DISTINGUISHING PLASMODIUM-FALCIPARUM TREATMENT FAILURES FROM REINFECTIONS BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM AND POLYMERASE CHAIN-REACTION GENOTYPING

The inability to distinguish recrudescent Plasmodium falciparum infect ions (treatment failures) from reinfections (new infections) is an imp ortant impediment to the evaluation of antimalarial treatment regimens . Ten paired primary and recrudescent isolates collected near the Thai -Cambodian border were analyzed by restriction fragment length polymor phism (RFLP) and by polymerase chain reaction (PCR) genotyping of the genes encoding the following proteins: circumsporozite (CS) protein, e rythrocyte binding antigen (EBA)-175 ring-infected erythrocyte surface antigen (RESA), merozoite surface protein-1 (MSP-1), and MSP-2. Both methods demonstrated that the fingerprint pattern of each recrudescent isolate was identical to or was contained within the pattern of the p rimary isolate. Each recrudescent isolate was unique when compared wit h the other nine primary isolates. Typing by PCR was more sensitive fo r the detection of multiclone infections and could be performed with s mall volumes of whole blood. The PCR genotyping could be a practical m ethod for distinguishing a recrudescent from a new infection when trea tment studies are conducted in areas with active malaria transmission.