Pathological Study of Infectious Bronchitis in Commercial Poultry Farms in Plateau State, North Central Nigeria

Infectious bronchitis (IB) caused by the coronavirus Infectious bronchitis virus (IBV) remains a persistent respiratory and production disease in commercial poultry operations in Nigeria's North Central geopolitical zone. This study examined the gross and histopathological lesions of infectious bronchitis in poultry flocks from four commercial farms in Plateau State, Nigeria, in 2023. Forty-six layer chickens presenting with respiratory distress, coughing, and notable drops in egg production were sacrificed and subjected to necropsy. Tissues from the trachea, lungs, kidneys, oviduct, and proventriculus were collected and processed for histopathological evaluation. Gross lesions included mucopurulent tracheal exudate, pulmonary consolidation, nephromegaly with pale swollen kidneys, and reproductive tract involution. Microscopically, the tracheal mucosa showed loss of ciliated epithelium, goblet cell hyperplasia, submucosal oedema, and lymphocytic infiltration. Renal tubular dilation with accumulation of urate crystals was observed in nephropathogenic IB-affected kidneys. Ovarian regression and oviductal epithelial metaplasia were documented in laying hens, explaining egg production decline. These findings are consistent with contemporary descriptions of nephropathogenic IBV in tropical poultry systems. Co-circulation of multiple IBV serotypes in North Central Nigeria emphasises the need for serotype-matched vaccination and enhanced molecular surveillance of IBV strains circulating on commercial farms. Keywords: infectious bronchitis, IBV, poultry, nephropathogenic, Plateau State