MMWR Morb Mortal Wkly Rep. 2009 Oct 23;58(41):1143-6.
In April 2009, in the United States, the first cases of 2009 pandemic influenza A (H1N1) virus infection were reported. On June 11, the World Health Organization (WHO) declared an influenza pandemic because of widespread transmission worldwide. As of September 13, all six WHO regions had reported approximately 296,471 cases of pandemic H1N1, including 3,486 deaths. On June 29, the first case of pandemic H1N1 was confirmed in Kenya. At that time, only four other countries in sub-Saharan Africa had reported cases, and secondary transmission had not been documented in the region. Surveillance activities in Kenya detected four separate introductions of the virus into the country. The introductions provided an opportunity to study transmission of the virus (including calculation of secondary household attack rates) in a virus-naive population that had not yet initiated the use of antiviral drugs. This report describes the four introductions and the accompanying analysis. The overall rate of secondary household transmission of laboratory-confirmed pandemic H1N1 was 26% (range: 7%-33%), which is comparable to secondary household attack rates reported for laboratory-confirmed seasonal influenza virus infection. However, additional and more rigorous studies are needed to better understand the secondary attack rates associated with the current pandemic.
2009年4月，美国报告了首例2009年甲型H1N1流感大流行病毒感染病例。6月11日，世界卫生组织（WHO）因该病毒在全球范围内广泛传播而宣布流感大流行。截至9月13日，WHO的所有六个区域均报告了约296,471例甲型H1N1流感大流行病例，其中包括3,486例死亡病例。6月29日，肯尼亚确诊了首例甲型H1N1流感大流行病例。当时，撒哈拉以南非洲地区仅有其他四个国家报告了病例，且该区域尚未记录到二代传播情况。肯尼亚的监测活动发现该病毒有四次分别传入该国的情况。这些传入事件为研究该病毒在尚未开始使用抗病毒药物的未接触过病毒的人群中的传播情况（包括计算家庭二代感染率）提供了机会。本报告描述了这四次传入事件及相关分析。实验室确诊的甲型H1N1流感大流行的家庭二代传播总体率为26%（范围：7%-33%），这与实验室确诊的季节性流感病毒感染报告的家庭二代感染率相当。然而，需要进行更多更严格的研究，以更好地了解与当前大流行相关的二代感染率。
