Abstract
Infectious bronchitis (IB) is a highly contagious disease of the respiratory and urogenital tract of chickens, caused by infectious bronchitis virus (IBV), a member of the family Coronaviridae. Due to the serious infectious and transmission features of the disease mostly in the reproductive and respiratory systems it causes potential economic loss. Hence a cross-sectional study was conducted from February 2022 to June 2022 on chicken serum and tracheal swab samples from backyard and commercial farms in central Gondar zone, Ethiopia, to determine the seroprevalence of IB, associated risk factors and for isolation and molecular detection of the virus. A total of 384 blood samples were collected and tested by an indirect ELISA and Anti-IBV antibody positivity was noted in 92.19% (95% confidence interval (89 % -94.6 %) of the samples. Logistic regression analysis was performed to determine the impact of possible risk factors on seropositivity. Higher prevalence was noted in young chickens than in adults (p< 0.05) and in exotic breeds than in local breeds (p<0.05). Though the difference was not statistically significant (p>0.05), higher prevalence was obtained in dual purpose chickens (93.75%) than in layers (92.17%) and broilers (90.98%). Higher prevalence was also noted in females (92.7%) than in males (90.98%) and in intensively managed chickens (93.39%) than in extensively managed chickens (90.69%) with p>0.05. Conventional RT-PCR test was also performed for the molecular detection of virus. The test was done on 52 tracheal swab samples collected from intensive and backyard unvaccinated chickens that were pooled in to 26 samples. Accordingly, 3 (11.54%) of the 26 pooled samples were IBV positive. The result showed that this was the first molecular evidence found in the study area. The seroprevalence of the disease in this study was very high for all age groups, breed types, and farm types. The risk factors mentioned and the management methods may have raised the likelihood of infection and the prevalence of the disease. Vaccination and biosecurity measures are advised to manage the disease. Identification and characterization of persistent IBV serotypes that are present in the field is also recommended to manage the disease.