Our modern lifestyle increases the possibilities of viral attack by exotic organisms. For example, a virus presently located in a remote rain forest could, by means of air travel, be in a major city by this time tomorrow. We now live in such crowded cities that the scope for transmission of a virus which travels through air is greater than ever before.
我们的现代生活方式增加了身体遭受外来微生物病毒攻击的可能性。例如，一种目前存在于偏远热带雨林地区的病毒，可以通过航空旅行，在明天这个时候就传到一个大城市。我们现在生活的城市人口这么拥挤，病毒在空中传播的范围比以往任何时候都要大得多。
