Department of Health Management Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
Zoonoses Public Health. 2012 Sep;59(6):424-33. doi: 10.1111/j.1863-2378.2012.01474.x. Epub 2012 Mar 6.
To determine the zoonotic potential of Cryptosporidium and Giardia in Prince Edward Island (PEI), Canada, 658 human faecal specimens were screened that were submitted to the Queen Elizabeth Hospital diagnostic laboratory. Overall, 143 (22%) samples were Cryptosporidium positive, while three (0.5%) were positive for Giardia. Successful genotyping of 25 Cryptosporidium isolates by sequence analysis of the HSP70 gene revealed that 28 and 72% were C. hominis and C. parvum, respectively. Cryptosporidium isolates from humans and previously genotyped C. parvum from beef cattle were subtyped by sequence analysis of the GP60 gene. Subtyping identified three subtypes belonging to the family IIa. All three subtypes IIaA16G2RI (55%), IIaA16G3RI (22%) and IIaA15G2RI (22%) were found in the animal isolates, while two of the subtypes found in the animals, IIaA16G2RI (80%) and IIaA15G2RI (20%), were also identified in the human isolates. Cryptosporidium infection in humans peaked in April-June. Molecular epidemiological analysis of the human data showed a C. parvum peak in the spring and a relatively smaller peak for C. hominis in July-September. The majority (57%) of human Cryptosporidium isolates were found in children between 5 and 10 years of age. All three Giardia isolates were identified as G. duodenalis assemblage A. The overall Cryptosporidium prevalence in our human samples was high relative to other studies, but because the samples were submitted to a hospital diagnostic laboratory, the results may not be representative of the general population. Further, the presence of the same zoonotic C. parvum subtypes in cattle and human isolates implies that transmission is largely zoonotic and cattle may be a source of sporadic human infections on PEI. The presence of Giardia in people on PEI is rare, and the assemblage A found in humans might originate from humans, livestock or other domestic or wild animals.
为了确定加拿大爱德华王子岛（PEI）的隐孢子虫和贾第鞭毛虫的人畜共患潜力，对提交给伊丽莎白女王医院诊断实验室的 658 个人类粪便标本进行了筛查。总体而言，143 份（22%）样本呈隐孢子虫阳性，3 份（0.5%）样本呈贾第鞭毛虫阳性。通过 HSP70 基因序列分析成功对 25 株隐孢子虫分离株进行基因分型，结果显示 28%和 72%分别为 C. hominis 和 C. parvum。通过 GP60 基因序列分析对来自人类和先前基因分型的牛肉源 C. parvum 分离株进行隐孢子虫亚型分析。亚型分析确定了属于 IIa 家族的三个亚型。在动物分离株中发现了三种亚型 IIaA16G2RI（55%）、IIaA16G3RI（22%）和 IIaA15G2RI（22%），而在动物分离株中发现的两种亚型 IIaA16G2RI（80%）和 IIaA15G2RI（20%）也在人类分离株中被鉴定出来。人类隐孢子虫感染在 4 月至 6 月达到高峰。对人类数据的分子流行病学分析显示，C. parvum 在春季达到高峰，C. hominis 在 7 月至 9 月达到较小的高峰。大多数（57%）人类隐孢子虫分离株来自 5 至 10 岁的儿童。所有 3 株贾第鞭毛虫分离株均鉴定为 G. duodenalis 组合 A。与其他研究相比，我们人类样本中的隐孢子虫总流行率较高，但由于样本是提交给医院诊断实验室的，因此结果可能不能代表一般人群。此外，牛和人类分离株中存在相同的人畜共患 C. parvum 亚型表明，传播主要是人畜共患的，牛可能是 PEI 散发性人类感染的来源。PEI 地区人类感染贾第鞭毛虫的情况很少见，在人类中发现的组合 A 可能来源于人类、家畜或其他家养或野生动物。
