SREL Reprint #2164

Neotropical schistosomiasis: African affinities of the host snail Biomphalaria glabrata (Gastropoda: Planorbidae)

David S. Woodruff1 and Margaret Mulvey2

1Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA, 92093-0116, USA
2Savannah River Ecology Laboratory, University of Georgia, Drawer E,, Aiken, SC 29802, USA

Abstract: Schistosoma mansoni, the blood fluke responsible for human intestinal schistosomiasis in the Neotropics, was imported repeatedly with African slaves during the period 1500-1800. This trematode, and its intermediate host snails of the genus Biomphalaria, are widely distributed across Africa and the disease is thought to have quickly become established in South America and the West Indies because of the presence of an endemic susceptible congener, B. glabrata. We compared B. glabrata with four other Neotropical and three African species of Biomphalaria using 20 allozyme loci and found that it is phonetically and phylogenetically more like the African species; both parasite and American host snail are apparently of historically or geologically recent African origin. Furthermore, genetic distances, cladistic analyses and fossil data suggest the African Biomphalaria species may themselves have evolved from Neotropical founders following an initial trans-Atlantic dispersal in the reverse direction 2.3-4.5 Mya. Interpretation of existing patterns remains problematic as few African snails have been characterized genetically and both B. pfeifferi appear to comprise several cryptic species.

Keywords: allozymes; biogeography; dispersal; Gastropoda; introduced species; phylogeny; phylogeography; Schistosoma mansoni

SREL Reprint #2164

Woodruff, D.S. and M. Mulvey. 1997. Neotropical schistomiasis: African affinities of the host snail Biomphalaria glabrata (Gastropoda: Planorbidae). Biological Journal of the Linnean Society 60:505-516.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).