Guinea worm disease is usually caught by drinking water containing water fleas that carry the parasite larvae.
The worms mate and grow inside the body, and after 10-14 months the one-metre-long adult worm emerges, usually from the arms or legs, to shed its larvae back into water.
The parasite causes disability and trauma in some of the world’s poorest communities in Chad, Ethiopia, Mali and South Sudan.
Eradication programmes have cut human cases of Guinea worm from millions a year in the 1980s to just 27 in 2020.
Guinea worm would be only the second human disease to be eradicated, after smallpox.
Just as eradication looked imminent, it has emerged that domestic dogs are also harbouring the parasite.
Targeted surveillance showed that in 2020, 93% of Guinea worms detected worldwide were in dogs in Chad, in central Africa.
Research by the University of Exeter, published today in Current Biology, has revealed a new pathway for transmission – by dogs eating fish that carry the parasite larvae. This means dogs maintain the parasite’s life-cycle and humans can still catch the disease.
Read more at University of Exeter