Duck plague.

 

Introduction : 

• Duck plague is an acute contagious viral disease of duck, geese and swans, caused by Herpesvirus (duck virus enteritis).

• Differences in virulence among DEV strains have been noted but all appear immunologically identical.

• Naturally occurring infection has been occurred in ages ranges from 7-day old ducklings to mature breeder ducks.

• Duck plague can be transmitted by direct contact between infected and susceptible birds of indirectly by contact with a contaminated environment.

Clinical signs :

• Sudden high persistent flock mortality, mature ducks die in good flesh and prolapse of the penis my be evident in dead mature male breeders.

• Affected ducks are unable to stand, and maintain a posture with drooping outstretched wings and head down.

• Photophobia, associated with half closed pasted eyelids, inappetence, extreme thirst, droopiness, ataxia, ruffled feathers, nasal discharge, soiled vent and watery diarrhoea appear in advanced cases.

• A marked drop in egg production may be noted during the period of highest mortality i laying flocks.

• Ducklings 2 to 7 weeks of age show dehydration, loos of weight, blue beaks and often a blood stained vent.

• Birds often die in a rather characteristic position with the neck twisted downwards sidewards of backward.

• The mortality in domestic ducks may vary from 5 to 100%.

Diagnosis :

• A presumptive diagnosis of Duck plague can be made on the basis of clinical findings and pathological changes. 

• The pathological changes induce haemorrhagic enteritis, diphtheritic cloacitis and oesphagitis and the oesophageal proventicular sphincter appears as a haemorrhagic ring.

• The isolation of the causative virus and identification by neutralization and FAT confirm the diagnosis.

Treatment : 

• There is no treatment known and prevention should include clean drinking water, and keeping wild, free flying water fowl away.

• A chicken embryo adapted Duck plague strain, avirulent for domestic ducks, has been developed and used extensively with good results.

Control : 

• The vaccine can also be used in the face of an outbreak, as it provides protection immediately after vaccination due to an interference phenomenon between the vaccine virus and the field virus.

• Vaccinated birds acquired resistance to infection as one day after vaccination due to interference phenomenon.

• The Duck plague vaccine is administered 0.5 ml SC or IM in domestic ducklings over 2 weeks of age, and flocks maintained immunity for more than one year, are re-vaccinated annually.