a mysterious epidemic suddenly struck two central African towns,

一個神祕的傳染病突然重創非洲的兩個小鎮，

killing the majority of its victims.

大多數受害者均無法生還。

Medical researchers suspected

醫學專家懷疑

the deadly Marburg virus to be the culprit.

致命的馬爾堡病毒是罪魁禍首。

But what they saw in microscope images was an entirely new pathogen,

但是他們在顯微鏡看到的的卻是一種前所未見的病原體，

which would be named after the nearby Ebola river.

他們以鄰近的伊波拉河將其命名。

Like yellow fever or dengue,

如同登革熱和黃熱病，

the disease caused by the Ebola virus is a severe type of hemorrhagic fever.

伊波拉病毒也會導致嚴重的出血性發熱。

It begins by attacking the immune system's cells

剛開始它會攻擊免疫細胞，

and neutralizing its responses,

中和他的回應能力，

allowing the virus to proliferate.

讓病毒能快速繁殖。

Starting anywhere from two to twenty days after contraction,

發病後的二至二十天，從任何地方都可能開始繁殖，

initial symptoms like high temperature,

最初的病徵包含高溫，

aching,

痛症，

and sore throat,

和喉嚨痛，

resemble those of a typical flu,

病徵類似流感，

but quickly escalate to vomiting,

但很快會逐漸擴大至嘔吐，

rashes,

紅疹，

and diarrhea.

和腹瀉。

And as the virus spreads,

隨著病毒擴散，

it invades the lymph nodes and vital organs,

他開始破壞淋巴結和重要器官，

such as kidneys and liver, causing them to lose function.

像是腎臟，肝臟，導致其失去功能。

But the virus itself is not what kills Ebola victims.

但是伊波拉病患並非死於病毒。

Instead, the mounting cell deaths trigger an immune system overload,

大量的細胞壞死使免疫系統負荷超載，

known as a cytokine storm,

也就是俗稱的高細胞因子症(細胞因子風暴)。

an explosion of immune responses that damages blood vessels,

大量的免疫反應破壞血管，

causing both internal and external bleeding.

導致內外出血。

The excessive fluid loss and resulting complications

過度的流失流質導致多重性的問題

can be fatal within six to sixteen days of the first symptoms,

第一波症狀在六到十六天內就能致死，

though proper care and rehydration therapy

適當的照護和補液療法

can significantly reduce mortality rates in patients.

能大量減少致死率。

Fortunately, while Ebola is highly virulent,

幸運的是，雖然伊波拉有著高致死率，

several factors limit its contagiousness.

有很多因素限制了他的傳染性。

Unlike viruses that proliferate through small, airborne particles,

不像細菌能在空氣粒子中繁殖，

Ebola only exists in bodily fluids,

伊波拉只能於體液中生存，

such as saliva,

比如唾液，

blood,

血液，

mucus,

組織液，

vomit,

嘔吐物，

or feces.

或排泄物。

in order to spread,

如果要擴展，

these must be transmitted from an infected person into another's body

這些液體必須要從一個感染者傳給另一個感染者

through passageways such as the eyes, mouth, or nose.

透過眼，口，鼻。

And because the disease's severity

因為這疾病的嚴重程度

increases directly along with the viral load,

隨病毒量增加而加劇，

even an infected person is unlikely to be contagious

就算一個已患病的病人

until they have begun to show symptoms.

在開始出現症狀之前也很難傳染給他人。

While Ebola has been shown to survive on surfaces for several hours,

但是伊波拉其實可以在外面存活幾小時的時間，

and transmission through sneezing or coughing is theoretically possible,

而且透過打噴嚏或咳嗽傳染理論上是有可能的，

virtually all known cases of contraction have been through direct contact

事實上所有已知的傳染都是透過與重病者

with the severely ill,

直接接觸，

with the greatest risk posed to medical workers

所以危險群包含醫護人員

and friends or relatives of the victims.

以及病人的親戚朋友。

This is why, despite its horrifying effects,

這也是為甚麼儘管伊波拉的症狀極為恐怖，

Ebola has been far less deadly overall than more common infections,

它的致死率卻比其他傳染病還要低，

such as measles,

比如說麻疹

malaria,

瘧疾，

or even influenza.

甚至流行性感冒。

Once an outbreak has been contained,

當疫情被穩定，

the virus does not exist in the human population

病毒就不存在於人類中

until the next outbreak begins.

直到下一波疫情。

But while this is undoubtedly a good thing,

這不一定是件好事，

it also makes Ebola difficult to study.

這讓伊波拉很難被研究。

Scientists believe fruit bats to be its natural carriers,

科學家相信果蝠是它的自然帶原者，

but just how it is transmitted to humans remains unknown.

但是它又是如何傳染給人類的尚屬未知。

Furthermore, many of the countries where Ebola outbreaks occur

除此之外，許多伊波拉疫情爆發的國家

suffer from poor infrastructure and sanitation,

皆為基礎建設和衛生設備較差的地區，

which enables the disease to spread.

使得疫情能快速擴散。

And the poverty of these regions,

這些地區的貧困，

combined with the relatively low amount of overall cases

加上發病案例相對低

means there is little economic incentive for drug companies to invest in research.

代表藥廠沒有甚麼利益動機能好好投入研究開發新藥。

Though some experimental medicines have shown promise,

雖然一些實驗性的藥物已經證明有效，

and governments are funding development of a vaccine,

政府也提供資金開發疫苗，

as of 2014,

在2014年，

the only widespread and effective solutions to an Ebola outbreak remain

最普及並有效控制伊波拉疫情的方式還是

isolation,

隔離，

sanitation,

增進衛生設備

and information.

和資訊透明。