Trichinellaand polar bears: a limited risk for humans

Abstract

In this review, we identified 63 cases reported since World War II of human trichinellosis linked to the consumption of parasitized polar bear (Ursus maritimus) meat. This low number contrasts to the numerous cases of human trichinellosis related to consumption of the meat of black (U. americanus) or brown bears (U. arctos). The prevalence of Trichinella infection is high in bears, but larval muscular burden is usually lower in polar bears compared to other bear species. Polar bears, therefore, seem to play a limited role in the transmission of trichinellosis to humans, as native residents living in the Arctic traditionally consume well-cooked bear meat, and travellers and foreign hunters have only limited access to this protected species due to the declining polar bear population.

Trichinella and trichinellosis in Europe

“…This species does not infect swine; however, sometimes, T. nativa-infected wild boars were detected in Estonia, Latvia and Lithuania, suggesting that starvation, infections and stress can reduce the immunity of this species favoring the development of T. nativa. In Europe in the last twenty years, human infections caused by this species were documented only in persons who consumed uncooked bear meat imported from North America or consumed bear meat in North America and developed the disease when they come back to Europe (Ancelle et al, 2005;Dupouy-Camet et al, 2017). Out of 1,287 isolates of T. nativa from Europe identified at the ITRC, only 8 (0.6%) originated from wild boars, whereas, 99.4% originate from wild carnivores ( Table 1).…”

The epidemiology of trichinellosis in the Arctic territories of a Far Eastern District of the Russian Federation

“…Some previous studies (Leclair et al ., 2004) indicated the degradation of larvae in a similar product after only 4–5 months. However, our results show otherwise (as do data from various periods in the recent review by Dupouy-Camet et al ., 2017) and, until further studies resolve this contradiction, we need to consider such products as at least potentially dangerous for human health for a period of a year or more after the start of preparation.…”

“…Recognized outbreaks of trichinellosis in the northern regions usually follow the consumption of polar bear, brown bear and walrus meat (Raush et al ., 1956). Trichinellosis outbreaks have been described in Alaska, the Northern Territories of Canada, Greenland and in the Arctic territories of the Russian Federation (Margolis et al ., 1979; MacLean et al ., 1989; Serhir et al ., 2001; Møller et al ., 2005, 2010; Ozeretskovskaia et al ., 2005; Odoevskaya et al , 2013a; Bukina, 2014; Dupouy-Camet et al ., 2017).…”

“…The recent review of trichinellid interactions with polar bears by Dupouy-Camet et al . (2017) noted a high prevalence of trichinellosis in this bear species and the capacity of these bears to ‘transport parasites very long distances’, citing an example of T. nativa -infected bears appearing on the Iceland coast (where no Trichinella infection had been detected in the native wildlife). However, their role in propagating human infection is assessed as low, due to a combination of limited numbers of these bears, lower parasite burden relative to other bear species (8 larvae/g for polar bears, 11 larvae/g for grizzly bears and 117 larvae/g for black bears) and the fact that native peoples of the region prefer to consume well-cooked polar bear meat, in comparison with the flesh of the walrus, etc.…”

Zoonoses and potential zoonoses of bears

“…One of the earliest reports of bear‐inflicted human trichinosis was a 1932 outbreak linked to consumption of bear jerky (Walker, ). Additional cases stemming from human consumption of bear meat have been reported across North America, as well as in Thailand (Clark et al, ; Doege et al, ; Dupouy‐Camet, Bourée, & Yera, ; Emson et al, ; Houzé et al, ; Hueffer, Parkinson, Gerlach, & Berner, ; McIntyre et al, ; Roselle et al, ; Schellenberg et al, ). Infected humans exhibit gastrointestinal symptoms, fatigue, rashes, fever and muscle pain.…”