一个国际研究小组4月17日说，季节性的流感病毒毒株通常首先在亚洲出现，然后在几个月内传至世界其他地区。这是科学家得出的最新的季节性流感病毒传播“路线图”，有望帮助更有针对性地监测流感。

来自欧洲、澳大利亚、日本和美国的科学家对多达1.3万个来自世界各地的H3N2亚型流感病毒的样本进行了研究。H3N2是A型（甲型）流感病毒的一个亚型，也是目前导致人类染病甚至死亡的主要流感亚型。

科学家在新一期美国《科学》杂志上报告说，他们分析了病毒样本的表面蛋白质“血凝素”（即红血球凝聚素）之间的差异，并比较了病毒负责编码“血凝素”的基因序列。“血凝素”在病毒的人际间传播过程中扮演重要角色，借助对“血凝素”的分析，科学家能够识别出传播至新地点的流感病毒新毒株。

分析结果表明，每年H3N2病毒毒株在东亚和东南亚出现，并在那里交叉传播。毒株不断变异，大约在6到9个月后抵达欧洲和北美。之后，病毒继续传播至南美，通常到南美之后即渐渐止息。

研究小组说，从流感病毒的传播路线来看，应该重点加强对东亚和东南亚地区的流感疫情监测，进而更准确地预测世界其他地区的流感病毒类型，每年为人们提供更有针对性的流感疫苗。另外，鉴于流感的跨地域传播特性，各国科研人员也应该加强在流感监测方面的合作和信息通报。

根据世界卫生组织的统计数据，全球每年有大约300万至500万人因感染流感病毒而严重发病。流感疫苗是人们抵御流感的有力武器，每年大约使3亿人免受流感侵袭。

原始出处：

The Global Circulation of Seasonal Influenza A (H3N2) Viruses

Colin A. Russell,1Terry C. Jones,1,2,3Ian G. Barr,4Nancy J. Cox,5Rebecca J. Garten,5Vicky Gregory,6Ian D. Gust,4Alan W. Hampson,4Alan J. Hay,6Aeron C. Hurt,4Jan C. de Jong,2Anne Kelso,4Alexander I. Klimov,5Tsutomu Kageyama,7Naomi Komadina,4Alan S. Lapedes,8Yi P. Lin,6Ana Mosterin,1,3Masatsugu Obuchi,7Takato Odagiri,7Albert D. M. E. Osterhaus,2Guus F. Rimmelzwaan,2Michael W. Shaw,5Eugene Skepner,1Klaus Stohr,9Masato Tashiro,7Ron A. M. Fouchier,2Derek J. Smith1,2*

Antigenic and genetic analysis of the hemagglutinin of 13,000human influenza A (H3N2) viruses from six continents during2002–2007 revealed that there was continuous circulationin east and Southeast Asia (E-SE Asia) via a region-wide networkof temporally overlapping epidemics and that epidemics in thetemperate regions were seeded from this network each year. Seedstrains generally first reached Oceania, North America, andEurope, and later South America. This evidence suggests thatonce A (H3N2) viruses leave E-SE Asia, they are unlikely tocontribute to long-term viral evolution. If the trends observedduring this period are an accurate representation of overallpatterns of spread, then the antigenic characteristics of A(H3N2) viruses outside E-SE Asia may be forecast each year basedon surveillance within E-SE Asia, with consequent improvementsto vaccine strain selection.

1 Department of Zoology, University of Cambridge, Cambridge, UK.
2 Department of Virology, Erasmus Medical Centre, Rotterdam, Netherlands.
3 Universitat Pompeu Fabra, Barcelona, Spain.
4 World Health Organization (WHO) Collaborating Centre for Reference and Research on Influenza, Melbourne, Australia.
5 WHO Collaborating Center for Influenza, Centers for Disease Control and Prevention, Atlanta, GA, USA.
6 WHO Collaborating Centre for Influenza, National Institute for Medical Research (NIMR), London, UK.
7 WHO Collaborating Center for Influenza, National Institute for Infectious Diseases, Tokyo, Japan.
8 Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA.
9 Novartis Vaccines and Diagnostics, Cambridge, MA, USA.