Occurrence and Molecular Characterization of Toxocara canis and Toxascaris leonina in Wild Canids in Lithuania

Toxocara spp. are globally distributed parasitic nematodes capable of infecting a broad range of animals, which may serve as definitive or paratenic hosts. Among these parasites, Toxocara canis is considered an important zoonotic species. In contrast to domestic dogs and cats, the role of wild carnivores as definitive hosts of Toxocara spp. has been comparatively understudied in Lithuania. A total of 33 intestinal samples from wild canids collected in Lithuania in 2023–2026, comprising 16 red foxes (Vulpes vulpes), 14 common raccoon dogs (Nyctereutes procyonoides), and three grey wolves (Canis lupus), were examined for the presence of Toxocara nematodes using microscopic and molecular techniques. The detected parasites were genetically characterized by analyzing the internal transcribed spacer (ITS1-ITS2) and NADH dehydrogenase subunit 5 (ND5) regions. Toxocara nematodes were found in 10 out of 33 (30.3%) intestinal samples from wild canids examined. Molecular analysis based on the ITS1-ITS2 and ND5 markers confirmed the occurrence of Toxocara canis and Toxascaris leonina in intestinal samples from wild canids, marking the first such record in Lithuania. Comparative sequence analysis demonstrated greater genetic variability within the ND5 marker than within the ITS1–ITS2 region, indicating that the mitochondrial marker may offer higher resolution for assessing genetic diversity. These preliminary findings expand current knowledge of the molecular epidemiology of ascaridoid nematodes in Lithuanian wildlife and provide a foundation for future comprehensive studies on their diversity, transmission, and zoonotic significance.