Epidemiological study of gastrointestinal parasites in yaks (Bos grunniens) from the Ganzi Tibetan autonomous prefecture, Sichuan Province, China

Yaks (Bos grunniens) serve as an indispensable economic pillar of the Qinghai-Tibet Plateau (QTP) of China, especially in the Ganzi Tibetan Autonomous Prefecture (GTAP), where they provide milk, meat, and economic security for local communities. Gastrointestinal parasites (GIP) are common in yaks and pose a significant threat to their health and productivity. This study investigated the prevalence and intensity of the yak GIP in ten breeding regions of GTAP in western Sichuan Province, China, from February to April 2024. A total of 326 yak fecal samples were collected for the qualitative and quantitative analyses. Overall, 173 samples were positive for one or multiple parasite taxa, yielding an overall infection rate of 53.07% (95% CI: 47.64%–58.48%). The identified parasites included strongyle-type species (42.94%; 95% CI: 37.57%–48.31%), Toxocara vitulorum (9.82%; 95% CI: 6.59%–13.05%), Nematodirus spp. (1.23%; 95% CI: 0.48%–3.11%), and Eimeria spp. (0.31%; 95% CI: 0.05%–1.71%). The strongyle-type species was the most predominant group, with a peak infection prevalence in high-altitude regions (49.65%; 95% CI: 41.45%–57.85%), suggesting that the altitude might modulate the parasite dynamics, possibly driven by the interplay of climatic envelopes and host physiological stress. Taken together, this study provided the first comprehensive overview of GIP prevalence and taxa distribution of yaks in the Western Sichuan Plateau, highlighting the need for targeted parasite control strategies and increased awareness among yak farmers to improve animal health and productivity.