A chemical ranked with the second-string players in the world's continuing contest with malaria has reappeared as a new drug, apparently capable of preventing the disease. Paired with an older, standard drug, it provides protection with an unusually small risk of drug resistance. In a study in the September American Journal of Tropical Medicine and Hygiene , researchers at Johns Hopkins describe how the drug atovaquone was 100 percent effective in keeping volunteers bitten by mosquitoes carrying Plasmodium falciparum, the parasite responsible for fatal forms of malaria, from developing the disease.
Drug resistance occurs when a few parasites in their human hosts manage to survive therapy.
The parasites then prosper and dominate as causes of disease. Malaria researchers report that drug-resistant forms of the parasite infest 80 percent of countries with the disease. With current preventives, travelers must take them weeks after a visit to a malaria-carrying country. All were then exposed to and bitten by five mosquitoes heavily infected with the malaria parasite. We carefully screened for volunteers who knew what was going on, who understood their consent papers, who knew the risks they were taking and who realized the importance of being 100 percent compliant in their follow-up visits.