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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.
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Classification
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OIE, List B disease
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Susceptible species
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Ducks and gooses (young animals).
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Distribution
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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.
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Clinical signs
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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.
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Post-mortem findings
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The liver is enlarged with haemorrhagic lesions (petechia,
ecchymosis) and decolouration.
The spleen and kidneys can be augmented.
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Differential diagnosis
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- Duck virus enteritis
- Coccidiosis
- Mycotoxicosis
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Pasteurella anatipestifera
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Specimens required for diagnosis
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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.
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Transmission |
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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.
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Risk of introduction |
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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.
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Control / vaccines
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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.
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| References
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Duck Viral Hepatitis, In Merck Veterinary Manual, National
Publishing Inc. Eight ed, 1998, Philadelphia, p. 1910-1911
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GEERING WA, FORMAN AJ, NUNN MJ, Exotic Diseases of Animals, Aust Gov
Publishing Service, Canberra, 1995, p.89-92
- Office International des Epizooties, 2002
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