Cutaneous Papillomaviruses in Cervids: A Hidden Threat to Wildlife Health and Conservation

Cutaneous papillomaviruses (PVs) are small, non-enveloped DNA viruses with strict host specificity and the capacity to induce proliferative epithelial lesions in a wide range of vertebrates. In wild cervids—including red deer (Cervus elaphus), moose (Alces alces), roe deer (Capreolus capreolus), white-tailed deer (Odocoileus virginianus), and reindeer (Rangifer tarandus)—multiple species-specific PVs have been identified, including CePV1, AaPV1, CcaPV1, OvPV1, and RtPV1. These viruses typically cause papillomas and fibro papillomas on the skin and mucous membranes, presenting as rough, verrucous, and sometimes ulcerated lesions. Although often benign, PV-induced lesions can compromise animal welfare by affecting feeding, vision, mobility, or mating behaviours. In high-prevalence populations, especially among juveniles and immunocompromised individuals, these infections may have broader population-level impacts. Histopathological findings typically include epidermal hyperplasia, koilocytosis, and papillomatosis, with replication confined to keratinocytes. Transmission occurs via direct contact, microtraumas, and potentially through hematophagous ectoparasites. From a conservation perspective, PV infections in cervids are significant for several reasons. First, lesions may reduce individual fitness and contribute to population stress, particularly in fragmented or vulnerable populations. Second, the presence of papillomaviruses in cervid species cohabiting with livestock or other wildlife raises concerns about cross-species transmission, including spillover from bovine PVs. Third, these lesions may be misidentified as more serious conditions (e.g., sarcoids or neoplasia), complicating health assessments in the field. With cervids playing crucial ecological roles and serving as sentinel species in many ecosystems, understanding PV diversity, transmission dynamics, and pathology is essential for wildlife health monitoring and conservation planning. Ongoing molecular surveillance, pathology, and ecological studies are critical to assess the true burden of PV infections and to support evidence-based conservation medicine practices