Molecular identification of schistosome intermediate hosts: case studies of Bulinus forskalii group species (Gastropoda : Planorbidae) from Central and East Africa

African freshwater snails of the genus Bullinus acr as intermediate hosts f or schistosomes, trematode parasites responsible for medical and veterinary forms of schitosomiasis. The relationship between these snails and their p arasites is an intricate one, with particular species of snail susceptible to infection only by certain species of schistosome. In common with other s elf-fertile hermaphrodite gastropods, Bulinus consists of a number of close ly related species complexes with restricted gene flow between populations of each taxon. Consequently, despite their medical and veterinary importanc e as intermediate hosts, unambiguous identification and differentiation of planorbid snails such as these remains problematic, often confounding attem pts to define the distribution and evolutionary relationships of conchologi cally similar taxa. Here we consider how morphological methods of discrimin ation can be used in conjunction with molecular based approaches to improve snail identification. thereby achieving a better understanding of the epid emiology of schistosomiasis. Data are presented from Central and East. Afri can taxa which illustrate how PCR-bared methods have begun to be used in co mbination with traditional analyses in an integrated approach to characteri ze the genus Bulinus, specifically the B. forskalii species group. particul ar emphasis is given to the analyses of Random Amplified Polymorphic DNA (R APDs) and die mitochondrial gene cytochrome oxidase I (COI). (C) 1999 The L innean Society of London.