Avian Hepatitis E Virus Infection in Organic Layers

Area of Science:

• Veterinary Pathology
• Virology
• Poultry Science

Background:

• Organic layer flocks experienced severe egg production decline and increased mortality.
• Common necropsy findings included hepatic foci and regressed ova.
• Histopathology revealed acute necrotizing hepatitis without significant bacterial or mycotoxin involvement.

Purpose of the Study:

• To identify the causative agent of disease in affected organic layer flocks.
• To characterize the avian hepatitis E virus (HEV) involved.

Main Methods:

• Necropsy and histological examination of 141 chickens from 10 flocks.
• Bacteriological culture and mycotoxin testing of liver samples.
• Serological testing for avian HEV antibodies (immunoglobulin Y).
• Detection and sequencing of avian HEV RNA in liver tissues.

Main Results:

• Avian HEV immunoglobulin Y antibodies were detected in 26 serum samples from four flocks.
• Avian HEV RNA was identified in liver samples from two flocks.
• Sequencing confirmed the avian HEV belonged to genotype 2.
• No significant bacterial pathogens or mycotoxins were identified.

Conclusions:

• Avian Hepatitis E virus (HEV) genotype 2 was identified as the cause of clinical disease in these organic layer flocks.
• The diagnosis was confirmed by detecting viral RNA and excluding other pathogens.
• The clinical presentation and pathological findings were atypical for HEV infection.