Survey of an epidemic of human infection with avian influenza A (H7N9) in Yunnan

Objective To understand the epidemiological characteristics of an epidemic of human infection with avian influenza A (H7N9) virus in Yunnan province and provide evidence for the prevention and control of human infection with avian influenza in the future.

Methods A field epidemiological survey was conducted among patients and close contacts and in live-poultry markets. The samples collected from the patients and outdoor environment were detected and analyzed.

Results During June-July 2017, five confirmed cases of human infection with avian influenza A (H7N9) virus were reported in Wenshan prefecture of Yunnan, including 2 cases detected in influenza like illness sentinel surveillance, 2 cases detected in unexplained pneumonia monitoring and 1 case detected in close contacts. Three cases were women and 2 cases were men. The median age was 37 years (4.5-55 years). Four cases had the exposures to live poultry before the onset. The average intervals between the onset and the first medical care seeking, diagnosis, admission hospital and antiviral treatment were 2, 3, 9 and 7 d respectively. All the cases were isolated and treated, and all the close contacts received medical observation, positive live poultry markets were closed. The epidemic was under control effectively.

Conclusion The monitoring of unexplained pneumonia and influenza sentinel surveillance in medical institutions are the important means for the timely detection of human infection with avian influenza virus. Regular disinfection and closure of live-poultry markets are key measures to reduce the exposure opportunity.