Objective To analyze the epidemiological characteristics of one case of human infection with avian influenza A (H9N2) virus in Beijing, so as to provide references for scientific management of similar diseases in the future.

Methods The methods of field epidemiology were used to collect the epidemiological data. Samples of the H9N2 case, the relevant environment and the close contact persons were collected and were tested in the laboratory. The epidemiological characteristics and possible sources of infection were then analyzed.

Results H9N2 avian influenza virus nucleic acid in the swab specimens were positive on the 3rd and 7th days after disease onset. The case had no contact history of live poultry within 10 days before onset. But there existed a possibility of exposure to his living environment contaminated by H9N2 avian influenza virus. The close contacts showed no influenza-like symptoms during medical observation period.

Conclusions The case was the second human case of avian influenza A (H9N2) virus infection, and the first confirmed adult case. Surveillance of influenza-like cases in medical institutions is an important mean to find cases of human infected with avian influenza A (H9N2) virus timely.