Epizootiology of pseudorabies (Aujeszky's disease) in the Florida puma

Feral swine (Sus scrofa), an important prey species for the endangered Florida puma (Puma concolor coryi, also known as Florida panther), are the natural host for pseudorabies virus (PRV). PRV infection is not clinically... [ view full abstract ]

Feral swine (Sus scrofa), an important prey species for the endangered Florida puma (Puma concolor coryi, also known as Florida panther), are the natural host for pseudorabies virus (PRV). PRV infection is not clinically significant in feral swine but is rapidly fatal to pumas and other secondary hosts. From 1979 through 2012, PRV was diagnosed in 2 of 144 (1.4%) radio-collared Florida pumas. Concurrently, however, the cause of death for 31 (21.5%) collared pumas went undiagnosed. To determine the impact of PRV on the Florida puma, we retrospectively reviewed necropsy and laboratory findings, re-examined histology, and/or tested archived tissues using real-time quantitative PCR from all (radio-collared and uncollared) undiagnosed Florida puma mortalities. We also prospectively conducted necropsies on pumas dying 2013-2016. We categorized panther mortalities from the combined time periods (1979-2016) based on the likelihood of PRV infection as Confirmed, Probable, Suspect, Possible, or Unlikely/Negative. PRV infection was diagnosed in 9 (6 Confirmed, 3 Probable) additional pumas for 11 cases overall. Of 164 radio-collared pumas necropsied during the combined time periods, PRV was the cause of mortality (Confirmed or Probable) in 7 (4.3%) and may have been responsible for up to 31 (Confirmed, Probable, Suspect, and Possible, 18.9%). Gross necropsy findings in confirmed cases were non-specific. Microscopic changes were subtle and included slight to mild perivascular cuffing and gliosis primarily in the brainstem, lymphoplasmacytic meningoencephalitis, and intranuclear inclusion bodies in the adrenal medulla. No serological evidence of prior exposure was seen in live-captured pumas. Geographic location was an important risk factor with confirmed cases primarily occurring in the northern and/or western portion of puma range – likely associated with higher feral swine densities. Sequences of the PRV gC gene from isolates is pending. Our findings indicate that PRV may be a significant, and heretofore underdiagnosed, mortality factor in Florida pumas.