What we know and dont know about Ebola Alex Gendler

In the summer of 1976,

a mysterious epidemic
suddenly struck two central African towns,

killing the majority of its victims.

Medical researchers suspected

the deadly Marburg virus
to be the culprit.

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

which would be named
after the nearby Ebola river.

Like yellow fever or dengue,

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

It begins by attacking
the immune system’s cells

and neutralizing its responses,

allowing the virus to proliferate.

Starting anywhere from two to twenty days
after contraction,

initial symptoms like high temperature,

aching,

and sore throat

resemble those of a typical flu,

but quickly escalate to vomiting,

rashes,

and diarrhea.

And as the virus spreads,

it invades the lymph nodes
and vital organs,

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

But the virus itself
is not what kills Ebola victims.

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

known as a cytokine storm,

an explosion of immune responses
that damages blood vessels,

causing both internal and external bleeding.

The excessive fluid loss
and resulting complications

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

though proper care and rehydration therapy

can significantly reduce
mortality rates in patients.

Fortunately,
while Ebola is highly virulent,

several factors limit its contagiousness.

Unlike viruses that proliferate through
small, airborne particles,

Ebola only exists in bodily fluids,

such as saliva,

blood,

mucus,

vomit,

or feces.

In order to spread,

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

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

And because the disease’s severity

increases directly along
with the viral load,

even an infected person
is unlikely to be contagious

until they have begun to show symptoms.

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

and transmission through sneezing
or coughing is theoretically possible,

virtually all known cases of contraction
have been through direct contact

with the severely ill,

with the greatest risk
posed to medical workers

and friends or relatives of the victims.

This is why,
despite its horrifying effects,

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

such as measles,

malaria,

or even influenza.

Once an outbreak has been contained,

the virus does not exist
in the human population

until the next outbreak begins.

But while this is undoubtedly a good thing,

it also makes Ebola difficult to study.

Scientists believe fruit bats
to be its natural carriers,

but just how it is transmitted to humans
remains unknown.

Furthermore, many of the countries
where Ebola outbreaks occur

suffer from poor infrastructure and sanitation,

which enables the disease to spread.

And the poverty of these regions,

combined with the relatively low amount
of overall cases

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

Though some experimental medicines
have shown promise,

and governments are funding development
of a vaccine,

as of 2014,

the only widespread and effective
solutions to an Ebola outbreak remain

isolation,

sanitation,

and information.

1976 年夏天,

一场神秘的流行病
突然袭击了中非的两个城镇,

大多数受害者丧生。

医学研究人员

怀疑致命的马尔堡
病毒是罪魁祸首。

但他们在显微镜图像中看到的
是一种全新的病原体,

它将以
附近的埃博拉河命名。

与黄热病或登革热一样,

由埃博拉病毒引起的疾病
是一种严重的出血热。

它首先
攻击免疫系统的细胞

并中和其反应,

从而使病毒增殖。

从宫缩后 2 到 20 天
开始,

最初的症状如高温、

疼痛

和喉咙痛

类似于典型流感,

但很快就会升级为呕吐、

皮疹

和腹泻。

随着病毒的传播,

它会侵入淋巴结
和重要器官,

如肾脏和肝脏,
导致它们失去功能。

但病毒
本身并不是导致埃博拉病毒受害者死亡的原因。

相反,越来越多的细胞死亡
引发免疫系统超负荷,

称为细胞因子风暴,

免疫反应的爆发
会破坏血管,

导致内部和外部出血。

尽管适当的护理和补液治疗

可以显着降低
患者的死亡率,但在出现第一个症状的 6 到 16 天内,过度的体液流失和由此产生的并发症可能是致命的。

幸运的是,
虽然埃博拉病毒的毒性很强,但有

几个因素限制了它的传染性。

与通过
空气传播的小颗粒扩散的病毒不同,

埃博拉病毒仅存在于体液中,

例如唾液、

血液、

粘液、

呕吐物

或粪便。

为了传播,

这些
病毒必须从感染者

通过眼睛、
嘴巴或鼻子等通道传播到另一个人的身体。

而且由于这种疾病的严重程度


随着病毒载量的增加而直接增加,因此

即使是感染者
也不太可能具有传染性,

直到他们开始出现症状。

虽然埃博拉病毒已被证明
可以在物体表面存活数小时,

并且通过打喷嚏
或咳嗽传播理论上是可能的,但

几乎所有已知的收缩
病例都是通过

与重症患者

直接接触,对医务工作者

和朋友或 遇难者亲属。

这就是为什么
尽管埃博拉病毒具有可怕的影响,但

总体而言,它的致命性远低于

麻疹、

疟疾

甚至流感等更常见的感染。

一旦疫情得到控制

,病毒就不会
在人群中存在,

直到下一次爆发开始。

但这无疑是一件好事,

但也让埃博拉病毒难以研究。

科学家们认为果
蝠是它的天然载体,

但它是如何传播给人类的
仍然未知。

此外,许多发生埃博拉疫情的国家

基础设施和卫生条件差,

这使疾病得以传播。

这些地区的贫困,

加上
总体病例数量相对较少,这

意味着制药公司几乎没有经济
动力投资于研究。

尽管一些实验性药物
已显示出前景,

而且政府正在资助
疫苗的开发,但

截至 2014 年,埃博拉疫情

唯一广泛有效的
解决方案仍然是

隔离、

卫生

和信息。