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Giardia duodenalis is a flagellated parasitic microorganism that parasitizes in the intestines of humans and animals. Although asymptomatic infections commonly exist in both humans and animals, some enteric symptoms have been reported in immunocompromised individuals, posing a threat to public health. Children could be infected with G. duodenalis through an environment contaminated by infective animals. Thus, the investigation of the prevalence and genotypes of G. duodenalis in zoo animals is important. In this study, 672 fecal samples of 113 species of animals, including non-human primates, artiodactyla, perissodactyla, proboscidian, marsupial, birds, carnivora, and rodents, were collected from three zoos in Hangzhou city, Dalian city, and Suzhou city in China. The samples were screened for the positivity of G. duodenalis by nested PCR based on the β-giardin (bg), triosephosphate isomerase (tpi), and glutamate dehydrogenase (gdh) gene loci. The overall G. duodenalis prevalence was 10.6% (71/672). The prevalence in non-human primates, artiodactyla, perissodactyla, proboscidian, marsupial, birds, carnivora, and rodent was 6.9% (10/144), 9.0% (12/133), 17.1% (6/35), 0% (0/6), 8.7% (2/23), 13.3% (28/211), 6.7% (7/105), and 40.0% (6/15), respectively. The region and category were considered risk factors for G. duodenalis infection in zoo animals (p < 0.001). Additionally, four genotypes of G. duodenalis were identified in zoo animals, including assemblage E (n = 46), assemblage A (n = 18), assemblage B (n = 6), and assemblage D (n = 1). The assemblages A, B, D, and E are also genotypes observed in humans and other animals. Among the sequences obtained in our study, one multilocus genotype (MLG) of the sub-assemblage AI was observed within assemblage A. Furthermore, three MLGs were detected within assemblage B. These findings reveal G. duodenalis genetic variability in zoo animals in three cities in China and suggest that zoo animals could be a potential source of human infection with G. duodenalis., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Blastocystis is a highly prevalent eukaryotic parasite of many animals and humans worldwide. It can compromise the gastrointestinal tract and cause gastrointestinal symptoms, constituting a serious threat to human health and animal growth. Many animals are potential sources of Blastocystis infection in humans. However, limited data are available regarding the prevalence and subtype distribution of Blastocystis infection among zoo animals in China. Therefore, the present study examined the prevalence and subtypes of Blastocystis in zoo animals in Hangzhou, Dalian, and Suzhou cities, China. Of 450 fecal samples from zoo animals, 27 (6.0%) were PCR-positive for Blastocystis, with 7.7% (8/104), 11.3% (7/62), 16.7% (3/18), 1.8% (2/114), 6.3% (1/16), 9.5% (2/21), and 3.6% (4/109) in artiodactyla, aves, rodentia, nonhuman primates, perissodactyla, marsupialia, and carnivora, respectively. Significant differences in the prevalence of Blastocystis were found among different animal groups (P < 0.05). Sequence analysis showed 7 known subtypes (ST2, ST4, ST5, ST7, ST8, ST10, and ST14) of Blastocystis in the present study, with ST10 (10/27) as the predominant subtype in all three of the examined zoos. To our knowledge, this is the first report of Blastocystis infection in Damaliscus dorcas, Cervus elaphus, Macropus rufogriseus, Grus japonensis, Trichoglossus haematodus, Panthera tigris ssp. tigris (white), Panthera tigris ssp. altaica, Lycaon pictus, Suricata suricatta, and Dolichotis patagonum in China. These results demonstrate the presence of Blastocystis infection in zoo animals and provided baseline data for preventing and controlling Blastocystis infection in zoo animals and humans in China.