Comparative pathomorphology of highly pathogenic avian influenza (H5N8) infection in Hungary during the 2016-17 outbreak

Abstract

SUMMARY Background: Highly pathogen avian influenza occurs from time to time in Hungary. The latest H5N8 outbreak during 2016-17 was especially devastating for the poultry industry. Objectives: The aim of this study is to summarize the comparative results of the pathomorphological examinations of infected birds during this outbreak, and also to provide up to date information for field veterinarians and poultry industry vets. Materials and Methods: Extensive pathological, histopathological and immunohistochemical examinations were carried out on H5N8 highly pathogenic avian influenza cases from each economically important poultry species that were submitted to our laboratory during the 2016-2017 outbreaks in Hungary. A range of organs was tested by PCR for HPAIV presence and sera of infected birds were tested by haemagglutination inhibition. Results and discussion: The involved H5N8 HPAI strain caused a disease with pronounced pathological lesions in waterfowl (goose, duck) and poor patho-logical lesions in gallinaceous birds (hen, turkey). The brain lesions related to viral infection were found in every species by histopathological examination and the specific virus protein was detected by immunohistochemistry. Microscopic lesions in the liver and pancreas were of major significance in the post mortem diagnostics of the disease in waterfowl. Viral nucleic acid was detected in every organ examined, but serological examinations yielded negative results in every case as expected. In summary, although the ultimate diagnosis of avian influenza should be based on direct detection of the virus, pathomorphological knowledge of the disease is essential in both field and laboratory diagnostics