An epidemiological study on the prevalence and associated risk factors of infectious bronchitis virus in poultry farms in northern Vietnam.

Abstract

Infectious bronchitis virus (IBV) remains a major respiratory pathogen of economic concern in the poultry industry. This study investigated the farm-level prevalence of IBV and evaluated associated risk factors in northern Vietnam by a cross-sectional study from June 2022 to June 2024. A total of 69 poultry farms were randomly selected across nine provinces, and pooled tracheal swab samples were purposively collected for IBV detection using RT-qPCR. The overall IBV farm-level prevalence was 34.78&#x202f;% (95&#x202f;% CI:23.71-47.21&#x202f;%). Although no statistically significant differences were found across provinces, production types, age groups, or flock sizes, IBV was detected in all subgroups, indicating widespread circulation of the virus. A total of 22 potential risk factors were initially assessed using univariate logistic regression. Of these, six variables with P&#x202f;<&#x202f;0.1, including farm size, number of poultry houses, presence of multiple age groups, vaccination at day-old, frequency of disinfection before chick placement, and proximity to live bird markets and residential areas, were selected for multivariable logistic regression. The final multivariable model retained two independent predictors: performing more than one disinfection before chick placement (P&#x202f;=&#x202f;0.035), and administration of a live IB vaccine at one day of age (P&#x202f;=&#x202f;0.006), both of which were significantly associated with reduced the odds of IBV infection at the farm level. These findings suggest that strategic vaccination and careful calibration of disinfection protocols are critical to minimizing IBV transmission at the farm level.