GENETIC-EVIDENCE THAT RI CHLOROQUINE RESISTANCE OF PLASMODIUM-FALCIPARUM IS CAUSED BY RECRUDESCENCE OF RESISTANT PARASITES

Isolates of Plasmondium falciparum from patients in a Sudanese village exhibiting RI resistance to chloroquine have been typed for allelic v ariants of 2 merozoite surface antigens, MSP1 and MSP2. Blood forms we re taken from each patient before chloroquine was administered, and af ter parasites had reappeared following treatment. Each patient was fou nd to be infected with genetically different parasites. However, in ea ch patient the parasites of the recrudescent infections possessed the same alleles of each gene as those of the primary infection. The resul ts show that the parasites which reappeared after chloroquine were a g enuine recrudescence of the primary forms, and not derived from a new infection.