Plasmodium falciparum genetic diversity in western Kenya highlands.

The present study examined the genetic diversity and population structure of Plasmodium falciparum in western Kenya by analyzing the polymorphism of 12 microsatellite loci and two antigen loci. Malaria in highland areas is unstable and epidemic whereas malaria in lowland areas is endemic. Transmission intensity and malaria prevalence are substantially lower in the highlands than in the lowlands. Despite that the highland parasite populations exhibited reduced number of alleles, lower expected heterozygosity, and infection complexity in comparison to the surrounding lowland population, genetic diversity of the highland populations remained high in comparison to parasites from other meso-endemic regions. More than 70% of infections from western Kenya highland study sites were mixed genotype infections. Small but statistically significant genetic differentiation between highland and lowland populations was detected. These findings are discussed in the context of human travel and local transmission in the study area.