Epidemiological detection and risk factor association of bovine viral diarrhea in Tibetan yaks

Bovine viral diarrhea virus (BVDV) is an important pathogen causing substantial economic losses in cattle worldwide, yet its epidemiology in Tibetan yaks remains poorly understood, limiting insight into viral transmission in high‑altitude production systems. This study aimed to determine the seroprevalence of BVDV in Tibetan yaks and to identify major host‑related risk factors. Using a commercial ELISA kit, we tested 920 serum samples collected from eight cities in Nagqu, Lhasa, and Shigatse, and applied chi‑square tests together with multivariable logistic regression to assess associations between serostatus and epidemiological variables. The overall seroprevalence was 5.11% (95% CI: 3.78-6.74%), indicating relatively limited viral circulation compared with other yak‑raising regions of China. Age was the only significant predictor of infection, with yaks aged three years or younger having 2.36‑fold higher odds of seropositivity than older animals (95% CI: 1.20-5.08; p = 0.02). These findings demonstrate that young yaks represent the most vulnerable group and suggest that BVDV, although present, circulates at a low level in the surveyed regions. Overall, this study provides essential baseline data on BVDV infection in Tibetan yak populations and highlights the need for age‑focused preventive strategies, particularly improved protection of juvenile animals, in future regional control programs.