ABSTRACT
Aim: To investigate outbreak of IBD in Zaria, Nigeria. Study Design: Prospective study. Place and Duration of Study: Sample: Poultry Unit of the Ahmadu Bello University Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria between March 2009 to July 2009. Methodology: Poultry cases reported to the clinics were investigated. Date, age, address, flock size, morbidity rate, mortality rate, breed, species, type of birds, vaccination history were noted; post mortem and agar gel precipitation test were done on 10 flocks, the incidence rate, morbidity rate, mortality rate and organ (bursa, spleen and thymus) to body weight ratio of the 10 flocks were calculated. Results: Chicks in all the flocks revealed the clinicopathologic manisfestation of IBD which include depressions, somnolence, anorexia, ruffled feathers, trembling, postration followed by death. In all the flocks, the BF were either turgid, swollen and or haemorrhagic, severe haemorrhages on the thigh and pectoral muscles, haemorrhages at the junction of proventriculus and gizzard or oesophagus, congested or pale carcasses, swollen kidneys with prominent tubules and enlarged pale or congested liver were also observed during postmortem examination. All the bursal homogenates from the 10 flocks gave precipitation line in the AGPT. An incidence of 12.1% was recorded. Average morbidity (40.5%) and mortality (40.7%) rates were recorded in ten outbreaks of IBD. Improved breeds of chickens were more likely to suffer from IBD with broilers 3.87 times at risk. Birds, 3-6 weeks-old were at a risk of being infected with IBDV. Chickens vaccinated once against IBD were 4.8 times more likely to suffer from IBD. Conclusion: IBD is a disease of improved breeds of poultry with clinical disease seen only in chickens. The disease mostly affects chickens of 3 to 6 weeks of age. Birds vaccinated twice are less susceptible to the disease.