SINGLE-STRAND CONFORMATIONAL POLYMORPHISM ANALYSIS DIFFERENTIATES PLASMODIUM-FALCIPARUM TREATMENT FAILURES FROM RE-INFECTIONS

Paired primary and recrudescent Plasmodium falciparum isolates were co llected from treatment failures identified during the course of antima larial drug studies on the Thai-Cambodian border. Ten paired samples w ere subjected to PCR-restriction fragment length polymorphism (RFLP) a nd PCR-single-strand conformational polymorphism (PCR-SSCP) analysis o f the MSP-2 gene. PCR-SSCP analysis of paired samples demonstrated tha t each recrudescent isolate was identical to, or a subpopulation of, i ts matched primary isolate and was distinct from all unrelated isolate s. This method represents a field applicable method to distinguish re- infections from treatment failures when antimalarial drug studies are performed in malaria-endemic areas.