Sero-survey of avian influenza and associated risk factors in backyard poultry of Lahore district, Pakistan

epidemiology of avian influenza viruses (AIV) in backyard poultry is mostly unknown. A cross-sectional survey of villages of Lahore district was conducted from July 2009 to August 2009 using two-stage cluster sampling with probability proportional to size sampling to estimate sero-prevalence and by evaluating associated biosecurity risk factors. Randomly 35 clusters out of 308 villages of Lahore were selected and from each cluster, six chickens of >2 months were selected. A total of 210 serum samples were collected and examined by the hemagglutination inhibition test for specific antibodies AIV subtype H9, H5 and H7. Overall weighted sero-prevalence of subtype H5 and H9 was 20.95% (95% CI: 13.78-28.11) and 66.98% (95% CI: 56.89-77.07) respectively. Average flock-size was 14.12 birds and main purpose of keeping poultry was for eggs/meat (78.23%, 95% CI: 69.50-86.96). Majority of them reared in a semi-caged system (79.58%, 95% CI: 71.59-87.57). Backyard birds exposed to mixed watering system i.e. tape water at home and water from street drainage channel were 3.2 times more likely to become AI seropositive than those not exposed (CI 95%: 1.38-7.44, p=0.007). Bird that were kept in a backyard, close to live poultry retail shop were 3.62 times more likely to be AI seropositive compared to those that did not (CI 95%: 1.36-9.65, p= 0.010). To reduce the risk of AIV in Pakistan, continuous surveillance of backyard poultry would be needed.