Advances in chemotherapy and prophylaxis of malaria

Abstract

Plasmodium falciparum, the most dangerous of the human malaria parasites, has now developed resistance to all the widely available antimalarial drugs. Few areas are now unaffected by chloroquine resistance, and resistance to the other drugs is spreading. Chloroquine resistance in Plasmodium vivax has now been confirmed in New Guinea. Fortunately quinine, usually combined with tetracycline, is still reliable, and mefloquine is effective in most areas, although high-grade resistance has now been reported in southeast Asia. The incidence of neuropsychiatric reactions to mefloquine in prophylaxis (≃ 1:10,000) is much lower than that in treatment (≃ 1:1700), and may be no different than that with chloroquine. For treatment of resistant infections, halofantrine is a well-tolerated alternative. The dihydrofolate reductase inhibitors (usually combined with a sulfonamide or sulfone) are effective in some areas, and recent studies of the molecular mechanisms of resistance have shown that resistance to one compound does not necessarily confer resistance to another. The most important recent development has been the introduction and evaluation in several countries of the Chinese drugs derived from qinghaosu (artemisinin). These compounds are the most rapidly acting of all antimalarials, and they appear to be safe.