a collaborative effort to engineer the perfect superbug?

作ろうとしているのかもしれない

A bug that could kill hundreds of millions of people?

何百万人殺せる細菌だ

Well, it is happening right now.

そんな事態が進行している

We are in the process of creating a superbacterium.

スーパーバクテリアの誕生だ

Bacteria are among the oldest living things on this planet.

細菌は地球最古の生物だ

The smallest thing we still consider life, they are masters of survival

最も小さく しぶとい生物で

and can be found everywhere.

どこにでもいる

Most bacteria are harmless to us.

ほとんどは無害だ

Your body hosts trillions of them, and they help you to survive.

人体にとって必要なものもある

But others can invade your body, spread quickly, and kill you.

しかし有害なものもある

Millions of people used to die as a result of bacterial infections.

細菌感染で大勢が死んだが

Until we developed a superweapon—antibiotics.

私たちは抗生物質を発明した

Together with vaccinations, antibiotics revolutionized medicine

医薬品における革命であり

and saved millions of lives.

多くの命を救った

Antibiotics kill the vast majority of susceptible bacteria fairly quickly,

抗生物質が細菌を大量に殺すことで

leaving only a small group of survivors

体の免疫系が楽に働けるようになる

that our immune system then deals with easily.

仕組みはこうだ

How do antibiotics do this?

細菌が 何千もの仕掛けで動く

Imagine a bacterium as a very complex machine

複雑な機械のようなものだとしよう

with thousands of complex processes going on that keep it alive and active.

抗生物質はこの機械の邪魔をする

Antibiotics disrupt this complex machinery,

たとえば代謝を妨害して 力を奪う

for example, by interfering with its metabolism,

DNAを攻撃し 複製を防ぐものもある

slowing down their growth significantly, so they are less of a threat.

増殖できなければ細菌は死ぬ

Other antibiotics attack DNA and prevent it from being replicated,

細胞壁を壊すものもあり

which stops bacteria from multiplying, ultimately killing them.

この場合 中身が漏れて死ぬ

Or by simply ripping the outer layer of the bacteria to shreds,

これらは体細胞には効かない

so that their insides spill out and they die quickly.

だが今 進化が事を複雑にした

All of this without bothering body cells.

偶然により わずかだが細菌の中に

But now, evolution is making things more complicated.

耐性を持つものが生まれる

By pure random chance, a small minority of the bacteria invading your body

抗生物質を無害化するような

might have evolved a way to protect themselves.

物質を出したり

For example, by intercepting the antibiotics

抗生物質を追い出すような

and changing the molecule so it becomes harmless.

ポンプを持っていたり

Or by investing energy in pumps that eject the antibiotics

数が少なければ

before they can do damage.

免疫系が処理して問題ない

A few immune bacteria are not that big a deal,

だが逃げて 増殖したら問題だ

because the immune system can take care of them.

どう増殖するのか

But if they escape, they might spread their immunity.

細菌は二種類のDNAを持つ

How can bacteria spread immunity?

染色体とプラスミドだ

First of all, bacteria have two kinds of DNA:

細菌同士はくっつくと

the chromosome and small free-floating parts called plasmids.

プラスミドを交換する

They can hug each other and exchange those plasmids

これにより能力が共有される

to exchange useful abilities.

またDNAを受け渡す

This way, immunity can be spread quickly through a population.

形質転換という作用もある

Or, in a process called transformation, bacteria can harvest dead bacteria

これは異種間でも行われるため

and collect DNA pieces.

耐性菌の出現に繋がる可能性がある

This even works between different bacteria species

すでに耐性菌は存在する

and can lead to superbugs, bacteria that are immune to multiple antibiotics.

特に病院で生まれやすい

A variety of superbugs already exist in the world.

人類は忘れている

Especially hospitals are the perfect breeding grounds for them.

細菌に支配されていた恐怖を

Humans have short memories.

今日 薬は簡単に買えるが

The horrors of the pre-antibiotic era have been forgotten.

薬の開発はそう簡単ではない

Today, we treat this powerful medicine as a commodity

これが問題を生む

instead of as the game-changing achievement of science that it is.

途上国では抗生物質が不足する一方

This has led to a strange disconnect:

先進国では余った抗生物質が

hundreds of millions of people still don’t have access

気軽に使われている

to antibiotics in developing countries,

抗生物質は重い病気に

while in other parts of the world antibiotics are prescribed too freely

最後の手段で使うべき薬だ

and taken without care.

肉生産での使われ方は深刻な問題だ

Antibiotics should be a last-resort drug,

現在 世界には

not something you take because your cold is annoying.

200～300億の家畜がいる

Another serious problem is antibiotic use in meat production.

家畜の飼育環境は劣悪だ

At any particular point in time, humanity holds

空間は狭く 衛生状態は良くない

between 20 and 30 billion animals as livestock.

菌にとっては良い環境だ

To make meat cheaper, many animals are held in horrible conditions,

そのため多くの家畜に

in very tight spaces, and in unhygienic conditions,

抗生物質が投与されている

the perfect breeding ground for disease.

安いチーズバーガーのためだ

So many animals are given antibiotics to kill as many bacteria as possible

この仕組みでは 耐性菌が

and prevent them from getting sick.

次々に生まれると予想されるため

Because a cheeseburger has to cost a dollar.

同じ薬品の使用は避け

Unsurprisingly, as a result of this system,

秘密兵器も用意している

we have created more and more bacteria

耐性菌も殺せる特別な抗生物質だ

that are resistant to antibiotics.

制限して使えば耐性菌は生まれない

To counteract this, we use different antibiotics

と思っていた

and we have another secret weapon: there are specific antibiotics

2015年 中国で事件は起きた

that are used to wipe out bacteria that have developed resistance.

コリスチンへの耐性菌が現れたのだ

There are strict rules for using these to avoid the creation of a superbacterium.

コリスチンは肝臓に悪いため

Or so we thought.

使用は控えられながらも

In late 2015, scary news arrived from China.

他の薬に耐性を持った細菌に対する

Resistance against Colistin, a last-ditch antibiotic,

最終手段としてよく効く薬だった

had been discovered.

この耐性菌は本当に悪いニュースだ

Colistin is an old drug and was rarely used, because it can damage the liver.

最終防衛ラインが破られたのである

So there was little resistance against it, which made it a great

なぜこうなったか

antibiotic of last resort for certain complex infections that occur in hospitals

中国で長年 豚にコリスチンが使われ

to fight bacteria that have become immune to a whole bunch of other drugs.

耐性菌が生まれると

Bacteria resistance to Colistin is very, very bad news.

素早く広まっていったのだろう

It might destroy a last line of defense and lead to a whole lot of dead people.

今や一日10万の飛行機が飛び

How could this happen?

世界の人々を繋いでいる

Millions of animals in Chinese pig farms have been given Colistin for years.

便利な現代世界はまた

Resistant bacteria developed, spreading first from animal to animal,

パンデミックの危険も大きい

and then to humans without being noticed.

慌てるのはまだ早い

On an average day, there are over 100,000 flights on Earth,

人類には科学の力がある

kind of connecting every human on the planet.

細菌は日々進化していくが

By creating the modern world, we have also built the infrastructure

技術も同時に進歩する

for a dangerous pandemic.

厳しいが 勝てない戦いではない

Still, we don’t need to panic just yet.

私たちが正しく対処すれば

Bacteria evolve, humans do research, new antibiotics are developed

怖いものはないだろう

as old ones become obsolete, technology is advancing every day.

Subtitles by the Amara.org community

The problem is real and serious, but the fight is far from over.

If humanity plays its cards right, superbugs might turn out to be

not very super after all.

This video was made possible by viewer support on Patreon.com

and a grant from the Bill & Melinda Gates Foundation.

If you want to support us to make more videos,

you can buy a Kurzgesagt poster or a mug or donate on Patreon.

Thank you so much for your help!

Subtitles by the Amara.org community