Seropositive Wild Boars Suggesting the Occurrence of a Wild Cycle of Trichinella spp. in Brazil

Simple Summary Trichinellosis is an important zoonotic disease with worldwide distribution and two types of cycles: the domestic cycle and the wild cycle, and spillover between them can occur occasionally. There are several cases of human and animal infection by Trichinella spp. in South America, but Brazil is considered free of the domestic cycle, even though there is unpublished serological evidence of Trichinella spp. in wild boars. This study investigates Trichinella spp. infection in wild boars and wild carnivores in Brazil by serological and artificial digestion tests. We tested 136 samples: 121 from wild boars and 15 from wild carnivores, the latter only by artificial digestion. No larvae were found in the artificial digestion tests, but 6.1% (95% CI 3.0-12.0) of the wild boars were positive in iELISA. These results suggest the occurrence of a Trichinella spp. wild cycle related to wild boars in Brazil, but further analyses should be performed to confirm the presence of the parasite. Trichinella is a zoonotic nematode traditionally detected worldwide in both domestic and wild animals. In South America, along with the occurrence of this parasite in domestic pigs and wild boars, there are reports of infection in wild carnivores. Brazil is considered free of the domestic cycle of Trichinella, but there is unpublished serological evidence of infection in wild boars, which changed the Brazilian status in OIE regarding the disease after an official communication. We investigated Trichinella spp. infection in wild boars and wild carnivores in the Southeastern region of Brazil. A total of 136 samples were tested, 121 from wild boars and 15 from wild carnivores. Artificial enzymatic digestion (AED) tests were performed on muscle samples from 37 wild boars and 15 wild carnivores, and 115 serum samples from wild boars were tested by iELISA. Seven serum samples from wild boars tested positive (7/115 = 6.1%, 95% CI 3.0-12.0), but no larvae were found in the AED. There was no significant difference between sex, age, and location of the samples. The serological results suggest that a wild cycle of Trichinella spp. may occur in Brazil, but further analyses should be performed to confirm the presence of the parasite.

Automated summary

Trichinellosis is an important zoonotic disease with two types of cycles, domestic and wild, worldwide. While Brazil is considered free of the domestic cycle of Trichinella, serological evidence suggests a potential wild cycle related to wild boars in the country. Further analyses are needed to confirm the presence of the parasite.