Population genetic analysis of Chadian Guinea worms reveals that human and non-human hosts share common parasite populations

We present the first extensive population genetic data for Guinea worm, inves tigating mitochondrial and microsatellite variation in adult female worms from both human and non-human hosts in the four endemic countries to elucidate the origins of Chad’s current outbreak and possible host-specific differences between parasites. Genetic diversity of Chadian Guinea worms was co nsiderably higher than that of the other three countries, even after controlling for sample size through rarefaction, and demographic analyses are consistent with a large, stable parasite population. Genealogical analyses eliminate the other three countries as possible sources of parasite reintroduc tion into Chad, and sequence divergence and distribution of genetic variation provide no evidence that parasites in human and non-human hosts are separate species or maintain isolated transmission cycles. Both among and within countries, geographic origin appears to have more influence on parasite p opulation structure than host species. Guinea worm infection in non-human hosts has been occasionally reported throughout the history of the disease, particularly when elimination programs appear to be reaching their end goals. However, no previous reports have evaluated molecular support of the par asite species identity. Our data confirm that Guinea worms collected from non-human hosts in the remaining endemic countries of Africa areDracunculus medinensis and that the same population of worms infects both humans...
Source: PLoS Neglected Tropical Diseases - Category: Tropical Medicine Authors: Source Type: research