Red foxes (Vulpes vulpes) as a reservoir for Trichinella in Western Austria

Introduction More than 65 % of the Austrian landscape is alpine. Red foxes (Vulpes vulpes) in these areas are known to be a reservoir for Trichinella larvae, with most positive cases found in the southern and western provinces. We examined muscle samples from red foxes hunted in the western provinces Salzburg, Tyrol and Vorarlberg for the presence of Trichinella larvae. The aim of the work was to reassess the epidemiological situation of Trichinella infection in wild carnivores in Austria. Materials and methods Based on a statistical sample plan, 1379 fox carcasses (Salzburg n = 475; Tyrol n = 476; Vorarlberg n = 428) were sampled between 2013 and 2018. Sex, age, weight, geographic origin and body condition were recorded. Samples were tested for the presence of Trichinella by the magnetic stirrer method for pooled samples in accordance with EU legislation. Pooled samples from muscle tissues (10 g per fox) from the front leg were digested and when Trichinella was recovered from the pooled sample the samples were tested individually to identify the infected animal. Multiplex PCR was used for species differentiation of the Trichinella larvae. Results Trichinella larvae were detected in 42 red foxes (3.0 %, with a 95 confidence interval of [2.2-4.1 %]). The apparent prevalence in Vorarlberg was 6.8 % [4.6-9.6 %], in Tyrol the apparent prevalence was 1.7 % [0.7-3.3 %] and in Salzburg it was 1.1 % [0.3 2.4 %]. Logistic regression analysis indicated that the geographic origin of samples (province) and the age category had a significant effect on the likelihood of the occurrence of Trichinella larvae in the foxes. More specifically, red foxes from Vorarlberg had a significantly higher chance of being Trichinella-positive than foxes fromTyrol (odds ratio = 4.3) and Salzburg (odds ratio = 7). Adult foxes were more likely to be infected than juveniles (odds ratio = 2.7). All larvae were identified as Trichinella britovi. Conclusions The results confirm that Trichinella britovi is prevalent in wild carnivores in Austria. In comparison to previous studies, we found a higher prevalence in red foxes from Vorarlberg, where there is a small but increasing population of wild boars (Sus scrofa). There is a potential risk of zoonotic transmission from red fox via wild boar to humans. More attention should be paid to the distribution and spread of wild boars, especially into areas where Trichinella spp. are prevalent in the wildlife. Wildlife monitoring is essential to gain knowledge on the epidemiology of Trichinella spp. in Austria.