tag:theconversation.com,2011:/africa/topics/head-lice-4787/articlesHead lice – The Conversation2023-06-13T20:06:12Ztag:theconversation.com,2011:article/2070242023-06-13T20:06:12Z2023-06-13T20:06:12Z‘Help, my kids keep getting head lice!’ Here’s how to break the cycle of nits<figure><img src="https://images.theconversation.com/files/530776/original/file-20230608-29-jdt55.jpg?ixlib=rb-1.1.0&rect=0%2C1800%2C5352%2C4335&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/P5MXtYfgmmw">Nathan Dumlao/Unsplash</a></span></figcaption></figure><p>Wrangling head lice, and the children they infest, must be up there with the most challenging duties a parent or carer has to face.</p>
<p>Primary school-aged children, who seem to always be in close proximity to one another, are the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-4362.1999.00680.x">most susceptible</a> to lice. </p>
<p>But by exploiting the <a href="https://www.dailymail.co.uk/health/article-4667628/Smartphones-young-children-head-lice.html">screen-sharing</a> and <a href="https://www.abc.net.au/news/2017-07-12/head-lice-expert-busts-myths-about-nits/8697362">selfie-taking</a> habits of tweens and teens, these little parasites are finding more ways to spread.</p>
<p>And they’re no easier to kill off.</p>
<h2>What are head lice and nits?</h2>
<p>Head lice, known by their scientific name <em>Pediculus humanus capitis</em>, are tiny insects that are only found among the hair on a human’s head. They’re not found anywhere else on the planet.</p>
<p>They scuttle up and down shafts of hair. They have perfectly designed claws, that look a little like carabiners, allowing them to move about how a rock climber uses guide ropes. They’re agile on our hair, but clumsy once they’re off.</p>
<p>They don’t jump or fly. They move from head to head through direct physical contact.</p>
<figure class="align-center ">
<img alt="Teenagers take a selfie" src="https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530806/original/file-20230608-29-3hd1zy.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">
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<span class="caption">Lice spread through head-to-head contact.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/dyTxwGriLoY">Unsplash/Priscilla du Preez</a></span>
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<p>Our hair is their home but our blood is their food. Head lice feed on the scalp and have specially designed mouth-parts to suck out blood up to a half dozen times a day. It means child with an average sized infestation of head lice may give up <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-4632.2005.02520.x">less than 0.01 ml of blood per day</a>.</p>
<p>When it comes time to lay eggs, that we affectionately refer to as “nits”, the lice don’t want the more than 100 or so eggs they can produce in a lifespan just rolling off our heads. They “<a href="https://academic.oup.com/mbe/article/39/2/msab351/6481551?login=false">cement</a>” their eggs to the shafts of hair. It’s some of the best “superglue” you can find!</p>
<p>Once laid, the eggs will hatch within a few days. Within a week, the lice are ready to lay more eggs. The adult lice can live for up to a month if conditions are right.</p>
<h2>My child has head lice, should I be worried?</h2>
<p>While closely related lice have been implicated in the spread of some of the <a href="https://www.cdc.gov/typhus/epidemic/index.html">most dangerous and deadly pathogens</a> to human health, head lice are much more benign. They’re annoying but <a href="https://www.cdc.gov/parasites/lice/head/disease.html">won’t make us sick</a>.</p>
<p>Their bites may cause an <a href="https://www.sciencedirect.com/science/article/abs/pii/019096229170190D">itchy irritation to our skin</a>. Our bodies react to the saliva they inject when they bite. In the same way we all vary in our reaction to <a href="https://theconversation.com/feel-like-youre-a-mozzie-magnet-its-true-mosquitoes-prefer-to-bite-some-people-over-others-128788">mosquito bites</a>, the same differences result from lice bites. Some people will hardly notice them, others will be driven wild with itchiness.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530796/original/file-20230608-17-dnukfp.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">
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<span class="caption">Feeling itchy?</span>
<span class="attribution"><span class="source">A/Prof Webb/NSW Health Pathology</span></span>
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<p><a href="https://www.health.nsw.gov.au/environment/headlice/Pages/default.aspx">Health authorities in Australia</a> do not consider head lice a risk of transmitting pathogens that are <a href="https://entomologytoday.org/2014/01/11/why-do-body-lice-spread-disease-while-head-lice-do-not/">harmful to humans</a>. </p>
<p>There is no doubt they’re annoying but perhaps the greatest health threat of head lice is to the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/nuf.12423">health and well-being of parents</a> responsible for their eradication. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/heres-how-you-beat-indestructible-head-lice-63594">Here's how you beat 'indestructible' head lice</a>
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</em>
</p>
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<h2>Do we really need chemicals?</h2>
<p>“Just kill them all, whatever it takes” is a common refrain among those trying to rid their children of the latest round of infestation.</p>
<p>There is a wide range of products available at your local pharmacy to treat head lice. These products should be registered with the <a href="https://www.tga.gov.au/">Therapeutic Goods Administration</a> and be assessed as both safe and effective to use. Most of these products are insecticides that kill the lice on contact.</p>
<p>However, evidence seems to be mounting that some of these insecticides <a href="https://academic.oup.com/jme/article/53/3/653/2222496">aren’t working as well as they once did</a>. Resistance in head lice to commonly used products may be the result of their excessive or incorrect use. The more lice that escape a treatment, the greater the chances of them developing resistance in much the same way bacteria are <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">developing tolerance and resistance to commonly used antibiotics</a>.</p>
<p>Head lice are still susceptible to alternative approaches. Products derived from Australian plants, such as <a href="https://bmcdermatol.biomedcentral.com/articles/10.1186/1471-5945-10-6">tea tree</a> or <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ajd.12626">eucalyptus</a>, may be better than insecticides. But these are still chemicals.</p>
<p>All these products should be used in accordance with the directions for safe use.</p>
<p>A range of products are marketed as “repelling” head lice. But there is little evidence these are a <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-4632.2007.03132.x">reliable way to avoid picking up head lice</a> from your friends or family.</p>
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<img alt="" src="https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/530797/original/file-20230608-21-cnp98t.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">
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<span class="caption">Head lice have perfectly designed claws to scuttle up shafts of hair.</span>
<span class="attribution"><span class="source">A/Prof Webb/NSW Health Pathology</span></span>
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</figure>
<h2>Is there a chemical-free approach?</h2>
<p>A strong recommendation by health authorities in Australia is to skip the sprays, creams, and lotions and embrace the “<a href="https://www.health.vic.gov.au/infectious-diseases/pediculosis-head-lice">conditioner and comb</a>” or “<a href="https://www.choice.com.au/babies-and-kids/health/conditions/articles/how-to-get-rid-of-head-lice">wet comb</a>” method and physically remove the lice.</p>
<p>This is not just good advice for those not wanting to avoid chemicals, it overcomes having to deal with insecticide-resistant lice.</p>
<p>The <a href="https://www.racgp.org.au/afp/2013/march/wet-combing">steps in this process</a> are relatively straight forward.</p>
<p>To immobilise the lice, apply hair conditioner to the child’s damp hair. Then use a fine toothed “lice comb” to systematically work through the hair and remove adult lice. Regularly wiping the comb on tissues or paper towel will reveal the dispatched lice.</p>
<p>This approach works but must be repeated twice, about a week apart, to break the life cycle of the head lice.</p>
<p>Head lice eggs are less susceptible to treatment, no matter what treatment you choose. As all the eggs will hatch within a week or so, repeating treatments again and targeting the adult lice before a new batch of eggs is laid will provide the best results.</p>
<p>The secret to effective eradication of the infestations is patience and persistence. Perhaps a new practice in <a href="https://www.smh.com.au/lifestyle/health-and-wellness/why-nitpicking-is-not-such-a-lousy-idea-for-me-20230306-p5cpon.html">mindfulness?</a></p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-whats-the-point-of-nits-116158">Curious Kids: what's the point of nits?!</a>
</strong>
</em>
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<h2>Will our household ever be free of them?</h2>
<p>Head lice are a normal part of life for young children. It doesn’t matter how clean and tidy your house is, you’ll inevitably have to deal with an infestation.</p>
<p>Frequent washing of bed sheets, towels, and vacuuming floors won’t keep them away. Head lice don’t survive long out of our hair so you’re unlikely to pick them up from carpet, furniture, or even sharing hats. They don’t <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-4632.2007.03011.x">float around in swimming pools</a> either.</p>
<p>If a child has persistent infestations and has an adverse reaction to the head lice, consult your local health professional. There are some alternative options, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1525-1470.2010.01317.x">including some medications</a>, that may also assist in reducing the bite reactions as well as the infestation itself.</p><img src="https://counter.theconversation.com/content/207024/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on mosquito biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p>Head lice are hard to get rid of and seem to come back again and again. Here’s what works.Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1646272021-07-22T05:46:51Z2021-07-22T05:46:51ZA major ivermectin study has been withdrawn, so what now for the controversial drug?<figure><img src="https://images.theconversation.com/files/412573/original/file-20210722-21-1cxqzeb.jpg?ixlib=rb-1.1.0&rect=1%2C1%2C997%2C559&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-illustration/ivermectin-tablets-bottle-on-pharmacy-shelf-1932929495">from www.shutterstock.com</a></span></figcaption></figure><p><a href="https://theconversation.com/ivermectin-is-still-not-a-miracle-cure-for-covid-19-despite-what-you-may-have-read-144569">Ivermectin</a>, an existing drug against parasites including head lice, has had a chequered history when it comes to treating COVID-19.</p>
<p>The bulk of studies so far show there’s <a href="https://theconversation.com/ivermectin-is-still-not-a-miracle-cure-for-covid-19-despite-what-you-may-have-read-144569">not enough evidence</a> ivermectin is useful in treating or preventing COVID-19, either alone or with antibiotics or supplements.</p>
<p>Yet interest in the drug remains, on social media, in some countries, with <a href="https://www1.racgp.org.au/newsgp/clinical/insufficient-evidence-to-currently-support-ivermec">some doctors</a> and with one politician in particular, Liberal MP Craig Kelly, <a href="https://www.sbs.com.au/news/the-feed/liberal-mp-says-doctors-should-be-given-choice-over-issuing-controversial-drug-to-covid-19-patients">touting its benefits</a>.</p>
<p>Now a large clinical trial that seemed to show positive results for ivermectin has been <a href="https://www.theguardian.com/science/2021/jul/16/huge-study-supporting-ivermectin-as-covid-treatment-withdrawn-over-ethical-concerns">withdrawn</a>. So you’d think that would be end of the ivermectin saga.</p>
<p>But research into ivermectin is ongoing. Here’s what the evidence says so far and what we can expect next.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-deal-with-the-craig-kelly-in-your-life-a-guide-to-tackling-coronavirus-contrarians-154638">How to deal with the Craig Kelly in your life: a guide to tackling coronavirus contrarians</a>
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<h2>How was ivermectin even a contender?</h2>
<p>Ivermectin was identified as a potential COVID-19 treatment based on experiments in <a href="https://www.sciencedirect.com/science/article/pii/S0166354220302011?via%3Dihub">isolated cells</a> and <a href="https://www.biorxiv.org/content/10.1101/2020.11.21.392639v1">animals</a>. The initial lab studies into ivermectin’s effect on the coronavirus involved <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7404744/">very high concentrations</a> of the drug. These were many times higher than can be achieved in the body at doses recommended to treat parasites.</p>
<p>As the pandemic progressed, so did ivermectin clinical trials. But when experts who write doctors’ prescribing guidelines reviewed the data, they found not enough evidence to back ivermectin to treat or prevent COVID-19. These groups included Australia’s <a href="https://covid19evidence.net.au/">National COVID-19 Clinical Evidence Taskforce</a> and the <a href="https://www.who.int/news-room/feature-stories/detail/who-advises-that-ivermectin-only-be-used-to-treat-covid-19-within-clinical-trials">World Health Organization</a>. Instead, they said ivermectin should only be used in <a href="https://app.magicapp.org/#/guideline/L4Q5An/section/nygMxj">clinical trials</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ivermectin-is-still-not-a-miracle-cure-for-covid-19-despite-what-you-may-have-read-144569">Ivermectin is still not a miracle cure for COVID-19, despite what you may have read</a>
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<p>The <a href="https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab591/6310839">most robust summary of the evidence</a> for ivermectin in COVID-19, published in June, goes one step further. It found available evidence showed ivermectin didn’t work.</p>
<p>This review carefully examined ten higher-quality (randomised-controlled) clinical trials, which involved more than 1,100 patients with COVID-19 being treated with ivermectin.</p>
<p>The researchers excluded many of the low-quality (observational) studies some commentators have used to support ivermectin as a COVID-19 treatment.
This was because observational studies cannot control other clinical factors that might influence how people respond to COVID-19, such as other treatments and supportive care.</p>
<p>This major review concluded ivermectin did not reduce death from any cause, the length of stay in hospital or people’s ability to clear the virus. The review also said ivermectin was safe but “not a viable option” to treat COVID-19.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/head-lice-drug-ivermectin-is-being-tested-as-a-possible-coronavirus-treatment-but-thats-no-reason-to-buy-it-135683">Head lice drug Ivermectin is being tested as a possible coronavirus treatment, but that's no reason to buy it</a>
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<h2>But what about the withdrawn study?</h2>
<p>In recent months, we heard the seemingly promising results from a <a href="https://www.researchsquare.com/article/rs-100956/v4">large randomised trial</a>, which was posted online as a <a href="https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(21)00011-5/fulltext">pre-print</a> and had not been independently verified (peer reviewed).</p>
<p>This study stood out because it found ivermectin led to “a substantial improvement and reduction in mortality rate in ivermectin treated groups” — by 90%.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1415835511365664768"}"></div></p>
<p>However, the excitement was tempered when the <a href="https://www.theguardian.com/science/2021/jul/16/huge-study-supporting-ivermectin-as-covid-treatment-withdrawn-over-ethical-concerns">pre-print was withdrawn</a> pending a “formal investigation”. <a href="https://steamtraen.blogspot.com/2021/07/Some-problems-with-the-data-from-a-Covid-study.html?m=1">Significant questions were asked</a> about the nature of the primary data on which the study was based and whether some of the paper had been plagiarised, among other issues. This <a href="https://grftr.news/why-was-a-major-study-on-ivermectin-for-covid-19-just-retracted/">called into question</a> the spectacular positive result for ivermectin. </p>
<p>The trial and publication are still under investigation.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/stopping-blocking-and-dampening-how-aussie-drugs-in-the-pipeline-could-treat-covid-19-162349">Stopping, blocking and dampening – how Aussie drugs in the pipeline could treat COVID-19</a>
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<h2>Surely, that’s the end of ivermectin now?</h2>
<p>But the ivermectin story continues. Researchers at the University of Oxford announced in June they would be starting <a href="https://www.principletrial.org/news/ivermectin-to-be-investigated-as-a-possible-treatment-for-covid-19-in-oxford2019s-principle-trial">another ivermectin trial</a>, called <a href="https://www.principletrial.org/">PRINCIPLE</a>.</p>
<p>This high-quality trial will involve investigating treatments for people at more risk of serious COVID-19. So far the trial has recruited more than 5,000 volunteers from across the UK. Another part of the trial (into another potential COVID-19 therapy) has already reported <a href="https://www.principletrial.org/results">results</a>.</p>
<p>This new ivermectin trial is just starting and will compare a three-day treatment of ivermectin in people within the first 14 days of COVID-19 symptoms, or having a positive test, with those having usual care. The trial is expected to report its results in the coming months.</p>
<h2>What next?</h2>
<p>Ivermectin remains a medicine of interest for treating and preventing COVID-19. Yet, key questions remain including the best ivermectin dose, how long ivermectin should be taken and when it should be given to people with COVID based on their stage of infection and illness.</p>
<p>Until then, <a href="https://www.mja.com.au/journal/2021/effectiveness-covid-19-vaccines-findings-real-world-studies">getting vaccinated</a> will give you the best chance of avoiding severe COVID rather than waiting for a COVID treatment, which may or may not be shown to work.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-well-do-covid-vaccines-work-in-the-real-world-162926">How well do COVID vaccines work in the real world?</a>
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<img src="https://counter.theconversation.com/content/164627/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew McLachlan receives research funding from the NHMRC and the Sydney Pharmacy School receives research scholarship funding from GSK for a PhD student under his supervision. Andrew has served as a paid consultant on Australian government committees related to medicines regulation. Andrew does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article. </span></em></p>Investigations have led to the withdrawal of a study backing ivermectin to treat COVID-19. But that’s not the last time we’ll hear about this controversial drug.Andrew McLachlan, Head of School and Dean of Pharmacy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1445692020-08-18T05:16:59Z2020-08-18T05:16:59ZIvermectin is still not a miracle cure for COVID-19, despite what you may have read<p>The head lice drug ivermectin has <a href="https://www.skynews.com.au/details/_6179108952001">yet again been touted in the media</a> as a possible treatment for COVID-19. But despite the <a href="https://www.biospectrumasia.com/news/91/16457/australian-develops-effective-triple-therapy-to-treat-covid-19.html">favourable headlines</a>, huge uncertainty remains about whether this treatment can be safely and effectively repurposed to tackle the coronavirus.</p>
<p>In recent weeks the media has been awash with <a href="https://www.trialsitenews.com/well-respected-australian-researcher-consider-triple-therapy-ivermectin-zinc-doxycycline-for-covid-19/">claims</a> ivermectin, when given in combination with the common antibiotic doxycycline and zinc supplements, is effectively a “cure” for COVID-19. </p>
<p>Yet there has been no definitive clinical trial so far showing this is the case. All we have are <a href="https://www.researchgate.net/publication/343305357_A_Case_Series_of_100_COVID-19_Positive_Patients_Treated_with_Combination_of_Ivermectin_and_Doxycycline">observational studies</a> and <a href="https://www.trialsitenews.com/well-respected-australian-researcher-consider-triple-therapy-ivermectin-zinc-doxycycline-for-covid-19/">clinicians’ opinions</a>. </p>
<p>The World Health Organisation’s <a href="https://clinicaltrials.gov/ct2/who_table">database of clinical studies for COVID-19</a> shows there are currently 16 trials investigating ivermectin. Even these studies are unlikely to provide the high-quality data necessary to show ivermectin can actually provide its touted benefits. </p>
<p>Many of the current studies have low numbers of participants, weak study designs, and inconsistent (and relatively low) ivermectin dosing regimes, with ivermectin frequently given in <a href="https://en.irct.ir/trial/48444">combination</a> with other drugs.</p>
<p>The <a href="https://www1.racgp.org.au/newsgp/clinical/insufficient-evidence-to-currently-support-ivermec">Royal Australian Council of General Practitioners</a> and the <a href="https://www.safetyandquality.gov.au/sites/default/files/2020-05/Potential%20medicines%20to%20treat%20COVID-19%20%281%20May%202020%29.pdf">Australian Commission for Quality and Safety in Health Care</a> have warned there is insufficient evidence ivermectin is a safe and effective treatment for people infected with the coronavirus.</p>
<h2>What do we know about ivermectin for COVID-19?</h2>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0166354220302011">Laboratory studies</a> using monkey cells in a test tube (as opposed to clinical studies in human patients) have shown ivermectin can shut down the replication of SARS-CoV-2, the coronavirus that causes COVID-19, within 24-48 hours of exposure to the drug.</p>
<p>Ivermectin is thought to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3327999/">inhibit the virus</a> by preventing viral proteins moving in and out of the host cell’s nucleus, which is essential for replication of the coronavirus. </p>
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Read more:
<a href="https://theconversation.com/head-lice-drug-ivermectin-is-being-tested-as-a-possible-coronavirus-treatment-but-thats-no-reason-to-buy-it-135683">Head lice drug Ivermectin is being tested as a possible coronavirus treatment, but that's no reason to buy it</a>
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<p>The problem is this process requires very high concentrations of ivermectin – well above the <a href="https://www.sciencedirect.com/science/article/pii/S0166354220302199#bib3">recommended dose for humans</a>. This means ivermectin’s virus-killing powers would be unlikely to be harnessed inside the human body. </p>
<p>A <a href="https://www.sciencedirect.com/science/article/pii/S0166354220302199#bib3%22%22">detailed analysis</a> of the relationship between dose and concentration of ivermectin suggests none of the currently used ivermectin dosing regimens would deliver high enough concentrations of ivermectin inside the body to activate its virus-killing effects.</p>
<p>Another <a href="https://www.tandfonline.com/doi/full/10.1080/13102818.2020.1775118">review</a> backs this up, suggesting all of the ivermectin doses being investigated in current clinical trials would fall well short of achieving drug concentrations high enough to wipe out SARS-CoV-2.</p>
<p>Even a 120 mg dose of ivermectin, which would be regarded as excessive (compared with the <a href="https://www.tga.gov.au/sites/default/files/auspar-ivermectin-131030-pi.pdf">recommended dose of 3-15mg</a> for treating parasitic infections) resulted in blood concentrations several orders of magnitude times lower than those needed to inhibit the virus.</p>
<figure class="align-center ">
<img alt="Head louse on human hair" src="https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/353309/original/file-20200818-16-yiitpt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&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">Great for killing head lice, but the jury’s still out on coronavirus.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Male_human_head_louse.jpg">GillesSM/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>How much ivermectin is too much?</h2>
<p>While ivermectin generally doesn’t cause problematic side effects at the currently used doses, there is limited information about whether much larger doses would also be safe.</p>
<p>Repurposing ivermectin as a “cure” for COVID-19 would require massive doses, which would substantially increase the risk of <a href="https://www.tandfonline.com/doi/full/10.1080/13102818.2020.1775118">side effects</a> such as nausea, rash, dizziness, immune suppression, abdominal pain, fever, raised heart rate and unstable blood pressure. </p>
<p>Ivermectin at usual doses <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2885.2008.01007.x">does not enter the central nervous system</a>, but after large doses of the drug it may <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5929173/">enter the brain</a>, potentially causing impaired vision, hampering the central nervous system (which could in turn affect breathing, heart rate and consciousness), and exaggerating the effects of other sedative medicines such as benzodiazepines.</p>
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Read more:
<a href="https://theconversation.com/tested-positive-for-covid-19-heres-what-happens-next-and-why-day-5-is-crucial-143687">Tested positive for COVID-19? Here's what happens next – and why day 5 is crucial</a>
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<p>Ivermectin is a hugely useful medicine in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043740/">treating parasitic illnesses</a> such as lice, worms and scabies, particularly in developing countries. But as we have already seen in the <a href="https://theconversation.com/could-taking-hydroxychloroquine-for-coronavirus-be-more-harmful-than-helpful-139309">case of the malaria drug hydroxychloroquine</a>, just because a medicine is useful for one purpose, it cannot automatically be considered a miracle cure for COVID-19. </p>
<h2>Repurposing drugs as COVID-19 treatments</h2>
<p>Repurposing existing drugs as possible COVID-19 treatments is a smart strategy, but requires <a href="https://www.sydney.edu.au/news-opinion/news/2020/06/10/for-successful-covid-19-treatments-pharmacological-benchmarks-ar.html">several key principles</a> to be addressed. The drug must have antiviral effects in cells and animals at doses relevant to humans. The drug must be able to get to the site of infection in the body (or reduce the inflammation associated with the infection). It is best if the antiviral mechanism is understood. And finally, <a href="https://bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/bcp.14416">well designed clinical trials are needed</a> to be sure the drugs works in people with the infection and it is safe to use (especially in older, vulnerable unwell people). </p>
<p>Thankfully, Australia’s National COVID-19 Clinical Evidence Taskforce continually assesses and updates the best evidence-based advice for treating COVID-19, which you can read <a href="https://covid19evidence.net.au/#living-guidelines">here</a>.</p><img src="https://counter.theconversation.com/content/144569/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew McLachlan receives research funding from the NHMRC and the Sydney Pharmacy School receives research scholarship funding from GSK for a PhD student under his supervision. Andrew has served as a paid consultant on Australian government committees related to medicines regulation and anti-doping. Andrew does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article.</span></em></p>The head lice drug ivermectin is being touted as a coronavirus killer. But studies suggest it would need to be taken in mega-doses far higher than those currently used, with unknown side-effects.Andrew McLachlan, Head of School and Dean of Pharmacy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1356832020-04-06T07:35:03Z2020-04-06T07:35:03ZHead lice drug Ivermectin is being tested as a possible coronavirus treatment, but that’s no reason to buy it<figure><img src="https://images.theconversation.com/files/325607/original/file-20200406-74206-1d5s531.jpg?ixlib=rb-1.1.0&rect=41%2C99%2C3452%2C2226&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/">Shutterstock</a></span></figcaption></figure><p>Researchers testing the head lice drug Ivermectin as a possible treatment for COVID-19 have <a href="https://www.sciencedirect.com/science/article/pii/S0166354220302011">seen promising results</a> in lab studies. </p>
<p>But the research is in its early stages and the drug is yet to be tested on people with COVID-19. There’s so much we don’t know, including the right dose and delivery method for people with coronavirus infection. </p>
<p>So if you’re thinking of buying some just in case, think again. </p>
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Read more:
<a href="https://theconversation.com/coronavirus-how-long-does-it-take-to-get-sick-how-infectious-is-it-will-you-always-have-a-fever-covid-19-basics-explained-132963">Coronavirus: how long does it take to get sick? How infectious is it? Will you always have a fever? COVID-19 basics explained</a>
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<h2>What is Ivermectin currently used for?</h2>
<p>Ivermectin is an antiparasitic agent that was isolated in the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043740/">1970s</a> from the fermented broth of a species of bacteria called <em>Streptomyces avermitilis</em>.</p>
<p>The drug has been used since the 1980s to treat and prevent diseases related to parasites in humans, <a href="https://www.ncbi.nlm.nih.gov/pubmed/2198752">pets and livestock</a>, and works by <a href="http://www.antimicrobe.org/drugpopup/Ivermectin.htm">paralysing invertebrate parasites</a>. </p>
<p>In Australia, Ivermectin is mainly used topically in creams and lotions for head lice. </p>
<p>It’s also used in tablet form to treat <a href="https://www.cdc.gov/parasites/strongyloides/gen_info/faqs.html">roundworm infection</a> and as a <a href="https://www.nps.org.au/radar/articles/ivermectin-stromectol-for-typical-and-crusted-scabies">second-line treatment for scabies</a> and <a href="https://www.mayoclinic.org/diseases-conditions/rosacea/symptoms-causes/syc-20353815">rosacea</a>, a skin condition that causes redness and visible blood vessels in your face.</p>
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<img alt="" src="https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325616/original/file-20200406-79380-1o0qzkp.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">
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<span class="caption">Ivermectin is a second-line treatment for scabies.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendered-medically-accurate-illustration-scabies-1181594593">Shutterstock</a></span>
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<p>The pharmaceutical company that makes Ivermectin, MSD, has also been <a href="http://www.msd.com/about/featured-stories/mectizan.html">donating the drug to developing countries</a> to treat the parasitic diseases river blindness and elephantiasis for the past 30 years.</p>
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Read more:
<a href="https://theconversation.com/how-2015-nobel-prize-drug-might-rid-africa-of-ancient-scourges-48674">How 2015 Nobel Prize drug might rid Africa of ancient scourges</a>
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<h2>What are the side effects and potential harms?</h2>
<p>When used at the recommended dose, Ivermectin is generally well tolerated. Some of the common <a href="https://www.nps.org.au/australian-prescriber/articles/ivermectin-1">side effects</a> include diarrhoea, nausea, dizziness and drowsiness. </p>
<p>Less common is a lack of energy, abdominal pain, constipation, vomiting, tremors, rashes and itching. </p>
<p>Ivermectin may also <a href="https://www.nps.org.au/medicine-finder/stromectol-blister-pack-tablets">interact with some medicines</a>, such as the blood-thinning drug warfarin, or <a href="https://www.mayoclinic.org/drugs-supplements/ivermectin-oral-route/side-effects/drg-20064397?p=1">worsen some conditions</a> such as asthma.</p>
<p>Ingesting Ivermectin found in topical products for head lice is dangerous. If this occurs, contact the <a href="https://www.poisonsinfo.nsw.gov.au/">Poison Information Hotline</a>.</p>
<h2>How might Ivermectin treat COVID-19?</h2>
<p><a href="https://doi.org/10.1016/j.antiviral.2020.104787">Recent laboratory data</a> from <a href="https://www.monash.edu/discovery-institute/news-and-events/news/2020-articles/Lab-experiments-show-anti-parasitic-drug,-Ivermectin,-eliminates-SARS-CoV-2-in-cells-in-48-hours">scientists at Monash University and the Doherty Institute</a> suggests Ivermectin is able to stop SARS-CoV-2, the virus that causes COVID-19, from replicating. </p>
<p>Ivermectin has also been shown to stop other viruses (such as HIV, dengue, influenza and Zika) replicating, at least in the laboratory. </p>
<p>The researchers found Ivermectin had an effect on SARS-CoV-2 after one exposure to the drug. Viral replication was shut down within 24 to 48 hours. </p>
<p>It’s still not clear <a href="https://doi.org/10.1016/j.antiviral.2020.104787">exactly how Ivermectin works</a>. But it appears to stop the processes that allow proteins to move within the virus. These proteins would normally dampen the body’s antiviral response, allowing the virus to replicate and enhance the infection. </p>
<h2>Where is the research on Ivermectin for coronavirus up to?</h2>
<p>This research on Ivermectin has been conducted in <a href="https://doi.org/10.1016/j.antiviral.2020.104787">cell culture</a> (cells grown in a laboratory) and is very preliminary. It provides some promise, but not evidence of an effective treatment in people (yet). </p>
<p>Rigorous clinical trials in people with or exposed to COVID-19 infection are needed to establish the drug works and is safe to use, and in what doses. The laboratory studies of Ivermectin suggest higher concentrations of the drug may be needed <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2751445/">beyond a standard dose</a> to have an <a href="https://academic.oup.com/jac/article/75/4/827/5710696">antiviral impact</a>. So safety monitoring will be important. </p>
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<img alt="" src="https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325614/original/file-20200406-74212-1w0df68.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">
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<span class="caption">Lab studies suggest higher concentrations may be needed for COVID-19.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/female-life-scientist-researching-laboratory-pipetting-268543742">Shutterstock</a></span>
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<p>If Ivermectin is found to work on people with COVID-19, it needs to be studied as a potential treatment. So researchers need to know: does it prevent COVID-19 infection, reduce the severity of the associated illness, or improve the time to recovery? These are important questions to be answered before it becomes a treatment for COVID-19.</p>
<p>On a positive note, <a href="https://onlinelibrary.wiley.com/doi/10.1002/ddr.21666">re-purposing drugs</a> such as Ivermectin as a potential treatment for COVID-19 is ideal because development can move quickly to clinical trial testing because we already know it’s safe to use in humans at currently recommended doses.</p>
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Read more:
<a href="https://theconversation.com/in-the-fight-against-coronavirus-antivirals-are-as-important-as-a-vaccine-heres-where-the-science-is-up-to-133926">In the fight against coronavirus, antivirals are as important as a vaccine. Here's where the science is up to</a>
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<h2>Should I buy some just in case?</h2>
<p>No. It’s too soon to know if the promising laboratory test results will translate into a safe and effective drug for COVID-19 patients. The researchers were very clear <a href="https://www.monash.edu/discovery-institute/news-and-events/news/2020-articles/Lab-experiments-show-anti-parasitic-drug,-Ivermectin,-eliminates-SARS-CoV-2-in-cells-in-48-hours">Ivermectin should not be used to treat COVID-19</a> until further testing is complete. </p>
<p>We certainly shouldn’t be stockpiling the drug to use later, especially since we don’t yet know the best way to take Ivermectin, including the right dose. And it could lead to unintended medicine shortages for people who need the drug to treat serious diseases caused by parasites.</p><img src="https://counter.theconversation.com/content/135683/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew McLachlan receives research funding from the NHMRC, research scholarship funding from GSK for a PhD student under his supervision and has previously received (and disclosed) in kind research support from Pfizer and GSK for investigator initiated research projects. Andrew serves and is paid as an expert on Australian government committees related to medicines regulation and anti-doping.</span></em></p>The head lice drug Ivermectin has stopped SARS-CoV-2, the virus that causes COVID-19, from replicating in lab tests. But we don’t know if it will work as a treatment for people with coronavirus.Andrew McLachlan, Head of School and Dean of Pharmacy, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1161582019-05-01T23:41:16Z2019-05-01T23:41:16ZCurious Kids: what’s the point of nits?!<figure><img src="https://images.theconversation.com/files/271325/original/file-20190429-194620-1x83pc9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3273%2C2196&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Here's a close-up picture of a head louse. The eggs of the female head louse are what we call 'nits'.</span> <span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast <a href="http://www.abc.net.au/kidslisten/imagine-this/">Imagine This</a>, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.</em> </p>
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<p><strong>What’s the point of nits?! – Connie, age 9, Nambour, Queensland.</strong></p>
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<p>Great question, Connie. I often find myself scratching my head trying to figure out the answer to that question too!</p>
<p>What we commonly call “nits” are actually the eggs of very small insects known as head lice. And head lice are found nowhere else on the planet except in human hair.</p>
<p>Head lice have adapted perfectly to life on us. They have specially designed claws at the ends of each of their six legs that are perfect for scuttling up and down the shafts of hair. </p>
<p>In fact, they’re so perfectly designed for life on our hair that once they come off they’re incredibly clumsy and have a tough time getting around at all. That’s why they’re <a href="https://theconversation.com/back-at-school-heres-how-to-keep-kids-free-of-head-lice-110344">most commonly spread between children</a> through direct head-to-head contact. Lice are tricky enough to navigate the tangle of two people’s hair. </p>
<p>Once lice have infested someone, they will climb down the hair to the scalp and bite. They need our blood to live and lay eggs. While we’ll sometimes get a reaction to their bites, that reaction is rarely as bad as they type we get from mosquitoes or ticks. Importantly, head lice don’t transmit the germs that make us sick like those other pests. At worst, we’ll just get a little itchy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271363/original/file-20190429-194620-19kfqvl.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">You can remove head lice and their eggs (nits) with a fine-tooth comb. But just one comb-out session is never enough.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-when-we-get-bitten-by-a-mosquito-why-does-it-itch-so-much-93347">Curious Kids: When we get bitten by a mosquito, why does it itch so much?</a>
</strong>
</em>
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<hr>
<p>So, what is the point of head lice? Perhaps they don’t have a “point” at all. We like to think that all creatures play a role in the local ecosystem. We’re especially interested in insects that provide a benefit for people too. A great example are the bees and other insects that pollinate our crops that are crucial in providing food.</p>
<p>But perhaps head lice don’t play what we would traditionally see as an important role in the ecosystem. They don’t pollinate plants, they’re not food for other animals, and they don’t exactly bring joy to our lives in the way other, cuter animals do. When it comes to charismatic insects, head lice aren’t quite up there with butterflies or dragonflies!</p>
<p>I think lice see <em>us</em> as playing a role – providing them with food – but the reverse may not be true.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271364/original/file-20190429-194609-ltn7m4.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>
<figcaption>
<span class="caption">Lice attach their eggs to the hair with a special glue.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-we-have-two-kidneys-when-we-can-live-with-only-one-113201">Curious Kids: why do we have two kidneys when we can live with only one?</a>
</strong>
</em>
</p>
<hr>
<p>Perhaps we need to take a different perspective when thinking about the “point” of head lice. We marvel at the ability of plants and animals around the world to adapt to all the weird and wonderful cracks and crevices in the environment. Why shouldn’t we take inspiration from head lice being able to adapt to life on the human body?</p>
<p>Like many of the other insect pests that impact our lives, it can be hard to be sympathetic to head lice. As concern is growing about <a href="https://ecologyisnotadirtyword.com/2019/02/16/insectageddon-is-a-great-story-but-what-are-the-facts/">global insect declines</a>, I’m sure parents and carers <a href="https://theconversation.com/heres-how-you-beat-indestructible-head-lice-63594">trying to wrangle lice-infested children</a> aren’t thinking about insect conservation!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=466&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=466&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271366/original/file-20190429-194603-60y8kp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=466&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 life-cycle of lice.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au</em></p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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</figure>
<p><em>Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/116158/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management as well as risk assessment of a wide range of arthropod pests of public health importance.</span></em></p>We like to think that all creatures play a role in the local ecosystem. We’re especially interested in insects that provide a benefit for people too. But that’s not always how it is.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1103442019-01-28T19:15:44Z2019-01-28T19:15:44ZBack at school? Here’s how to keep kids free of head lice<p>A new school year, and another battle between bloodsucking parasites and the kids they love to live on. </p>
<p>But the real casualties are the stressed-out parents and carers trying to keep their kids free of lice.</p>
<p>Here are some tips for delaying the inevitably tricky task of lice treatment for as long as possible.</p>
<h2>Remind me, what are head lice?</h2>
<p>Head lice (<em>Pediculus capitis</em>) are insects found almost exclusively in the hair on human heads. These parasites aren’t found anywhere else on the planet. </p>
<p>They’re perfectly designed to scuttle up and down strands of hair, feeding on blood from the scalp of those infested. They typically feed about three times a day, spending up to 15 minutes on each occasion.</p>
<p>While their bites may cause some mild irritation, lice don’t spread bugs that make us sick.</p>
<p>Head lice don’t live long – not much more than a month. The adults lay eggs (commonly known as nits), which typically hatch in around a week or so. This life cycle is simple, but crucial for identifying and eradicating infestations.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=234&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=234&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=234&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=295&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=295&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255517/original/file-20190125-108348-dvlvtd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=295&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">You want to remove the adult lice, then treat again two weeks later to get rid of the newly hatched lice before they have a chance to lay more eggs.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/640318279?src=WQ2mkQMwfqF8OTCVCCOvZA-1-1&size=huge_jpg">By Blamb/Shutterstock</a></span>
</figcaption>
</figure>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255516/original/file-20190125-108355-891o0o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It’s worth investing in a lice comb.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?u=http%3A%2F%2Fdownload.shutterstock.com%2Fgatekeeper%2FW3siZSI6MTU0ODQxMTk0MywiYyI6Il9waG90b19zZXNzaW9uX2lkIiwiZGMiOiJpZGxfNDY3MzA2NjY5IiwiayI6InBob3RvLzQ2NzMwNjY2OS9odWdlLmpwZyIsIm0iOjEsImQiOiJzaHV0dGVyc3RvY2stbWVkaWEifSwiOFZVVXRXSFNKUHF3SHhkUGgyQWFaVU1teTRVIl0%2Fshutterstock_467306669.jpg&pi=41133566&m=467306669&src=WQ2mkQMwfqF8OTCVCCOvZA-1-12">By Jiri Hera</a></span>
</figcaption>
</figure>
<p>The eggs are immovably cemented to shafts of hair. These eggs, even when the lice have hatched, will remain and grow out with the hair strands. </p>
<p>This means that spotting nits <a href="http://conditions.health.qld.gov.au/HealthCondition/condition/14/165/351/head-lice">more than a centimetre or so from the scalp</a> may not require treatment at all.</p>
<p>Instead, look for the live lice moving about. This is the most reliable way to confirm an infestation. Use a special lice comb from the local pharmacy to make the search easier.</p>
<h2>How do children become infested?</h2>
<p>Head lice don’t jump or fly or swim. They move from head to head through direct contact as the strands of hair from two people make contact, creating a bridge for adventurous lice to a new world. </p>
<p>But lice can be fussy, with one study showing hairs need to be <a href="https://www.sciencedirect.com/science/article/pii/S0022202X15417713">specifically aligned</a> to allow the parasites to skip from one strand to another. </p>
<p>This is why transmission of lice from one person to another doesn’t happen as readily as urban myths suggest.</p>
<p>Sharing hats, towels, or <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-4362.2003.01927.x">pillows</a> won’t dramatically increase the chance of picking up head lice. They’re not going to crawl <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-842X.2002.tb00675.x">across the classroom floor</a> either.</p>
<p>Direct head-to-head contact is the best way to share an infestation, so keep an eye out for <a href="https://www.abc.net.au/news/2017-07-12/head-lice-expert-busts-myths-about-nits/8697362">kids crowded around smartphones and tablets</a>!</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255391/original/file-20190124-135130-toa1w5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Head lice may be small but they can cause big worries for parents and carers of school aged children!</span>
<span class="attribution"><span class="source">Eran Finkle/Flickr</span></span>
</figcaption>
</figure>
<p>Lice don’t necessarily have a particular predilection for clean or dirty hair. Short hair isn’t immune from infestation, but <a href="https://academic.oup.com/fampra/article/33/1/23/2450445#84322874">long hair means the chances of picking up lice are greater</a>.</p>
<p>Ensuring hair is neatly pulled back will dramatically reduce the risk of picking up head lice.</p>
<h2>Are head lice really a problem in Australia?</h2>
<p>Head lice are a problem the world over. But they are more of a nuisance than a health risk in most instances.</p>
<p>Research suggests around <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-4362.1999.00680.x">one-third of Australian primary school-aged children</a> could currently have head lice. With <a href="http://www.acara.edu.au/reporting/national-report-on-schooling-in-australia-2013/schools-and-schooling/school-numbers">more than 2.1 million primary school students in Australia</a>, that’s about 700,000 potentially infested children.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/B_RsAp542x0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The thought of head lice may be actually worse than the itchiness resulting from an actual infestation. The Australian Academy of Science provides an entertaining breakdown of why this maligned parasites cause so much stress.</span></figcaption>
</figure>
<p>It’s more difficult to control head lice than in the past. International studies indicate lice are <a href="https://academic.oup.com/jme/article/53/3/653/2222496">becoming resistant</a> to commonly used insecticide treatments. This is also likely to be a <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1440-0960.2000.00447.x">problem in Australia</a> but more research is needed to better understand the situation here.</p>
<p>Alternatives to traditional insecticides, such as <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/ajd.12626">botanical extracts</a>, may be more useful in the future. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/heres-how-you-beat-indestructible-head-lice-63594">Here's how you beat 'indestructible' head lice</a>
</strong>
</em>
</p>
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<p>Most <a href="https://www.health.nsw.gov.au/environment/headlice/Pages/treatment.aspx">health authorities in Australia</a> recommend avoiding insecticides, and instead suggest wetting the hair (or using conditioner) and then combing the lice out. </p>
<p>Essential to eradicating head lice infestations is two treatments, each about a week apart. This ensures adult lice are killed, then any eggs remaining are allowed to hatch but those newly hatched lice are killed by the second treatment before they have an opportunity to lay more eggs.</p>
<h2>I’m itchy already!</h2>
<p>Perhaps the biggest health issue associated with head lice is the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-4632.2011.05300.x">stress and anxiety</a> for parents and carers of infested children. </p>
<p>Even before a single louse is even spotted, finding a note from the school warning of a “lice outbreak” <a href="https://www.washingtonpost.com/news/parenting/wp/2016/04/22/how-to-combat-a-case-of-psychosomatic-lice-after-receiving-the-dreaded-letter-from-school/?noredirect=on&utm_term=.954302171a44">could be enough to trigger frantic head scratching</a>! There is even a term for this: psychosomatic itching.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/255518/original/file-20190125-108364-qezbj2.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">Don’t worry – head lice are annoying but they’re not harmful.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-girl-walking-through-her-nursery-447181969?src=rGzWkl0S3Y8Z9N89FVdc6Q-1-3">By DGLimages</a></span>
</figcaption>
</figure>
<p>Unfortunately, there are no quick fixes for getting rid of lice. And no matter what social media claims, <a href="https://www.lifehacker.com.au/2012/11/kill-lice-with-mayonnaise/">using mayonnaise</a>, <a href="https://www.dailymail.co.uk/femail/article-2723821/Mum-uses-hair-straighteners-kill-childrens-head-lice-nits.html">hair straighteners or household cleaning products</a>) is a bad idea.</p>
<p>The most important thing to remember is lice aren’t going to cause health problems, nor are they indicators of poor household hygiene or quality of care.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-keep-school-lunches-safe-in-the-heat-89868">How to keep school lunches safe in the heat</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/110344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p>Here are some tips to beat the bite of these bloodsuckers for as long as possible.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1048782018-11-19T12:39:19Z2018-11-19T12:39:19ZHow to get rid of head lice without spending loads of money<figure><img src="https://images.theconversation.com/files/245048/original/file-20181112-83599-1qv8zau.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's enough to make your head itch.</span> <span class="attribution"><span class="source">shutterstock</span></span></figcaption></figure><p>Parents are being warned there could be a big rise in head lice outbreaks in schools this winter. The health charity <a href="https://www.chc.org/">Community Hygiene Concern</a> has predicted that <a href="https://www.theguardian.com/society/2018/sep/29/head-lice-invasion-gp-nit-kits">low-income families will be hit hardest</a> after a change in NHS England guidance, means GPs are now routinely prevented from prescribing any treatment for the parasites. </p>
<p>Transmission of head lice among toddlers and children is common and is often the result of close and frequent head or hair contact. Toys, furniture, carpets and clothing can all offer temporary habitats to lice that will jump on a child if the chance arises – offering head lice the opportunity to be <a href="http://pediatrics.aappublications.org/content/110/3/638.short">transferred and to thrive</a>.</p>
<p>But while schools and parents often talk about “head lice outbreaks” the reality is that humans have had head lice living on them for thousands of years. And they were so common in the past that almost every family was in possession of a <a href="https://watermark.silverchair.com/ae54-0164.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAiowggImBgkqhkiG9w0BBwagggIXMIICEwIBADCCAgwGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMLVuLD20IrVWaURTHAgEQgIIB3fChH9rFG9TItlOcuZhAXpoI7lnM8_yPT4Mn46DGY3myEoSh6-cqeb5HrWTxDeHgELug9r-MXNGHhvy4pSlCWhBeo-B_hWW3tBMFeHUL5KVIEE-rhzsXUMJ5CkMguVl7jNtEqkUUQHJoSWnzqN3rcOHv9KGY1gLY7bxWF_zy7TO2EikuAXsjzy-SkCx5sUDtZ1KdKqMHLoQ9l8rrb4JcdeDudcXQ7g5YfziPcgEDbgMw97WXJ3dJfu13hbXpAj6uLhlqVbhjZgLuGk-XUr6lS0nuJEYBQTVpoeJcYG69PrBcFIu2QvSCgNepguCWpoCFXv4J8qd3SQueCyFFfWAqRlJy2tEdl5nmnxWzK5LXq5jVKErvqJT5wh1in4INcRG8j5Rt0R5AuFDO_sfj28hj_TRHnLwZCZ9Aeoi5npcoo6TBB_4ieH8mhUhDTEgDjirIFX8szyFYvQ6H3WT6gUchlN_fVmLCEmKk-GGlXef02qTnkEj5pUscMiHvDNyqO4jCwvpWDJzJOU9lVZeBz2P_GRAKmigmBBnBcqEMdUUCacK0_BSDuo10_ZpyMsNmzig-GI_G5AnbMrjAOGb4MuAOU0TDdOcuSfIg7i5jRdS9i90AIAe56CP-8B3Qo1_Q_w">special comb</a> to remove and keep them under control or in low numbers. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241124/original/file-20181017-41122-ih4t6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A female head louse.</span>
<span class="attribution"><span class="source">M. Alejandra Perotti</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Our ancestors produced these fine combs using different materials, including bone, wood and even cactus spines, to allow a minimum space between the teeth of the comb to remove lice. And as the majority of people in the community had head lice – not just infants – these combs were the main or only tools used to tease or brush the hair. </p>
<p>In fact in Poland in the 1600s, a hair style known as “<em>plica polonica</em>” or <a href="https://www.hairscientists.org/hair-and-scalp-conditions/plica-polonica">Polish plait</a>, was quite <a href="https://vugradhistory.wordpress.com/2018/04/11/plica-polonica-a-mixture-of-religious-superstition-scientific-inquiry-racist-implication-and-the-stuff-of-folklore/">fashionable</a>. The style, which resembles a matted mass of hair, formed as the result of neglect – often combined with a severe head lice infestation – and would be sticky and moist. </p>
<h2>The science of head lice</h2>
<p>The cycle of head lice starts when a female lice lays eggs which are attached to the hair by gluing them at the root end. The lice produce a very strong, cement-like substance to do this.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=901&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=901&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=901&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1132&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1132&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245574/original/file-20181114-194519-jjjogp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1132&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ancient cactus comb from South America.</span>
<span class="attribution"><span class="source">Museo Chileno de Arte Pre-Colombino/Alejandra Perotti</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The position of the newly delivered egg (known as a nit) is approximately 5mm from the scalp. This distance cannot be modified, or the embryo will not develop – because the temperature won’t be right.</p>
<p>During development, nits follow a specific regime of temperatures, a slight decreasing gradient of temperature as the hair grows and the nits become more and more distant from the scalp. So those nits closest to the scalp are the most recently laid on the hair – and chances are these are healthy living embryos. Those nits more than two centimetres away from the scalp look very obvious, with a whitish reflection. These are the empty eggs shells.</p>
<h2>How to get rid of them</h2>
<p>Two forms of head lice should be certainly considered as targets for control: the females and the newly born nits. To remove both forms, a fine comb – known as lice or louse comb – has been shown to be effective in terms of <a href="https://link.springer.com/article/10.1007/s00436-015-4311-8">treatment and prevention of heavy lice infestations</a>. </p>
<p>Of course, pharmacies tend to be well stocked with formulas and solutions to kill head lice – but there are other natural or non-chemical treatments that may still be worth a try. Traditional plant remedies are still used in continental Europe – for example, a herbal infusion from the chickpea plant. The infusion is made from dried beans and is then <a href="https://www.sciencedirect.com/science/article/pii/S0378874111007306?via%3Dihub">applied on the scalp</a>. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245049/original/file-20181112-83573-1gay85k.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">To clean a metal nit comb, dip it in a bowl of soapy water, or wipe it with a paper towel after each swipe.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>In the UK in Tudor times, Hyssop’s oil, an aromatic herb was also <a href="http://journals.sagepub.com/doi/pdf/10.1177/014107689608901219">used as treatment for head lice</a>. And Hyssop’s oil is still used to control lice to this day.</p>
<p>Considering the specific temperature needed for lice eggs to develop – and that drastic changes in temperature kills them – new methods are also now being developed to <a href="https://patents.google.com/patent/US20180255901A1/en">incorporate heat as part of regular treatment</a>. Investigations on devices producing hot air indicates high efficacy when properly <a href="https://academic.oup.com/jme/article/48/1/67/905557">applied on a regular basis</a>.</p>
<p>So to combat head lice without using messy shampoos and toxic chemicals, parents may want to try a combination of treatments: a traditional metal louse comb, as well as herbal infusions to apply topically on the hair or scalp, along with exposure to short but regular use of a hot hair dryer.</p><img src="https://counter.theconversation.com/content/104878/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alejandra Perotti receives funding from the BBSRC. </span></em></p>A huge rise in head lice and nits is expected in schools due to the NHS scrapping treatment.Alejandra Perotti, Associate Professor in Invertebrate Biology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/739562017-03-09T05:37:54Z2017-03-09T05:37:54ZResearch Check: will using lice products give my children behavioural problems?<figure><img src="https://images.theconversation.com/files/159495/original/image-20170306-943-9wvkvo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pyrethroids can be found in some head-lice products.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p><a href="http://www.smh.com.au/business/consumer-affairs/pyrethroid-insecticides-linked-to-abnormal-behaviour-in-children-study-shows-20170301-guo1dd.html">Reports of a French study claimed</a> last week that exposure to certain insecticides during pregnancy were linked to “abnormal behaviour” in children. </p>
<p>Called pyrethroids, these chemicals are present in some common treatments for <a href="https://www.nettopet.com.au/fido-s-pyrethrin-shampoo-500ml.html?gclid=CMWQmMv8wNICFQoQvQod0yUGCA">dog ticks</a> and head lice. The <a href="http://www.dailymail.co.uk/health/article-4273614/Poor-behaviour-linked-head-lice-treatments.html#ixzz4aVrYSBVO">Daily Mail</a> zeroed in on this fact with the headline: </p>
<blockquote>
<p>Poor behaviour is linked to head lice treatments: Chemicals used to tackle the problem may effect [sic] nerve activity in the brain.</p>
</blockquote>
<p>The study’s lead author, Professor Jean-François Viel, told The Conversation he was surprised media reporting focused on head-lice treatment rather than “the overall exposure to pyrethroid insecticides we attempted to address”. You can view his full response at the end of the article.</p>
<p>Published in the <a href="http://oem.bmj.com/content/early/2017/02/02/oemed-2016-104035">Occupational and Environmental Medicine</a> journal, the study suggests an association between exposure to pyrethroids in pregnancy and behavioural issues in six-year-olds. But an association isn’t the same as causation – and as far as associations go, the one in this study was pretty weak.</p>
<p>We asked a chemistry expert to explain, and a toxicologist to review the analysis.</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/160116/original/image-20170309-21026-7gc4of.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<hr>
<h2>What are pyrethroids?</h2>
<p>Pyrethroids are synthetic versions of the naturally occurring insecticide, pyrethrin. They are widely used in agriculture and also in the home to control fleas and head lice. </p>
<p>Pyrethroids are neurotoxins (nerve poisons) that work by making cell membranes more permeable (easy to cross for various molecules). This can impair nerve transmission in insects, as well as humans. Most people are <a>widely exposed to pyrethroids</a>, mainly through diet (as they are used in agriculture) and indoor use. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=898&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=898&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=898&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1129&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1129&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159721/original/image-20170307-14946-tc7pj8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1129&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Pyrethroids are found in some products used to kill head lice.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Pyrethroids enter the body through food, skin and the airways. Once absorbed, they are quickly broken down into byproducts called metabolites. These are excreted through urine and their presence indicates a person has been exposed to pyrethroids.</p>
<p>Earlier work, by the <a href="http://dx.doi.org/10.1016/j.envint.2015.05.009">same group of researchers</a> as the study in question, had shown that the presence of pyrethroid metabolites in children, but not in their mothers when pregnant, was negatively associated with children’s verbal comprehension scores. </p>
<p>Several years ago, Canadian research reported that some pyrethroid metabolites – found in 97% of 779 children aged six to 11 years – were associated with parent-reported behavioural problems.</p>
<h2>How was this study conducted?</h2>
<p>The study had two aims. The first was to test the effect of children’s exposure to pyrethroids <em>in utero</em>; the second tested for exposure to pyrethroids during childhood.</p>
<p>Researchers randomly selected 571 pregnant women from a sample of 3,421 women from an agricultural region of France, who were <a href="http://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-9-71">recruited for a broader study</a>. Of the 571 pregnant women selected, 287 agreed to a neurological (nervous system) and chemical and psychological follow-up when their children were six years old.</p>
<p>Mothers completed a list of 25 questions, drawn from a French version of the <a href="http://www.sdqinfo.com/">International Strengths and Difficulties Questionnaire</a>, to describe their children’s behaviour over the previous six months. Children’s behaviours were also assessed by visiting psychologists.</p>
<p>Researchers tested mothers’ urine at weeks six to 19 of gestation, and their children’s at age 5.99 to 6.27 years. They analysed the urine samples for pyrethroid metabolites.</p>
<p>Pyrethroid metabolites were absent from the urine of 82 mothers and four of their children. So the study only reported results for the remaining 205 women and 283 children. Metabolite concentrations in these women and children were very low – typically in the region of sub-micrograms per litre. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159716/original/image-20170307-14957-1dkp3wx.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">Psychologists performed assessments on the children.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>One metabolite (<em>cis</em>-DCCA) was detected in almost all the women and children. Another (3-phenoxy benzoic acid) was detected in some samples, but its concentrations were very low. And in as many as 36% of the childhood urine samples, its levels were not detectable. </p>
<p>Different metabolites arise from different pyrethroids, so the presence or absence of a metabolite is likely to be a consequence of exposure to different pyrethroids rather than different metabolism.</p>
<p>Psychologists assessed children for altruism (social behaviour), internalising disorders (inability to share problems and ask for help) and externalising disorders (defiant and disruptive behaviour). Mothers also sent in reports on their children’s behaviour.</p>
<h2>What were the results?</h2>
<p>Concentrations of the most commonly observed metabolite (<em>cis</em>-DCCA) in the urine of pregnant mothers in the first trimester was positively correlated with internalising difficulties – such as being anxious or withdrawn – of their six-year-olds.</p>
<p>The variant of <em>cis</em>-DCCA, called <em>trans</em>-DCCA, in the urine of the six-year-olds was associated with reduced externalising behaviours – such as being aggressive or defiant. This is a counter-intuitive finding for which the researchers had no explanation.</p>
<p>Authors also report childhood exposure to the metabolite 3-phenoxy benzoic acid was associated with “increased odds of behavioural disorders”. But this was the metabolite that, in 36% of the urine samples, was below the level of detection.</p>
<h2>What are the issues with this study?</h2>
<p>There’s a possibility the sample is biased because only about half of the chosen pregnant women agreed to participate. No explanation was offered as to why mothers might have declined the invitation. </p>
<p>Reasons that would affect the study’s validity would include mothers declining due to feeling the research didn’t apply to them as they had never been exposed to pyrethroids, or that participation might lead to revelations of bad parenting.</p>
<p>To their credit, the authors themselves describe the associations they sought in this research as “limited” and advance a number of factors that could have affected them. These included that stored maternal urine samples could have degraded over the six years between their collection and that of the childhood samples.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/159720/original/image-20170307-14973-1t5n3oj.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">High concentrations of one metabolite in pregnant mothers’ urine were associated with internalising behaviours in children, such as being withdrawn.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Second, the authors don’t have a distinct way of knowing whether the behavioural issues seen in some of the children were a direct result of exposure to pyrethroids <em>in utero</em>. Authors used statistical analyses to link childhood behaviour to their potential exposure <em>in utero</em>, but this is not an exact science.</p>
<p>Third, children differ in their ability to metabolise pyrethroids, which makes it difficult to compare like for like. And, finally, there is the possibility of “reverse causality” – children with behavioural problems such as hyperactivity might increase their exposure to pesticides, through deliberately disobeying parents’ orders, for instance.</p>
<p>There is also <a href="http://eprints.qut.edu.au/56403/">some evidence</a> that the developing fetus may susceptible to “poisoning” by a particular pesticide for only short windows of time during gestation. If this were true of the pyrethroids and their metabolites, one might not expect to see strong correlations with general measures of exposure like urinary metabolites. </p>
<p>Pyrethroid metabolites are cleared from the body within a few days. This means “snapshots” of their presence at one point in time in children – such as those used in this study – may not serve as good indicators of repeated exposure.</p>
<h2>So, what’s the verdict?</h2>
<p>Cause and effect is very hard to establish, despite efforts of researchers to control for other factors. And it’s terribly hard to link behaviours back to chemicals. So this study did not establish causation between exposure to pyrethroids and behavioural problems. It only suggested an association. </p>
<p>If parents are concerned about head-lice treatments, they should know there is a <a href="https://theconversation.com/health-check-how-do-you-catch-and-get-rid-of-head-lice-43699">non-chemical method</a> of controlling these pests. It uses a fine-tooth comb to separate them from the hair, repeated over a week or so.</p>
<p>As for insect sprays that contain pyrethroids, it is wise to use them sparingly if you are concerned about health impacts. <strong>– Ian Rae</strong></p>
<hr>
<h2>Peer Review</h2>
<p>Pyrethroid-based pesticides have largely replaced older pesticides, such as DDT, at least in part because they are much less toxic to humans. They are between 1,000 to 30,000 times <a href="http://onlinelibrary.wiley.com/doi/10.1002/ps.3881/full">less toxic to mammals</a> than insects. But they are <a href="http://www.sciencedirect.com/science/article/pii/S0378427416333549">neurotoxins</a> and there is concern long-term exposure to pyrethroids could affect development of parts of the nervous system. </p>
<p>The observational study published in the <a href="http://oem.bmj.com/content/early/2017/02/02/oemed-2016-104035">Occupational and Environmental Medicine</a> journal sought to address this issue. This Research Check fairly covers the research in question and highlights most of its strengths and limitations. </p>
<p>A strength of the study is that psychologists performed independent tests of child behaviour, rather than self-reports, which are open to bias. </p>
<p>The Research Check correctly points out that what was found is an <em>association</em> between the pyrethroid metabolites and some behaviour, rather than a <em>causal</em> relationship. </p>
<p>The association between the pyrethroid metabolites is weak and does not appear to be dependent on exposure. That is, children with the highest exposure levels do not seem to have more effects on behaviour than those with mid-level exposure. </p>
<p>Importantly, statistical tests performed to link behaviours with exposure were not corrected for the mathematical effects of doing multiple tests. This means the associations may be false positives. </p>
<p>The researchers’ statement that there is “no current explanation for the counter-intuitive association observed between childhood high trans-DCCA concentrations and reduced externalising disorders” is consistent with these results being false positives. </p>
<p>This Research Check’s overall verdict is appropriate. <strong>– Ian Musgrave</strong></p>
<hr>
<h2>Full response from study author on media reports</h2>
<p>Some headlines refer to “head lice killer” or “chemicals used to kill lice”.</p>
<p>It is true that pyrethroid insecticides are used to treat head lice (but also scabies) in humans and fleas in pets. But they are also used to control pests in residential and agricultural settings.</p>
<p>In our paper, we assessed pyrethroid exposure through concentrations of pyrethroid metabolites in urine (and not through specific usages collected from questionnaires). As a result, we cannot identify and quantify the various sources of exposure. Therefore, this focus on head lice is somewhat surprising to me.</p>
<p>Many pictures show a child with long hair. In the same way, these pictures refer to a single source of exposure (head lice treatment) and not to the overall exposure to pyrethroid insectides that we have attempted to assess. </p>
<p><strong><em>Professor Jean-François Viel, Department of Epidemiology and Public Health, University of Rennes France</em></strong></p><img src="https://counter.theconversation.com/content/73956/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Musgrave receives funding from the National Health and Medical Research Council to study adverse reactions to herbal medicines and has previously been funded by the Australian Research Council to study potential natural product treatments for Alzheimer's disease. He is co-investigator of a grant to explore the metabolism of rodenticides.</span></em></p><p class="fine-print"><em><span>Ian Rae 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>An association isn’t the same as causation – and as far as associations go, the one in this study was pretty weak.Ian Rae, Honorary Professorial Fellow, School of Chemistry, The University of MelbourneIan Musgrave, Senior lecturer in Pharmacology, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/635942016-08-05T07:22:24Z2016-08-05T07:22:24ZHere’s how you beat ‘indestructible’ head lice<figure><img src="https://images.theconversation.com/files/133212/original/image-20160805-484-bau0kd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Head lice are an itchy problem to solve. But don't panic, there are alternatives to insecticides.</span> <span class="attribution"><span class="source">Cameron Webb</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Head lice don’t pose a particularly serious <a href="http://www.health.nsw.gov.au/environment/headlice/pages/default.aspx">threat to our health</a> but they do cause great anxiety among parents and carers. This anxiety, and associated stress, is made even worse given the perceived social stigma of a family infested with parasites, and the seemingly endless battle to exterminate these pests.</p>
<h2>What are head lice?</h2>
<p>Head lice are small insects that are highly adapted to one type of environment: hair on a human’s head (especially the hair and head of primary school-aged children). </p>
<p>Infestation with head lice is affectionately known as “pediculosis”, but while the lice will scuttle up and down the strands of hair, feeding on blood at the scalp, they don’t seem to cause anything other than very mild irritation. They’re not involved in the spread of any nasty diseases either.</p>
<p>But head lice are highly contagious. If you or someone in your family has them, you’ll probably want to get rid of them.</p>
<h2>Are head lice becoming ‘indestructible’?</h2>
<p>For many years we’ve known that commonly used insecticides (particularly permethrins and pyrethroids) <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-0691.2012.03806.x/full">aren’t working as well as they once did</a> against head lice. Similar types of insecticides are currently being employed to battle outbreaks of mosquito-borne Zika virus in South America. </p>
<p>In much the same way that <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev-ento-010814-020828">mosquitoes</a>, <a href="https://entomologytoday.org/2016/04/21/new-research-shows-how-different-strains-of-bed-bugs-are-able-to-resist-insecticides/">bed bugs</a> and many agricultural insect pests are becoming resistant to commonly used insecticides, so are head lice.</p>
<p>A recent study published in the <a href="http://jme.oxfordjournals.org/content/53/3/653">Journal of Medical Entomology</a> provides some insight into just how prevalent insecticide resistance in head lice may be.</p>
<p>Thanks to school nurses and “professional lice combers”, scientists from the University of Massachusetts were able to analyse more than 14,000 head lice from almost 140 locations across 48 US states. They were looking for the genetic markers that indicate potential resistance to insecticides such as pyrethrins or pyrethroids. </p>
<p>The researchers found a very high prevalence of “knockdown resistance”, a mutation in the insect that make it less susceptible to insecticides. The results suggest that more than 98% of head lice analysed may not be susceptible to many head lice treatment products currently available.</p>
<p>The result isn’t surprising. With so much use of insecticides against head lice, the development of resistance should almost be expected.</p>
<p>Before everyone panics, it is important to note that while the mutations that confer insecticide resistance were found to be widespread, that doesn’t necessarily mean that all head lice will be resistant to commonly used insecticides. They may be, but we just don’t know to what extent. </p>
<p>There are also likely to be differences between head louse populations across the world.</p>
<h2>What about Australia?</h2>
<p>Insecticide resistance <a href="http://link.springer.com/article/10.1007/s00436-003-0881-y">also occurs in Australian head lice</a>.</p>
<p>Any local product marketed as a head lice treatment must be registered with the <a href="https://www.tga.gov.au/">Therapeutic Goods Administration</a>. While the evidence seems to be mounting that some of these insecticides aren’t working well against some head lice, there are also other products available.</p>
<p>Australian plant extracts may be useful in beating insecticide-resistant head lice. Tea tree oil products are commonly available and have been <a href="http://bmcdermatol.biomedcentral.com/articles/10.1186/1471-5945-10-6">shown to be effective</a>. </p>
<p>Some recent research indicates the extracts of the “Tick Bush” may be <a href="http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10253554&fulltextType=RA&fileId=S2055709415000023">useful for head lice treatment too</a>.</p>
<h2>We can even ditch the insecticides</h2>
<p>Here is the really good news. We don’t have to rely on insecticides to control head lice.</p>
<p>The “<a href="https://theconversation.com/head-lice-infestations-dont-let-back-to-school-bloodsuckers-drain-your-patience-11473">conditioner and comb</a>” method works well enough. By applying conditioner to the hair, any adult lice present will be “paralysed” and can then be removed with specially designed “lice combs”. (Interestingly, the earliest known “lice combs” <a href="http://ae.oxfordjournals.org/content/ae/54/3/164.full.pdf">date back to 1500 BC</a>). </p>
<p>Repeat the process a week later to catch any lice that hatch from eggs remaining in the hair and you should be done – at least until next time.</p>
<p>The biggest barrier to success is getting the children to sit still long enough to methodically work through their hair. Wrangling the kids is probably more difficult than wrangling the lice!</p><img src="https://counter.theconversation.com/content/63594/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on biting insect biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p>New research confirms what many parents already know: head lice are getting harder to kill. How else can we control these itchy pests plaguing our playgrounds?Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/436992015-08-10T05:12:36Z2015-08-10T05:12:36ZHealth Check: how do you catch – and get rid of – head lice?<figure><img src="https://images.theconversation.com/files/91245/original/image-20150810-12474-1op80p4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The head louse is usually relatively harmless and more of a nuisance than a disease.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>We humans think we sit on top of the food chain, but the <em>pediculosis capitis</em> mite – the head louse – sits above us, on the top of our heads.</p>
<p>The head louse is a small, wingless insect that feeds on human blood. It moves around our scalp swinging from hair to hair, mates and then lays its eggs in special cases (nits) attached to the base of our hair fibres.</p>
<p>Around <a href="http://www.ncbi.nlm.nih.gov/pubmed/15469530">13% of school-age children</a> are thought to have head lice at any given time, with girls more than twice as likely to be infected than boys. </p>
<p><em>Pediculosis capitis</em> has been around for millions of years. But <em>homo sapiens</em> are the only known host for the modern day head louse. The chimpanzee has a similar but genetically distinct mite, as do most mammals. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91249/original/image-20150810-12477-1v827bw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The head louse is a small, wingless insect that feeds on human blood.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/sanmartin/4900275659/in/photolist-8t2cen-4rYoSP-8t5e5w-8t5e9N-8t5eeq-8t2bUR-8t5dUW-8t5dPb-89vRyJ-6KD6zp-o7rrz1-dQWwTw-nS1k2M-5RkocK-nRZqSj-5YTHnQ-o9oW8J-7qUNZF-5YPuap-5YTHgN-ZVEsq-8MAqTV-o9bDZ4-7G2icu-81Rq8b-r83AkN-nRZrqd-hyx9q1-a86UkR-oJNeQg-8STDPj-4ojwPK-8z9dbV-8zcRf9-kWjBxq-9cHyFS-6eGjhC-nv5nT5-r7wDKA-8Wpb5y-ZRPpH-8WpdqG-7N4CE1-aqVmfz-4tgmQL-6VxueP-9LMBb1-8WpcMs-6VByj3-8Wm6hT">Gilles San Martin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The head louse is usually relatively harmless and more of a nuisance than a disease. </p>
<p>But in World War One, head lice were a <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1633565/">major cause</a> of sickness and, occasionally, death. Because soldiers were wearing the same uniform for days, lice were able to migrate off the scalp and inhabit the seams of the uniform. These lice became the vector for <em>Bartonella</em> infection, which caused <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1633565/">trench fever</a>. Three famous sufferers were authors JRR Tolkien, AA Milne and CS Lewis.</p>
<p>Head lice are very itchy and scratching can lead to secondary infection with golden staph, a potentially serious illness. </p>
<p>That being said, the biggest problem most people have with head lice is finding a way to get rid of them. Over the past 50 years, we have seen one insecticide after another lose effectiveness as the lice find a way to adapt, evolve and become resistant. </p>
<p>For the past ten years, the most reliable way of getting rid of head lice has been the application of a thick film of conditioner to the hair and daily combing to manually extract the lice. If you have a daughter with long thick hair, this procedure can take half an hour a day. If you have got two or three daughters infected with lice, the treatment process quickly becomes a nightmare.</p>
<h2>How do you catch head lice?</h2>
<p>A female louse will lay between three and eight eggs per day. The eggs attach to the hair fibres within 1.5 centimetres of the scalp and rely on the warmth from the head to hatch. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91248/original/image-20150810-12465-1wz4vxd.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">People get head lice from direct head-to-head contact with someone who has it.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Head lice do not have wings so they cannot fly, and their short stumpy legs mean that they cannot jump from head to head. They can only crawl.</p>
<p>People get head lice from direct, head-to-head contact with another person who has head lice. This can happen when people play, cuddle or are close together. Head lice are most common among children and their families. If your family has head lice, tell anyone who has had contact to check their family. </p>
<p>In general, there is no need to treat the whole family unless they also have head lice. There is no evidence that you need to clean the house or the classroom or that either changing the bed linen or pillow cases helps.</p>
<h2>Finding head lice</h2>
<p>Half the people who have head lice never scratch their head, so itching is not a reliable sign. Lice can be hard to spot because they move quickly.</p>
<p>If you suspect you or a child has head lice, the easiest and most effective way to find them is to use the conditioner and comb treatment. Massage 50 millilitres of conditioner into a dry scalp. Then comb through the scalp with a broad-tooth comb to detangle the hair. This makes it difficult for the lice to grip onto the hair. </p>
<p>Then, using a very fine tooth nit comb, divide the scalp into six sections and comb through from root to tip, wiping the conditioner from the comb onto a paper towel or tissue to see if there are any lice, and remove them if there are.</p>
<h2>Treatment for head lice</h2>
<p>Two treatments are available for use at home without prescription and one is available only on prescription from your doctor or dermatologist. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=897&fit=crop&dpr=1 600w, https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=897&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=897&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1127&fit=crop&dpr=1 754w, https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1127&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/91247/original/image-20150810-12471-1kyvq02.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1127&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The most reliable way to get rid of head lice is the conditioner and comb method.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/coyotecreek/15694857533/in/photolist-pUUfkX-9DpZAk-bf3jwk-eeMR6-5SnLgi-7rpye-3ZzwWe-8UUWCb-3xHtAG-bni5EZ-4FAheG-dmEN-3tuMBF-yLe1k-5A9Vwi-44nE9g-9rohiK-nUb6Lb-j7XFQB-hJTJf-jCyb6b-hSnYUV-j9Mdij-6shkKg-enmv4d-3oT1Mt-4ZKDSA-4FjQTP-d7ygZw-6J1sJy-5bsSH-53mJ7b-dHhD8x-b83Xs-3UAQE-9u61zD-nuvvS-bLCifr-9pJhvZ-n2a9gG-6ai8kM-mCiUx-4CYA8k-e7YGBm-7HtRB3-7qjmke-e4zU4w-ac7dES-7wXQPj-qKFcqN">Kevin Schraer/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The non-prescription treatments are the conditioner and comb method as described above, or to use an insecticide. For the conditioner and comb method, you’ll need to repeat it at least once a week until you’re no longer extracting any lice.</p>
<p>A large number of insecticide products are available over the counter in pharmacies without prescription. Take care when using these products if you’re pregnant or breastfeeding or if the child is less than 12 months old. </p>
<p>No topical insecticide treatment kills 100% of the eggs so you’ll need two applications, seven days apart. If the insecticide works, the lice will be dead within 20 minutes. If the lice are not dead, the treatment has not worked and the lice are resistant to the product.</p>
<h2>Tablets for head lice</h2>
<p>If the initial non-prescription treatments have failed and you’re still removing live lice with the conditioner and comb, see your doctor for a referral to a dermatologist for specialist treatment.</p>
<p>Ivermectin is a <a href="http://www.australianprescriber.com/magazine/23/3/62/3/">prescription</a> medication available either as a tablet to take orally or a lotion to apply to the scalp. </p>
<p>While a single dose will stop the lice in their tracks, it should be repeated after seven days to ensure any unhatched eggs are also killed. </p>
<p>For children too young to swallow a tablet, the ivermectin can be formulated as a syrup. For very young children, pregnant women and women who are breastfeeding, the ivermectin can be used as a lotion in the scalp. </p>
<p>Ivermectin has been available in Australia for the past 15 years. But while it was added to the pharmaceutical benefits schedule (PBS) last year, it’s only subsidised to treat scabies (mites that burrow into the skin), so you may have to pay full price when filling scripts for head lice.</p><img src="https://counter.theconversation.com/content/43699/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rodney Sinclair 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>We humans think we sit on top of the food chain, but the pediculosis capitis mite – the head louse – sits above us, on the top of our heads.Rodney Sinclair, Professor of Dermatology, Epworth Hospital, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/114732013-02-13T19:23:49Z2013-02-13T19:23:49ZHead lice infestations: don’t let back-to-school bloodsuckers drain your patience<figure><img src="https://images.theconversation.com/files/20183/original/6ckpdtyq-1360710651.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Getting infested children to sit still long enough to complete a treatment is probably more difficult than removing the head lice themselves.</span> <span class="attribution"><span class="source">Vera Davai/AAP</span></span></figcaption></figure><p>Across the country, tiny blood-sucking parasites are settling in for the new school year. Head lice infestation, officially known as pediculosis, is <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-4362.1999.00680.x/full">common</a> in primary school-aged children. But don’t worry, head lice don’t transmit any disease-causing pathogens and the irritation they cause is relatively minor.</p>
<p>For carers of children affected by head lice, however, anxiety and stress brought on by perceived social ramifications probably causes more problems than the physical impact of the lice themselves.</p>
<h2>What are head lice?</h2>
<p>Head lice (Pediculus capitis) are small insects less than half a centimetre in length. They’re typically a light grey to brown colour and have strong claws that they use to cling onto hairs. These claws enable the lice to move up and down and across the strands of our hair, and scurry down to the scalp to feed on blood. Despite common misconceptions, head lice don’t jump, they don’t fly and they don’t swim.</p>
<p>A female louse can lay over 100 eggs (commonly known as nits) in her lifetime. The eggs are attached to the hair shaft close to the scalp with a super strong adhesive secreted by the louse itself. Immature lice generally hatch after a week, and reach maturity in less than two weeks. Lice may live for up to a month. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=489&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=489&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=489&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=615&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=615&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20170/original/zrnsxk62-1360642741.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=615&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Emma/Flickr</span></span>
</figcaption>
</figure>
<p>The main hotspots for head lice activity in Australia are <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-4362.1999.00680.x/full">primary schools</a>. Studies have shown that, in some areas, up to four in five children may be infested. Girls are particularly susceptible, which isn’t surprising given all that long hair waving about and close contact between friends.</p>
<p>Head-to-head contact is essentially the only way lice are transmitted between children. And they rarely discriminate. Dirty or clean, blonde or black, lice will swing across at the first chance of setting up a new home.</p>
<p>You may be surprised that <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-4362.2000.00914-5.x/full">sharing hats or hair brushes</a> may not be a fast track to head-lice infestation. While the lice’s claws are perfectly suited to life among hair strands, they’re not much use for crawling around on the ground, furniture or on clothing. Once off hair, they don’t live for long.</p>
<h2>My child has nits!</h2>
<p>So what to do if your child gets head lice? First, don’t panic. There’s no need to “decontaminate” your home. Head lice cannot complete their life cycle on animals such as dogs, cats, possums or birds. And bedding, furniture and other household objects don’t act as <a href="http://www.benthamscience.com/open/todj/articles/V004/62-todj-hot-topic/72TODJ.pdf">hiding spots</a> for head lice either. </p>
<p>As noted in the latest <a href="http://www.nhmrc.gov.au/guidelines/publications/ch55">guidelines</a> from National Health and Medical Research Council, there’s no need to keep children home from school if treatment has commenced. And while you could shave your child’s head, that’s probably a little drastic and there are less dramatic options available.</p>
<p>It’s a good idea to check, and treat if required, all the children and the adults in the family at the same time.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20175/original/x8d47b53-1360646778.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Head-to-head contact, no matter how or why it takes place, is the only way lice are transmitted between children.</span>
<span class="attribution"><span class="source">Tim Meaney/Flickr</span></span>
</figcaption>
</figure>
<p>The non-chemical “wet comb” or “comb and conditioner” method is generally considered the preferred option for head-lice control. This is effective but it can be time consuming. Getting infested children to sit still long enough to complete the process is probably more difficult than removing head lice themselves.</p>
<p>There are a number of <a href="http://www0.health.nsw.gov.au/publichealth/environment/headlice/treatment.asp">steps</a> in this process but, in summary, it involves applying hair conditioner to dry hair to stun the lice, which also allows them to be more easily combed out. A good quality fine-tooth lice comb is essential. </p>
<p>It’s important to then systematically work through all the hair, combing from scalp to the tip of the hair strands. Wipe conditioner from the comb onto a tissue or paper towel and you’ll see any lice. Combing should be repeated until no live lice are detected. As some eggs will escape this process, it’s important to do it all over again a week later. </p>
<p>It’s essential to collect any newly hatched lice before they’re able to mate and lay a new batch of eggs.</p>
<h2>Chemical treatments</h2>
<p>For persistent infestations, chemical treatments are often needed.</p>
<p>Chemical treatments (generally known as pediculicides) need to be listed or registered on the <a href="http://www.tga.gov.au/industry/artg.htm">Australian Register of Therapeutic Goods</a> (administered by the Therapeutic Goods Administration). There are almost 100 products available including insecticides, repellents and lice combs.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/20059/original/82572f8g-1360291252.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/20059/original/82572f8g-1360291252.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">
<figcaption>
<span class="caption">A male human head louse.</span>
<span class="attribution"><span class="source">Gilles San Martin</span></span>
</figcaption>
</figure>
<p>Pediculicide formulations generally work well against lice but are less effective against eggs so, like the wet comb method, treatment needs to be repeated after seven days. The benefit of these formulations is that treatment may only be required for 20 minutes or so (although some products are recommended for use overnight).</p>
<p>In recent years, the development of resistance to many of the over-the-counter head-lice treatments has been documented in the <a href="http://www.sciencedirect.com/science/article/pii/S0048357504000926">United States</a>, <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2133.2002.04473.x/full">the United Kingdom</a> and <a href="http://link.springer.com/article/10.1007/s00436-003-0881-y/fulltext.html">Australia</a>. </p>
<p>An oral medication currently used to treat internal parasites, Ivermectin, has been <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1525-1470.2010.01317.x/full">proposed</a> as an alternative to topical pediculicides and studies to determine if this could work are currently underway in <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1525-1470.2010.01317.x/full">Australia</a>.</p>
<h2>Natural products and alternative strategies</h2>
<p>Products containing botanical extracts are also available. While some may <a href="http://link.springer.com/article/10.1007/s00436-011-2687-7">help prevent reinfestation</a>, it may actually be the <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-4632.2007.03132.x/abstract">slippery nature of oils</a> in the formulations, rather than their repellent qualities, that keep head lice away.</p>
<p><a href="http://www.pediatricsdigest.mobi/content/118/5/1962.short">Hair dryers</a> may provide a non-chemical treatment option, and similarly, hair straighteners may kill lice. But keep in mind that these devices are known to cause <a href="http://journals.lww.com/burncareresearch/Abstract/2008/07000/Burns_in_Children_Caused_by_Hair_Straighteners_.14.aspx">injuries</a> to children.</p>
<p>At the end of the day, the key to an effective strategy in your household will be to find a treatment that your children will tolerate and that won’t test your patience too much. </p><img src="https://counter.theconversation.com/content/11473/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb 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>Across the country, tiny blood-sucking parasites are settling in for the new school year. Head lice infestation, officially known as pediculosis, is common in primary school-aged children. But don’t worry…Cameron Webb, Clinical Lecturer and Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.