Avian Hepatitis E virus (HEV)
Avian Hepatitis E Virus (HEV) is a nonenveloped, positive-sense, single-stranded RNA virus. Avian HEVs have been identified from chickens with big liver syndrome and hepatitis–splenomegaly (HS) syndrome. Avian HEV, similar to swine HEV, is genetically and antigenically related to human HEV. Molecular epidemiologic investigations have shown that avian HEV infection in chickens is endemic to the United States, Spain, and parts of Asia.
In May 2009, hepatitis–splenomegaly syndrome affected a flock of 37-week-old broiler breeder hens in Shandong, China which had a history of decreased egg production. Antibodies against avian HEV ORF2 were detected in 80 of 94 serum samples from the same chicken flock, according to ELISA.
In 2013, a 95% seroprevalence of aHEV antibodies was discovered in 61 chicken flocks throughout Taiwan. All chickens (1,326 of them) appeared healthy. 40% of the total number of chickens were affected.