Pathological and Molecular Characterization on Clinically Sick Chickens with Infectious Bronchitis Virus in Small Scale and Commercial Poultry Farms in Bishoftu Town, Ethiopia

Abstract Poultry diseases are considered to be one of the most leading factors which are responsible for reducing both the total number and productivity of chickens. Infectious bronchitis virus is internationally important disease of high concern due its adverse effects on poultry production in different aspects. The Cross-sectional study was conducted from November, 2021 to June 2022 in Bishoftu town, Ethiopia with the aim of confirming the presence of infectious bronchitis virus (IBV) in the samples collected from suspected chicken through the combined result molecular, gross and histopathology. Depression with different severity, respiratory related signs, diarrhea and retardation in growth were the clinical signs which frequently seen and recorded in majority of them. Tissue (lungs, trachea and kidneys) and tracheal swab samples were collected from 40 chickens clinically suspected of infectious bronchitis virus. Among these 25 were from farm A and 10 were from farm B commercial poultry farms and 5 were from farm C small scale farm. The texture, shape, size and color of the organs were properly examined for gross pathology characterization. Accordingly, mild to severe tracheal hemorrhage, unevenly distributed color on the kidney and lung were observed during gross examination of the organs. From all grossly examined organs, the most frequently affected organs were the trachea, 22(55%) and kidney, 15 (37.5%) followed by lung, 11 (27.5%). From 40 swab specimens collected for molecular characterization, 8 were found positive for IBV. From a total of 32 tissue samples, 20 were found positive by histopathological analysis and the microscopic lesions described were infiltration of inflammatory cells at different condensation state, mild to severe congestion and hemorrhages, tracheal mucosal epithelium damage, degenerative changes in the renal tubule. The overall results of the current study indicate the production and reproductive performance of chickens in the study area were highly influenced by the presence of infectious bronchitis virus. Thus, further scientific investigation should be conducted through using advanced diagnostic tools for explaining the disease in vast.