First record of natural Baylisascaris transfuga (Ascaridoidea, Nematoda) infection in wild rodents.

The intestinal parasitic nematode, Baylisascaris transfuga, was recorded in wild rodents for the first time. Representatives of four murid species (15 Myodes rufocanus, 10 M. rutilus, 3 M. glareolus and 27 Microtus oeconomus) were collected in the White Sea coastal habitats in the south of the Kola Peninsula, Russia in July 2015 and examined for parasites. Encapsulated nematode larvae were detected in the mesentery and the large intestine wall of one grey-sided vole (M. rufocanus) and one tundra vole (M. oeconomus). Based on morphology, the larvae were identified as belonging to the genus Baylisascaris Sprent 1968. The partial 18S rDNA sequence of the larvae from the voles was obtained and fully corresponded to the sequence of Baylisascaris transfuga in the NCBI GenBank. The ITS rDNA and CoxI mtDNA sequences these larvae were also similar to the respective B. transfuga sequences in GenBank. The presence of B. transfuga in wild rodents suggests that rodents can participate in the B. transfuga life cycle.