Drawbacks of the artemisinins are their short half-lives, and the fact that the standard 3-day treatment course is often followed by recurrent bloodstream infection and illness within days or weeks. Consequently, artemisinins are often administered in combination with a longer-acting antimalarial drug such as mefloquine, lumefantrine, amodiaquine, or piperaquine. Combination therapy also reduces development of drug resistance. Increased development of drug resistance may occur when artemisinins are taken alone.
Dr. Ringwald, who directs the antimalarial drug resistance surveillance in the WHO Global Malaria Programme, discussed evidence of P. falciparum resistance to artemisinin in Western Cambodia, as manifest by marked prolongation of parasite clearance times. He also cited evidence of a smaller but nonetheless significant increase in clearance times on the western border of Thailand and adjacent Myanmar. "These drugs are designed to kill the parasites within 24 to 48 hours, but we're finding that it sometimes takes four or five days to kill them," he observed. "In some studies, half of the parasites are not killed within 72 hours after the beginning of the treatment, which indicates a growing resistance problem." While these data are indeed cause for serious concern, it should be noted that the vast majority of individuals are still being cured with current artemisinin-based treatments.
The WHO, with support from the Bill & Melinda Gates Foundation, and the United States Agency for International Development, and the Global Fund for AIDS, Tuberculosis, and Malaria (GFATM) has steadily intens
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