First Report of Fascioliasis of Ruminants in the Kharaa River Basin and Identification of Snail Hosts in Mongolia

Fascioliasis is a parasitic liver disease of mammals induced by liver flukes, Fasciola hepatica and Fasciola gigantica. Fasciola spp. rely on their definitive hosts, ruminants, and intermediate hosts, snails, to survive and can incidentally infect humans as definitive hosts. Ruminant (goat, sheep, and cattle) liver and fecal samples were collected from the Kharaa River Basin (KRB) of Mongolia during 2018–2020. A total of 807 adult liver flukes were found in livers of 18 goats, 21 sheep, and 1 cattle, with morphological identification of F. hepatica species. A total of 350 fecal samples selected using a “risk‐based surveillance” method in the KRB were tested for Fasciola spp. eggs with 50.3% (n = 151/350) positive. By animal, cattle had the highest percentage of Fasciola spp. positive samples of 70% (14/20), followed by sheep with 49.4% (87/176) and goats with 32.5% (50/154). Six‐hundred Lymnaied spp. snails, an intermediate host of Fasciola, were obtained from 18 locations in six provinces and one provincial municipality and morphometrically identified as Radix bactriana (94.8%) and Lymnaea stagnalis (5.2%). This study represents the first report of fascioliasis in indigenous animals in Mongolia and when paired with the detected prevalence of Fasciola spp. eggs in feces, suggests endemic circulation in the KRB region.