Avian hepatitis E virus in an outbreak of hepatitis--splenomegaly syndrome and fatty liver haemorrhage syndrome in two flaxseed-fed layer flocks in Ontario.
Two commercial layer chicken flocks that were fed a flax-based diet beginning at 28 weeks of age for the production of omega-3 fatty-acid-enriched eggs experienced increased mortality when the birds reached 37 weeks. The average weekly mortality was 0.34% over a 20-week period, with peak mortality of 0.9% for 1 week. Reduced feed consumption, reduced body weight gain and poor peak production were noticed prior to the onset of increased mortality. A total of 245 birds were necropsied and 78% of these had lesions in the liver and spleen, with 44% of those necropsied having changes consistent with hepatitis-splenomegaly syndrome, with lesions ranging from acute periportal lymphoplasmacytic hepatitis to chronic severe cholangiohepatitis with haemorrhage, vasculitis and amyloidosis. A total of 11% of the birds had lesions typical of fatty liver haemorrhagic syndrome, and 22% had lesions found in both hepatitis-splenomegaly syndrome and fatty liver haemorrhagic syndrome. No significant bacteria or viruses were recovered from samples of the liver/bile or spleen but 11 of 21 bile samples contained avian hepatitis E virus RNA detectable with a reverse transcriptase-polymerase chain reaction assay. Comparative sequence analysis found identities of 82 to 92% and 78 to 80% between the helicase and capsid protein genes, respectively, of the virus detected in this outbreak and those of other avian hepatitis E virus isolates, suggesting extensive genetic heterogeneity in avian hepatitis E viruses in Ontario flocks.
Agunos
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Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
Yoo
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Youssef
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SA
Ran
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D
Binnington
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B
Hunter
D B
DB
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002645:Chickens / Q000821:virology*; D004032:Diet; D004196:Disease Outbreaks / Q000662:veterinary*; D005234:Fatty Liver / Q000150:complications / Q000453:epidemiology / Q000662:veterinary / Q000821:virology; D005260:Female; D019597:Flax; D006470:Hemorrhage / Q000150:complications / Q000453:epidemiology / Q000662:veterinary / Q000821:virology; D006524:Hepatitis, Viral, Animal / Q000453:epidemiology / Q000473:pathology* / Q000821:virology*; D052678:Hepevirus / Q000235:genetics / Q000302:isolation & purification*; D009864:Ontario / Q000453:epidemiology; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology / Q000473:pathology / Q000821:virology*; D012327:RNA Virus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D013163:Splenomegaly / Q000150:complications / Q000453:epidemiology / Q000662:veterinary / Q000821:virology; D013577:Syndrome