Prevalence of Avian Influenza in Live Bird Markets, Bird Gardens, and Zoos in Iran in ۲۰۱۵: A Cross-sectional Study

Avian Influenza (AI) H۹N۲ 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 ۲۰۱۵ 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 H۵, H۷, and H۹. Regarding H۵ and H۷, the antigens H۵N۲ and H۷N۱ were used in this study. Positive samples on the first test were examined with the second antigens, namely H۵N۱ and H۷N۷. Moreover, sera with titers ≥۴ (i.e. log۲) were considered positive and premises with at least one positive bird were considered as positive units. In total, ۸۷ 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 H۹N۲ were ۸۳.۹% and ۳۱.۸% at the premises and bird levels, respectively. Totally, ۹.۲% of pooled swab samples were positive for H۹N۲. However, all sera and swab samples were negative for H۵ and H۷. Hot and humid weather (OR=۰.۱۳, ۹۵% CI ۰.۰۲ – ۰.۷۸) as well as bird-keeping condition (i.e., enclosed area) (OR=۰.۱۱, ۹۵% CI ۰.۰۱۲ – ۱.۰۲) were protective factors for H۹N۲. High seroprevalence rate of H۹ 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.