Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
School of Public Health, University of Alberta, Edmonton Clinic Health Academy, Edmonton, AB, Canada.
Zoonoses Public Health. 2021 May;68(3):277-283. doi: 10.1111/zph.12822. Epub 2021 Mar 2.
The prevalence of Toxoplasma gondii exposure in Inuit living in Nunavut (20%) is twice that of the US (11%); however, routes of exposure for Inuit communities in North America are unclear. Exposure to T. gondii in humans has been linked with consumption of raw or undercooked shellfish that can accumulate environmentally resistant oocysts. Bivalve shellfish, such as clams, are an important, nutritious, affordable and accessible source of food in many Northern Communities. To date, presence of T. gondii in clams in Northern Canada has not been reported. In this study, we tested for T. gondii presence in clams (Mya truncata) that were harvested in Iqaluit, Nunavut over a 1-week period in September 2016. Of 390 clams, eight (2.1%) were confirmed to contain T. gondii DNA (≥99.7% identity), as determined using polymerase chain reaction (PCR) and sequence confirmation. Additionally, three clams (0.8%) were confirmed to contain Neospora caninum-like DNA (≥99.2% identity). While N. caninum is not known to be a zoonotic pathogen, its presence in shellfish indicates contamination of the nearshore with canid faeces, and the potential for marine mammal exposure through marine food webs. Notably, the PCR assay employed in this study does not discriminate between viable and non-viable parasites. These findings suggest a possible route for parasite exposure through shellfish in Iqaluit, Nunavut. Future research employing viability testing will further inform public health messaging on the infectious potential of T. gondii in shellfish.
在努纳武特（20%）生活的因纽特人中，感染刚地弓形虫的流行率是美国（11%）的两倍；然而，北美因纽特社区的感染途径尚不清楚。人类感染刚地弓形虫与食用未煮熟或未煮熟的贝类有关，这些贝类可能会积累环境抗性卵囊。双壳贝类，如蛤蚌，是许多北方社区重要、营养丰富、负担得起和可获得的食物来源。迄今为止，尚未报告加拿大北部蛤蚌中存在刚地弓形虫。在这项研究中，我们检测了 2016 年 9 月在努纳武特伊卡卢伊特（Iqaluit）采集的 390 只蛤蚌中是否存在刚地弓形虫。通过聚合酶链反应（PCR）和序列确认，8 只（2.1%）蛤蚌证实含有刚地弓形虫 DNA（同一性≥99.7%）。此外，3 只蛤蚌（0.8%）证实含有新孢子虫样 DNA（同一性≥99.2%）。虽然新孢子虫尚未被认为是一种人畜共患病病原体，但它在贝类中的存在表明近岸受到犬类粪便的污染，并且通过海洋食物网使海洋哺乳动物接触的可能性增加。值得注意的是，本研究中使用的 PCR 检测方法不能区分活寄生虫和非活寄生虫。这些发现表明，在因纽特的伊卡卢伊特，通过贝类感染寄生虫的可能性。未来的研究采用生存能力测试将进一步为公众健康信息提供关于刚地弓形虫在贝类中的感染潜力的信息。
