Plasmodium falciparum Spatial Analysis, Western Kenya Highlands

摘要

We carried out a population-based study to determinethe unbiased, age-specific Plasmodium falciparum preva-lence, asexual and sexual parasite density, and spatial dis-tribution to establish rates of infection at a site in westernKenya. Three cross-sectional surveys were carried out inwestern Kenya highlands. Blood samples were taken from1,388 persons from 6 months to 75 years of age. Parasiteprevalence and densities in the population decreased withage and distance from valley bottoms. Children from 1 to 4years of age had the highest parasite prevalence(38.8%–62.8%); in adults, prevalence declined to2.9%–24.1%. Malaria prevalence declined by an averageof 19% from July to December 2002 across age groups.These observations suggest that parasite transmission isintense at this altitude. Asexual parasite density indicatedclustering near major vector breeding habitats. Variability inseasonal prevalence indicates transmission instability andsusceptibility to epidemics