Molecular evidence of Echinococcus canadensis (G6/G7) predominance in Mongolian livestock and its implications for control

Abstract

BACKGROUND: Cystic echinococcosis (CE), caused by Echinococcus granulosus sensu lato (E. granulosus s.l.), is a major zoonotic disease causing substantial health and economic losses, particularly in pastoral communities. WHO and WOAH recommend combining regular dog deworming with sheep vaccination (EG95) for control. However, genotype data are important for vaccination planning, as EG95 mainly targets G1/G3 in sheep and evidence of protection against other genotypes is limited. In Mongolia, molecular data from livestock, especially sheep, remain scarce despite the large sheep population. We therefore aimed to determine the genotype distribution of E. granulosus s.l. among livestock, particularly sheep, across Mongolia's endemic provinces. METHODS: From August to December 2024, we conducted an abattoir-based cross-sectional survey in four provinces (Umnugobi, Bayankhongor, Dundgobi, and Tuv). Sheep, goats, and camels were examined for hydatid cysts. DNA was extracted, the COX1 gene was amplified by PCR and sequenced using the Sanger method, and published diagnostic COX1 sites were used to refine G6/G7 assignments; phylogenetic and haplotype analyses were performed with regional reference data. RESULTS: Cysts were detected in 2.5% (115/4,578) of animals, and 0.31% (14/4,578) were molecularly confirmed as E. granulosus s.l. Among them, 93% (13/14; 10 sheep, 2 goats, 1 camel) were Echinococcus canadensis (G6/G7) and 7% (1/14; 1 sheep) were Echinococcus granulosus s.s. (G1/G3). Five COX1 haplotypes were identified: four E. canadensis haplotypes (H1-H4) and one E. granulosus s.s. haplotype (H5). Haplotypes H1-H3 were consistent with G6, whereas H4 was consistent with G7a. These haplotypes grouped with reference isolates from Mongolia and neighbouring countries, as well as from other endemic regions included in the network. CONCLUSIONS: This study strengthens evidence that E. granulosus s.l. infections in Mongolian livestock are predominantly caused by Echinococcus canadensis G6/G7 and shows, for the first time, that this taxon predominated among successfully genotyped isolates from sheep in the surveyed areas. These findings support genotype-informed surveillance for vaccination planning, particularly in mixed-genotype settings, while underscoring the importance of dog deworming and safe offal disposal. Our findings further clarify CE transmission patterns in Mongolia and the wider region, highlight the transboundary nature of CE, and support the need for coordinated cross-border surveillance and control.