最近各地接二连三发生多宗传染病,市民宜特别小心饮食卫生。不过,最难预防的还是流行性感冒,原因是流感病毒每数年突变一次,使往年研制出来的疫苗无效。本文探讨近百年来为患世界各地的几种常见流感。 In recent days, a number of infectious diseases have been reported in different places. People should be especially careful about their diet and hygiene. However, the hardest-to-reach prophylaxis is influenza because influenza viruses mutate every few years and invalidate vaccines developed in previous years. This article explores several common forms of flu that have taken the world over the past century.