Molecular Characterization of Giardia duodenalis and Enterocytozoon bieneusi Isolated from Tibetan Sheep and Tibetan Goats Under Natural Grazing Conditions in Tibet.

In the present study, fecal samples from a total of 620 Tibetan sheep and 260 Tibetan goats from six counties in Tibet were examined by nested PCR. The results showed that the overall infection rates of Giardia duodenalis and Enterocytozoon bieneusi were 0.8% (5/620) and 15% (93/620), respectively, in Tibetan sheep, and 0% (0/260) and 9.6% (25/260), respectively, in Tibetan goats. Based on sequence analysis of the SSU rRNA, tpi, bg, and gdh genes of G. duodenalis, only assemblage E was identified. Based on sequence analysis of the ribosomal internal transcriptional spacer (ITS) region of E. bieneusi, a total of 12 genotypes (three novel and nine known) were detected, and these clustered into two separate phylogenetic groups. Genotypes CHG19, EbpA, EbpC, H, PigEBITS5, and CTS3 clustered into Group 1 with high zoonotic potential, while genotypes BEB6, CHC8, CHG1, I, CTS1, and CTS2 fell within the host-specific Group 2. Ten genotypes were detected in Tibetan sheep, and two genotypes were found in Tibetan goats. The current study indicated that E. bieneusi infections are widespread among these livestock, and Tibetan goats may play an important role as a reservoir of zoonotic E. bieneusi genotypes.