The virus spread through the air, attacking the skin cells, bone marrow, spleen, and lymph nodes of its victims.

此病毒藉由空氣傳播，攻擊皮膚細胞、骨髓、脾臟及淋巴結。

The unlucky infected developed fevers, vomiting, and rashes.

不幸感染的人會發燒、嘔吐、起疹子。

30% of infected people died during the second week of infection.

30% 患者會在感染後第二週死亡。

Survivors bore scars and scabs for the rest of their lives.

倖存下來的人也會留下永久性傷疤與結痂。

Smallpox had arrived.

這個病毒就是天花。

In 1350 B.C., the first smallpox epidemics hit during the Egypt-Hittite war.

天花第一次爆發是在西元前 1350 年埃及與西臺的戰爭期間。

Egyptian prisoners spread smallpox to the Hittites, which killed their king and devastated his civilization.

埃及的囚犯把天花傳染給西臺人，導致西臺國王死亡，間接摧毀了西臺文明。

Insidiously, smallpox made its way around the world via Egyptian merchants,

不知不覺間，天花因埃及商人遍佈全世界，

then through the Arab world with the Crusades,

隨十字軍東征傳播到阿拉伯世界，

and all the way to the Americas with the Spanish and Portuguese conquests.

而後又因西班牙與葡萄牙殖民而傳至美洲。

Since then, it has killed billions of people with an estimated 300 to 500 million people killed in the 20th century alone.

自那時起，天花導致了數十億人死亡，光是二十世紀期間，就造成三至五億人口死亡。

But smallpox is not unbeatable.

但天花並非無藥可解。

In fact, the fall of smallpox started long before modern medicine.

事實上，天花感染早在現代醫學前就已逐漸減少。

It began all the way back in 1022 A.D.

一切始於西元 1022 年。

According to a small book, called "The Correct Treatment of Small Pox,"

於《天花正確療法》書中記載著，

a Buddhist nun living in a famous mountain named O Mei Shan, in the southern province of Sichuan,

一名住在四川南部峨眉山上的尼姑

would grind up smallpox scabs and blow the powder into nostrils of healthy people.

將天花造成的疙瘩磨碎，並吹入健康者的鼻孔中。

She did this after noticing that those who managed to survive smallpox never got it again,

她這麼做是因為注意到那些熬過天花的倖存者，都沒有再次感染，

and her treatment worked.

而她的療法真的有用。

The procedure, called variolation, slowly evolved,

這個被稱為「人痘托種」的療法慢慢演化，

and by the 1700s, doctors were taking material from sores and putting them into healthy people through four or five scratches on the arm.

至十八世紀， 醫生會從病人瘡疤中取出部分物質，並於健康者的手臂上割出四到五個傷口，放入擷取物。

This worked pretty well as inoculated people would not get reinfected, but it wasn't foolproof.

此方法相當有效，接種過的人們從此不會再感染，但這方法並非全然無虞。

Up to 3% of people would still die after being exposed to the pus.

仍有 3% 的人於接種後死亡。

It wasn't until English physician Edward Jenner noticed something interesting about dairy maids that we got our modern solution.

直到有位叫愛德華．琴納的英國醫師察覺到發生在牧場女工身上的有趣現象，現代醫學解法才出現。

At age 13, while Jenner was apprentice to a country surgeon and apothecary in Sodbury, near Bristol,

琴納十三歲時，在布里斯托附近的薩德貝禮當外科醫師兼藥劑詩學徒，

he heard a dairy maid say, "I shall never have smallpox, for I have had cowpox."

聽到一名牧場女工說：「因為我得過牛痘， 所以不會得天花。」

"I shall never have an ugly, pockmarked face."

「我不會有滿臉痘痕的醜臉。」

Cowpox is a skin disease that resembles smallpox and infects cows.

牛痘是種和天花很像的皮膚病，但主要是感染牛隻。

Later on, as a physician, he realized that she was right.

不久後，作為醫生的他發現女工所說的沒錯。

women who got cowpox didn't develop the deadly smallpox.

感染過牛痘的女性不會得到致命的天花。

Smallpox and cowpox viruses are from the same family.

天花與牛痘是同源的病毒。

But when a virus infects an unfamiliar host, in this case cowpox infecting a human, it is less virulent,

但若感染的宿主不同，也就是人感染牛痘，毒性就會較弱。

so Jenner decided to test whether the cowpox virus could be used to protect against smallpox.

因此琴納決定做個實驗， 看看牛痘是否能用來對抗天花病毒。

In May, 1796, Jenner found a young dairy maid, Sarah Nelmes,

1796 年 5 月，琴納發現一名叫莎拉·芮姆的牧場女工，

who had fresh cowpox lesions on her hand and arm caught from the udders of a cow named Blossom.

她最近才從乳牛布洛森的乳房得到了牛痘病毒。

Using matter from her pustules, he inoculated James Phipps, the 8-year-old son of his gardener.

他將莎拉膿包裡的膿接種到園丁的八歲兒子，詹姆士．菲普身上。

After a few days of fever and discomfort, the boy seemed to recover.

經過幾天的發燒與不適之後，小男孩漸漸康復。

2 months later, Jenner inoculated the boy again, this time with matter from a fresh smallpox lesion.

兩個月後，琴納又將天花病毒膿包萃取物接種到同一名小男孩身上。

No disease developed, and Jenner concluded that protection was complete.

病毒沒有引發疾病，琴納因此斷定此療法有效。

His plan had worked.

計畫成了。

Jenner later used the cowpox virus in several other people and challenged them repeatedly with smallpox,

琴納接著用牛痘病毒接種到其他人身上，並以天花病毒不斷驗證，

proving that they were immune to the disease.

證明他們對這種天花具免疫力。

With this procedure, Jenner invented the smallpox vaccination.

琴納利用這個程序發明了牛痘疫苗接種。

Unlike variolation, which used actual smallpox virus to try to protect people,

不像人痘托種使用天花病毒來產生保護力，

vaccination used the far less dangerous cowpox virus.

牛痘接種用的是毒性較弱的牛痘病毒。

The medical establishment, cautious then as now, deliberated at length over his findings before accepting them.

然而醫學界一向十分嚴謹，慎重考慮了很長一段時間才慢慢接受此療法。

But eventually, vaccination was gradually accepted and variolation became prohibited in England in 1840.

最終，疫苗接種總算被眾人肯定，而英國也在 1840 年禁止了人痘托種。

After large vaccination campaigns throughout the 19th and 20th centuries,

經過 19 到 20 世紀間長時間的努力，

the World Health Organization certified smallpox's eradication in 1979.

世界衛生組織總算在 1979 年時確認天花病毒已被根除。

Jenner is forever remembered as the father of immunology,

琴納也因此被稱為免疫學之父永留青史，

but let's not forget the Buddhist nun, dairy maid Sarah Nelmes, and James Phipps,

但也別忘了那名尼姑、牧場女工莎拉·芮姆、詹姆斯·菲普斯，

all heroes in this great adventure of vaccination, who helped eradicate smallpox.

以及所有助力根除天花的無名英雄。