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

Following almost 10 years of no reported cases, Guinea worm disease (GWD
or dracunculiasis) reemerged in Chad in 2010 with peculiar epidemiological
patterns and unprecedented prevalence of infection among non-human hosts,
particularly domestic dogs. Since 2014, animal infections with Guinea
worms have also been observed in the other three countries with endemic
transmission (Ethiopia, Mali, and South Sudan), causing concern and
generating interest in the parasites’ true taxonomic identity and
population genetics. We present the first extensive population genetic
data for Guinea worm, investigating 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 considerably 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 reintroduction 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 population
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 parasite species identity. Our data confirm that Guinea worms
collected from non-human hosts in the remaining endemic countries of
Africa are Dracunculus medinensis and that the same population of worms
infects both humans and dogs in Chad. Our genetic data and the
epidemiological evidence suggest that transmission in the Chadian context
is currently being maintained by canine hosts.