College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou 450002, China; International Joint Research Laboratory for Zoonotic Diseases of Henan, Zhengzhou, China.
Institute of Animal Health, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, Guangdong Province, China.
Infect Genet Evol. 2018 Dec;66:95-100. doi: 10.1016/j.meegid.2018.09.019. Epub 2018 Sep 20.
Giardia duodenalis is a gastrointestinal parasitic protozoan with important veterinary and public health implications worldwide. In this study, a total of 1440 fecal specimens were collected from dairy calves in Guangdong Province, China. The overall prevalence of G. duodenalis was 2.2% (31/1440) by polymerase chain reaction (PCR). The prevalence was 8.4% and 1.1% in pre- and post-weaned calves, respectively. Both assemblages A (6.5%, 2/31) and E (93.5%, 29/31) were found based on sequence analysis of the SSU rRNA gene. All G. duodenalis-positive samples were assayed with PCR followed by sequencing the beta giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes, and 20, 23, and 18 sequences were obtained, respectively. Multilocus genotyping yielded 10 assemblage E multilocus genotypes (MLGs). All assemblage E MLGs were genetically distinct from those obtained in cattle from Henan, Xinjiang, Shanghai, and Shaanxi in China. This finding was also supported by F, N, and median-joining network analysis. Results of this study indicated that G. duodenalis was found in low prevalence in dairy calves in Guangdong Province, southern China; nevertheless, the infected calves might represent a public health risk in this region. Additionally, the differences in assemblage E MLGs from the five analyzed regions revealed significant geographic segregation of G. duodenalis in China.
十二指肠贾第鞭毛虫是一种具有重要兽医和公共卫生意义的胃肠道寄生原虫。本研究共采集广东省奶牛场犊牛粪便标本 1440 份，采用聚合酶链反应（PCR）检测，结果显示十二指肠贾第鞭毛虫总感染率为 2.2%（31/1440）。其中，断奶前和断奶后犊牛的感染率分别为 8.4%和 1.1%。根据 SSU rRNA 基因序列分析，发现了两个虫株，即虫株 A（6.5%，2/31）和虫株 E（93.5%，29/31）。对所有十二指肠贾第鞭毛虫阳性样本进行 PCR 扩增，然后对β-微管蛋白（bg）、谷氨酸脱氢酶（gdh）和磷酸丙糖异构酶（tpi）基因进行测序，分别获得了 20、23 和 18 个序列。多位点基因分型获得了 10 个虫株 E 多位点基因型（MLGs）。所有虫株 E MLGs 与中国河南、新疆、上海和陕西的牛源虫株在遗传上均有明显差异。这一发现也得到了 F、N 和中位数连接网络分析的支持。本研究结果表明，广东省奶牛场犊牛十二指肠贾第鞭毛虫感染率较低，但感染的犊牛可能对该地区的公共卫生构成威胁。此外，从五个分析地区获得的虫株 E MLGs 的差异表明，中国的十二指肠贾第鞭毛虫存在明显的地理隔离。
