Why we mustn't let malaria defences crumble

Why we mustn't let malaria defences crumble
 22 June 2009 by Martin de Smet New Scientist

Our best anti-malaria drug could be rendered useless by the emergence of resistance (Image: Lehtikuva OY/Rex Features)
REPORTS from Cambodia that malaria is developing resistance to artemisinins have set alarm bells ringing. Artemisinins are the best drugs we have to treat malaria, and until recently there have been no reports of resistance.
Containing resistance in Cambodia is an urgent priority. But sadly, the factors that led to it emerging are all too common in countries where malaria is endemic. Unless we stamp them out there is a risk of artemisinin drugs becoming useless.
To prevent the parasite evolving resistance, artemisinins must not be used alone but with a companion drug such as amodiaquine. Combination pills are available to ensure that this happens. But in many countries, including Cambodia, artemisinins are widely available as a monotherapy. Patients are also prescribed co-blister packs, in which the two drugs are packaged together rather than combined in one pill. There is therefore a risk that patients will take only one drug. We clearly need exclusive use of combination therapies and international commitment to subsidise only combination drugs.
There is another problem. In many countries during transmission season, anyone presenting to a clinic with fever is treated as a malaria patient. In fact no more than 70 per cent of these patients will have malaria, and sometimes as few as 30 per cent. The millions treated unnecessarily are a potential source of resistance: if they become infected shortly after treatment, the malaria parasite is exposed to sub-therapeutic doses of drugs still in the bloodstream, which allows resistance to develop. Use of rapid diagnostic tests or microscopy to confirm malaria is therefore imperative.