2009年广东省甲型H1N1流感流行特征分析

Characteristics of pandemic influenza A(H1N1) in Guangdong Province,2009

目的分析2009年广东省甲型H1N1流感大流行的流行特征,为采取相应的防控措施提供科学依据。方法收集中国疾病监测信息报告管理系统及广东省流感监测系统的流感样病例监测、病原学监测及暴发疫情监测数据,采用描述性流行病学方法分析2009年广东省甲型H1N1流感的流行特征,并用流感监测数据来估算广东省2009年到医院就诊者中的甲型H1N1流感病例数。结果2009年5月18日广东省报告首例甲型H1N1流感病例,截止2009年12月31日共有21个地级市累计报告甲型H1N1流感确诊病例9 784例,其中重症病例346例,危重病例141例,死亡36例;每周报告甲型H1N1流感病例数占全年病例总数的构成比高峰与流感监测的甲型H1N1流感就诊指数高峰相一致,均出现在2009年11月,并在12月回落,且流感样病例就诊指数也降至警戒线(5%)以下,与季节性流感高峰(7月)完全不同。从病例输入到社区传播可划分为:以国外病例输入为主的输入散发期(5月18日至6月17日);出现聚集性病例,病例主要局限于珠江三角洲的有限传播期(6月18日至7月30日);在全省流感监测网络中连续检出甲型H1N1流感核酸阳性病例为特征的持续传播期(7月31日至8月31日);病例以学校暴发为特征并在全省各市蔓延的广泛传播期(9月1日至12月31日)。分析834例临床资料完整的病例的临床表现主要以发热(95.56%)、咳嗽(59.11%)、咽痛(42.45%)等呼吸道症状为主。估算广东省2009年到医院就诊者中甲型H1N1流感感染数不少于270万例。结论广东省2009年甲型H1N1流感流行高峰出现在11月份,为单月高峰,多数病例临床表现温和,推算在全人群中感染率尚在低水平。

Objective To analyze the epidemiological characteristics of pandemic influenza A（H1N1） in Guangdong Province（GD）.Methods Influenza like illness（ILI） cases and etiological data,and outbreak reports were collected from China information system for disease control and prevention and GD influenza surveillance network,and case data of the novel H1N1 patients from clinics.Descriptive epidemiological method was used to analyze the epidemic characteristics of influenza A（H1N1） in 2009 in GD,and the influenza surveillance data were used to estimate the number of influenza A（H1N1） cases who visited hospital.Results The first influenza A（H1N1） case was confirmed in GD on May 18th,2009.A total of 9 784 H1N1 cases were reported in GD by all 21 cities in this year.Of these cases,487 were severe cases and 36 were dead.The weekly number of H1N1 case reported was associated with ILI visiting clinics from surveillance data.And the peak appeared in November 2009,not in July as the seasonal influenza shown.The proportion of outpatient visits for ILI decreased since December and was below the epidemic baseline（5%） in GD.H1N1 transmission in GD from the case imported to the community epidemic can be divided into 4 phases： Imported distribution phase（from 18 May 2009 to 17 June 2009）,Limited distribution phase（from 18 June 2009 to 30 July 2009）,mainly localized in the Pearl River Delta,Continued distribution phase（from 31 July 2009 to 31 August 2009） and Wide range distribution phase（from 1 September 2009 to 31 December 2009）.Most outbreaks occurred in schools.From clinic records of 834 cases,the main symptoms of influenza A（H1N1） were fever（95.56%）,cough（59.11%）and sore throat（42.45%）.The estimated number of cases of Influenza A（H1N1） visiting hospital were over 2.7 million.Conclusion The peak of pandemic influenza A（H1N1） in GD appeared in November 2009.The major symptoms of these cases were mild.It is accessed that the H1N1 infection level in general population of GD was low in 2009.