24/08/14

Drug-resistant malaria threatens control programmes

Copyright: Ian Teh / Panos

By: Brendon Lee

We encourage you to republish this article online and in print, it’s free under our creative commons attribution license, but please follow some simple guidelines:

You have to credit our authors.
You have to credit SciDev.Net — where possible include our logo with a link back to the original article.
You can simply run the first few lines of the article and then add: “Read the full article on SciDev.Net” containing a link back to the original article.
If you want to also take images published in this story you will need to confirm with the original source if you're licensed to use them.
The easiest way to get the article on your site is to embed the code below.

For more information view our media page and republishing guidelines.

The full article is available here as HTML.

Press Ctrl-C to copy

<div class="article-wrap">
<div id="article-introduction">
<h1>Drug-resistant malaria threatens control programmes</h1>
<h4>By: Brendon Lee</h4>
</div>
<br />
<br />

<div id="article-body">
<p>[KUALA LUMPUR] South-East Asia could be the catalyst of a <a href="http://www.scidev.net/asia-pacific/health/malaria/">malaria</a> pandemic if drug-resistant malaria parasites are not brought under control, researchers warn.</p>
<p>A new study published in <a><em>The New England Journal of Medicine</em> </a>(31 July) revealed that malaria parasites discovered in the malaria-critical regions of Cambodia, Thailand and Vietnam displayed resistance to artemisinin, currently the most effective <a href="http://www.scidev.net/asia-pacific/health/medicine/">drug</a> against the mosquito-borne <a href="http://www.scidev.net/asia-pacific/health/disease/">disease</a>.</p>
<p>The study, which analysed blood samples from 1,241 malaria patients in 10 countries across Asia and Africa, has shown that <em>Plasmodium falciparum,</em> the parasite species responsible for the most common form of malaria, had developed resistance to artemisinin-based drugs and required extended treatment period and dosage.</p>
<p>Counterfeit or substandard anti-malarial drugs, and the unregulated use of artemisinin alone instead as part of a combination treatment, are some of the factors resulting in drug-resistant malaria parasites. </p>
<p>“The lack of regulation of antimalarial drug manufacture and prescription worldwide needs to be addressed. This could be particularly important in the not too distant future in African countries where numerous artemisinin-based combination therapies of variable quality are freely available,” according to the study’s lead author Elizabeth Ashley.</p>
<p>“One of the biggest challenges is that resistance always starts in South-East Asia where young working men in forested areas are most at risk,” Ashley noted.<br />
Standard antimalaria treatment often last for three days but the new mutated strain of <em>P. falciparum</em> (identified as the <em>kelch</em> 13 gene) requires treatment to be extended to six days. However, experts warn that this is only a temporary solution.</p>
<p>One trait of the mutated <em>P. falciparum</em> strain is that it has a higher chance of remaining in its host body after treatment. Hence, patients with slow-clearing infections are more likely to infect mosquitoes even though they do not display any symptoms of the disease.</p>
<p>According to the study, this is not the first time that malaria parasites have developed resistance to frontline drugs. Before artemisinin, chloroquine and sulphadoxine-pyrimethamine were used from the 1950s to the 1970s to suppress the parasite before it evolved and developed resistance.</p>
<p>“When there is drug pressure on a parasite or a bacterium, the weaker strains get killed while mutations develop in some that survive. Prolonged exposure to lower levels of the drug can lead to emergence of drug resistance. But the exact mechanism is really unknown,” explains Balbir Singh, director of the Malaria Research Centre at Universiti Malaysia Sarawak.</p>
<p>Currently, new antimalarial medicines are being developed but these still require several years of <a href="http://www.scidev.net/asia-pacific/enterprise/rd/">testing</a> before they can be distributed worldwide. Experts recommend reinforcing standard control measures and improving availability of early diagnosis and treatment with effective drugs.<br />
 <br />
<a href="http://dx.doi.org/10.1056/NEJMoa1314981">Link to full paper in <em>The New England Journal of Medicine</em></a></p>
<p><em>This article has been produced by SciDev.Net's South-East Asia & Pacific desk.</em> </p>

</div>
<div class="quick-links-wrapper">
<h3>You might also like</h3>
[related-articles]
</div>
<p>This article was originally published on <a href="https://www.scidev.net" target="_blank">SciDev.Net</a>. Read the <a href="https://www.scidev.net/asia-pacific/news/drug-resistant-malaria-threatens-control-programmes/" target="_blank">original article</a>.</p>
<script type="text/javascript">
(function(e,t,n,r,i,s,o){e["GoogleAnalyticsObject"]=i;e[i]=e[i]||function(){(e[i].q=e[i].q||[]).push(arguments)},e[i].l=1*new Date;s=t.createElement(n),o=t.getElementsByTagName(n)[0];s.async=1;s.src=r;o.parentNode.insertBefore(s,o)})(window,document,"script","//www.google-analytics.com/ga.js","ga");var _gaq=_gaq||[];var _gaq=_gaq||[];_gaq.push(["_setAccount","UA-3223906-8"],["_trackEvent","article interaction","republished","https://www.scidev.net/asia-pacific/news/drug-resistant-malaria-threatens-control-programmes/",null,true])
</script>
</div>

[KUALA LUMPUR] South-East Asia could be the catalyst of a malaria pandemic if drug-resistant malaria parasites are not brought under control, researchers warn.

A new study published in The New England Journal of Medicine (31 July) revealed that malaria parasites discovered in the malaria-critical regions of Cambodia, Thailand and Vietnam displayed resistance to artemisinin, currently the most effective drug against the mosquito-borne disease.

The study, which analysed blood samples from 1,241 malaria patients in 10 countries across Asia and Africa, has shown that Plasmodium falciparum, the parasite species responsible for the most common form of malaria, had developed resistance to artemisinin-based drugs and required extended treatment period and dosage.

Counterfeit or substandard anti-malarial drugs, and the unregulated use of artemisinin alone instead as part of a combination treatment, are some of the factors resulting in drug-resistant malaria parasites.

“The lack of regulation of antimalarial drug manufacture and prescription worldwide needs to be addressed. This could be particularly important in the not too distant future in African countries where numerous artemisinin-based combination therapies of variable quality are freely available,” according to the study’s lead author Elizabeth Ashley.

“One of the biggest challenges is that resistance always starts in South-East Asia where young working men in forested areas are most at risk,” Ashley noted.
Standard antimalaria treatment often last for three days but the new mutated strain of P. falciparum (identified as the kelch 13 gene) requires treatment to be extended to six days. However, experts warn that this is only a temporary solution.

One trait of the mutated P. falciparum strain is that it has a higher chance of remaining in its host body after treatment. Hence, patients with slow-clearing infections are more likely to infect mosquitoes even though they do not display any symptoms of the disease.

According to the study, this is not the first time that malaria parasites have developed resistance to frontline drugs. Before artemisinin, chloroquine and sulphadoxine-pyrimethamine were used from the 1950s to the 1970s to suppress the parasite before it evolved and developed resistance.

“When there is drug pressure on a parasite or a bacterium, the weaker strains get killed while mutations develop in some that survive. Prolonged exposure to lower levels of the drug can lead to emergence of drug resistance. But the exact mechanism is really unknown,” explains Balbir Singh, director of the Malaria Research Centre at Universiti Malaysia Sarawak.

Currently, new antimalarial medicines are being developed but these still require several years of testing before they can be distributed worldwide. Experts recommend reinforcing standard control measures and improving availability of early diagnosis and treatment with effective drugs.

Link to full paper in The New England Journal of Medicine

This article has been produced by SciDev.Net's South-East Asia & Pacific desk.