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Prevalence and multilocus genotyping of potentially zoonotic Giardia duodenalis in pigs in Shanghai, China

Liu, Hua, Xu, Ning, Yin, Jianhai, Yuan, Zhongying, Shen, Yujuan, Cao, Jianping
Parasitology 2019 v.146 no.9 pp. 1199-1205
Giardia lamblia, animal pathogens, farms, genes, genotyping, giardin protein, glutamate dehydrogenase, humans, intestines, loci, parasites, polymerase chain reaction, sequence analysis, swine, triose-phosphate isomerase, Australia, China
Giardia duodenalis is a common intestinal parasite in humans and other mammals, and it causes major public and veterinary health problems worldwide. China is a major pig-raising country, and studies on Giardia in pigs have important public health significance. The present study was conducted to investigate the prevalence of Giardia and assess its genetic characterization. A total of 93 samples were collected from two farms in Shanghai. The presence of Giardia was determined using PCR and sequence analysis of glutamate dehydrogenase, beta-giardin and triose phosphate isomerase genes. The average prevalence of G. duodenalis infection was 26.88% (25/93) in the pigs, with 28.13% (18/64) in farm 1 vs 24.14% (7/29) in farm 2. All the PCR-positive products were successfully sequenced, and assemblage E was more prevalent. Zoonotic assemblages A and B and canine-specific assemblage C were identified in farm 1, whereas, only assemblage E was detected in farm 2. Interestingly, two pig isolates showed 100% homology with human-derived isolates from Australia and China at the bg and tpi loci respectively. Pigs infected with Giardia infect humans by polluting the environment; whether pigs are a potential environmental source of the human pathogen in China requires more epidemiological data.