ABSTRACT
Influenza virus H9N2 Low Pathogenicity of the viruses that are causing the disease in 1999, two 1 and 4-year-old girl in Hong Kong. Although influenza A H9N2 subtype virus is considered as widely spread low pathogen in poultry, however there are a few reports of human infection by this virus. This study was conducted to evaluate if such infection in human related by Poultry Farm Industries i.e. workers of slaughter house, poultry farms, and poultry clinics in Iran has occurred or not. In this study, sera and swabs-nasal and throat-were collected from workers of slaughter houses, poultry farms, Razi institute. To prevent false positive and negative results in HI test the sera were treated by trypsin-periodate and concentrated RBC respectively. RT-PCR was accomplished seeking HA and NP genes of H9N2 subtype influenza viruses. Of 148 sera HI titers, two and 17 samples were 1/160 and 1/40 respectively for antibody against H9N2 influenza virus. The higher titers belonged to slaughter house workers. No viruses were detected in RT-PCR. The positive sera for antibody against H9N2 influenza virus showed a changing tendency of these viruses toward infecting human tracheal epithelia. However the highest titer in slaughter house worker showed the need to close contact with poultry and their feeces for infection to be occurred. It means that the virus needs more circulation in human population to be adapted as true human influenza virus