Epidemiology of human infection with avian influenza A(H7N9) virus in China, September-December,2014

Objective To understand the epidemiological characteristics of human infection with avian influenza A(H7N9) virus in the mainland of China during September-December,2014,and provide scientific evidence for the improvement of preventive strategy and control measures. Methods The information of demographic characteristics and epidemiological histories of the human H7N9 virus infection cases were collected through from field epidemiological investigation and communicable disease reporting system. Results A total of 31 cases were reported during this period, including 9 deaths, an increase of 2.1 times over the same period in 2013. The 31 cases were distributed in 7 provinces, in which 13 occurred in previous epidemic areas and 18 occurred in new epidemic areas. The median age of the confirmed cases was 54 years(range 7-83 years), and the male cases accounted for 48%(15/31). Up to 93.5% of the cases had exposure to live poultry or contaminated environments. Conclusion The incidence of human infection with avian influenza A(H7N9) in the Mainland of China showed an obvious increase during September-December 2014 compared with the same period in 2013 and cases clustering were observed in some areas. Most cases had live poultry or poultry market exposure histories before illness onset. New sporadic cases and new affected area would continue to appear in this influenza season. Reducing the exposure to poultry or live poultry market is essential in the prevention of human infection with H7N9 virus.