Forbes L B
Health of Animals Laboratory, Centre for Animal Parasitology, Canadian Food Inspection Agency, 116 Veterinary Road, Saskatoon, S7N 2R3, Saskatchewan, Canada.
Vet Parasitol. 2000 Dec 1;93(3-4):321-34. doi: 10.1016/s0304-4017(00)00349-6.
Trichinella in marine mammals has a circumpolar arctic distribution and a narrow range of host species. It is commonly found in polar bears (Ursus maritimus), and increasingly in walruses (Odobenus rosmarus) where it presents a significant zoonotic hazard. This has resulted in the implementation of food safety programs in some arctic communities to test harvested walrus meat for Trichinella larvae prior to consumption. Trichinella has been reported infrequently in bearded seals (Erignathus barbatus) and ringed seals (Phoca hispida), and was once observed in a Beluga whale (Delphinapterus leucas). Cannibalism is probably the most important factor in maintaining a Trichinella cycle in polar bears. Arctic carnivores such as polar bears, arctic foxes (Alopex lagopus) and domestic dogs (Canis familiaris) have a high prevalence of Trichinella infection and the carcasses of at least some of these animals are deposited in the ocean. Scavenging of these carcasses by walruses probably occurs, but may not account for the high prevalence the parasite seen in this host species. Predation, carrion feeding and cannibalism have been documented for walruses and a sylvatic cycle similar to that of bears may exist in walrus populations. Seals and whales are likely infected through infrequent exposure to infected carcasses, either directly by scavenging or indirectly by consuming amphipods or fish that have fed on infected carcasses. The inefficiency of this mechanism may account for the low prevalence of Trichinella in seals and whales. It is known that isolates from marine mammals are cold tolerant, and infectious for man, and have been identified as Trichinella nativa (T2). Molecular and other phylogenetic studies would be useful to facilitate studies on the inter-relationship of Trichinella cycles involving marine and terrestrial mammals in the arctic and subarctic, and in the investigation of human outbreaks of trichinellosis in these areas.
海洋哺乳动物体内的旋毛虫呈环北极分布，宿主种类范围狭窄。它常见于北极熊（Ursus maritimus），在海象（Odobenus rosmarus）中也越来越常见，在海象身上它构成了重大的人畜共患病风险。这导致一些北极社区实施食品安全计划，在食用收获的海象肉之前检测其中的旋毛虫幼虫。在髯海豹（Erignathus barbatus）和环斑海豹（Phoca hispida）中旋毛虫的报告较少，曾在一头白鲸（Delphinapterus leucas）中观察到。同类相食可能是北极熊维持旋毛虫循环的最重要因素。北极食肉动物，如北极熊、北极狐（Alopex lagopus）和家犬（Canis familiaris）旋毛虫感染率很高，这些动物中至少有一些的尸体被丢弃在海洋中。海象可能会 scavenging 这些尸体，但这可能无法解释在该宿主物种中看到的寄生虫高感染率。海象的捕食、食腐和同类相食现象已有记录，海象种群中可能存在与熊类似的野生动物循环。海豹和鲸鱼可能通过偶尔接触受感染的尸体而被感染，要么直接通过 scavenging，要么间接通过食用以受感染尸体为食的桡足类动物或鱼类。这种传播机制的低效可能解释了海豹和鲸鱼中旋毛虫感染率低的原因。已知从海洋哺乳动物分离出的菌株耐低温，对人类有传染性，已被鉴定为本地旋毛虫（T2）。分子和其他系统发育研究将有助于促进对北极和亚北极地区涉及海洋和陆地哺乳动物的旋毛虫循环之间相互关系的研究，以及对这些地区人类旋毛虫病爆发的调查。 （注：scavenging 此处原英文表述有误，结合语境推测可能是“scavenging”，意为“食腐”，翻译时按此处理。）
