DISTRIBUTION AND GENETIC DIVERSITY OF SCHISTOSOMA-HAEMATOBIUM WITHIN ITS BULINID INTERMEDIATE HOSTS IN MALI

Random amplified polymorphic DKA (RAPD) markers were used to assess di stribution and genetic diversity of Schistosoma haematobium population s within their bulinid intermediate hosts in Mall. Naturally infected snails (Bulinus truncatus and B. globosus) were collected at four site s in the Bamako district. S. haematobium cercariae from single snails were used to infect mice and genotypes of the resultant adult worms we re characterized using RAPD markers. Diversity indices were calculated at the scale of one snail, both within and among sites. One third of the molluscs harboured multiple miracidial infections (the maximum num ber equal to five) with slightly overdispersed distributions in three sites and a random distribution at one site. Similarity indices reveal ed significantly less variation among populations compared to within p opulations, indicative of the absence of distinct S. haematobium popul ations within the Bamako district. RAPD markers represent an accurate tool for determining genetic diversity and amount of gene flow among p arasite populations contained within different individual snails and a mong intermediate host populations. (C) 1997 Elsevier Science B.V.