-uk/">is not currently established</a> in the UK, and so the threat, for now, is very low. </p>
<p>Still, there are many other types of ticks in the UK, including those responsible for causing Lyme disease, which are usually found on vegetation. They cannot walk or fly, so the <a href="https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1148613/Tick-awareness-A5-leaflet-April-2023.pdf">public health advice</a> for protecting against tick bites includes avoiding brushing against vegetation when out for walks, carrying out regular tick checks and using repellents. </p>
<p>In areas where <a href="https://www.ecdc.europa.eu/en/crimean-congo-haemorrhagic-fever/facts/factsheet">CCHFV</a> is a higher risk, such as during or after an outbreak, hygienic storage of meat is thought to be important, and restrictions around the transport of animals may be introduced.</p>
<p>There is concern from the WHO and other health experts about the global spread of this Hyalomma tick. The wide range of animals on which the tick is found means there is potential for it to become endemic in new communities. The tick has also been <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3557898/">detected</a> in long-range migratory birds, and was found in 2018 in <a href="https://pubmed.ncbi.nlm.nih.gov/32037097/">Sweden</a> for the first time.</p>
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Read more:
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<p>Viral haemorrhagic fevers like CCHFV can cause severe illness and death in some people who become infected. Also, localised outbreaks can have other consequences for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9147186/">poor farming communities</a>, such as the slaughter of their cattle and subsequent loss of trade.</p>
<p>There is unlikely to be a significant number of cases of CCHFV in the UK at any point soon. However, as globalisation increases and climate change continues to alter patterns of disease, it’s plausible that the virus might pose a sustained threat in the future.</p><img src="https://counter.theconversation.com/content/207996/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Head has previously received funding from the Bill & Melinda Gates Foundation and the UK Department for International Development.</span></em></p>Catching this virus can be serious, but the risk at this stage in the UK is very low.Michael Head, Senior Research Fellow in Global Health, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2036192023-04-17T16:11:35Z2023-04-17T16:11:35ZTick-borne encephalitis virus in the UK – what it is and how to protect yourself<figure><img src="https://images.theconversation.com/files/521078/original/file-20230414-28-3lyvi9.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C4790%2C3264&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/patient-tick-spring-vegetation-101121742">PHOTO FUN/Shutterstock</a></span></figcaption></figure><p>A confirmed case of <a href="https://www.nhs.uk/conditions/tick-borne-encephalitis/">tick-borne encephalitis</a> (TBE) was recently <a href="https://www.bbc.co.uk/news/health-65177440">reported in England</a>. TBE is a disease that can lead to inflammation in the brain and is caused by a virus transmitted by the bite of a tick.</p>
<p>These blood-feeding arthropods can <a href="https://www.sciencedirect.com/science/article/abs/pii/S1877959X20304775">harbour and transmit</a> various infectious diseases. Many associate tick bites with Lyme disease, however, in much of Europe (northern, central, and eastern regions and beyond through to parts of Asia), <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">TBE virus</a> can be transmitted by the same ticks. </p>
<p>In fact, more than <a href="https://www.ecdc.europa.eu/en/publications-data/tick-borne-encephalitis-annual-epidemiological-report-2020">3,800 cases</a> of TBE were reported across 24 European countries during 2020, according to the European Centre for Disease Prevention and Control. The incidence in Europe was 0.9 cases per 100,000 people in 2020, but this shows significant variation by country. For example, the rate was 7.9 per 100,000 in the Czech Republic and 24.3 per 100,000 in Lithuania. </p>
<p>A general upward trend in human cases has been noted over recent years, while there have been expansions to the usual known areas for TBE. We don’t fully understand the reasons for this, but climate change is likely to be an important factor.</p>
<p>This virus wasn’t present in the UK until recent years. An initial case was reported <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6885749/">in 2019</a> in an infant who acquired the infection in southern England. This was followed by another probable case from southern England <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">in 2020</a>. In June 2022 a case was reported <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">in Scotland</a>, and the most recent case, reported in October 2022, was a person thought to have become infected while visiting England’s North Yorkshire Moors.</p>
<p>Taken together, this evidence suggests that the TBE virus is now successfully circulating in the UK, albeit at low levels.</p>
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<h2>How did it get here?</h2>
<p>Ticks can “hitch a lift” on migratory birds, which is probably the route of entry into the UK. However, for the virus to <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217206">establish and circulate</a>, specific climatic conditions are needed that allow the different life stages of a tick to feed on the blood of their vertebrate host (such as a rodent). The virus can be transferred from infected to non-infected ticks when both feed on the same host.</p>
<p>Since 2019, studies of <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30040-4/fulltext">ticks in the UK</a> have detected low levels of TBE virus in ticks from both <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924911/">Thetford forest</a> and the Hampshire and Dorset border region. Ticks infected with TBE virus have also been detected in <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">the New Forest</a> and the North Yorkshire Moors.</p>
<p>Slight differences have been found in the genetic background between these viruses, suggesting there have been introductions from multiple locations.</p>
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<strong>
Read more:
<a href="https://theconversation.com/ticks-spread-plenty-more-for-you-to-worry-about-beyond-lyme-disease-118102">Ticks spread plenty more for you to worry about beyond Lyme disease</a>
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<p><a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001492">TBE virus</a> can be divided into five variants based on the geographical areas in which they’re generally found. The variant being detected in the UK to date belongs to the European subtype of TBE virus and has been one of the milder variants.</p>
<p>Each variant consists of multiple strains. Those detected in the UK have <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">shown similarity</a> to the Norwegian Mandal, a strain identified in 2009, and a strain detected in 2017 in the Netherlands.</p>
<h2>Symptoms</h2>
<p>Although the virus has encephalitis in its name, becoming infected doesn’t necessarily mean you will get <a href="https://www.nhs.uk/conditions/encephalitis/">encephalitis</a> (swelling of the brain).</p>
<p>The <a href="https://www.ecdc.europa.eu/en/tick-borne-encephalitis/facts/factsheet">effects of this virus</a> can range from having no symptoms at all, to fever, fatigue and body pains, through to infection of the central nervous system where it results in inflammation (meningitis to severe encephalitis) that can lead to long-term neurological damage or death. Encephalitis is more common in older patients.</p>
<p>More serious symptoms to look out for that may indicate encephalitis include severe headache, a stiff neck, confusion, and weakness in the arms and legs.</p>
<figure class="align-center ">
<img alt="A warning sign indicating on a forest path." src="https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521248/original/file-20230417-24-hr46sn.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">TBE wasn’t detected in the UK until 2019.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/infected-ticks-warning-sign-forest-risk-2113458593">24K-Production/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Preventing TBE</h2>
<p>Typically, TBE shows <a href="https://www.ecdc.europa.eu/en/publications-data/tick-borne-encephalitis-annual-epidemiological-report-2020">a seasonal pattern</a> with a peak in July and August.</p>
<p>There is <a href="https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/vaccines-quality/tick-borne-encephalitis-vaccine">a vaccine</a> that has been used to prevent TBE in endemic regions for many years. The vaccines are safe and highly effective, but require boosters.</p>
<p>While the levels of TBE virus are low in the UK, vaccination is probably not justifiable, but this needs to be actively monitored. Vaccination might be considered for selected groups at high risk of tick exposure, such as forestry workers.</p>
<p>The vaccine is also worth considering <a href="https://www.nhs.uk/conditions/tick-borne-encephalitis/">for people</a> visiting a country where TBE is common and planning to do outdoor activities while there. The vaccine isn’t available on the NHS but can be accessed through travel clinics.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-climate-change-causing-a-rise-in-the-number-of-mosquito-and-tick-borne-diseases-105097">Is climate change causing a rise in the number of mosquito and tick-borne diseases?</a>
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<p>As we’re seeing TBE virus become established in the UK, we need to ensure that those who become sick after tick bites receive a screen for a full range of tick-borne pathogens, rather than just the better-known Lyme disease tests. Accordingly, the <a href="https://www.gov.uk/government/publications/hairs-risk-assessment-tick-borne-encephalitis/hairs-risk-assessment-tick-borne-encephalitis">UK Health and Security Agency</a> has recommended changes to testing in hospitals to ensure quick detection of new cases.</p>
<p>Also, enhanced surveillance of ticks will be important to help us understand TBE risk in different areas of the UK. </p>
<p>While the overall risk to the public is very low, people can take <a href="https://www.bbc.co.uk/news/health-65177440">simple measures</a> to reduce the risk of tick bites when outdoors in moorlands and woodlands. These include walking on clearly marked paths, covering skin with clothing as much as possible, and using insect repellents such as Deet. </p>
<p>It’s also worthwhile checking your body for ticks after time spent in potentially tick-infested areas. Anyone who becomes unwell after a tick bite should see a doctor.</p><img src="https://counter.theconversation.com/content/203619/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Cutler 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>Although the UK has seen a handful of cases, the risk remains very low.Sally Cutler, Professor, Medical Microbiology, University of East LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1719172021-11-17T19:02:06Z2021-11-17T19:02:06ZA lab-stage mRNA vaccine targeting ticks may offer protection against Lyme and other tick-borne diseases<figure><img src="https://images.theconversation.com/files/432279/original/file-20211116-27-1h08z62.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As the rate of tick-borne diseases rises, vaccines that stop ticks in their tracks could be an essential preventive tool.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/the-fingers-of-the-hand-catch-an-encephalitis-royalty-free-image/1289080738">rbkomar/Moment via Getty Images</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>A new laboratory-stage mRNA vaccine that teaches the immune system to recognize the saliva from tick bites could prevent these bugs from feeding on and transmitting tick-borne diseases to people, according to <a href="https://doi.org/10.1126/scitranslmed.abj9827">a recent study</a> my colleagues and I conducted in the <a href="https://medicine.yale.edu/lab/fikrig/">Fikrig Lab</a> at the Yale School of Medicine.</p>
<p>Some animals repeatedly exposed to tick bites are eventually able to develop resistance to tick feeding, where the ticks either detach soon after biting or cause skin redness that alerts the host to remove them. Scientists have observed this <a href="https://doi.org/10.2307/3272354">tick immunity</a> in several animals that don’t typically serve as hosts to ticks, including guinea pigs, rabbits and cows. </p>
<p>In laboratory settings, guinea pigs bitten 2-3 times by ticks are able to develop robust <a href="https://doi.org/10.4269/ajtmh.1998.58.780">immunity</a> <a href="https://www.jstor.org/stable/3283729">against</a> them. While there have not been any formal studies on tick immunity in humans, people who have been repeatedly exposed to ticks <a href="https://doi.org/10.3201/eid1101.040303">can get</a> <a href="https://doi.org/10.1089/vbz.2008.0091">itchy skin</a> after getting bitten, a symptom that may be associated with tick immunity.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1421475512447381511"}"></div></p>
<p>Our lab was curious if we could induce tick immunity without tick bites. So we developed an <a href="https://www.nature.com/articles/d41586-021-02483-w">mRNA vaccine</a> called <a href="https://doi.org/10.1126/scitranslmed.abj9827">19ISP</a> that teaches cells to recognize 19 selected proteins present in the spit that <em>Ixodes scapularis</em>, also known as the deer or black-legged tick, leaves on the skin during a bite. Instead of targeting proteins on the invading pathogen – like the spikes on the outside of the coronavirus – our vaccine targets proteins naturally found in the tick’s saliva.</p>
<p>We found that guinea pigs vaccinated with 19ISP developed skin redness after they were bitten, indicating that their immune system was activated and recruited inflammatory cells to the site to fight off infection. Like other animals that developed tick immunity after repeated bites, the ticks were unable to feed on the guinea pigs and quickly detached. None of the vaccinated guinea pigs tested positive for <em>Borrelia burgdorferi</em>, the bacteria that causes Lyme disease. Conversely, almost half of the non-vaccinated guinea pigs tested positive for <em>Borrelia</em> infection.</p>
<h2>Why it matters</h2>
<p>Tick-borne diseases, including Lyme disease, are <a href="https://doi.org/10.1016/j.pt.2017.12.006">rising in North America</a> and <a href="https://doi.org/10.3389/fvets.2020.604910">Europe</a>, with <a href="https://www.cdc.gov/lyme/datasurveillance/recent-surveillance-data.html">almost 40,000 annual reported cases</a> in the U.S. Ticks aren’t just a cause of trouble for wilderness hikers – they also pose a danger to farm workers and anyone outdoors. Beyond Lyme disease, ticks also transmit <a href="https://theconversation.com/ticks-spread-plenty-more-for-you-to-worry-about-beyond-lyme-disease-118102">several other pathogens</a> that can cause serious and potentially life-threatening conditions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Tick perched on the the edge of a leaf." src="https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/432278/original/file-20211116-27-lsupm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&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">Tick ranges have increased with climate change, putting more people and animals at risk for tick-borne diseases.</span>
<span class="attribution"><span class="source">Jaqueline Matias</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
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<p>What’s unique about the 19ISP mRNA vaccine is that instead of directly targeting the pathogen that causes the disease like traditional vaccines, 19ISP was able to stimulate resistance to the carrier of the disease, ticks, and prevent them from transmitting the pathogen in the first place. Our study also suggests that this form of tick-based vaccination – teaching the body to rapidly recognize and react to being bitten by a tick – may be sufficient to prevent infection.</p>
<h2>What still isn’t known</h2>
<p>While guinea pigs were able to develop tick immunity, we’ve found that animals like mice do not. We plan to test this mRNA vaccine model in other animals, such as rabbits, to better understand how tick immunity varies in different tick hosts. We also plan to develop vaccines for other tick-borne pathogens and test for whether immunity extends to different tick species as well.</p>
<p>Our hope is that vector-based mRNA vaccines targeting the disease carrier can be applied to other vector-borne diseases. However, the feeding strategies of each disease vector is different – tick bites are not the same as mosquito bites, for instance. Because the way disease-carriers transmit pathogens may be different, vaccines may need to be modified for each vector.</p>
<h2>What’s next</h2>
<p>We plan on conducting studies on people who already have Lyme disease or who are repeatedly exposed to ticks to see if they have developed antibodies that recognize the proteins in 19ISP. This will further clarify how tick immunity works, and may eventually lead to clinical trials testing these vaccines in people.</p>
<p>[<em>Climate change, AI, vaccines, black holes and much more.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-various">Get The Conversation’s best science and health coverage</a>.]</p><img src="https://counter.theconversation.com/content/171917/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andaleeb Sajid currently for National Institutes of Health.</span></em></p>The study found that ticks were unable to feed on guinea pigs vaccinated with an mRNA vaccine, preventing transmission of the pathogen that causes Lyme disease.Andaleeb Sajid, Staff Scientist, National Institutes of HealthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1391042020-05-27T12:20:11Z2020-05-27T12:20:11ZLyme disease symptoms could be mistaken for COVID-19, with serious consequences<figure><img src="https://images.theconversation.com/files/337500/original/file-20200526-106862-15q5xan.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C1280%2C921&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ticks like this one, shown magnified with an electron microscope, can transmit bacteria that cause severe illnesses in humans.</span> <span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Summer is field season for <a href="https://biology.richmond.edu/faculty/jbrinker/">ecologists like me</a>, a time when my colleagues, students and I go out into fields and woods in search of ticks to study the patterns and processes that allow disease-causing microbes – primarily bacteria and viruses – to spread among wildlife and humans. </p>
<p>That field work means we’re also at risk of getting the very diseases we study. I always remind my crew members to pay close attention to their health. If they get a fever or any other signs of sickness, they should seek medical treatment immediately and tell their doctor that they may have been exposed to ticks.</p>
<p>When summer <a href="http://doi.org/10.1128/JVI.01680-06">flu-like illnesses</a> develop in anyone who spends time outdoors in areas where ticks are common, tick-transmitted diseases like Lyme disease should be considered a likely culprit. </p>
<p>This summer, however, the global emergence of the novel coronavirus and COVID-19 is presenting a whole new set of challenges for diagnosing Lyme disease and other tick-borne illnesses. </p>
<p>Lyme disease <a href="https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html">shares a number of symptoms</a> with COVID-19, including fever, achiness and chills. Anyone who mistakes Lyme disease for COVID-19 could unknowingly delay necessary medical treatment, and that can lead to severe, potentially debilitating symptoms.</p>
<h2>Delaying medical treatment can be dangerous</h2>
<p>As we move from spring into summer, and into the peak period of tick activity in much of the Northern Hemisphere, time spent outdoors will increase, as will risk of tick-transmitted disease.</p>
<p>In some cases, there are key symptoms of a tick-transmitted disease that can help with diagnosis. For example, early Lyme disease, which is caused by the bite of an infected black-legged tick, sometimes called the deer tick, is commonly associated with an expanding “bull’s-eye rash.” <a href="https://www.cdc.gov/lyme/signs_symptoms/index.html">Seventy percent to 80% of patients have this symptom</a>. </p>
<p>However, <a href="https://www.cdc.gov/lyme/signs_symptoms/index.html">other symptoms</a> of Lyme disease – fever, head and body aches and fatigue – are less distinctive and can be easily confused with other illnesses, including COVID-19. This can make it more difficult to diagnose a patient who did not notice a rash or was unaware that they ever had a tick bite. As a result, Lyme disease cases can be <a href="http://doi.org/10.4081/or.2011.e14">misdiagnosed</a>. Nationally, Lyme disease may be undercounted to the point that only <a href="https://www.cdc.gov/lyme/datasurveillance/index.html">one in 10 cases is reported to the CDC</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337494/original/file-20200526-106815-1090qjs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A student plucks samples off a drag cloth used to collect ticks.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Jory Brinkerhoff/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If Lyme disease is identified and treated quickly, <a href="https://www.cdc.gov/lyme/treatment/index.html">two to four weeks of antibiotics</a> can usually knock out <em>Borrelia burgdorferi</em>, the species of spirochete bacteria that causes it.</p>
<p>But delays in the treatment of Lyme disease <a href="http://doi.org/10.1038/nrdp.2016.90">can lead to more severe and persistent symptoms</a>. If Lyme disease goes untreated, <a href="https://www.columbia-lyme.org/signs-and-symptoms">neurological and cognitive problems</a> and <a href="https://www.healio.com/cardiology/practice-management/news/online/%7Bcb44ad64-eb7c-4ccd-b320-ac529225468a%7D/cardiologists-know-the-signs-of-lyme-disease">potentially fatal heart problems</a> can develop, and <a href="http://doi.org/10.1016/j.idc.2015.02.004">painful arthritis that is much more difficult to treat</a> can set in.</p>
<h2>Lyme disease isn’t the only tick problem</h2>
<p>Lyme disease is most common in the Northeast and North Central U.S., but that does not mean that people in areas without Lyme disease are free from worry about tick-transmitted disease. Ticks throughout North America can spread a <a href="https://www.cdc.gov/ticks/tickbornediseases/index.html">wide range of diseases,</a> many of which also present with flu-like symptoms, leading to the potential for <a href="https://doi.org/10.1016/j.ttbdis.2015.06.005">misdiagnosis</a>, especially when these diseases are not especially common in the general population.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337504/original/file-20200526-106832-1gndpez.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 closeup of a tick’s head under an electron microscope.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Spotted fevers are <a href="https://www.cdc.gov/otherspottedfever/index.html">another group of tick-transmitted diseases</a>. The most severe of these is Rocky Mountain spotted fever, which can be fatal. Spotted fevers, as the name suggests, are typically associated with a rash. But the rash may not show until after fever and other flu-like symptoms, creating the same risk of being mistaken for COVID-19. Like Lyme disease, spotted fevers <a href="https://www.cdc.gov/otherspottedfever/treatment/index.html">can be treated with anitibiotics</a>, and early treatment can head off more severe infections, so quick, accurate diagnosis is critical. </p>
<h2>Is COVID-19 increasing chances of tick bites?</h2>
<p><a href="https://www.scientificamerican.com/article/how-the-coronavirus-has-changed-animals-landscape-of-fear/">Recent reports</a> from across the nation and around the globe suggest that wildlife have become more bold this spring, wandering into suburbs and cities where human and vehicle traffic are reduced because of COVID-19.</p>
<p>Whether this phenomenon is being driven by changes in animal behavior or is simply an artifact of humans spending <a href="https://www.popsci.com/story/environment/wildlife-in-cities-covid-shutdown/">more time in their homes and becoming more aware of their surroundings</a> is not clear, but changes in wildlife behavior and habitat use could affect tick-transmitted disease. For example, white-tailed deer are important hosts to multiple human-biting tick species in eastern North America, including black-legged ticks, and more deer around our homes and in our neighborhoods could lead to more ticks that have a chance to bite humans.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337506/original/file-20200526-106811-vw1f8j.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 closeup of a tick’s mouth parts under an electron microscope shows the barbs that allow it to hang on after it penetrates skin.</span>
<span class="attribution"><a class="source" href="https://biology.richmond.edu/research/research-labs/brinkerhoff-lab.html">Fernando Otalora-Luna/University of Richmond</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Ticks do not move very far by themselves – <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1948-7134.2009.00034.x">perhaps about a foot per day for some species</a> – but can be dispersed dozens of miles or more while hitching a ride on a highly mobile host like a deer, coyote or bird. Thus, the wildlife we observe exploring our neighborhoods while we are encouraged to stay at home may be leaving behind ticks that are carrying pathogens, or that could acquire infection from the more common wildlife already near our homes.</p>
<h2>Staying safe</h2>
<p>Awareness is a key component of preventing and treating tick-borne disease. People should be aware of the activities that could <a href="https://www.cdc.gov/lyme/prev/index.html">expose them to ticks</a>, and <a href="https://pubmed.ncbi.nlm.nih.gov/10780095/">physicians should consider the possibility of tick-borne disease</a>, especially given the potential overlap in symptoms with COVID-19.</p>
<p>As with COVID-19, mitigation efforts can <a href="https://www.cdc.gov/lyme/prev/on_people.html">substantially reduce the risk</a> of tick-borne diseases. Wear long sleeves and long pants and use an <a href="https://www.epa.gov/insect-repellents">EPA-registered repellent</a> when you are in tick habitat, and check yourself thoroughly for ticks when you get home.</p>
<p>It is important to be aware of ticks when spending time outside, but fear of ticks should not stop people from enjoying nature.</p>
<p>[<em>Get facts about coronavirus and the latest research.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-facts">Sign up for The Conversation’s newsletter.</a>]</p><img src="https://counter.theconversation.com/content/139104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jory Brinkerhoff receives funding from the U.S. Department of Agriculture and the National Institutes of Health and has previously been funded by the Jeffress Memorial Trust and the Fulbright Scholar Program. </span></em></p>What might look like a mild case of COVID-19 could actually be a bacterial infection from a tick bite, with potentially debilitating symptoms if it goes untreated.Jory Brinkerhoff, Associate Professor of Biology, University of RichmondLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1208792019-07-26T13:03:48Z2019-07-26T13:03:48ZNo, Lyme disease is not an escaped military bioweapon, despite what conspiracy theorists say<figure><img src="https://images.theconversation.com/files/285644/original/file-20190724-110195-7h3jyk.JPG?ixlib=rb-1.1.0&rect=382%2C48%2C3206%2C2344&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ticks could spread weaponized bacteria – but _B. burgdorferi_ that causes Lyme isn't one of them.</span> <span class="attribution"><span class="source">Kelvin Ma/Tufts University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Could Lyme disease in the U.S. be the result of an accidental release from a secret bioweapons experiment? Could the military have specifically engineered the Lyme disease bacterium to be more insidious and destructive – and then let it somehow escape the lab and spread in nature? </p>
<p>Is this why <a href="https://www.cdc.gov/lyme/stats/humancases.html">300,000 Americans are diagnosed annually</a> with this potentially debilitating disease?</p>
<p>It’s an old conspiracy theory currently enjoying a resurgence with lots of sensational <a href="https://www.nhregister.com/news/article/House-orders-Lyme-disease-investigation-14109717.php">headlines</a> and <a href="https://twitter.com/SITSSHOW/status/1153998823011823616">tweets</a>. Even Congress has ordered that the <a href="https://www.rollcall.com/news/congress/house-orders-pentagon-report-whether-weaponized-ticks">Pentagon must reveal whether it weaponized ticks</a>.</p>
<p>And it’s not true.</p>
<p>Ticks can indeed carry infectious agents that could be used as biological weapons. Military research has long <a href="https://apps.dtic.mil/dtic/tr/fulltext/u2/a221956.pdf">focused on ticks</a>. Sites around Long Island Sound, near the military’s Plum Island research lab, were some of the first places where the American Lyme disease epidemic was identified.</p>
<p>But there was no release of the Lyme disease agent or any other onto American soil, accidental or otherwise, by the military.</p>
<p>I started working on Lyme disease in 1985. As part of my doctoral thesis, I investigated whether museum specimens of ticks and mice contained evidence of infection with the bacterial agent of Lyme disease prior to the first known American human cases in the mid 1970s. </p>
<p>Working with microbiologist <a href="http://www.cepheid.com/us/about-us/news-events/events/18-site-pages-us/about-us/14-board-of-directors">David Persing</a>, we found that ticks from the South Fork of Long Island <a href="https://doi.org/10.1126/science.2402635">collected in 1945 were infected</a>. Subsequent studies found that mice from Cape Cod, <a href="https://doi.org/10.1093/infdis/170.4.1027">collected in 1896, were infected</a>.</p>
<p>So decades before Lyme was identified – and before military scientists could have altered or weaponized it – the bacterium that causes it was living in the wild. That alone is proof that the conspiracy theory is wrong. But there are plenty of other lines of evidence that show why Lyme disease did not require the human hand changing something Mother Nature had nurtured.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285750/original/file-20190725-136749-1gpzbk.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">Ticks and the diseases they spread can do just fine without being altered in the lab as weapons.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Thriving-Ticks/38cfe58d17fc4edeba3199c45ada7609/1/0">AP Photo/Robert F. Bukaty</a></span>
</figcaption>
</figure>
<h2>Lyme is an unlikely bioweapon</h2>
<p>I teach a graduate course in biodefense. <a href="https://doi.org/10.1038/sj.embor.embor849">Biowarfare</a>, the use of biological agents to cause harm, was once an interest of the U.S. military and that of many other countries.</p>
<p>One of the most important characteristics of a biowarfare agent is its ability to quickly disable target soldiers. The bacteria that cause Lyme disease are not in this category.</p>
<p>Many of the agents that biowarfare research has focused on are transmitted by ticks, mosquitoes, or other arthropods: plague, tularemia, Q fever, Crimean Congo hemorrhagic fever, Eastern equine encephalitis or Russian spring summer encephalitis. In all of them, the early disease is very debilitating, and the fatality rate can be great; <a href="https://doi.org/10.1093/cid/ciy923">30% of Eastern equine encephalitis cases die</a>. <a href="https://www.routledge.com/Rats-Lice-and-History/Zinsser/p/book/9781412806725">Epidemic typhus killed 3 million people</a> during World War I.</p>
<p><a href="https://doi.org/10.1038/nrdp.2016.90">Lyme disease</a> does make some people very sick but many have just a flu-like illness that their immune system fends off. Untreated cases may subsequently develop arthritis or neurological issues. The disease is rarely lethal. Lyme has a weeklong incubation period – too slow for an effective bioweapon.</p>
<p>And, even though <a href="https://doi.org/10.1001/archderm.1962.01590100024007">European physicians had described cases</a> of Lyme disease in the first half of the 20th century, the cause had not been identified. There was no way the military could have manipulated it because they did not know what “it” was. None of us knew – until 1981, when the late <a href="https://irp.nih.gov/blog/post/2015/02/the-great-willy-burgdorfer-1925-2014">Willy Burgdorfer, a medical entomologist</a>, made his serendipitous discovery.</p>
<h2>Burgdorfer’s discovery of the Lyme bacterium</h2>
<p>Burgdorfer had done his graduate studies in Switzerland in the late 1940s, investigating the biology of <a href="https://www.cdc.gov/relapsing-fever/index.html">tick-borne relapsing fever</a>, a bacterial disease that can spread from animals to people. During the course of that work, he developed new methods to detect infection in ticks and to infect ticks with specific doses of a pathogen. Those methods are still used today by people like me.</p>
<p>Eventually, Burgdorfer moved to the Rocky Mountain Laboratories in Montana, an outpost of the U.S. Public Health Service and National Institutes of Health – at the time, the <a href="https://archive.org/stream/rockymountainspo00hard/rockymountainspo00hard_djvu.txt">world center for tick research</a></p>
<p>Burgdorfer’s unique expertise was studying how microbial agents were adapted to the internal tissues of their tick hosts, using experimental infections and microscopy. Until Lyme disease came along, his reputation was as the world’s expert on the life cycle of <a href="https://www.cdc.gov/rmsf/index.html">Rocky Mountain spotted fever</a> (RMSF).</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=663&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=663&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=663&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=833&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=833&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285636/original/file-20190724-110195-fbytw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=833&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Burgdorfer at the microscope.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/historyatnih/33713226946">NIH</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>It was RMSF that led Burgdorfer to the cause of Lyme disease. He had been working to better understand RMSF on Long Island in New York. Why were dog ticks, the acknowledged vector, uninfected even in areas where people were getting sick? He knew that a new tick, the deer tick, had recently become common on Long Island and been incriminated as a disease vector.</p>
<p>So Burgdorfer asked his colleague <a href="https://renaissance.stonybrookmedicine.edu/mgm/program/faculty/benach">Jorge Benach at Stony Brook University</a> for some deer ticks to test for the presence of RMSF bacteria. Benach happened to have some from nearby Shelter Island that he sent along.</p>
<p>In testing the “blood” of the deer ticks, Burgdorfer did not find RMSF bacteria. But he did <a href="https://www.ncbi.nlm.nih.gov/pubmed/6516454">find spiral-shaped bacteria</a> called spirochetes. The spirochetes were very similar to what he had studied as a graduate student: the cause of relapsing fever. If spirochetes caused relapsing fever, perhaps other spirochetes were responsible for the mysterious new Lyme arthritis for which a cause was not known.</p>
<p>This ah-ha moment led to the landmark 1982 paper in Science with a question for a title: “<a href="https://doi.org/10.1126/science.7043737">Lyme disease – a tick-borne spirochetosis?</a>”</p>
<h2>Conspiracy theory can’t account for the facts</h2>
<p>Some have overanalyzed the fact that Lyme disease spirochetes were first found in ticks from New York’s Shelter Island, right next to Plum Island, an isolated facility used as a military research lab <a href="https://dmna.ny.gov/forts/fortsT_Z/terryFort.htm">until 1954</a>.</p>
<p>But it was just a coincidence that Benach’s Shelter Island ticks were the ones in which Burgdorfer made his serendipitous finding. By 1984, once researchers knew what to look for, Lyme disease spirochetes were found in ticks from coastal <a href="https://doi.org/10.4269/ajtmh.1983.32.818">Connecticut</a>, <a href="https://doi.org/10.1126/science.6710158">New Jersey</a> and even <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590008/">California</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=383&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=383&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=383&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285752/original/file-20190725-136759-11tsqq0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&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 research center on Plum Island focuses on animal diseases that could damage the agroeconomy.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Associated-Press-Domestic-News-New-York-United-/4fa54deae2e6da11af9f0014c2589dfb/2/0">AP Photo/Ed Betz</a></span>
</figcaption>
</figure>
<p>But let’s pretend the military started working immediately on the newly found agent of Lyme disease in 1981. That’s long after Fort Terry on Plum Island was repurposed in 1954 by the U.S. Department of Agriculture to <a href="https://www.dhs.gov/science-and-technology/plum-island-animal-disease-center">study exotic animal diseases</a>. It’s also after President <a href="https://fas.org/irp/offdocs/nsdm-nixon/nsdm-35.pdf">Richard Nixon outlawed biowarfare research</a> in 1969. If the bacteria was manipulated, it had to have been done after 1981 – so the conspiracy theory’s timeline just doesn’t work. </p>
<p>The real nail in the coffin for the idea that Lyme disease in the U.S. was somehow accidentally released from military bioweapons research is to be found in the fact that the first American case of Lyme disease turns out not to have been from <a href="https://doi.org/10.1002/art.1780200102">Old Lyme, Connecticut, in the early 1970s</a>. In 1969, a physician identified <a href="https://doi.org/10.1001/asrchderm.1970.04000070106017">a case in Spooner, Wisconsin</a>, in a patient who had never traveled out of that area. And Lyme disease was found infecting people <a href="https://doi.org/10.1001/archderm.1978.01640140071018">in 1978 in northern California</a>. </p>
<p>How could an accidental release take place over three distant locations? It couldn’t.</p>
<p><a href="https://doi.org/10.1128/AEM.01704-09">Population genetics research on <em>Borrelia burgdorferi</em></a>, the bacterial agent of Lyme disease, suggest that the northeastern, Midwestern and Californian bacteria are separated by geographical barriers that <a href="https://doi.org/10.1111/j.1558-5646.2010.01001.x">prevent these populations from mixing</a>. Had there been a lab strain, particularly one engineered to be more transmissible, that escaped within the last 50 years, there <a href="https://doi.org/10.1038/s41559-017-0282-8">would be greater genetic similarity</a> between these three geographic populations. There is no evidence for a recent single source – such as a release from a lab – for Lyme disease spirochetes.</p>
<p>The <a href="https://doi.org/10.1093/jipm/pmx024">real reasons for the epidemic</a> becoming so burdensome include reforestation, suburbanization and a failure to manage deer herds.</p>
<p>Conspiracy thinkers make much of the military’s interest in tick-borne infections and how it influenced top researchers. Until Lyme disease came along, the number of tick laboratories in the world could be counted on both hands. As an acknowledged expert on ticks and the infections they transmit, it’s surely possible that Willy Burgdorfer received funding from the military, undertook studies for them, or was consulted by them. They were one of the few sources of research funds for tick projects in the period from 1950 to 1980. The overarching <a href="https://www.acq.osd.mil/eie/afpmb/aboutus.html">goal of such applied work</a> would have been understanding the tick-related risks American soldiers faced while deployed, and how to protect them.</p>
<p>That Burgdorfer alluded to biowarfare or biodefense programs in interviews toward the end of his life should not be construed as an admission of participation in top-secret work. I met Burgdorfer several times and was struck by his wry sense of humor. It’s my guess that his hints that there was a bigger story to what he did for the military was a prankster’s way to toy with the interviewer.</p>
<figure>
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<figcaption><span class="caption">Sam Telford provides tips on avoiding tick-borne infections.</span></figcaption>
</figure>
<p>As someone who has worked for more than three decades to understand the epidemiology and ecology of Lyme disease in order to reduce the risk of Americans getting infected, I am appalled that this conspiracy theory is taken so seriously that Congress is now involved. The idea that Lyme disease is due to bioweapons research gone wrong is easily disproven. Our legislators could better spend their time fighting for efforts to prevent disease instead of investigating a far-fetched story that’s based on misinterpretation and innuendo.</p>
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<p class="fine-print"><em><span>Sam Telford is currently supported by research funding from the National Institutes of Health and from the Rainwater Foundation. He consults for diverse companies on tick-borne disease diagnostics and prevention. The opinions expressed in this article are personal and do not necessarily reflect those who provide support for his research, nor of those for whom he consults. He has been a registered Republican voter for many years.</span></em></p>Scientists know the bacterium that causes Lyme disease has been out in the wild since long before any biological weapons research could have focused on it. And that’s just for starters.Sam Telford, Professor of Infectious Disease and Global Health, Tufts UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1181022019-07-12T12:06:07Z2019-07-12T12:06:07ZTicks spread plenty more for you to worry about beyond Lyme disease<figure><img src="https://images.theconversation.com/files/283715/original/file-20190711-173334-1u1skq3.jpg?ixlib=rb-1.1.0&rect=404%2C134%2C3325%2C2317&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's a short window between when a tick bites and when it passes on bacteria or virus.</span> <span class="attribution"><span class="source">MSU Ag Communications, Courtesy Dr. Tina Nations</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>When it comes to problems caused by ticks, Lyme disease hogs a lot of the limelight. But various tick species carry and transmit a collection of other pathogens, some of which cause serious, even fatal, conditions.</p>
<p>In fact, the <a href="https://doi.org/10.1016/j.pt.2012.07.003">number of tick-borne disease cases is on the rise</a> in the United States. The range where various species of ticks live in North America may be <a href="http://dx.doi.org/10.1155/2009/593232">expanding due to climate change</a>. Researchers continue to discover <a href="https://doi.org/10.1128/microbiolspec.EI10-0012-2016">new pathogens that live in ticks</a>. And <a href="https://www.cdc.gov/ticks/longhorned-tick/index.html">new, invasive tick species</a> keep turning up.</p>
<p>In <a href="https://scholar.google.com/citations?user=JVfeckwAAAAJ&hl=en&oi=ao">my career as a</a> <a href="https://doi.org/10.1201/b12686">public health entomologist</a>, I’ve been amazed at the ability of ticks to bounce back from all the ways people try to control them, including with pesticides. Ticks excel at finding new ecological niches for survival. So people and ticks frequently cross paths, exposing us to their bites and the diseases they carry.</p>
<p>Here are some of the lesser-known, but growing, threats from ticks.</p>
<h2>Ticks can spread bacterial diseases</h2>
<p>Certain very small species of bacteria that can cause human diseases, such as rickettsia, ehrlichia and anaplasma, live in ticks. Ticks ingest these bacteria when they drink animals’ blood. Then when the ticks take a subsequent blood meal, they pass the bacteria along to the next animal or person they feed on.</p>
<p>Probably the most well known of these bacterial diseases is <a href="https://www.cdc.gov/rmsf/index.html">Rocky Mountain spotted fever</a>, the most frequently reported rickettsial disease in the U.S., with <a href="https://wonder.cdc.gov/nndss/static/2017/annual/2017-table1.html">about 6,000 cases each year</a>. The number of diagnoses seems to be increasing nationwide, <a href="https://doi.org/10.4269/ajtmh.2009.80.601">especially among Native Americans</a>, probably due to exposure on reservations to free-roaming dogs that can carry ticks.</p>
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<a href="https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/278758/original/file-20190610-52758-1y6uqpg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&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">Rocky Mountain spotted fever usually comes with a rash, as on this child.</span>
<span class="attribution"><a class="source" href="https://phil.cdc.gov/Details.aspx?pid=1962">Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>When people get sick with Rocky Mountain spotted fever, they usually come to a clinic with three things: fever, rash and history of tick bite. They may also report severe headache, chills and muscle pains, and gastrointestinal symptoms such as abdominal pain and diarrhea. A skin rash is usually present after a few days, but not always. Mental confusion, coma and death can occur in severe cases. Untreated, the mortality rate is about 20%; and even with treatment, 4% of those infected die.</p>
<p>Not all tick species are effective transmitters of the rickettsia bacteria. Even within the vector species, often <a href="https://doi.org/10.1056/NEJMoa050043">only 1% to 5% of ticks in an area are infected</a>. So getting bitten by a tick that passes rickettsia bacteria on to you is like getting stuck with a needle in a haystack. The primary carriers are the American dog tick in the eastern U.S. and Rocky Mountain wood tick in the West. The brown dog tick has also recently been <a href="http://dx.doi.org/10.15585/mmwr.rr6502a1">shown to be a vector</a>. </p>
<p>In most tick-borne diseases, the <a href="https://jcm.asm.org/content/25/3/557.short">tick needs to feed for some amount of time</a> before any pathogens it’s carrying are transmitted to the animal whose blood it’s eating. Rocky Mountain spotted fever organisms generally take between one and three hours for transmission to occur, so attached ticks need to be removed quickly. Doctors usually prescribe the antibiotic doxycycline to treat Rocky Mountain spotted fever, which works quite well if the disease is recognized early.</p>
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<p><a href="https://www.cdc.gov/ehrlichiosis/index.html">Ehrlichiosis</a> is another bacterial disease transmitted from ticks to people. In the U.S. it’s most commonly caused by <em>Ehrlichia chaffeensis</em> bacteria, carried by lone star ticks which are common in the eastern U.S. Ehrlichia bacteria infect a type of blood cell called leukocytes. Human monocytic ehrlichiosis occurs mostly in the southern and south-central U.S.; <a href="https://wonder.cdc.gov/nndss/static/2017/annual/2017-table1.html">1,642 cases were reported</a> to the CDC in 2017. </p>
<p>Ehrlichiosis patients usually have fever, headache, muscle aches and a progressive low white blood cell count. As opposed to Rocky Mountain spotted fever, people get a rash only about 20% to 40% of the time. Doctors usually treat ehrlichiosis with doxycycline.</p>
<p>Another tick-borne bacterial disease to worry about is <a href="http://dx.doi.org/10.15585/mmwr.rr6502a1">human granulocytic anaplasmosis</a>. In human granulocytic anaplasmosis, <em>Anaplasma phagocytophilum</em> bacteria infects a type of white blood cell called granulocytes. It mostly occurs in the upper midwestern and northeastern U.S., and the incidence is increasing, with <a href="https://wonder.cdc.gov/nndss/static/2017/annual/2017-table1.html">5,762 cases of human granulocytic anaplasmosis reported</a> to the CDC in 2017.</p>
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<a href="https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283720/original/file-20190711-173370-18run1w.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">A female <em>Ixodes scapularis</em> tick.</span>
<span class="attribution"><span class="source">Dr. Blake Layton, MSU</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Symptoms include fever, headache, muscle aches and progressive low white blood cell count. It’s the deer tick <em>Ixodes scapularis</em> – famously also responsible for Lyme disease – that transmits the Anaplasma bacteria to humans. There’s the unlucky chance that a bite from a deer tick could infect you with both diseases. Again, recommended therapy is doxycycline.</p>
<h2>Ticks can carry viruses, too</h2>
<p>People usually think of mosquitoes when they think of insect-transmitted viruses – dengue, Zika or West Nile garner a lot of headlines. But ticks can transmit viruses, too.</p>
<p>Scientists have historically grouped tick-borne viral diseases into two categories. One is diseases similar to dengue fever. The main dengue-like viral disease transmitted by ticks in the U.S. is <a href="https://www.ncbi.nlm.nih.gov/pubmed/19954">Colorado tick fever</a>, which occurs in mountainous areas of the West.</p>
<p>The other group of tick-borne diseases resemble mosquito-borne encephalitis. Most of these illnesses, characterized by brain inflammation, are not found in the U.S. <a href="https://doi.org/10.1146/annurev-ento-112408-085446">Powassan encephalitis is the one that is</a>, occurring in the northeastern U.S. and adjacent regions of Canada.</p>
<p>Powassan is a relatively rare but serious human disease, characterized by sudden onset of fever with temperature up to 104 degrees Fahrenheit, along with convulsions. Brain inflammation is usually severe, with vomiting, respiratory distress and prolonged fever.</p>
<p><a href="https://wonder.cdc.gov/nndss/static/2017/annual/2017-table1.html">Fewer than 100 cases of Powassan have been reported</a> in North America, with about half of them fatal. Its incidence seems to be increasing; there were 34 cases of Powassan reported during 2017. POW is maintained in a natural cycle when ticks – primarily <em>Ixodes cookei</em> – infect animals with the virus via their bites. Then these infected animals may serve as what scientists call <a href="https://en.wikipedia.org/wiki/Natural_reservoir">disease reservoirs</a>, infecting new ticks when they feed on their blood.</p>
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<a href="https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=412&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=412&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=412&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=517&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=517&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283723/original/file-20190711-173347-19l9cwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=517&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">Tiny larval lone star ticks next to a penny.</span>
<span class="attribution"><span class="source">Jerome Goddard</span></span>
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<p>In the last decade, researchers have found additional new tick-borne viruses in the U.S. About <a href="https://europepmc.org/articles/pmc5779346">30 cases of Heartland virus</a> have thus far been identified. It’s associated with the lone star tick and has been recognized in Missouri, Oklahoma, Kentucky and Tennessee.</p>
<p>A few cases of a new Thogotovirus <a href="https://doi.org/10.3201/eid2312.170532">called Bourbon virus</a> have been identified in the Midwest and southern U.S. The lone star tick may be the vector of Bourbon virus as well.</p>
<h2>A food allergy triggered by a tick bite</h2>
<p>Maybe the most bizarre threat from ticks is the “<a href="https://doi.org/10.1097/ACI.0b013e3283624560">red meat allergy</a>” scientists have recently traced back to tick bites. People can become allergic to eating meat when a tick’s saliva passes on the carbohydrate galactose-α-1.3-galactose it had previously picked up in a blood meal from an animal. If prone to allergies, the person can get sensitized to that alpha-gal molecule that’s found in animal blood and other tissues.</p>
<p>Then days or weeks later, he or she may develop hives, swollen skin and lips, or even life-threatening anaphylactic shock three to six hours after eating red meat. Meats containing alpha-gal include beef, pork, lamb, squirrel, rabbit, horse, goat, deer, kangaroo, seal and whale. People who become sensitized to alpha-gal may still eat chicken, turkey and fish.</p>
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<a href="https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283738/original/file-20190711-173347-3jgt7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&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">Take precautions, like tucking pants into socks, when you’re in tick territory.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/protecting-against-ticks-by-tucking-pants-322456178?studio=1">rck_953/Shutterstock.com</a></span>
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<p>Overall, people should be aware of what tick-borne diseases are present in their area and use <a href="https://www.cdc.gov/ticks/avoid/on_people.html">personal protection techniques</a> whenever outdoors in tick-infested areas. Remember that ticks often come into close contact with people via pet dogs or cats. It’s a good idea to inspect yourself for ticks after being outdoors in tick-infested areas. Reducing the number of tick bites and the amount of time ticks remain attached can go a long way to protecting you from tick-borne diseases.</p>
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<p class="fine-print"><em><span>Jerome Goddard 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>Tick-borne diseases are becoming more common in the United States. A public health entomologist outlines some of the lesser-known threats ticks pose to human health.Jerome Goddard, Extension Professor of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.