College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, China.
Key Laboratory of Clinical Diagnosis and Treatment Technology in Animal Disease, Ministry of Agriculture and Rural Affairs, Hohhot, China.
BMC Vet Res. 2023 Aug 25;19(1):134. doi: 10.1186/s12917-023-03696-z.
Cryptosporidium is a gastrointestinal protozoan that widely exists in nature, it is an established zoonotic pathogen. Infected cattle are considered to be associated with cryptosporidiosis outbreaks in humans. In the present study, we aimed to assess the prevalence and species distribution of Cryptosporidium in dairy cattle in Central Inner Mongolia.
We focused on the small subunit ribosomal RNA gene (SSU rRNA) of Cryptosporidium and 60-kDa glycoprotein gene (gp60) of Cryptosporidium parvum. We collected 505 dairy cattle manure samples from 6 sampling sites in Inner Mongolia in 2021; the samples were divided into 4 groups based on age. DNA extraction, polymerase chain reaction (PCR), sequence analysis, and restriction fragment length polymorphism (RFLP) using SspI and MboII restriction endonucleases were performed. RFLP analysis was performed to determine the prevalence and species distribution of Cryptosporidium.
SSU rRNA PCR revealed that the overall prevalence of Cryptosporidium infection was 29.90% (151/505), with a prevalence of 37.67% (55/146) and 26.74% (96/359) in diarrheal and nondiarrheal samples, respectively; these differences were significant. The overall prevalence of Cryptosporidium infection at the 6 sampling sites ranged from 0 to 47.06% and that among the 4 age groups ranged from 18.50 to 43.81%. SSU rRNA sequence analysis and RFLP analysis revealed the presence of 4 Cryptosporidium species, namely, C. bovis (44.37%), C. andersoni (35.10%), C. ryanae (21.85%), and C. parvum (11.92%), along with a mixed infection involving two or three Cryptosporidium species. Cryptosporidium bovis or C. andersoni was the most common cause of infection in the four age groups. The subtype of C. parvum was successfully identified as IIdA via gp60 analysis; all isolates were identified as the subtype IIdA19G1.
To the best of our knowledge, this is the first report of dairy cattle infected with four Cryptosporidium species in Inner Mongolia, China, along with a mixed infection involving two or three Cryptosporidium species, with C. bovis and C. andersoni as the dominant species. Moreover, this is the first study to identify C. parvum subtype IIdA19G1 in cattle in Inner Mongolia. Our study findings provide detailed information on molecular epidemiological investigation of bovine cryptosporidiosis in Inner Mongolia, suggesting that dairy cattle in this region are at risk of transmitting cryptosporidiosis to humans.
隐孢子虫是一种广泛存在于自然界中的胃肠道原生动物，它是一种已确立的人畜共患病病原体。感染牛被认为与人类隐孢子虫病的爆发有关。本研究旨在评估内蒙古中部奶牛中隐孢子虫的流行率和种系分布。
我们专注于隐孢子虫的小亚单位核糖体 RNA 基因（SSU rRNA）和隐孢子虫 60kDa 糖蛋白基因（gp60）。我们于 2021 年从内蒙古的 6 个采样点收集了 505 份奶牛粪便样本；根据年龄将样本分为 4 组。进行 DNA 提取、聚合酶链反应（PCR）、序列分析和 SspI 和 MboII 限制性内切酶的限制性片段长度多态性（RFLP）。通过 RFLP 分析确定隐孢子虫的流行率和种系分布。
SSU rRNA PCR 显示，隐孢子虫感染的总流行率为 29.90%（151/505），腹泻和非腹泻样本的流行率分别为 37.67%（55/146）和 26.74%（96/359）；这些差异具有统计学意义。6 个采样点的隐孢子虫感染总流行率范围为 0%至 47.06%，4 个年龄组的流行率范围为 18.50%至 43.81%。SSU rRNA 序列分析和 RFLP 分析显示，存在 4 种隐孢子虫，即 C. bovis（44.37%）、C. andersoni（35.10%）、C. ryanae（21.85%）和 C. parvum（11.92%），以及两种或三种隐孢子虫的混合感染。在四个年龄组中，C. bovis 或 C. andersoni 是最常见的感染原因。通过 gp60 分析成功鉴定了 C. parvum 的亚型为 IIdA；所有分离株均鉴定为 IIdA19G1 亚型。
据我们所知，这是首次在中国内蒙古报告感染了四种隐孢子虫的奶牛，同时还存在两种或三种隐孢子虫的混合感染，以 C. bovis 和 C. andersoni 为主导种。此外，这是首次在内蒙古牛中鉴定出 C. parvum 亚型 IIdA19G1。我们的研究结果提供了内蒙古牛隐孢子虫病分子流行病学调查的详细信息，表明该地区的奶牛有向人类传播隐孢子虫病的风险。
