中国内地人感染H7N9禽流感疫情流行病学特征分析

Epidemiological characteristics of human avian influenza A （H7N9） virus infection in China

目的 分析中国内地人感染H7N9禽流感疫情.方法 以2013年以来我国内地报告的确诊H7N9禽流感病例为研究对象,采用描述性流行病学方法分析病例的时间、空间和人群分布特点.结果 截至2014年6月4日中国内地共确诊人感染H7N9禽流感病例433例,死亡163人.2013年3-4月及2014年1-2月分别为2个发病高峰.病例分布在14个省（市）,报告病例数前五位的省份为浙江、广东、江苏、上海、湖南,占总报告病例数的85％;病例年龄1～91岁（M=58岁）;男性占70％.82％的病例在发病前有活禽相关的暴露史.共发生14起聚集性病例,其中9起发生人传人的可能性大.结论 中国内地人感染H7N9禽流感疫情有较明显的季节分布特点,同时呈现一定的区域聚集性;感染人群以老年人为主,男性多于女性;感染来源主要为禽类.

Objective To investigate the epidemiological characteristics of human infections with avian influenza A （H7N9） in China and to provide scientific evidence for the adjustment of preventive strategy and control measures.Methods Demographic and epidemiologic information on human cases were collected from both reported data of field epidemiological investigation and the reporting system for infectious diseases.Results A total of 433 cases including 163 deaths were reported in China's Mainland before June 4,2014.Two obvious epidemic peaks were noticed,in March to April,2013 and January to February,2014.Confirmed cases emerged in 14 areas of China.Five provinces,including Zhejiang,Guangdong,Jiangsu,Shanghai,and Hunan,reported about 85％ of the total cases.Median age of the confirmed cases was 58 years （range,1-91）,with 70％ as males.Of the 418 cases with available data,87％ had ever exposed to live poultry or contaminated environments.14 clusters were identified but human to human transmission could not be ruled out in 9 clusters.Conclusion Human infections with avian influenza A （H7N9） virus showed the characteristics of obvious seasonal distribution,with certain regional clusters.The majority of confirmed cases were among the elderly,with more males seen than the females.Data showed that main source of infection was live poultry and the live poultry market had played a significant role in the transmission of the virus.