Genetic diversity of Plasmodium falciparum and its relationship to parasite density in an area with different malaria endemicities in West Uganda

Field populations of Plasmodium falciparum can be effectively genotyped by PCR-amplification of selected fragments of the Merozoite Surface Proteins 1 and 2 (MSP1 and MSP2). Genetic diversity of P. falciparum populations in a reas with different transmission levels (holo- vs. mesoendemic) was investi gated in Kabarole District, West Uganda. 225 samples positive for P. falcip arum were analysed by amplification of polymorphic regions and classified a ccording to prevalence of allelic families. A large number of alleles was d etected for each locus: 22 for MSPI block 2 and 24 for MSP2 and, 175 (78%) of MSP1 alleles and 143 (64%) of MSP2 showed multiple infections within a r ange of 2-8 clones. Significant differences between holoendemic and mesoend emic areas in regards of population structure and number of multiclonal inf ections of P. falciparum were not apparent. However, a significant correlat ion between parasite density, selected MSP2 loci and differences between pa rasite density in monoclonal vs. multiclonal infections occurred. Multiplic ity of infection was age-dependent.