Detection of circovirus and herpesvirus co-infection in suddenly dead

Abstract This article investigates the causes of the sudden death of six common ravens ( Corvus corax ). All six birds were found on the same day in central Poland. The ravens were necropsied, and samples were collected for bacteriological, histopathological, and toxicological examinations. The presence of genetic material from common viral and some bacterial pathogens was examined using molecular methods. The ravens were found to be in good nutritional condition. Two birds had enlarged spleens with petechiae on their surface. Histopathological examination revealed multifocal hemorrhages and inflammatory infiltrates composed of mononuclear cells in the liver, and intranuclear inclusion bodies in hepatocytes. In the kidneys, inflammation, hemorrhages, parenchymal degeneration, and necrosis of the renal tubular epithelium were detected. Mild lymphocytic-plasmacytic inflammation was found in the intestines. Molecular tests were performed for circoviruses, herpesviruses, flaviviruses, adenoviruses, polyomavirus, avian bornavirus, avian paramyxovirus-1, rotavirus, avian reovirus, avian influenza viruses, Chlamydia spp., Salmonella spp., Clostridium spp., botulin toxins (A-E). Only PCR tests for circoviruses and herpesviruses yielded positive results. Toxicological tests were performed for the presence of organophosphate pesticides, rodenticides, coccidiostats, mycotoxins, and fungicides. Low and trace concentrations of brodifacoum (an anticoagulant rodenticide) and pentobarbital (a barbiturate) were detected. The remaining results were negative. There is a strong suspicion that the primary cause of death in the studied birds was raven herpesvirus, described in this case for the first time, with possible involvement of circovirus. However, other factors, including poisoning or other unknown viruses, cannot be ruled out. Although the toxicology profile was broad, it did not include all possible toxins.