What makes tuberculosis (TB) the world's most infectious killer? - Melvin Sanicas

翻译人员: Wentao Chian 校对人员: Heze Ma

In 2008, archeologists uncovered two 9,000-year old skeletons.

2008年考古学家发现了 两具9000年前的骸骨，

There’s no definitive way of knowing what killed these ancient people,

这些古人的死因虽然尚未知晓，

but we do know their bones were infected by an all too familiar bacterium.

但感染这些骸骨的病菌 我们再熟悉不过了。

The ancient Greeks knew its consumptive effects as phthisis;

古希腊人将这一肺病称为“癆”；

the Incans called it chaky oncay; and the English called it tuberculosis.

印加人将其称为“癆瘵” ， 英国人称之为“肺结核”。

Today, tuberculosis, or TB,

肺结核或TB如今

is still one of the world’s biggest infectious killers,

仍是世界上最大的致命性感染病之一，

causing more deaths than malaria or even HIV and AIDS.

导致死亡的人数超过 疟疾或HIV病毒和艾滋病。

But what exactly is this disease, and how has this pathogen persisted for so long?

但这到底是何种疾病？ 这一病原体又为何如此难缠？

Typically, TB bacteria called mycobacterium tuberculosis, are airborne.

导致肺结核的结核杆菌 一般是由空气传播的。

They travel into our airways and infect our lungs.

它们会进入气管并感染肺脏。

Here, immune cells called macrophages rush to the infection site,

肺里的巨噬细胞会赶到 受感染处做出免疫反应，

attempting to absorb and break down the bacterial invaders.

努力吞噬、分解这些细菌侵略者。

In many cases, this response is enough to remove the bacteria.

多数情况下这样就能消灭细菌。

But in individuals with other medical conditions–

但患有其它病症的人，

ranging from malnutrition and HIV to diabetes and pregnancy

如营养不良，患有HIV、 肥胖症或是怀有身孕，

–the immune response may not be strong enough to destroy the intruder.

免疫系统则可能无法 有效地消灭这些病菌。

If so, mycobacterium tuberculosis will reproduce inside those macrophages,

这时结核杆菌会在巨噬细胞内繁殖，

and form colonies in the surrounding lung tissue.

并在周边组织中形成菌落。

As they infect more cells,

受感染细胞不断增多，

the bacteria employ cell-degrading enzymes that destroy the infected tissue,

同时病菌会分泌酶素降解细胞 并破坏受感染的组织，

triggering chest pain, and causing patients to cough up blood.

这会带来胸痛，使病人咳血。

The damage to the lungs leads to oxygen deprivation.

肺部受损会导致缺氧，

This begins a flood of hormonal changes–

这会打乱荷尔蒙平衡，

including a decrease in appetite and iron production.

因此胃口会变差， 铁元素的生成会降低。

From here, microbes can spread to the skeletal system,

然后细菌会扩散到骨骼系统，

causing back pain and difficulty moving;

带来背部疼痛、行动不便，

to the kidneys and intestines, causing abdominal pain;

或扩散到肾脏和肠道，带来腹痛；

and to the brain, causing headaches and even impaired consciousness.

或扩散到大脑， 导致头疼甚至神智不清。

These symptoms produce the classic image of TB:

这些会带来典型的肺结核病象：

weight loss, a hacking, bloody cough, and ashen skin.

变瘦、干咳、咳血、面色苍白。

This ghostly appearance earned TB the title of the ‘White Plague’

因此肺结核在维多利亚时期的英格兰

in Victorian-era England.

也有着“白色瘟疫”的恶名。

During this period, tuberculosis was considered a ‘romantic disease,'

这一时期，肺结核被看作是“浪漫之疾”，

because it tended to affect poverty- stricken artists and poets–

因为患者通常是贫穷至极的 艺术家和诗人——

those with weaker immune systems.

因为他们的免疫系统较差。

TB’s outward symptoms even helped fuel the popular myth of vampirism.

肺结核的病象让 吸血鬼的传说更加盛行。

In spite of– or perhaps because of these less than scientific concerns,

即使这种担忧没有任何科学依据， 或者可能正因如此，

this period also marked the first strides toward curing TB.

这一时期在治愈肺结核的 道路上迈出了一大步。

In 1882, the German physician Robert Koch

1882年，德国医生罗伯特∙科赫

identified the disease’s bacterial origins.

找到了该疾病的细菌源。

13 years later, physicist Wilhelm Roentgen  discovered the X-ray,

13年后，物理学家 威廉·伦琴发现了X光，

enabling physicians to diagnose and track its progression through the body.

这使得医生们能诊断 并跟踪细菌在体内的蔓延。

These techniques allowed researchers to develop reliable and effective vaccines–

研究人员用这些技术 研制出了可靠、有效的疫苗——

first for smallpox, and again in 1921,

首先是针对天花，然后在1921年，

when scientists developed the BCG vaccine to battle TB.

科学家又研发出了卡介苗， 用于对抗肺结核。

These developments laid the groundwork for the modern field of antibiotics–

这些研发为当下的 抗生素研究奠定了基础——

currently home to our most effective TB treatments.

目前抗生素是针对 肺结核最有效的治疗手段。

But, antibiotics fail to address a major diagnostic complication:

但是抗生素无法克服的 一个诊断难点是：

about 90% of people infected with TB don’t show any symptoms.

约90%的肺结核病菌携带者 并没有表现出任何症状。

In these latent infections, the TB bacterium may be dormant,

在这些肺结核病菌携带者体内的 结核杆菌可能处于休眠状态，

only activating when someone’s immune system is too weak to mount a defense.

只有在免疫力下降、 抵抗力减弱时才会苏醒。

This makes TB much harder to diagnose.

这也让肺结核很难被诊断出来。

And even when properly identified,

即使诊断成功，

traditional treatments can take up to 9 months,

传统治疗手段也会长达9个月，

requiring multiple drugs and a high potential for side effects.

用药诸多，潜在副作用大。

This discourages people from finishing the full course,

很多人因此无法完成疗程，

and partial treatment enables bacteria to develop resistance to these drugs.

治疗的中断也会使细菌产生抗药性。

Today, the disease is still prevalent in 30 countries,

目前肺结核仍然盛行于30个国家，

most of which face other health crises

其中大部分国家 还面临着其它的健康危机，

that exacerbate TB and trigger latent cases.

这使得肺结核更加棘手、 潜伏病例增多。

Worse still, accessing treatment can be difficult in many of these countries,

雪上加霜的是，在这些国家 的患者接收治疗往往很难，

and the stigma towards TB can discourage people from getting the help they need.

很多人会因肺结核所带来的 耻辱感而不寻求治疗。

Health experts agree we need to develop better diagnostics,

卫生专家一致认为我们需要 研发更好的诊断手段、

faster acting antibiotics, and more effective vaccines.

见效更快的抗生素和更有效的疫苗。

Researchers have already developed a urine test that yields results in 12 hours,

研究人员已开发出一种尿检方法， 可在12小时内得到诊断结果，

as well as a new oral treatment that could cut treatment time by 75%.

以及一种新的口服药物， 可将治疗时间减少75%。

Hopefully, with advancements like these,

希望这些进步

we’ll finally be able to make TB exclusively a thing of the past.

终有一天能让肺结核成为历史。