School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA 6150, Australia.
Exp Parasitol. 2012 Apr;130(4):437-41. doi: 10.1016/j.exppara.2012.01.014. Epub 2012 Feb 7.
Cryptosporidium is an enteric parasite of public health significance that causes diarrhoeal illness through faecal oral contamination and via water. Zoonotic transmission is difficult to determine as most species of Cryptosporidium are morphologically identical and can only be differentiated by molecular means. Transmission dynamics of Cryptosporidium in rural populations were investigated through the collection of 196 faecal samples from diarrheic (scouring) calves on 20 farms and 63 faecal samples from humans on 14 of these farms. The overall prevalence of Cryptosporidium in cattle and humans by PCR and sequence analysis of the 18S rRNA was 73.5% (144/196) and 23.8% (15/63), respectively. Three species were identified in cattle; Cryptosporidium parvum, Cryptosporidium bovis and Cryptosporidium ryanae, and from humans, C. parvum and C. bovis. This is only the second report of C. bovis in humans. Subtype analysis at the gp60 locus identified C. parvum subtype IIaA18G3R1 as the most common subtype in calves. Of the seven human C. parvum isolates successfully subtyped, five were IIaA18G3R1, one was IIdA18G2 and one isolate had a mix of IIaA18G3R1 and IIdA19G2. These findings suggest that zoonotic transmission may have occurred but more studies involving extensive sampling of both calves and farm workers are needed for a better understanding of the sources of Cryptosporidium infections in humans from rural areas of Australia.
隐孢子虫是一种具有公共卫生意义的肠道寄生虫，通过粪便-口腔污染和水传播引起腹泻病。由于大多数隐孢子虫种在形态上是相同的，只能通过分子手段来区分，因此很难确定隐孢子虫的动物源传播。通过收集 20 个农场的 196 份腹泻（腹泻）犊牛粪便样本和其中 14 个农场的 63 份人类粪便样本，研究了农村人群中隐孢子虫的传播动态。通过 PCR 和 18S rRNA 的序列分析，牛和人类隐孢子虫的总体流行率分别为 73.5%（144/196）和 23.8%（15/63）。在牛中鉴定出三种隐孢子虫；小隐孢子虫、牛隐孢子虫和瑞安隐孢子虫，在人类中鉴定出小隐孢子虫和牛隐孢子虫。这是牛隐孢子虫在人类中的第二份报告。在 gp60 基因座的亚型分析中，确定小隐孢子虫亚型 IIaA18G3R1 是犊牛中最常见的亚型。在成功亚分型的 7 个人类小隐孢子虫分离株中，5 株为 IIaA18G3R1，1 株为 IIdA18G2，1 株为 IIaA18G3R1 和 IIdA19G2 的混合物。这些发现表明可能发生了动物源传播，但需要更多涉及广泛采集犊牛和农场工人样本的研究，以更好地了解澳大利亚农村地区人类隐孢子虫感染的来源。
