Since humanity's earliest days, we've been plagued by countless disease-causing pathogens.

从人类早期开始，我们就一直被各种致病的病原体所困扰。

Invisible and persistent, these microorganisms and the illnesses they incur have killed more humans than anything else in history.

这些无形且持久的微生物及其导致的疾病已经是剥夺人类性命之物的王中之王。

But which disease is deadliest varies across time and place.

然而，最致命的疾病会随着时间和地点的改变而变化。

Because while the march of progress has made us safer from some infectious threats, human innovation often exposes us to surprising new maladies.

虽然人类不断的进步会让我们免受一些传染病的威胁，但人类的创新往往让我们面临措手不及的新的疾病。

Our tour of history's deadliest diseases begins when humans lived in small hunter-gatherer communities.

历史上最致命疾病始于人类活在小型狩猎采集社区的时期。

The illnesses these pre-agricultural nomads encountered most likely came from the various animals they ate,

这些早期游牧民族最常遇到的疾病可能来自他们所食用的各种动物，

and the soil and water they interacted with.

以及他们接触的土壤和水源。

There are no written records to help us identify these diseases, however, some illnesses leave distinct growths or lesions on the skeleton,

虽然没有书面记录可以 帮助我们弄清楚这些疾病，但有些疾病会在骨骼上留下独特的生长物或病变，

allowing bioarchaeologists to diagnose ancient remains.

能够让生物考古学家对古代的遗骸进行诊断。

And researchers have found that bones from this era suggest the presence of tuberculosis and treponemal infections.

研究人员发现这个时期的骨骼显示出存在肺结核和梅毒感染。

While these conditions are life-threatening, the deadliest diseases are invariably part of widespread epidemics,

虽然这些疾病威胁生命，但最致命的疾病无一例外都是广泛流行的大疫情。

and there's no evidence of any large-scale outbreaks in this lengthy pre-agricultural period.

没有证据表明在这段漫长的农前时期出现了大规模疫情。

However, when humans started developing agriculture around 12,000 years ago, it brought a whole new crop of diseases.

然而，当人类在大约一万两千年前开始发展农业时，农业带来了一整套新的疾病。

Early farmers knew little about waste and water management, setting the stage for diarrheal diseases like dysentery.

早期的农民对废物和水资源的管理知之甚少，为像痢疾这样的腹泻性疾病铺平道路。

Much worse, the proliferation of open fields and irrigation created standing pools of water which brought mosquitoes and in turn malaria— one of history's oldest and deadliest diseases.

更糟糕的是开阔的田地和灌溉造成了滞水，带来了蚊子，从而带来了疟疾--历史上最古老也是最致命的疾病之一。

We don't know exactly how many early farmers malaria killed, or how many it left vulnerable to other lethal infections.

我们不知道究竟有多少早期的农民因疟疾丧生，或者有多少人因此变得易受其他致命感染的侵袭。

But we do know this mosquito-borne illness continued to spread through humanity's next major development: urbanization.

但我们确实知道，这种由蚊子传播的疾病继续在城市化， 这一人类下一个重大发展进程中传播。

In small communities, infectious diseases like measles and smallpox can only circulate so long before running out of hosts.

在小社区中，像麻疹和天花这样的传染病只能在宿主群体中传播一段时间。

But in densely populated regions with high birth rates,

但在人口密集且出生率高的地区，

fast-evolving viruses like the flu can continually infect new individuals and morph into various strains.

像流感这样快速演变的病毒可以不断感染新的个体并演化成各种毒株。

When large settlements became common, medical science hadn't advanced enough to effectively treat or even distinguish these variants.

当大型定居点变得普遍时，医学科学还没有进步到足以有效治疗，甚至区分这些病毒变种，

Nor was it prepared to deal with one of the deadliest pandemics of all time: the Black Death.

也没有准备好应对有史以来最致命的大流行病之一：黑死病。

From the 1330s to the 1350s, the bubonic plague swept Asia, Africa and Europe,

从13世纪的30年代到50年代，鼠疫席卷了亚洲，非洲和欧洲，

reducing the global population from 475 million to roughly 350 million.

全球人口从4.75亿减少到大约3.5亿。

Like most Afro-Eurasian diseases, the plague didn't cross the Atlantic until Europeans did in the late 1400s.

和大多数非洲-欧亚疾病一样，鼠疫直到15世纪末欧洲人穿越大西洋后才进入美洲，

But at the height of the plague in Europe, Asia, and North Africa, infection was almost guaranteed,

但在欧洲、亚洲和北非鼠疫的高峰期，感染几乎是必然的，

and the plague's fatality rate ranged from 30 to 75%.

而鼠疫的死亡率在30%到75%之间。

However, the illness wasn't equally distributed among the population.

然而，疾病在人口中的分布并不平均，

Many wealthy lords and landowners were able to stay safe by hiding away in their spacious homes.

许多富有的领主和地主通过躲在宽敞的家中保持安全。

As medical knowledge became more robust, this kind of class disparity began reflecting who had access to medical care.

随着医学知识变得越来越扎实，这种阶级差异开始折射出谁可以得到医疗服务。

And that divide became particularly apparent during the reign of our next deadly disease.

在我们下一个致命疾病的统治期间，这种差距变得尤为明显。

By the beginning of the 19th century, tuberculosis was already one of the most common causes of death in Europe and the Americas.

到19世纪初，肺结核已经是欧洲和美洲最常见的死亡原因之一。

But the Industrial Revolution led to working and living conditions that were overcrowded and poorly ventilated,

但工业革命导致工作和生活条件拥挤且通风很差，

turning TB into an epidemic that killed a quarter of Europe's adult population.

使得肺结核成为一种疫情，杀死了欧洲成年人口的四分之一。

The unhealthiest environments were largely populated by impoverished individuals who often went untreated,

贫困的人口大多居住在最不健康的环境，他们通常得不到治疗，

while doctors provided wealthier victims with the era's most cutting-edge care.

而医生为富有的病患提供了那个时代最先进的护理。

Throughout the 20th century, vaccines became common in many countries, even eradicating the centuries-old viral threat of smallpox.

在20世纪，疫苗在许多国家逐渐普及，甚至根除了肆虐了几个世纪的病毒——天花。

The advent of vaccination, alongside improvements in nutrition and hygiene, have helped people live longer lives on average.

疫苗的出现，加上营养和卫生的改善，帮助人们的延长了平均寿命。

And today, medical advances in rapid testing and mRNA vaccines can help us tackle new outbreaks in record time.

如今，快速检测和mRNA疫苗方面的医学进步可以帮助我们在创纪录的时间内应对新的疫情。

However, countless regions around the world remain unable to access vaccines, leaving them vulnerable to older threats.

然而，世界上仍有无数地区无法获得疫苗，使他们容易受到之前病毒的威胁。

Malaria still takes the lives of over 600,000 people every year, with 96% of deaths occurring in communities across Africa.

每年仍有超过60万人死于疟疾，其中96%的死亡发生在非洲各地。

Tuberculosis continues to infect millions, almost half of whom live in Southeast Asia.

结核病继续感染数百万人，其中近一半受感染的人生活在东南亚。

Addressing these ailments and those yet to emerge will require scientists to develop new and more effective medicines.

为解决这些疾病以及那些还未出现的疾病将需要科学家研发更新且更有效的药物。

But something governments and health care systems can do today is working to make the treatments we have already accessible to all.

但政府和医疗系统今天可以做的是努力是让所有人都能用上当下我们已有的治疗方案。