| australia | | trichostrongylus retortaeformis | species | 4 | 0 |
| australia | western australia | trichostrongylus retortaeformis | species | 0 | 2 |
| finland | central finland region | trichostrongylus retortaeformis | species | 0 | 1 |
| spain | canary islands | trichostrongylus retortaeformis | species | 0 | 1 |
| united kingdom | england | trichostrongylus retortaeformis | species | 0 | 1 |
| united kingdom | scotland | trichostrongylus retortaeformis | species | 0 | 8 |