Limited genetic diversity of Plasmodium falciparum in field isolates from Honduras

The genetic diversity displayed by Plasmodium falciparum field isolates, th e occurrence of variant forms of the parasite at different frequencies in d ifferent geographic areas, and the complexity of the infections represent m ajor obstacles for the development of effective malaria control measures. H owever, since most of the existing studies have been performed in regions w here P. falciparum transmission is high, little is known about the diversit y and complexity of parasite populations circulating in areas of low malari a endemicity. We investigated the extent of genetic polymorphism in P. falc iparum field isolates from Honduras, a region where its transmission is low and seasonal. Allelic diversity was analyzed in the highly polymorphic par asite genes encoding the merozoite surface proteins-1 (MSP-1) and -2 (MSP-2 ) and the glutamate-rich protein (GLURP) by the polymerase chain reaction. Gene polymorphism was also assessed in the EB200 region derived from the hi ghly size polymorphic Pf332 gene. Limited size polymorphism was detected in all genes analyzed, with four and three variants for the MSP-1 and MSP-2 a lleles, respectively, and two size variants for the GLURP and Pf332 genes. Moreover, based on the studied genetic markers, most infections consisted o f only a few genetically distinct parasite clones. These results suggest th at the P, falciparum parasite populations circulating in this region are ge netically homogeneous and point to an association between the extent of par asite genetic diversity and the intensity of malaria transmission.