Duck Viral Enteritis
Also Known As – DEV - Duck Plague Virus (DPV) – Duck plague
Introduction
Duck viral enteritis is caused by a herpesvirus which can also infect geese and swans. The disease is acute and highly infectious, causing high morbidity and mortality
DVE is not zoonotic.
This disease is notifiable to the World Organisation for Animal Health (OIE)
Distribution
Endemic in Northern America, Europe and Asia.
Transmission is mainly horizontal via the faecal-oral route or contaminated environments and equipment/personnel. Wild waterfowl are often asymptomatic carriers and shedders of DEV.
Vertical transmission also occurs from persistently infected female ducks to their eggs.
Signalment
Although ducks are the primary host, geese, swans and many other waterfowl can be infected with DEV.
Canada geese and blue winged teal appear particularly susceptible and disease course is rapid in these species.
Herring gulls and black headed gulls appear resistant.
Clinical Signs
DEV causes primarily greenish diarrhoea, which can lead to dehydration, anorexia, weakness, a typical drooped wing appearance and neurological signs. Haematochezia is often a feature. Birds often refuse to drink, further exacerbating the dehydration and its sequelae.
Diptheroid plaques commonly form on the eyelids and also internally on the mucosae of the respiratory system and gastrointestinal system.
Opthalmic signs sometimes present in DEV, including lacrimation, watery ocular discharge and photophobia.
Repiratory disease often manifests as a hoarse chirp but is non-specific.
These signs are often accompanied by a drop in egg production and a ruffled, unkempt appearance.
Solid natural immunity develops in recovered birds.
Sudden and persistent increases in flock mortality involving both young and adult birds is often the first observation of DEV. Outbreaks can last for several weeks in natural conditions.
Diagnosis
Diagnosis can usually be made using history of clinical disease and necropsy:
On post-mortem, petechial haemorrhage in the conjunctivae, mucous membranes, trachea, syrinx and intestine are pathognomonic for DEV. This pathology is caused by increased vascular permeability.[1] In advanced disease, the same sites may become covered by yellow-white necrotic plaques, sometimes forming pseudomembranes in the cloaca and oesophagus.[1]
In young birds, these pathological changes are often associated with the gut-associated lymphoid tissue (GALT).
Organs often also demonstrate degenerative and necrotic changes and the gizzard and intestines are commonly filled with blood.
Intranuclear inclusion bodies can be detected via electron microscopy.
Serology can indicate previous exposure but is of limited use in active outbreaks.
Treatment
The immediate efficacy of vaccines suggests that they may be indicated for use during developing outbreaks.[2]
Control
Vaccination is the mainstay of control of DVE. Only attenuated vaccines are efficacious.
Prevention must also focus upon prevention of exposure to wild waterfowl and contaminated water. All new stock should also be screened for DVE. Once DVE is present, depopulation, relocation and intensive disinfection are required to overcome an outbreak which may last for a significant period.
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References
- ↑ 1.0 1.1 Richter, J. H. M., Horzinek, M. C (1993) Duck plague. Virus infections of birds.77-90;35
- ↑ Sandhu, T. S., Leibovitz, L (1997) Duck virus enteritis (Duck Plague). Calnek, B. W., Barnes, H. J., Beard, C. W., McDougald, L. R., Saif, Y. M. eds. Diseases of Poultry, ed 10. Ames, USA: Iowa State University Press, 675-683.
Animal Health & Production Compendium, Duck plague virus datasheet, accessed 20/06/2011 @ http://www.cabi.org/ahpc/
Animal Health & Production Compendium, Duck viral enteritis datasheet, accessed 20/06/2011 @ http://www.cabi.org/ahpc/