流感是由流感病毒引起的急性呼吸道传染病。其传染速度快 ,发病率高。由于流感病毒抗原易发生变异 ,所以它是人类至今尚不能有效控制的世界性传染病 ,并被世界卫生组织列为 2 1世纪重点防治的传染病之一。 2 0世纪 ,全球共发生 4次流感大流行 ,其中 3次起源于中国。 1 998年广 Flu is an acute respiratory infection caused by the flu virus. Its contagious speed, high incidence. Due to the variation of influenza virus antigen, it is a world-wide infectious disease that human beings have not been able to effectively control so far and has been listed as one of the key infectious diseases controlled by the World Health Organization in the 21st century. In the 20th century, there were four influenza pandemics worldwide, of which three originated in China. 1 998 years wide