背景:弓形虫是全世界人类和动物中非常常见的人畜共患寄生虫。在加拿大北部的一些地区,人类血清阳性率很高,被认为与传统制备的乡村食品的消费有关。比如驯鹿,海象,环海豹和白鲸。虽然许多研究报道了弓形虫在这些动物中的患病率,在北方普遍缺乏明确宿主的情况下,关于感染源的争论相当多,尤其是海洋哺乳动物。有人提出,鱼类可能参与这种传播。
目的:本研究的目的是进行有针对性的调查,以确定努纳维克采样的各种组织中弓形虫DNA的患病率。魁北克,并调查这种通常食用的鱼类在将感染传播给加拿大北部的人类和海洋哺乳动物中的可能作用。
结果:总共从努纳维克的几个地点采样了126个单独的北极炭,使用PCR测试各种组织中弓形虫DNA的存在。总的来说,在本研究中测试的126个(9.5%)北极炭黑中有12个是PCR阳性,如DNA测序所证实。脑组织最常见的是阳性,其次是心脏组织,而测试的背侧肌肉样本均未呈阳性。
结论:尽管弓形虫DNA在北极炭的大脑和心脏组织中的存在非常有趣,这些鱼的感染,以及它们在将这种寄生虫传播给人类和海洋哺乳动物中的可能作用,需要使用小鼠生物测定法进行确认。北极炭很可能通过摄入地表水和洋流从确定的猫科动物宿主更丰富的更南端地区运输的卵囊而暴露于弓形虫。如果可以确认北极的感染,这些鱼可能在弓形虫病向因纽特人的传播中起重要作用,直接通过食用生鱼或间接通过感染作为乡村食品收获的食鱼海洋哺乳动物。
BACKGROUND: Toxoplasma gondii is a very common zoonotic parasite in humans and animals worldwide. Human seroprevalence is high in some regions of Canada\'s North and is thought to be associated with the consumption of traditionally prepared country foods, such as caribou, walrus, ringed seal and beluga. While numerous studies have reported on the prevalence of T. gondii in these animals, in the general absence of felid definitive hosts in the North there has been considerable debate regarding the source of infection, particularly in marine mammals. It has been proposed that fish could be involved in this transmission.
OBJECTIVE: The objectives of the present study were to perform a targeted survey to determine the prevalence of T. gondii DNA in various tissues of anadromous Arctic charr sampled in Nunavik, Québec, and to investigate the possible role of this commonly consumed fish in the transmission of infection to humans and marine mammals in Canada\'s North.
RESULTS: A total of 126 individual Arctic charr were sampled from several sites in Nunavik, and various tissues were tested for the presence of T. gondii DNA using PCR. Overall, 12 out of 126 (9.5%) Arctic charr tested in the present study were PCR-positive, as confirmed by DNA sequencing. Brain tissue was most commonly found to be positive, followed by heart tissue, while none of the dorsal muscle samples tested were positive.
CONCLUSIONS: Although the presence of T. gondii DNA in brain and heart tissues of Arctic charr is very intriguing, infection in these fish, and their possible role in the transmission of this parasite to humans and marine mammals, will need to be confirmed using mouse bioassays. Arctic charr are likely exposed to T. gondii through the ingestion of oocysts transported by surface water and ocean currents from more southerly regions where the definitive felid hosts are more abundant. If infection in Arctic charr can be confirmed, it is possible that these fish could play an important role in the transmission of toxoplasmosis to Inuit, either directly through the consumption of raw fish or indirectly through the infection of fish-eating marine mammals harvested as country foods.