Usually this occurs when a wild flu virus circulating in ducks and farm poultry
通常这会发生在的强烈的传染性病毒在鸭群和农畜中不断传播，
meets a pig virus, and they exchange genes.
遇上了猪流感，它们转变了基因。
This process is known as antigenic shift and has occurred throughout human history.
这一过程就是众所周知的抗原转移，并贯穿在整个人类历史。
The first recorded pandemic occurred in 1580.
第一个被记录的流行病是在1580年。
The 18th and 19th centuries saw at least six further pandemics.
在18和19世纪生活的人见证了至少六种以上的流行病。
In terms of mortality, none can compare with the Great Flu Pandemic of 1918.
但在死亡率方面，没有什么能与1918年的大流感比拟。
The first indication of the pandemic came in the spring,
第一次大流感爆发的迹象是在春季，
when American troops in northern France began complaining of chills, headaches and fever.
当时美军在法国北部，军士们开始抱怨寒冷，头痛和发热。
Then, the following September, at a U.S. Army barracks near Boston,
然后，在接下来的九月份，在美国波士顿军营中，
soldiers started collapsing on parade, prompting their removal to the camp infirmary.
士兵们开始崩溃，他们被转移到到军医处。
As a surgeon there recalled, two hours after admission, they had the mahogany spots over the cheekbones
外科医生被召到军医处，入院后的两个小时，他们的颧骨已经有了红褐色的斑点。
and a few hours later you can begin to see the cyanosis extending from their ears and spreading all over the face.
再过几个小时，你们就能看见黄萎病已经蔓延到他们的耳朵，还遍布了全脸。
It is only a matter of a few hours then until death comes,
这离他们病逝只是几个小时的时间，
and it is simply a struggle for air until they suffocate.
他们一般会因为呼吸困难最终窒息而死。
On the S.S. Leviathan, a huge American transport en route to Bordeaux,
在利维坦轮船--一艘开往波尔多的美国运输轮上
sick men hemorrhaged blood from their noses, turning the decks between their bunks slick with bodily fluids.
病人鼻孔出血，把甲板都变成了充满体液的光滑床铺。
