Trichinella spiralis

Malone, Cody J., Oksanen, Antti, Mukaratirwa, Samson, Sharma, Rajnish & Jenkins, Emily, 2024, From wildlife to humans: The global distribution of Trichinella species and genotypes in wildlife and wildlife-associated human trichinellosis, International Journal for Parasitology: Parasites and Wildlife 24, pp. 100934-100934 : 100934-

3.1.1. Trichinella spiralis in Europe

Trichinella spiralis was the species most commonly associated with human trichinellosis historically, although a growing proportion of reported outbreaks are caused by sylvatic Trichinella species (Bruschi and Murrell, 2002). In Europe, T. spiralis is commonly found in wild boar, with several studies testing tens of thousands of samples or more, because of their omnipresence and their importance in consumption by humans ( Table 1). Trichinella spiralis has also been shown to readily infect carnivores and omnivores ( Table 1). In experimental infection of red foxes ( Vulpes vulpes ), T. spiralis led to a higher larval burden than equal infection doses of other species found in Europe ( T. britovi , T. nativa , T. pseudospiralis ), but when inoculated as a mixed infection with equal doses, T. nativa outcompeted T. spiralis (Webster and Kapel, 2005) . As T. spiralis is not the most common species in sylvatic carnivores in Europe, it has been proposed that wild carnivores may not be an important reservoir for T. spiralis and cannot sustain the infection in the absence of other hosts ( Pozio and Murrell, 2006; Pozio et al., 2009b). However, this hypothesis was challenged in the 2000s in Finland, as T. spiralis was found in ~15% of Trichinella isolates tested from wild carnivores and was found as far north as ~ 69 ◦ N in one red fox, despite no reports in domestic pigs in Finland over the same time period (Airas et al., 2010; Oivanen et al., 2002). However, in the following decade, T. spiralis prevalence in Finnish wild carnivores drastically decreased, indicating a delay in the disappearance from the sylvatic cycle after the cessation of spill-over from the domestic cycle ( Oksanen et al., 2018). Trichinella spiralis in Europe causes hundreds of cases of human trichinellosis each year in Europe, the vast majority from independently raised domestic pigs, but also from wild boar meat ( EFSA & ECDC, 2021; Pozio, 2014) ( Table 2) ( Fig. 2 ).

Figures

Fig. 2. Global distribution of Trichinella spiralis in wildlife reported in this review.