From time to time certain strains of virus return. A disagreeable Russian virus known as H1N1 caused severe outbreaks over wide areas in 1933, then again in the 1950s, and yet again in the 1970s. Where it went in the meantime each time is uncertain. One suggestion is that viruses hide out unnoticed in populations of wild animals before trying their hand at a new generation of humans. No one can rule out the possibility that the Great Swine Flu epidemic might once again rear its head.
有几种病毒不时重复出现。一种名叫H1N1的讨厌的俄罗斯病毒分别于1933年、20世纪50年代和70年代在广大地区猛烈爆发。在每次爆发的间歇期间，那种病毒去了哪里，我们仍不清楚。有的人认为病毒藏在野兽体内，不为人们所察觉，然后把黑手伸向新一代人类。谁也无法排除这种可能性：猪大流感会再度出现。

And if it doesn't, others well might. New and frightening viruses crop up all the time. Ebola, Lassa, and Marburg fevers all have tended to flare up and die down again, but no one can say that they aren't quietly mutating away somewhere, or simply awaiting the right opportunity to burst forth in a catastrophic manner. It is now apparent that AIDS has been among us much longer than anyone originally suspected. Researchers at the Manchester Royal Infirmary in England discovered that a sailor who had died of mysterious, untreatable causes in 1959 in fact had AIDS. But for whatever reasons the disease remained generally quiescent for another twenty years.
即使猪大流感不出现，别的流感也很可能出现。骇人的新病毒在不断地的产生。伊波热、拉沙热和马尔堡经常爆发，然后再度消失，但谁也说不准这些病毒是悄悄隐伏在什么地方，还是仅仅在等待合适的机会以灾难性的方式爆发。现在已经很明显，艾滋病在我们中间停留的时间之长，已经超过了任何人原先的想象。曼彻斯特皇家医院的研究人员发现，1959年死于神秘不治之证的那名海员，实际上是患了艾滋病。然而，不管什么原因，那种疾病总的来说是悄无声息地潜伏了随后的20年。
The miracle is that other such diseases haven't gone rampant. Lassa fever, which wasn't first detected until 1969, in West Africa, is extremely virulent and little understood.
别的这样的疾病没有变得那么猖獗，这是个奇迹。直到1969年，拉沙热才在西非首次发现，那是一种极其致命的疾病，我们对其了解甚少。