Sero-survey of Avian Influenza in backyard poultry and wild bird species in Iran-2014.

In almost all villages in Iran backyard birds, especially chickens, are kept for egg and meat production. AI H9N2 subtype is endemic in Iran. Therefore, estimation of AI prevalence among these birds is important to determine the risk of transmission of infection to commercial farms. The aim of this study was to estimate subclinical infections or previous exposure to H5, H7, and H9 subtypes and to identify potentially important determinants of prevalence of this infectious at premises level in backyard poultry, bird gardens, zoos, and wild bird markets in Iran. A survey was conducted using a cross-sectional design throughout the entire country. A total of 329 villages, seven bird gardens, three zoos and five wild bird markets were included. In each village four families that kept birds were included in the collection of biological samples and background information. The Enzyme-Linked Immunosorbent Assay (ELISA) was used as the screening test and all ELISA-positive samples were examined with the HI test to differentiate H5, H7, and H9. Among the bird gardens, eight of 15 premises (53.3%) were positive in both the ELISA test and HI for H9N2. Testing of samples collected in the villages revealed that 296 out of 329 villages (90%) had positive ELISA tests and also HI tests for H9. The HI-H9 mean titers in positive units were significantly higher than negative units (P<.001). This study revealed no significant statistical differences between risk variables in seropositive and seronegative bird gardens in the case of H9 (P>.05). The results of this study showed that among the risk variables, mountainous area was a protective factor and lack of hygienic disposal of dead birds was a risk factor for AI; this was also observed in rural poultry. The high sero-prevalence of influenza H9N2 in rural domestic poultry indicates that the disease is endemic. It is necessary to include backyard poultry in any surveillance system and control strategy due to the existence of AIV in backyard poultry and the possibility of transmission of infection to commercial poultry farms. Implementation of an AI surveillance program and biosecurity measures can be useful to control this infection and prevent AI from spreading to commercial farms. Furthermore in Iran there is no program for destruction of birds infected with the H9N2, so an effective vaccination program with regard to issues such as acceptability and cost-benefit must play an important role in reducing infections in backyard poultry.