RII and RIII type resistance of Plasmodium falciparum to combination of mefloquine and sulfadoxine/pyrimethamine in Indonesia.

2 of 36 Plasmodium falciparum infections were resistant (RII and RIII) in vivo to the combination of mefloquine (M) and sulfadoxine-pyrimethamine (SP) in Jayapura, Irian Jaya, Indonesia. Expected absorption of mefloquine and pyrimethamine was confirmed in the one resistant patient from whom sera were available, and the isolate from this patient was sensitive to mefloquine in vitro. Only 2 of 41 infections studied at the same time were resistant in vivo to SP. There was no clinical advantage of MSP compared with SP, and limited observations suggest there may be a disadvantage.