The effect of various dosages of mefloquine hydrochloride (WR 142,490) and sulfadoxine-pyrimethamine in the suppression of malaria infections was studied in an area of northeastern Thailand highly endemic for both chloroquine-resistant Plasmodium falciparum and for P. vivax. Both preparations, in all regimens studied, were effective in greatly reducing the incidence of falciparum infections. Mefloquine was more active in preventing vivax parasitemia than sulfadoxine-pyrimethamine; however, this combination remains the commercially available regimen of choice where both parasites occur and P. falciparum is resistant to chloroquine.
Present address: 279th Station Hospital, APO New York 09185.
Present address: Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Washington, D.C. 20012.
Present address: Kabinburi Health Center, Prachinburi Province, Thailand.
Present address: Department of Epidemiology, U.S. Army Medical Component, Armed Forces Research Institute of Medical Science, Rajvithi Road, Bangkok 4, Thailand.