Molecular characterization of Cryptosporidium spp. and Giardia duodenalis in pet dogs in Xinjiang, China.

Cryptosporidium spp. and Giardia duodenalis are opportunistic zoonotic protozoa transmitted through several routes. In this study, a total of 604 fecal samples were collected from pet dogs in Xinjiang, China to detect the presence of Cryptosporidium spp. and G. duodenalis by PCR amplification of the small subunit (SSU) rRNA gene. The incidence rate of Cryptosporidium spp. or G. duodenalis was 5.3% (32/604). Among the collection sites, a higher number of Cryptosporidium spp. or G. duodenalis positive dogs were detected in Hotan (9.9%, 21/213) and Shihezi (9.8%, 4/41) were higher than those in Aksu (4.5%, 1/22), Urumqi (2.1%, 4/191), and Korla (1.5%, 2/137). Among the sources, dogs in pet shops (7.4%, 19/256) showed a significantly higher incidence rate than those in pet hospitals (3.0%, 4/134) and pet kennels (2.3%, 5/214). When the data were examined by age, dogs < 1 year of age (6.1%, 28/459) were more likely to be infected by Cryptosporidium spp. or G. duodenalis than older (≥ 1 year) dogs (2.8%, 4/145). No significant differences were observed when animals were grouped by sex (5.0%, 14/278 for males; 5.5%, 18/326 for females). Sequence analysis revealed that the Cryptosporidium spp. (n = 10) in dogs were identified as C. canis. The G. duodenalis detected belonged to assemblages A (n = 1), C (n = 14), and D (n = 7). Among the identified 22 G. duodenalis isolates, eight samples were subtyped according to β-giardin (bg) and the results were consistent with the identified assemblages. To our knowledge, this is the first report of Cryptosporidium spp. and G. duodenalis infections in domesticated canines in Xinjiang, China. The C. canis and G. duodenalis assemblage A identified in pet dogs in the present study were previously associated with infections in humans, indicating the potential for zoonotic transmission.