Bloomberg:Drug-Resistant Malaria in Thailand Fuels Global Spread...

[The Sculptor]

Drug-Resistant Malaria in Thailand Fuels Global Spread Concern 2012-04-05 18:00:00.0 GMT

 

By Simeon Bennett April 5

 

(Bloomberg) -- Drug-resistant malaria has appeared in western Thailand, researchers reported in a study that adds to concerns the parasite may spread further and render the best treatments useless. Among 3,202 people along Thailand’s border with Myanmar treated with the drug, artemisinin, parasite clearance half lives -- a measure of the therapy’s effectiveness — lengthened to an average to 3.7 hours in 2010 from 2.6 hours in 2001, researchers from Mahidol University in Bangkok wrote in The Lancet journal today. The slower clearance times signal that the bugs are developing resistance, though the clearance isn’t as slow as it is in western Cambodia, where the drug-resistant form was first confirmed. The trend suggests that efforts to contain the strain to Cambodia may need to be reviewed, and fuels concern that it may spread to Africa, which accounts for most cases. “Containment efforts should no longer be restricted to Cambodia,” Anne-Catrin Uhlemann and David Fidock, from Columbia University in New York, wrote in an editorial accompanying the study. “Resistance could be starting to emerge in various parts of southeast Asia, including Myanmar, where the malaria burden is high and public health infrastructure is weak.” The proportion of cases that took more than 6.2 hours to clear jumped to 20 percent in 2010, from 0.6 percent in 2001, the authors wrote. It’s likely the resistance in western Thailand has developed independently of the strain in Cambodia, and hasn’t spread from there, they wrote.

Containing the Strain The World Health Organization has been working, with funds from the Gates Foundation, to contain artemisinin-resistant malaria to Cambodia. The Lancet study was funded by The Wellcome Trust and the U.S. National Institutes of Health. Malaria strikes about 216 million people each year and kills about 655,000, mostly children under 5 in Africa, according to the Geneva-based WHO.

The disease is caused by a tiny parasite called Plasmodium that’s carried in the saliva of female mosquitoes. When they bite, the parasites travel to the liver, where they multiply before spilling into the bloodstream. There they invade red blood cells, leading to fever, chills, nausea and diarrhea. Left unchecked, they cause the cells to stick to the walls of capillaries, slowing blood flow. Sufferers can die from organ failure.

Sharp Shock Artemisinin-based drugs give malaria a short, sharp shock, clearing most of the parasites within hours. Their main drawback is they don’t last long in the body, so are usually paired with another less powerful but longer-acting drug that mops up the stragglers. “Antimalarial control efforts are vitally dependent on artemisinin combination treatments,” Uhlemann and Fidock wrote in the editorial. “Should these regimens fail, no other drugs are ready for deployment, and drug development efforts are not expected to yield new antimalarials until the end of this decade.”

Novartis AG developed a new class of experimental malaria drugs, called imidazolopiperazines, that attack the parasites earlier than currently approved therapies, according to a study published online by the journal Science in November. GlaxoSmithKline Plc, the U.K.’s biggest drugmaker, is developing a product that would be the first malaria vaccine if approved. The shot, known as RTS,S, safely reduced illness in African infants by more than half in a study, the London-based company said in October.

Edited April 5, 2012 by The Sculptor