Detection and genetic characterization of Giardia duodenalis in pigs from large-scale farms in Xinjiang, China.

To study the presence of Giardia duodenalis in Xinjiang, northwest China, we collected 801 fecal specimens from seven large-scale pig farms and screened them using PCR targeting the SSU rRNA gene. Twenty-one (2.6%) of the specimens from five farms were G. duodenalis-positive, with a significant difference in prevalence among different farms (0-8.7%) (p < 0.01). Giardia duodenalis prevalence was highest in fattening pigs (5.4%, 7/129), followed by sows (3.2%, 7/222), post-weaning piglets (1.8%, 5/281), and pre-weaning piglets (1.2%, 2/169), but there was no significant difference in prevalence among the age groups (p > 0.05). Sequence analysis of the SSU rRNA gene revealed that the 21 G. duodenalis strains belonged to three assemblages: A (n = 2), B (n = 16), and E (n = 3). Assemblage B was the predominant assemblage and was widely distributed in all G. duodenalis-positive farms and age groups. All G. duodenalis-positive specimens were further assayed at the β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes, and two tpi, four gdh, and two bg sequences were identified. These data indicate that pigs may be a zoonotic risk and can potentially spread G. duodenalis infection from animals to humans.