Chicken anemia virus infection in broiler chickens vaccinated and not vaccinated for avian influenza in Iran

To study the role of influenza vaccination in inducing chicken anemia infection in broiler chickens in Iran, 25 flocks vaccinated for avian influenza (AI) and 25 nonvaccinated flocks were randomly selected. In this study, we attempted to select flocks with similar mortality and growing conditions. At the end of the rearing period, 15 thymus samples were taken, and after DNA extraction, a 713-bp viral protein 2 (VP2) gene of the chicken anemia virus (CAV) was amplified by specific primers. In addition, 20 batches belonging to 10 different commercial chicken vaccines were examined for evidence of CAV contamination. A total of 105 out of 375 chickens were vaccinated for AI (28%) and 135 out of 375 nonvaccinated chickens (36%) were infected with CAV. The frequency of CAV infection in the 750 studied chickens was 32% at slaughter age. The CAV VP2 gene was not detected in any commercial chicken vaccines. On the basis of statistical analyses, there were no significant correlations between vaccination for AI and CAV infection. Furthermore, comparison of the infection rate for CAV in AI-vaccinated and nonvaccinated chickens revealed no significant differences between these 2 groups. Vaccination against AI seems to play no role in increasing or reducing the prevalence of CAV.