Identification of Trichinella taxa by ITS-1 amplicon next-generation sequencing with an improved resolution for detecting underrepresented genotypes in mixed natural infections

TRICHINELLA INFECTIONS IN WILDLIFE FROM PENNSYLVANIA: VARIATION IN EXPOSURE AMONG COYOTE (CANIS LATRANS), GRAY FOX (UROCYON CINEREOARGENTEUS), AND RED FOX (VULPES VULPES)

During a survey for Sarcocystis infections in Pennsylvania in wild canids, muscles from the tongue and limb were examined microscopically for sarcocysts. Between 9 February 2024 and 11 February 2024, muscle samples were collected from 76 coyotes, 46 gray foxes, and 21 red foxes from Pennsylvania hunter harvested animals. Around 5 g of muscle was examined microscopically by compression between a glass slide and coverslip. Trichinella murrelli larvae were detected in 1 of 76 coyotes (Canis latrans), 1 of 46 gray foxes (Urocyon cinereoargenteus), and in 7 of 21 red foxes (Vulpes vulpes) muscles. Diet and individual host susceptibility probably contributed to the differences in prevalence of T. murrelli in these hosts. This is the first report of Trichinella infection in coyotes from Pennsylvania. The reasons for differences in Trichinella species could be due to inherent susceptibility or the area sampled.

From wildlife to humans: The global distribution of Trichinella species and genotypes in wildlife and wildlife-associated human trichinellosis

Zoonotic nematodes of the genus Trichinella are foodborne parasites that have a global distribution in wild carnivores and omnivores, with spillover and spillback into domestic livestock and people, with concomitant trade and health consequences. Historically, most human cases were linked to domestic pigs infected with Trichinella spiralis, but under current high biosecurity swine production in many countries, wildlife have become a more important source of human trichinellosis. The aim of this review is to update the global distribution of Trichinella species and genotypes reported in wildlife, as well as reported human outbreaks from the consumption of wildlife. Using several online databases and by "snowballing" references, hundreds of reports of Trichinella spp. in wildlife published between January 1991 and December 2023 provide an important update to the host and geographic range for each of the recognized 13 species/genotypes, grouped by continent. Surveillance effort was highest in Europe and North America, while Africa, Asia, Oceania, Central and South America have had limited surveillance, in some instances with human cases serving as sentinels of transmission in a region. Dozens of human outbreaks are described, with wild boars (Sus scrofa) being the most frequently implicated wildlife species in human outbreaks globally. Bears are an important source of infection in North America, for wildlife tourism, and importation of bear meat has also been implicated in multicountry outbreaks. The largest study limitation was the dearth of molecular identification of larvae in both wildlife surveillance studies and human outbreaks, particulary in under-studied regions. We highlight the need for enhanced molecular epidemiological approaches to outbreaks of this important foodborne parasite, and emphasize the need for a One Health approach to manage Trichinella spp. which transmit among terrestrial and marine wildlife (including migratory birds), pigs, horses, and people, often across large geographic scales and borders.