B304 - DUCK VIRAL HEPATITIS

IDevice Icon

B304 - DUCK VIRAL HEPATITIS

Nature of the disease
Duck viral hepatitis (DHV) is caused by three different kind of viruses. The most severe and widely distributed virus, DHV I,  is an enterovirus of the family Picornaviridae, and causes disease in ducklings before 6 weeks old. Other viruses include an astrovirus, DHV II, which causes disease in ducklings between 6 and 10 weeks old and DHV III caused by another Picornaviridae unrelated to DHV I which causes milder disease. 
Classification
OIE, List B disease
Susceptible species
Ducks and gooses (young animals).
Distribution
DHV I is present in Northern America, Europe and Asia, DHV II is restricted to the United Kingdoms, DHV III is restricted to the United States of America.

DHV is not present in the Pacific Region.

Clinical signs 
DHV is the most severe with DHV I, the incubation period lasts 1 to 2 days and clinical signs include lethargy, anorexia and sudden death with opisthotonos within a few days.

Morbidity is often 100% and mortality reaches 80%.

Disease is less severe in ducks older than 7 weeks.

Post-mortem findings 
The liver is enlarged with haemorrhagic lesions (petechia, ecchymosis) and decolouration. The spleen and kidneys can be augmented.
Differential diagnosis 
  • Duck virus enteritis
  • Coccidiosis
  • Mycotoxicosis
  • Pasteurella anatipestifera
Specimens required for diagnosis 
Liver specimen can be collected at post mortem for virus identification. 

Serological test is possible using serum neutralisation, however due to the short course of the disease serological test is not used for diagnosis on live animals.

Transmission   
The disease is very contagious and the virus excreted by faeces is transmitted by direct contact between birds or through fomites such as brooders, water, feed, equipment. Recovered animals can shed the virus for up to 8 weeks.
Risk of introduction   
DHV could be introduced by the importation of live ducks from an infected country. Introduction by duck meat or duck product is possible but at low risk according to the instability of the agents.

Rats have been described as a reservoir and control of this pest on arrival should be systematic.

Control / vaccines  
If accidentally introduced, strict isolation and control of rats are necessary measures to control DHV.

Vaccination against DHV I and DHV III is possible using live attenuated vaccines. A killed vaccine is also available against DHV I.

References
  • Duck Viral Hepatitis, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p. 1910-1911
  • GEERING WA, FORMAN AJ, NUNN MJ, Exotic Diseases of Animals, Aust Gov Publishing Service, Canberra, 1995, p.89-92
  • Office International des Epizooties, 2002