or, come to that, any other vertebrates—but if you are a shrimp or worm or fruit fly, it can make you wish you had never been born. 或者可以说根本不伤害任何别的脊椎动物——不过，要是你是个小虾、蠕虫或果蝇，你会但愿自己真没有被生出来。

　　Altogether, only about one microbe in a thousand is a pathogen for humans, according to National Geographic, 据《国家地埋杂志》说，总的来说，大约每1000种微生物当中，只有一种是对人类致病的，

　　though, knowing what some of them can do, we could be forgiven for thinking that that is quite enough. 虽然我们知道其中还会有一些干坏事，情有可原地这么认为就够了。

　　Even if mostly benign, microbes are still the number-three killer in the Western world, 即使大多数生物是无害的，微生物仍是西方世界的第三杀手，

　　and even many less lethal ones of course make us deeply rue their existence. 虽然许多不要我们的命，但也弄得我们深深地后悔来到这个世界上。

　　Making a host unwell has certain benefits for the microbe. 把寄主弄得很不舒服，对微生物是有某种好处的。

　　The symptoms of an illness often help to spread the disease. 病症往往有利于传播细菌。

　　Vomiting, sneezing, and diarrhea are excellent methods of getting out of one host and into position for another. 呕吐、打喷嚏和腹泻是细菌离开一个寄主，准备入住另一寄主的好办法。

　　The most effective strategy of all is to enlist the help of a mobile third party. 最有效的方法是找个移动的第三者帮忙。

　　Infectious organisms love mosquitoes because the mosquito's sting delivers them directly to a bloodstream 传染性微生物喜欢蚊子，因为蚊子的螫针可以把它们直接送进流动的血液，

　　where they can get straight to work before the victim's defense mechanisms can figure out what's hit them. 趁受害者的防御系统尚未搞清受到什么攻击之前，它们可以马上着手干活。

　　This is why so many grade-A diseases—malaria, yellow fever, dengue fever, encephalitis, 因此，许多A级疾病——疟疾、黄热病、登革热、脑炎，

　　and a hundred or so other less celebrated but often rapacious maladies—begin with a mosquito bite. 以及100多种其他不大著名而往往又很严重的疾病——都是以被蚊子叮咬开始的。

　　It is a fortunate fluke for us that HIV, the AIDS agent, isn't among them—at least not yet. 对我们来说，很侥幸的是，艾滋病的介体——人体免疫缺陷病毒——不在其中，至少目前还不在其中。