Epidemiological survey of infection source of the first case of human infection with avian influenza A (H7N9) virus in Huairou District, Beijing

On 5 February 2014, a case of pneumonia with unknown origins was reported by the First Hospital of Huairou District, Beijing. The case had poultry exposure history. The sample collected from the case was detected to be nucleic acid positive for avian influenza A (H7N9) virus by Hairou District Center for Disease Control and Prevention (CDC), and the human infection with H7N9 virus was confirmed by Beijing Municipal CDC. Then the epidemiological survey was conducted by Huairou District CDC to trace the infection source of this case.