Gross pathology and epidemiological features of mule deerpox virus infections in farmed white-tailed deer (Odocoileus virginianus) in Florida

Mule deerpox virus (DPV) is a member of the Poxviridae family that affects various deer species, causing crustaceous skin lesions and potentially lethal infections. In this study, we aimed to investigate the spatial and temporal distribution of DPV in farmed white-tailed deer (WTD; Odocoileus virginianus) in Florida, USA, from 2017 to 2023. Necropsies were performed, and specimens were collected from 776 deer. Focusing on 145 animals with DPV-like lesions, polymerase chain reaction (PCR) testing and whole genome sequencing confirmed the presence of DPV in multiple specimen types. The results indicated that 49 out of 145 deer (33.8 %, 95 % CI: 25.7 %-40.9 %) tested positive for DPV. Mule deerpox virus was identified in 20 of the 37 counties and 8 of the 10 deer management units (DMUs) where we collected specimens. All DPV infection cases occurred in summer and fall. Lesion swabs (4/4, 100 %) and lesion tissues (16/18, 89 %) exhibited the highest PCR-positivity rates among the specimens collected from DPV-infected animals, while no whole blood samples (0/13, 0 %) tested positive. Additionally, DPV nucleic acid was also detected in fecal swabs (4/9, 44 %), suggesting that DPV may be transmitted through the oral-fecal route. Fawns aged 1-3 months (37/70, 52.9 %, 95 % CI: 41.3 %-64.1 %) exhibited statistically higher positivity rates than other age groups. This is the first study investigating the spatial and temporal patterns of DPV in farmed WTD in Florida. The findings emphasize the need for enhanced disease surveillance, non-invasive testing methods, and preventive measures to mitigate the impact of DPV on the deer farming industry and wildlife conservation.