Reduced In-vitro Susceptibility to Mefloquine in West African Isolates of Plasmodium Falciparum

West African isolates of Plasmodium falciparum were more susceptible to chloroquine but less susceptible to mefloquine than were Southeast Asian isolates. The West African isolates were more sensitive to halofantrine than to mefloquine. Since neither mefloquine nor halofantrine has been used in West Africa, the findings suggest that P falciparum may be inherently resistant to mefloquine and that mefloquine should be introduced cautiously to West Africa. Moreover, halofantrine may be of greater value than mefloquine for controlling multidrug-resistant falciparum malaria in West Africa.