valentina zenobio, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise

The Apennine brown bear (Ursus arctos marsicanus) is a critically endangered and geographically isolated subspecies confined to the central Apennines. Its long-term conservation relies on demographic stability and effective health surveillance. The latest official estimate (2014) reported 50 individuals (range 45–69) within the core area of the Abruzzo, Lazio and Molise National Park (PNALM).

Since 2011, a health monitoring protocol has been applied to all bear carcasses submitted for necropsy at the Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise. Viral pathogens at the wildlife–domestic dog interface—canine distemper virus (CDV), canine parvovirus type 2 (CPV-2), and canine adenovirus type 1 (CAdV-1)—were systematically investigated using real-time PCR.

Between 2013 and 2025, 20 bears found dead within PNALM were examined. CDV was detected in lung tissue from one animal and CPV-2 in small intestinal samples from four individuals; no CAdV-1 infection was detected. No gross or histopathological lesions attributable to these infections were observed.

The detection of CDV and CPV-2 confirms viral circulation at the wildlife–domestic dog interface. In such a small and genetically constrained population, infectious diseases may act as stochastic drivers of demographic instability, increasing extinction risk. Multi-host pathogens such as CDV and CPV-2 are maintained by abundant sympatric species, particularly domestic dogs serving as reservoirs, while environmental persistence and broad host range enhance spillover potential. Continuous surveillance within a One Health framework is essential for early detection, adaptive management, and prevention at the human–domestic–wildlife interface. Further molecular characterization and phylogenetic comparison with strains circulating in domestic animals are needed to clarify transmission dynamics and assess potential spillback risks.