Genetic diversity of a population of Schistosoma haematobium derived from schoolchildren in east central Zimbabwe

To characterize the extent of genetic diversity of Schistosoma haematobium within and among its definitive host (intra- and interhost parasite diversi ty), 133 individual isolates from 25 infected schoolchildren were compared using randomly amplified polymorphic DNA markers. With 4 primers. 53 unambi guous loci were identified, and of these, 22 were polymorphic. Mean heteroz ygosity in the population was 0.116 +/- 0.043. Analysis of molecular varian ce showed the majority of variance occurred within, rather than between, ho sts. Frequencies of certain alleles segregated the parasite population into 13 distinct clusters of associated genotypes, with 4 of these first appear ing 10 mo after the initial survey. Considering the level of diversity with in this limited geographical area and the possibility of rapid turnover of genotypes, parasite variance may impact acquired immunity and clinical outc ome of the infection.