Or duck plague is an acute contagious infection of ducks, geese, and swans caused by a herpes virus. Usually seen in domestic and feral waterfowl in urban/farm settings during breeding season.

Diagnosis
is based on clinical signs, pathology supported by the isolation and identification of the virus.

Identification

The virus may be isolated from the liver and spleen
of birds dying from this infection. Virus can be recovered by infecting susceptible ducklings, in which the disease can be reproduced; by inoculating embryonated Muscovy duck eggs on the chorioallantoic membrane; or by inoculating cell cultures of duck embryo or Muscovy duck embryo origin. The identity of the virus can be confirmed by neutralsation tests using specific antiserum to inhabit pathological changes in duck embryos or the cytopathological effects in the cell cultures, or by direct or indirect fluorescent antibody tests on infected cell cultures.

Diagnostic Techniques 

Duck virus enteritis (D V E ) is an acute, sometimes chronic, contagious virus infection that occurs naturally only in ducks, geese and swans. The agent is a herpes virus and similar to Newcastle Disease in chickens. The infection has not been reported in other avian species, mammals or humans. In domestic ducks and ducklings,
D V E has been reported in birds ranging from 7 days of age to mature breeders. In susceptible flocks, the first signs are often sudden, high and persistent mortality with a significant drop in egg production. In chronically infected, partially immune flocks, only occasional deaths occur.

Clinical Signs

Associated with a D V E outbreak vary with the species, age and sex of the affected birds, and the virulence of the virus. In breeder ducks, the range of signs include; Photophobia (fear of light, or apparent blindness), Polydisia, loss of appitite, Ataxia, watery diarrhea and nasal discharge. Birds often have ruffled feathers and soiled vents.  Sick birds may maintain an upright stance by using their wings for support, but their overall appearance is one of weakness and depression. In ducklings 2-7 weeks of age, losses may be lower than older birds, and the signs associated with D V E infection include, dehydration, loss of weight, a blue coloration of the beaks, and bloodstained vents.

Requirement For Vaccines

A live attenuated virus vaccine can be used to control D V E in birds over 2 weeks of age. Fattening or breeding ducks may be vaccinated subcutaneously or intramuscularly to produce an active immunity. The vaccine is not thought to spread by contact from vaccinated to unvaccinated ducks, as the unvaccinated birds remain susceptible to infection.