Molecular epidemiology of malaria in Yaounde, Cameroon. VII. Analysis of recrudescence and reinfection in patients with uncomplicated falciparum malaria

In an endemic area where malaria transmission is intense and continuous, re appearance of asexual parasites may be ascribed to either recrudescence or reinfection. To distinguish between recrudescence and reinfection after ora l treatment with chloroquine, amodiaquine, pyronaridine, sulfadoxine-pyrime thamine, halofantrine, or artesunate, three polymorphic markers (circumspor ozoite protein, merozoite surface antigens 1 and 2) from pre-treatment and post-treatment samples were amplified by the polymerase chain reaction, and the in vitro response to chloroquine was determined for comparison. Of 52 paired samples, 22 (42%) were reinfections. Recrudescence occurred more fre quently on or before Day 14 (22 of 30 cases, 73%). Except for one case, all reinfections were observed beyond Day 14. The phenotype determination was not sufficiently precise to distinguish between recrudescence and reinfecti on. Our results suggest that beyond Day 14 land until Day 42), recrudescenc e and reinfection cannot be distinguished at our study site unless molecula r techniques are used and that some results derived from the polymerase cha in reaction need to be compared with the microscopic examination of thick b lood smear to exclude gametocyte carriers without asexual parasites after t reatment.