Abstract: [Objective] To clarify the species and distribution of Cryptosporidium in introduced Tibetan pigs in Tacheng Area. [Methods] A total of 506 fecal samples were collected from Tibetan pigs in three introduction farms in Tacheng Area, including 126 samples from pre-weaning piglets （<30 days old）, 126 from post-weaning piglets （31-90 days old）, 130 from fattening pigs （91-180 days old）, and 124 from adult pigs （>240 days old）. Detection and sequence analysis were performed using nested PCR to identify Cryptosporidium species, and phylogenetic analysis was conducted to examine their genetic characteristics. [Results] Based on the Cryptosporidium SSU rRNA gene locus, the overall positive rate of Cryptosporidium infection in Tibetan pigs across the three farms was 11.26% （57/506）. The positive rates in Farm A, Farm B and Farm C were 8.00% （16/200）, 10.00% （20/200） and 19.81% （21/106）, respectively, showing an extremely significant statistical difference （P<0.01）. The positive rates in pre-weaning and post-weaning piglets were 8.73% （11/126） and 36.51% （46/126）, respectively, while no Cryptosporidium infection was detected in fattening pigs and adult pigs, with an extremely significant statistical difference （P<0.01）. Sequence alignment identified two Cryptosporidium species, namely C. suis （n=36） and C. scrofarum （n=21）. These two species clustered in the same clades as C. suis and C. scrofarum isolates from different hosts, respectively, and formed distinct clades and subclusters from other Cryptosporidium species. [Conclusion] Cryptosporidium infection is prevalent in Tibetan pigs from the three introduction farms in Tacheng Area, with pre-weaning and post-weaning piglets being highly susceptible. The infecting species are C. suis and C. scrofarum, suggesting that enhanced environmental control and Cryptosporidium prevention measures should be implemented in introduction farms.

Key words: Tibetan pig, Cryptosporidium, species, identification, detection