Clinico-pathological Studies on Natural and Experimental Infectious Bursal Disease in Broiler Chickens

Abstract

The clinico-pathological studies on infectious bursal disease (IBD) were carried out in naturally occurred outbreaks of 19 to 22-day-old broilers (population 1000) and experimentally produced infection in 40-day-old 23 broiler chickens during the period from November 2002 to January 2003. Each of the experimental birds received 100 µl of 20% bursal homogenates intraocularly with a wild-type field strain (BD-3 Wt) of a Bangladeshi isolate of vvIBDV (BD-3/99). The natural infection caused 29.2% mortality and experimental infection resulted in 26.8% mortality after an incubation period of 48 to 72 hrs. Clinical investigation showed almost similar clinical signs in both the natural and experimental cases. Dullness, depression, anorexia, whitish loose diarrhoea, bloody diarrhoea in some chickens, ruffled feathers and severe dehydration were the recorded clinical manifestations. Necropsy examination revealed no significant pathological differences between chickens died of natural and experimental IBDV infection. Oedematous swelling of the bursa with petechial haemorrhages and slimy to gelatinous materials on the inner surface, and petechial haemorrhages on the thigh muscles were the main gross pathological lesions in both cases. Haemorrhages at the junction between proventriculus and gizzard found in chickens of natural infection but not in chickens of experimental infection. The experimentally infected chickens that survived up to the last day of 10 days observation revealed atrophied bursa with creamy or yellowish discolouration at necropsy.

Key words: Infectious bursal disease; broiler chickens; clinical signs; pathology

doi: 10.3329/bjvm.v2i1.1931

Bangl. J. Vet. Med. (2004). 2 (1) : 31-35