MOLECULAR ANALYSIS OF RECRUDESCENT PARASITES IN A PLASMODIUM-FALCIPARUM DRUG EFFICACY TRIAL IN GABON

Recrudescent Plasmodium falciparum parasites were sampled from 108 chi ldren taking part in a drug efficacy trial in Gabon. A finger prick bl ood sample was taken from each child before treatment, and a post-trea tment sample taken of the recrudescent parasites. Sample deoxyribonucl eic acid was amplified by the polymerase chain reaction using primers specific to the P. falciparum antigen genes MSP-1, MSP-2 and GLURP. Se venty-seven children had identical parasites in their pre-and post-tre atment samples, indicating genuine recrudescences of resistant parasit es. Fourteen children had completely different parasites in their pre- and post-treatment samples, indicating either a fresh infection from a mosquito or growth of a population of parasites not detected in the p re-treatment sample, perhaps due to sequestration. The remaining 17 ch ildren had a mixture of pre-treatment and new parasites in their post- treatment samples. This study demonstrated the use of polymorphic mark ers to confirm whether parasites in patients with clinical recrudescen ces after drug treatment are genuinely resistant.