Throughout Europe, it was known as variola, meaning " spotted."

整个欧洲将其称为“痘斑”，意为 “斑点”。

But the vaccinia virus is only distantly related to the variola virus that causes smallpox.

但是牛痘病起天花的天花病关系疏远。

At some point a critical threshold is reached and variola starts its attack for real.

在某个时刻，达到了临界阈值，天花就会真正开始攻击。

How could variola be so incredibly deadly for  so long and how could we have forgotten its horror so quickly?

天花怎么能在这么长时间内如此令人难以置信地命，我们又怎么能这么快就忘记它的恐怖呢？

The immune system will forever remember variola, making  you immune forever.

免疫系统将永远记住天花，让您永远免疫。

And so, with little resistance variola spreads  everywhere and infects billions of your cells all over your body.

因此，天花在几乎没有抵抗力的情况下会传播到感染全身数十亿个细胞。

Variolation probably worked because it introduced  the variola in a part of the body the virus wasn't prepared for, disabling most of its nasty  tricks.

天花接种之所以有效，可能是因为它将天花入了病未准备好的身体部位，从而使其大部分令人讨厌的伎俩失效。

Other systems would usually help  - like the complement system, a sort of mobile minefield that can destroy viruses but  variola also manages to shut this down too.

其他系统通常会有所帮助——比如补体系统，这是一种可以消灭病的移动雷区，但天花也能成功地关闭它。

Pus and cellular junk fills it up as  your body swells up with hundreds of lesions, all over your skin and inside, even on your organs,   all filled with billions of variola viruses.

当你的身体因数百个病变而肿胀时，脓液和细胞垃圾就会填满它，遍布你的皮肤和内部，甚至在你的器官上，都充满了数十亿的天花病。

As immune cells begin cleaning up dead  cells, eating viruses and killing infected cells , variola infects a crucial cell of  your immune system: Your Dendritic cells, intelligence cells that gather information  and leave the battlefield to get help.

当免疫细胞开始清理死亡细胞、吞噬病杀死受感染的细胞时，天花会感染您免疫系统的关键细胞：树突状细胞，即收集信息离开战场寻求帮助的情报细胞。