An outbreak of adenoviral infection in inland bearded dragons (Pogona vitticeps) coinfected with dependovirus and coccidial protozoa (Isospora sp.)

Thirty of 200 (15%) hatchling inland bearded dragons were found dead after a short period (48 hours) of weakness and lethargy. The most common clinical signs were head tilt and circling. Six bearded dragons with neurological signs were euthanized, and postmortem examination revealed no gross abnormalities. Microscopically, severe, randomly distributed hepatocellular necrosis with large basophilic intranuclear inclusion bodies in numerous hepatocytes was noted. Small-intestinal enterocytes contained intracytoplasmic coccidial protozoa (Isospora sp.) and occasional enterocytes had basophilic intranuclear inclusion bodies. Transmission electron microscopy revealed both 80- and 20-nm-diameter viral particles, which were consistent with adenoviruses and dependoviruses, respectively. Adenoviral outbreaks in groups of animals are uncommon. An adverse synergistic effect of the coccidiosis with the adenoviral infection may have played a critical role in the high morbidity and mortality in this case.