Hepatitis A Virus in Ducks

Duck Viral Hepatitis (DVH) is caused by Duck Hepatitis A Virus (DHAV), a member of the genus Avihepatovirus. Duck Viral Hepatitis was historically subdivided into types I, II, and III. The originally described Duck Viral Hepatitis type I is caused by one of at least three genotypes of Duck Hepatitis A Virus of the genus Avihepatovirus in the Picornaviridae family. The most widespread and virulent is Duck Hepatitis A Virus type 1 (DHAV-1).

Two antigenically distinct genotypes have been identified in Taiwan (DHAV-2) and in China and the Republic of Korea (DHAV-3).

Duck Hepatitis A Virus is readily propagated in chicken and duck embryos. Field experience with DHAV-1 indicates that egg transmission does not occur. The disease can be transmitted experimentally by parenteral or oral administration of infected tissues.

Viruses that differ from Duck Hepatitis A Virus have been recognized as additional causes of Duck Viral Hepatitis in ducklings. Duck Viral Hepatitis type II, now classified as duck astrovirus type 1 (DAstV-1), is difficult to propagate under laboratory conditions. It has been reported in ducklings from 10 days to 6 weeks of age, and causes pathological changes similar to those of Duck Hepatitis A Virus-1.

Duck Viral Hepatitis type III is now also classified as an astrovirus (DAstV-2) and can be propagated in duck (but not chicken) embryos. It is considered distinct from DAstV-1 and has been reported only in the United States of America. It causes similar liver lesions in young ducklings, but is less virulent than Duck Hepatitis A Virus.

At least 10 genera of hepatotropic viruses across at least 6 viral families have been implicated in Duck Viral Hepatitis disease, which further complicates disease classification.