Plasmodium falciparum: a comparative analysis of the genetic diversity in malaria-mesoendemic areas of Brazil and Madagascar

For a better definition of the polymorphic features of Plasmodium falciparu m parasite populations, the polymerase chain reaction (PCR) typing techniqu e was used to investigate the genetic diversity and complexity of parasites harbored by acute P. falciparum carriers from three yet unexplored malaria -mesoendemic areas with different transmission levels: two localities in no rthwestern Brazil (Ariquemes and Porto Velho) and a village in Madagascar ( Ankazobe). A total of 89 DNA samples were analyzed by amplification of poly morphic domains from genes encoding merozoite surface antigens 1 and 2 (MSP -1, MSP-2) and thrombospondin-related anonymous protein (TRAP) and by hybri dization with allelic-family-specific probes or random-fragment-length poly morphism (RFLP). In all three localities, extensive polymorphism was observ ed for each marker, but the MSP-2 central repeat was the most diverse one. Similar levels of genetic diversity, allelic frequency, and infection compl exity were observed in the two Brazilian localities, although the isolates had been sampled at 2-year intervals, suggesting the stability of the infec ting parasite populations presenting in these regions of the Brazilian Amaz on. Unexpectedly, although the entomologic inoculation rate was at least 3 times lower in Ankazobe than in the Brazilian areas, Malagasi samples appea red more complex than the Brazilian ones. The implications of these data wi th regard to parasite population-dynamics studies are discussed.