heart disease, asthma, arthritis, multiple sclerosis, several types of mental disorders, many cancers, even, it has been suggested (in Science no less), obesity. 心脏病、哮喘、关节炎、多发姓硬化、几种精神病、多种癌症，甚至有人提出（反正在《科学》杂志上是这样写的）糖尿病——中，都有或很可能有某种细菌的份儿。

The day may not be far off when we desperately require an effective antibiotic and haven't got one to call on. 我们迫切需要而又弄不到一种有效的抗生素的日子也许已经为期不远。

It may come as a slight comfort to know that bacteria can themselves get sick. 我们知道细菌本身也会得病，这也许是个稍稍的安慰。

They are sometimes infected by bacteriophages (or simply phages), a type of virus. 它们有时候会被一种名叫噬菌体的病毒所侵染。

A virus is a strange and unlovely entity—"a piece of nucleic acid surrounded by bad news" in the memorable phrase of the Nobel laureate Peter Medawar. 病毒是一种古怪而又讨厌的实体——用诺贝尔奖获得者彼得·梅达沃的话来说——是“身边都是坏消息的一点儿核酸”。

Smaller and simpler than bacteria, viruses aren't themselves alive. 病毒比细菌还小，还简单，本身没有生命。

In isolation they are inert and harmless. 在孤立状态中，病毒是中性的，没有害处。

But introduce them into a suitable host and they burst into busyness—into life. 但是，要是进入一个适当的寄主，它们就马上忙个不停——有了生命。

About five thousand types of virus are known, and between them they afflict us with many hundreds of diseases, 已知的病毒大约有5000种，它们致使我们患好几百种疾病，

ranging from the flu and common cold to those that are most invidious to human well-being: 从流行性感冒和普通感冒，到对人类健康极其有害的疾病：

smallpox, rabies, yellow fever, ebola, polio, and the human immunodeficiency virus, the source of AIDS. 天花、狂犬病、黄热病、伊波拉病、脊髓灰质炎和艾滋病。