Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4 Virus: Equivocal Pathogenicity and Implications for Surveillance Following Natural Infection in Breeder Ducks in the United Kingdom.

摘要: Since early 2014, several outbreaks involving novel reassortant highly pathogenic avian influenza (HPAI) A(H5N8) viruses have been detected in poultry and wild bird species Asia, Europe North America. These apparently healthy dead migratory birds, as well domestic chickens, turkeys, geese ducks. In this study, we describe the pathology of an outbreak H5N8 HPAIV breeder ducks UK. A holding with approximately 6000 ducks, aged 60 weeks, showed a gradual reduction egg production increased mortality over 7-day period. Post-mortem examination revealed frequent fibrinous peritonitis, severely haemorrhagic ovarian follicles occasional splenic pancreatic necrosis high incidence mycotic granulomas air sacs lung. Low-to-moderate levels HPAI virus were mainly respiratory digestive tract, minor involvement other organs. Although histopathological confirmed gross findings, intralesional viral antigen detection by immunohistochemistry was not observed. Immunolabelled cells rarely only present inflamed serosa, usually superficial to granulomatous inflammation. Abundant bacterial microcolonies observed ovaries oviduct. The limited tissue distribution presence inter-current fungal infections suggest role for clinical disease layer