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Also Known As: '''''Duck Viral Hepatitis''''' — '''''DVH''''' — '''''DH'''''
Also Known As: '''''Duck Viral Hepatitis''''' — '''''DVH''''' — '''''DH'''''
Caused By: '''''Duck Hepatitis Virus 1 and 3'' — ''DHV-I'' — ''DHV-III''
Caused By: '''''Duck Hepatitis Virus 1 and 3'' — ''DHV-1'' — ''DHV-3''
==Introduction==
==Introduction==
Duck hepatitis is caused by the [[:Category:Enteroviruses|'''enteroviruses''']] DHV-I and DHV-III.
Duck hepatitis is caused by the [[:Category:Enteroviruses|'''enteroviruses''']] DHV-1 and DHV-3.
It is a '''highly fatal''' disease of ducklings causing very high '''mortality''', '''opisthotonus''' and '''hepatitis'''.
It is a '''highly fatal''' disease of ducklings causing very high '''mortality''', '''opisthotonus''' and '''hepatitis'''.
==Signalment==
==Signalment==
Ducks are the only species naturally affected.
Ducks are the only species naturally affected.
DHV-I occurs only in '''young ducklings''', usually '''<6 weeks''' of age and spreads rapidly within a flock. It is the '''most virulent''' of the three.
DHV-1 occurs only in '''young ducklings''', usually '''<6 weeks''' of age and spreads rapidly within a flock. It is the '''most virulent''' of the three.
DHV-II is only reported in outdoor ducks on open fields.
DHV-2, an astrovirus (duck astrovirus 1), not an enterovirus, has only been reported in outdoor ducks on open fields.
Duck Hepatitis is not considered zoonotic.
Duck Hepatitis is not considered zoonotic.
==Distribution==
==Distribution==
DHV-I is present worldwide.
DHV-1 is present worldwide.
DHV-III has only occurred in the USA.
DHV-2 has only been reported in Norfolk, England <ref> Asplin, F. D. (1965) '''Duck hepatitis: vaccination against two serological types. '''''Vet. Rec.'', 77:1529-1530</ref> and no outbreaks have been recorded since the 1980’s.
DHV-3 has only been reported in the USA.
==Clinical Signs==
==Clinical Signs==
'''Sudden deaths, Opisthotonus, Paresis''', Paralysis, Enopthalmos.
'''Sudden deaths, Opisthotonus, Paresis''', Paralysis, Enopthalmos.
DHV-I infection is most virulent. Death usually occurs within 1-2 hours of clinical signs.
DHV-1 infection is most virulent. Morbidity is 100%, with mortality <95% up to one week of age, <50% for 1-3 weeks of age and negligible thereafter. Death usually occurs within 1-2 hours of clinical signs.
Mortality rates are lower in DHV-II infections, reaching only 20%.
Mortality rates are lower in DHV-2 infections, reaching only 20%.
==Diagnosis==
==Diagnosis==
On post-mortem examination, the '''[[Avian Liver - Anatomy & Physiology|liver]]''' is '''enlarged''', appears '''greenish''' and displays distinct '''ecchymotic haemorrhages'''.
On post-mortem examination, the '''[[Avian Liver - Anatomy & Physiology|liver]]''' is '''enlarged''', appears '''greenish''' and displays distinct '''ecchymotic haemorrhages'''.
Splenic and [[Exotic Urinary System - Anatomy & Physiology#Avian||kidney]] swelling may also be evident. Cutaneous haemorrhage is often noted.
Splenic and [[Exotic Urinary System - Anatomy & Physiology#Avian|kidney]] swelling may also be evident. Cutaneous haemorrhage is often noted.
On histopathology, '''necrosis''' and inflammatory infiltrate are visible within hepatic cells.
On histopathology, '''necrosis''' and inflammatory infiltrate are visible within hepatic cells.
'''Innoculation''' from liver suspensions can be used for confirmation of all DHVs.
'''Innoculation''' from liver suspensions can be used for confirmation of all DHVs using embryonated duck eggs, chicken eggs and tissue culture.
'''Direct [[immunofluorescence]]''' can also confirm presence of DHV-I.
'''Direct [[immunofluorescence]]''' can also confirm presence of DHV-I.
==Control==
==Control==
'''Vaccination''' is only commercially available against '''DHV-I'''. Immunisation involves two or three innoculations. Live, live attenuated and inactivated forms are available.
'''Vaccination''' is only commercially available against '''DHV-I'''. Immunisation involves two or three innoculations. Live, attenuated and inactivated forms are available.
DHV-I can be prevented by '''strict isolation''' in the first 4-5 weeks of life.
DHV-I can be prevented by '''strict isolation''' in the first 4-5 weeks of life.