Prevalence of Avian Influenza in Live Bird Markets, Bird Gardens, and Zoos in Iran in 2015: A Cross-sectional Study

Avian Influenza (AI) H9N2 is endemic in Iran; therefore, it is necessary to estimate the disease prevalence among birds in live bird markets (LBMs) and assess the risk spread across the country. Accordingly, this study aimed to estimate the prevalence of AI subtypes in LBMs, bird gardens, and zoos during October and November 2015 in Iran and investigate the associated risk factors. Data related to independent variables for birds and premises were collected using a prepared questionnaire which included items about previously known potential risk factors associated with avian influenza infection. Serological testing was carried out to detect the antibodies against H5, H7, and H9. Regarding H5 and H7, the antigens H5N2 and H7N1 were used in this study. Positive samples on the first test were examined with the second antigens, namely H5N1 and H7N7. Moreover, sera with titers ≥4 (i.e. log2) were considered positive and premises with at least one positive bird were considered as positive units. In total, 87 premises were included in this cross-sectional study. Serum samples were examined utilizing hemagglutination inhibition, and RT-PCR was conducted on swab samples. Regarding the molecular test, the RNA was extracted using the High Pure Viral RNA Kit (Roche, Germany). In addition, real-time RT-PCR was conducted based on the described method. The seroprevalence rates of H9N2 were 83.9% and 31.8% at the premises and bird levels, respectively. Totally, 9.2% of pooled swab samples were positive for H9N2. However, all sera and swab samples were negative for H5 and H7. Hot and humid weather (OR=0.13, 95% CI 0.02 – 0.78) as well as bird-keeping condition (i.e., enclosed area) (OR=0.11, 95% CI 0.012 – 1.02) were protective factors for H9N2. High seroprevalence rate of H9 indicates that the disease is endemic in Iranian LBMs. Active surveillance must be carried out in LBMs, especially in the northern provinces of Iran. In addition, cleanliness and improved hygiene would be useful to prevent the spread of disease in LBMs.