Duck plague outbreak in a Chara-Chemballi duck farm.

Background: Duck rearing is one of the important livelihoods of rural people. Duck plague is one of the diseases causing heavy mortality resulting in economic losses. Case description: An outbreak of duck plague in a farm in Kadavakathi Village near Tenkasi, Tirunelveli Dt., is reported. Findings/treatment and outcome: Two thousands out of 4500 Chara-Chemballi breed of ducks which were recently purchased from Chenganacherry in Kerala died, with a mortality rate of 44.4%. Clinical signs of inappetence, partial closure of eyelid, conjunctivitis, corneal opacity, oculo-nasal discharge, soiled vent with green white watery diarrhoea, ataxia, incoordination and sudden death were observed. Necropsy examination revealed diphtheritic membrane in the oesophagus, congestion, petechial haemorrhages and multifocal gray white areas on the surface of the liver, epicardial haemorrhages, congested trachea, lung, kidneys, splenomegaly with mottled appearance and enteritis. Microscopical examination revealed presence of eosinophilic intranuclear and intracytoplasmic inclusions in the epithelial cells of the intestine and hepatocytes, degeneration and necrosis of enterocytes, dilated crypt epithelial cells with presence of eosinophilic intranuclear and intracytoplasmic inclusions, congestion and lymphoid cell depletion in the spleen, vasculitis, congestion, and haemorrhages in the trachea and lungs, proventriculitis, and congested kidneys. Polymerase chain reaction (PCR) also confirmed the duck plague viral infection by the amplification of polymerase gene fragment (446 bp). Conclusion: Based on the above findings, the Chara-Chemballi duck disease outbreak was diagnosed as duck viral enteritis infection.