C Durrant7; N Holroyd7; E A Thiele5; 6; S R Doyle7; G Sallé2; A Tracey7; G Sankaranaranayan7; M Lotkowska7; E Ruiz-Tiben3; 4; M Eberhard1; M Berriman7; J A Cotton7;
1 Centers for Disease Control and Prevention, United States; 2 INRA, France; 3 The Carter Center, UK; 4 The Carter Center, United States; 5 Vassar College, UK; 6 Vassar College, United States; 7 Wellcome Trust Sanger Institute, UK
DiscussionHistorically, Guinea worm - Dracunculus medinensis - was one of the major parasites of humans. It is also one of the best known, and has been known since antiquity. Today, Guinea worm is on the brink of eradication, as control efforts have reduced the burden of disease from millions of infections per year in the 1980s to only 30 human cases reported globally last year. Despite this enormous success of the control efforts to date, one major complication has arisen, as last year there were 817 dogs in Chad reported to be infected with this previously apparently anthroponotic parasite. In an effort to shed light on the peculiar epidemiology of Guinea worm in Chad, we have generated a reference genome for Dracunculus medinensis and a related species, and genomic sequence data for worms from dog and human infection. We show that the same population of worms are causing both infections, can confirm transmission between host species and detect signs of a population bottleneck due to the eradication efforts. The diversity of worms in Chad appears to exclude the possibility that there were no, or very few, worms present in the country during a 10-year absence of reported cases.