Seasonal Prevalence and Molecular Characterization of Cryptosporidium spp. in Dairy Cattle of Inner Mongolia, Northern China

Background: Cryptosporidium spp. are zoonotic pathogens that threaten animal husbandry and public health. Systematic data on the seasonal distribution of Cryptosporidium in dairy cattle of Inner Mongolia, China, are lacking. This study investigated the effects of seasonal variation on the prevalence and genetic diversity of Cryptosporidium in dairy cattle. During the four seasons of 2024, 505 fecal samples were collected from an intensive dairy farm in Hohhot, Inner Mongolia. Cryptosporidium species were identified using nested PCR targeting the SSU rRNA gene, and C. parvum subtypes were determined by gp60 sequencing. Results: The overall prevalence was 39.21% (198/505), with significant seasonal variation (spring 36.57%, summer 16.22%, autumn 45.38%, winter 55.38%; χ2 = 41.37, p < 0.001). No significant differences were observed among age groups or between diarrheic (40.48%) and nondiarrheic (38.58%) cattle. Five species were identified: C. andersoni (46.46%), C. bovis (23.74%), C. ryanae (16.16%), C. parvum (12.12%), and C. suis (1.52%). Two C. parvum subtypes were detected: IIdA20G1 (79.17%) and IIdA19G1 (20.83%). Conclusions: This is the first systematic investigation of the seasonal distribution of Cryptosporidium in cattle in Inner Mongolia and the first detection of C. suis in Chinese cattle. Both C. parvum subtypes detected are zoonotic, highlighting the need for public health surveillance.