REVEALING SCHISTOSOME DIVERSITY IN SOUTH AMERICA (PATAGONIA): THE ENDEMIC

BRANT S. V.; FLORES V.; LOCKER E. S,

Richmond Virgnina

Congreso; 87th Annual Meeting,; 2012

American Society of Parasitologists

Our current knowledge of the trematode family Schistosomatidae from South America is rudimentary in all respects: the identity and diversity of species present, their life cycles, patterns of host use, and evolutionary affinities. For the past several decades, many of the reports from South America relating to schistosomes (other than Schistosoma) detailed outbreaks of cercarial dermatitis. These studies linked the outbreaks not only to the snail host Chilina, but also to other families of snails including those from marine waters. The diversity of snails contributing to outbreaks of cercarial dermatitis suggests that there is a wealth of diversity to be discovered in Argentina, and South America. We collected freshwater snails of the monotypic genus Chilina (Chilinidae) from Argentina in search of schistosome infections. Chilinidae is unusual among the freshwater pulmonate (Hygrophila) families for being confined to a single continent. We collected six known species of Chilina (720 individuals) from 14 localities. From these samples we found three distinct groups of schistosomes based both on morphology of the cercariae and the genetic analyses of three genes (one mitochondrial and two nuclear). Interestingly, we found that each Chilina species we examined hosted at least one schistosome species. Coupling this new information with our current genetic dataset of schistosomes,  phylogenetic analyses revealed that the three borne schistosome species do not group with any recognized clade, but represent lineages unique to South America and Chilina spp. While there has been previous work on schistosomes in South America, currently there are no reports linking genetic diversity to morphology, especially for the cercariae, which are often difficult to identify to genus and certainly to species by morphology alone. The Framework incorporating both morphological and molecular data that is emerging for Nearctic and Palearctic avian schistosomes will be particularly useful for unraveling the complex of schistosome species that likely exploits the diverse avian fauna of South America.