Sylvatic trichinellosis in southwestern Spain

The epidemiology of Trichinella spp. in their main sylvatic hosts, wild boa r (Sus scrofa ferus and red fox (Vulpes vulpes), in Extremadura (southweste rn Spain) was studied. We examined 88 Trichinella spp.-positive wild boar m uscle-tissue samples from a total of 29,333 killed animals, referred to the Veterinary Parasitology Department (University of Extremadura, Spain) by t he Extremadura Veterinary Service. Additionally, 227 red foxes killed durin g the hunting season and thus not subject to veterinary controls were exami ned for trichinellosis. Trichinella spp. larvae were found in six (3%) of t he red foxes. All samples were examined using direct diagnostic techniques, including trichinoscopy and artificial digestion. The mean intensity of in fection was 74.8 larvae/g (LPG) of muscle tissue in wild boars, compared to 30.6 LPG in foxes. Trichinella spiralis (sensu stricto) predominated over T. britovi in wild boars. Random amplified polymorphic DNA (RAPD) and alloe nzyme typing showed that 74% of infected wild boars had only T. spiralis, 2 1% had only T. britovi, and 5% showed mixed infections. In contrast, 33% of infected foxes were infected only with T. spiralis, while 67% had T. brito vi, suggesting a clear predominance of the latter in foxes. We suspect the existence of a paranthropic or sylvatic cycle in large areas of this region ; given the ease of transfer between sylvatic and domestic or semi-domestic animals, this implies a high epidemiological risk.