ABSTRACT: Wild carnivores, both introduced and native species, are able to adapt well to peri-urban environments, facilitating cross-species pathogen transmission with domestic animals, and potentially humans. The role of wild living reservoir hosts cannot be ignored because of their known carriage of E. bieneusi zoonotic genotypes. In the past decades, populations of wild living carnivores, i.e., native, such as red foxes, and invasive, such as raccoon dogs and raccoons, have increased and adapted to synanthropic environments across Europe, including Poland. The knowledge concerning E. bieneusi genotype identification and distribution in wild carnivores is limited worldwide. A total of 322 individual fecal samples from six carnivore species, i.e., raccoon, raccoon dog, red fox, European badger, pine and beech martens, were collected and then analysed for the presence of E. bieneusi using the nested PCR method. Overall prevalence of the pathogen was estimated to be as high as 27.3%. The infection rates for E. bieneusi varied between the carnivore species, from 13.7% in beech martens to 40.4% in raccoon dogs. Based on sequence analysis of the ITS region of the rRNA gene marker, we detected five known genotypes of E. bieneusi in examined animals. In the invasive species, E. bieneusi NCF2 and D genotypes have been identified, whereas in the native ones, E. bieneusi NCF2, D, C, EbCar2 and Type IV genotypes were identified. All E. bieneusi genotypes recorded in this survey clustered in Group 1, showing their zoonotic potential. Our results provide the first description of the occurrence and genotypes of the microsporidian E. bieneusi in wild living population of raccoon dogs in Europe. Our findings are important for the study of pathogen epidemiology and emphasize the fact that the invasive and the native wild living carnivores, both widely distributed, should be considered more seriously as significant sources of zoonotic pathogens hazardous to domestic and farmed animals and humans.
