Seasonal population dynamics and dietary switching of Vulpes spp. amplify Echinococcus spp. transmission in the Eastern Tibetan plateau: implications for wildlife-mediated zoonotic risks.

Background: Echinococcosis, a severe zoonosis caused by Echinococcus spp., poses a significant public health challenge in the eastern Tibetan Plateau. This study aimed to investigate the interplay among seasonal shifts in definitive host ecology (Vulpes ferrilata and V. vulpes), dietary shifts, and infections with E. multilocularis and E. shiquicus within a high-altitude ecosystem.

Results: Statistical analyses revealed that V. ferrilata dominated the local fox community (90.48%, n = 441), with the highest number of samples collected in fall (46.49%), likely linked to dispersal behaviors after the breeding season. Dietary analysis showed a strong predation preference, with lagomorphs (primarily Ochotona curzoniae) accounting for 79.57% (74/93) of the diet. There was also a significant seasonal shift: among Vulpes spp., the consumption of rodents increased to 26.92% in the fall from being absent in the summer. This dietary diversification correlated with seasonal resource scarcity, driving foxes to exploit alternative prey. The infection rates of Echinococcus in V. ferrilata displayed the U-shaped seasonal patterns. Specifically, the infections of E. multilocularis peaked in the fall (12.29%), which was significantly higher than that in the spring (2.38%) and summer (0.74%), showing a positive correlation with the predation proportion on rodents (R = 0.61, P = 0.036). Meanwhile, E. shiquicus infections peaked in fall (29.32%) and dipped in summer (17.65%), but showed no dietary association, suggesting alternative transmission factors.

Conclusions: These findings highlight that seasonal prey switching amplifies E. multilocularis transmission by increasing fox exposure to infected voles. The competitive pressure during resource-limited periods drives a shift in the predation strategies of the definitive hosts, inadvertently exacerbating the zoonotic risks of alveolar echinococcosis. The study underscores the importance of seasonally targeted interventions, providing a scientific foundation for alleviating echinococcosis in high-altitude regions under climate change pressures.