DISTRIBUTION OF SCHISTOSOME GENETIC DIVERSITY WITHIN NATURALLY INFECTED RATTUS-RATTUS DETECTED BY RAPD MARKERS

Random amplified polymorphic DNA markers (RAPD) were used to visualize the genetic diversity within and between infrapopulations of Schistos oma mansoni recovered from the natural vertebrate host, Rattus rattus, trapped at an insular Guadeloupean focus. Phenotypes were characteriz ed by the sex of the parasites and by 8 polymorphic markers generated by 3 primers. Among the 212 parasite individuals recovered from 10 inf ected rats, 78 genotypes were characterized. All the hosts naturally i nfected harboured multiple parasite genotypes with a maximum diversity of 28 genotypes/host. Phenotypic and genotypic diversity calculated b y Shannon-Wiener's indices and Lynch and Milligan's estimators respect ively is, on average, greater within than between hosts. Considering t he very low snail infection rates observed in this focus and the rapid turnover of the vertebrate hosts, our results suggest that the high m obility of the vertebrate host and/or plurimiracidial snail infections could be factors responsible for parasite genetic diversity within ho sts.