A population genetic analysis of the nematode Strongyloides stercoralis in Asia shows that human infection is not a zoonosis from dogs
- Yuchen Liu
- A. H. M. Raihan Sarker
- Banchob Sripa
- Sirikachorn Tangkawattana
- Virak Khieu
- William Nevin
- Steve Paterson
- Mark Viney
2025-07-15
Gut nematode worms are important parasites of people and other animals. The parasitic nematode Strongyloides stercoralis infects an estimated 600 million people worldwide and is one of the soil-transmitted helminthiases, a WHO-defined neglected tropical disease. It has long been suggested that human S. stercoralis infection may be a zoonosis from dogs. We investigated this by whole genome sequence analysis of S. stercoralis from sympatric human and dog populations in Asia. We find that human- and dog-derived S. stercoralis have genetically distinct nuclear genomes, but we also find evidence of rare cross-infection. Analysis of the S. stercoralis mitochondrial genome reveals evidence of historical introgression between human- and dog-derived parasites. Based on these data, we suggest that S. stercoralis was originally a parasite of canids, that began to infect humans when people domesticated dogs, since when human- and dog-derived parasites have differentiated, but have not become separate species.