First report of Taenia arctos (Cestoda: Taeniidae) from brown bears (Ursus arctos) in Romania.

BACKGROUND

The brown bear (Ursus arctos) is an apex predator with significant ecological importance and serves as a valuable indicator species for monitoring parasitic burdens in forest ecosystems. Owing to its complex ecology and varied diet, this species may play a key role in the life cycle of numerous pathogens, including cestodes of the genus Taenia, such as the recently described Taenia arctos. Among the potential intermediate hosts for T. arctos is the moose (Alces alces), a species sporadically present in northern Romania, where its habitat may overlap with that of U. arctos. In this context, the present study aimed to identify and molecularly characterize cestodes isolated from the small intestines of U. arctos.

METHODS

Between May 2022 and December 2024, small intestines from 91 U. arctos individuals were collected across 16 counties in Romania. Biological samples were preserved by freezing and analyzed using both classical methods (macroscopic and microscopic examination) and molecular biology techniques (through amplification and sequencing of mitochondrial gene fragments, cox1 and 12S rRNA).

RESULTS

Out of the 91 samples analyzed, only 1 specimen tested positive for an adult cestode (prevalence 1.1%). Genetic analysis confirmed its identification as T. arctos, a species not previously reported in Romania.

CONCLUSIONS

This study represents the first molecular identification of T. arctos in U. arctos in southeastern Europe, thereby extending the known geographic range of the parasite. The findings may indicate that trophic interactions compatible with the life cycle of T. arctos occur in this area, although the evidence is limited to a single detection.