HISTOPATHOLOGICAL CHANGES ASSOCIATED WITH INFECTIOUS BURSAL DISEASE OUTBREAK IN VACCINATED COCKEREL FLOCK

Abstract

Infectious bursal disease (IBD) was diagnosed in two hundred (200) five week-old vaccinated cockerels at the Faculty of Veterinary Medicine, University of Nigeria Nsukka. Two hundred 5 week-old cockerel flock were naturally infected with infectious bursal disease virus (IBDV) following re-vaccination at age of 28 days old. The major clinical signs observed were sudden drop in feed intake, huddling together, white-yellowish diarrhoea, prostration and death. The morbidity and mortality was up to 100 and 80 % respectively. At necropsy, lesions observed include, dehydration, enlargement of the bursa and kidney, ecchymotic haemorrhage on thigh and breast muscles, haemorrhage on the mucosal surface of the
Proventiculus-gizzard junction. The bursa cavity contained yellowish gelatinous exudates, serosanguineous fluid and caseous plugs. Histopathologically, section of the bursa showed lymphocytic depletion on day 2 post infection. There was interfollicular oedema in the bursa, marked reticular cell hyperplasia, lymphoid cell depletion and heterophilic infiltration. The bursa also showed hyperplasia of corticomedullary layer. There was depletion of lymphoid cells of the periarterial lymphoid sheaths in the spleen.