a mom, and her son on the right.

そして右にいるのが息子だ

And it turns out that mom has tuberculosis,

ママが結核に感染してることが分かったとする。

let's assume that.

考えてみよう

And sometimes when you see "Tuberculosis"

Tuberclosis（結核）

written out the way I'm writing it out,

と書くより

you'll actually see it shorthanded,

簡単に

or kind of use the quick way of saying it,

もっと早く説明できるように

which is two letters: TB.

TB（結核）と言うよ

So let's say mom has TB.

さて、ママはTB(結核)に感染している

Now, this is actually a diagnosis, right?

それが診断名だね

This is a description of her illness.

つまりママの病気の名前

This is telling us what she actually has,

ママは

what she is sick with.

病気だ

But we have to remember that tuberculosis is

でも、ここで知っておいてもらいたい。

actually caused by an organism.

結核はとても小さな生物によって引き起こされるんだ

It's actually caused by a bacteria, it turns out.

それが細菌ということも分かっている

And this bacteria has the name "Mycobacterium".

この細菌は「マイコバクテリウム属」というグループに属している

Mycobacterium Tuberculosis.

本名はMycobacterium Tuberculosis（結核菌）

So this is actually a very easy one to remember,

覚えやすいね

because "tuberculosis" is right here in the name.

本名の中にtuberculosis（結核）が入ってるからね

Now I should point out Mycobacterium Tuberculosis

注目すべきは

is actually not the only cause of tuberculosis.

ただ単に結核菌が結核を起こす訳ではないということだ

It turns out there are few other kind of related

他のいくつかのマイコバクテリウム属の仲間も

mycobacterium, using this word "myco", that also cause TB.

結核を引き起こすんだ。

But this one, the one I wrote out for you,

結核は

this is definitely the most common around the world,

世界中のいろんな場所で確認されている

and that's the one I'm going to focus on.

今日は結核とは何かを知ってもらいたい

And in fact this "myco", this is actually Greek

「myco」っていうのは

for the term "fungus".

ギリシャ語で菌類、カビとかキノコ、の意味

And the reason that this is here actually kind of tells us

そう呼ばれる理由は

a little bit about how this bacteria grows,

この細菌の成長と関係がある

because it grows really slowly, like a fungus,

この細菌はまるで菌類のように成長が遅いんだ

and that's actually the reason that they use the term "myco".

なので「myco」が頭につくようになった

But nevertheless it is a bacteria, and so if we're going to

それでもやっぱりこいつは細菌

put a little bracket around the diagnosis,

だから

I also want to put a little bracket around this part,

ここのところに「細菌」と書いておくよ

to kind of distinguish the two.

「診断」と同じように目立たせておこう

So now you can see very clearly TB,

これで分かりやすくなった

the diagnosis is caused by a bacteria.

結核は細菌が引き金となる

So now let's talk about how mom, who we said already

それで

is sick with TB... I'm going to actually just

病気のママだけど、

sketch out what her lungs might look like,

彼女の肺がどうなっているのか、

assuming that the TB is in her lungs.

結核菌が肺で何をしているのか書いてみよう

This is actually the most common place we think of

結核菌は肺に住み着くって思っているよね

with TB, but not the only place.

だけどそこだけじゃないんだけどね

But let's say that she's got little red, I'm going to draw it

赤で書いてみるよ

in red, bacteria here in her lungs, causing her to be

細菌は肺にいる

very, very sick with tuberculosis.

だから彼女はとっても具合が悪い

She could spread it to her son.

さらに息子に伝染させてしまった

But what are the different ways that she might spread it?

どうやってうつしてしまったのかな？

What are the most common ways?

感染経路はなんだろう？

Well, let me sketch out a few possibilities,

いくつかの可能性があるな

and we're going to go over whether these possibilities

どれが一番

are very likely or unlikely to be a way for her

可能性が高いのか

to spread disease to her son.

考えてみよう

Let' say first they are sharing this delicious pizza

まず、おいしいピザを一緒に食べた場合

I'm drawing here. Let's say they are very into pizza

これがピザ。 この親子はピザが大好きで

and they like to share food, and they both chow down

よくシェアするんだ

on this little pizza here, that's one way they might

この小さなピザを食べる、

potentially you might think of as a way to spread it.

これが感染経路になってる可能性があるね

Maybe they're even sharing a drink.

もしかしたら飲み物もシェアしてるかも

Maybe there is a drink here, and they are sharing again.

これが飲み物、また一緒に飲んじゃう

You might also think about what's going on

こういうことが家の中で行われている

in their house: maybe they're opening and closing doors,

家のドアを開けたり閉めたりもするよね

and maybe they're touching door knobs,

そうするとドアノブを触るから

there is another way, right, maybe they're touching stuff

これがもう一つの感染経路となる

in common. Maybe she says to him:

よくタッチしあってるかもしれない、こんな風に

"Hey, here, grab these keys" and she's been holding

「鍵をしっかり持っててね」

the keys all day, and then she gives him the keys

で、一日中持っていた鍵を

and he holds the keys.

息子が受け取る

There is another way, maybe the TB can touch objects

直接のタッチじゃなくても、ドアノブとか鍵とか

in the environment, like a door knob or a key.

物を介して、という経路もある

And then there's the most obvious way

そしてもっとも確実なのが

you might be thinking: maybe she's coughing,

分かってるかもしれないけど、

maybe she has a loud cough, maybe she's coughing

咳。彼女は一日中激しく咳をする

all day and some of these bacteria get in the air.

そうすると細菌が空気中にでてくる

That's another way that you might imagine that the

これによって息子にうつしてしまう

bacteria could spread from her to her son.

ってことが想像できるよね

So different ways, right. Now, of these ways,

これらの異なる経路

I'm actually going to label this one over here,

…最後のは

let's say this is through the air.

分かりやすく空気と書いておこう

Which are the most common ways to be really concerned

どれが結核菌のもっともよくある

about TB spreading?

感染経路なんだろうね？

I'm actually going to just put it in green,

緑で菌を書いておこう

so it really sticks out.

目立たせて、と

The most common way is what we call

一番よく起こるのは

"Person to person through the air".

人から人への空気感染だ

So in this case the first person would be mom,

このケースでは、最初の感染者はママ

because she is sick, and it's going to go

ママから

through the air, down to her son.

息子へ空気感染

And these other ways, for example food and drink,

他の経路、例えば食べ物飲み物は

that's really not so common, that's really really unlikely

実はそれほど結核菌の拡散においては

to be a way of spreading TB and in fact,

頻繁には起らないんだ

even this down here is really not likely either.

下のタッチによる感染も同じ

So the idea of getting TB by sharing food and drink

食べ物のシェアやお互い・

or touching objects in your environment

鍵やドアノブの接触による

like the keys or the door knob, or things like that,

結核菌の感染は

that's really not how TB spreads usually.

実はそれほど多くない

Usually it spreads through the air.

もっとも多いのは空気感染

And one person, the sick person is usually coughing a lot,

患者はよく咳をするから

and then the other person might breathe it in.

他の人が呼吸時に感染してしまうんだ

So let me make a little bit of space on this canvas

ちょっとだけキャンバスを移動するよ

and let's talk about what happens next.

よし。じゃあ次に何が起るかを話そう

I'm going to draw one alveolus here,

肺胞を書いてみよう

and I'm going to copy it a few times just so you can see

これから起ることの違いが分かるように

a few different possibilities in terms of what might happen,

いくつか書いてみよう

and these represent the son's alveoli.

これらは息子の肺胞ね

These are the son's alveoli.

肺胞っていうのは

And of course these are the tiny little air sacks

肺の末端にある

at the very ends of the bronchial tree, right?

小さな空気袋だ

So we'll make a few copies of this.

これもいくつか書いてみよう

There we go, we have four possibilities:

４つの可能性がある

Possibility 1, 2, 3 and 4.

可能性１、２、３、４、と

Basically, we'll go through different scenarios,

ママが咳をしたとき

different things that might happen when mom coughs.

４つのことが起こりうるんだ

So maybe she coughs and the first possibility could be

まず一つ目が

that the bacteria just don't get far enough,

細菌がそんなに飛ばず

they don't actually make it to the son,

息子まで到達もせず

and he never ends up breathing them in.

それを吸い込むこともないという可能性

So if this was the case, there would be no bacteria

この場合、彼の肺胞には細菌がいないので

in his alveoli, of course his lungs are nice and clean,

肺は元気だしきれいだ

let me draw his lungs in, they look nice and clean,

元気できれいな肺を書いてみよう

with no bacteria, and he's feeling great.

細菌もいないし、気分も良い

Right, this is our son over here feeling really good,

これが元気な息子

and we would say basically in this case,

これがシナリオ1

in scenario one, he's healthy, because the bacteria

彼は健康

never even got to his lungs.

なぜって細菌は肺にまで来ていないから

Now, Scenario 2.

次、シナリオ２

Let's say that the cough actually was very strong

咳が大きくて

and he was close by and he ended up breathing

さらにママの側にいたものだから

some of these in through his nose or his mouth

鼻か口から入った細菌が

and they went down into his lungs.

肺にまで到達してしまった

That's another possibility.

起こりうるよね

Once the bacteria get there, let me actually draw them

一度細菌が到達すると、

on this little alveoli, in possibility number 2,

細菌を書くよ、

they might actually get picked up by little immune cells.

小さな免疫細胞がそいつを捕らえる

So he has little cells that are patrolling the lungs,

小さい細胞が元気できれいで健康な状態を保つために

making sure they are nice and clean and healthy,

肺をパトロールしてるんだ

and these little immune cells, we'll label them over here,

この小さな免疫細胞は

these are Macrophages, this literally means

マクロファージという名前

"Big eater", because "phage" means "to eat",

意味は「大食い」。 「pharge」っていうのは「食べる」って意味

so these immune cells, they might come by and gobble up

これがやってきて、細菌をがつがつ食べる

these bacteria, and take them in, and destroy them.

そして破壊するんだ

That's another possibility.

これが

So that would be possibility number two.

シナリオ2

So here the bacteria are gone.

細菌はいなくなった

Now let's play it out again.

もう一度やってみよう

And let's say in Scenario 3 also you have a couple

シナリオ3では

of bacteria in here, and just as before, you got a couple

さっきと同じように

of immune cells that come by, and they swallow up these

マクロファージが食べに来るんだけど、

little bacteria, these are the macrophages I'm drawing,

…これがマクロファージ、

swallowing up the bacteria, but let's say that

残念ながら、少し細菌が残ってる

unfortunately in Scenario 3, now, these macrophages,

なぜだか分からないけど、シナリオ3では

for whatever reason, cannot destroy the bacteria.

マクロファージが細菌をやっつけられなかったようだ

The bacteria is still living, and that's why I draw them here

細菌はまだ生きている

as little red dots. They are still living, still there.

赤い点々が細菌ね

And now let me draw the fourth scenario,

じゃあシナリオ4

which is again let's say a couple of bacteria get in,

さっきと同じだね

and the immune cells again get alerted, and they come by,

また細菌が来る、マクロファージが警報を出して

and pick up one of them, maybe thîs immune cell is

やつらを捕まえる

trying to go after this other one, maybe it's really close by,

がんばるんだけれども

but here the key difference is that these bacteria

さっきと違うのは細菌がどんどん増えてしまうということ

are actually multiplying, so I'm going to draw lots of them.

だからいっぱいこいつらを書こう

These bacteria are multiplying and they're filling up

こいつらはどんどん増えて

this space. So this space is filling up with

隙間を埋め尽くしてしまう

little tiny red bacteria.

…これが細菌

So the key difference here is that

どんどん増えるということが

these ones are multiplying.

さっきとは違う点だね

And we didn't really talk about the other scenarios

他のシナリオでは

having bacteria that are multiplying.

増えるってことはなかったからね

But now, that's the key new thing here.

新しい言葉を使うよ。このシナリオのことを

And in this scenario, we'd call it "Active"...

「アクティブ（活動性がある）」と言うんだ

because you're actually seeing the bacteria thriving,

この細菌は繁殖している状況を

we call this "Active TB infection".

「活動性の結核感染」と言うんだ

And that goes back to what we would label

他のはどうだろう

the other scenarios, these ones, and these ones together,

これと、これは

we actually call both of them "Latent TB infection".

「潜在性結核感染」と言う

And the reason I'm putting them together is because

なぜシナリオ2と3をまとめて言ったかというと

it's very hard clinically to distinguish Scenario 2

臨床上この二つを区別するのはとても難しいからだ

from Scenario 3, because in both cases,

どちらのケースも

the immune system has previous experience with

免疫システムは過去に結核菌と出会っている

the TB bacteria, it's seen the TB bacteria,

で、どちらのケースでも

and in both cases you're not seeing lots and lots

結核菌がどんどん増えている

of bacteria dividing or multiplying,

ようには見えない

so we lump these together and call them both

だからまとめて

"Latent TB infection".

「潜在性結核感染」と呼ぶんだ

The real key, and this kind of the take home that I want

違いを覚えてもらいたい

to point out, is that there is difference then between

ここでいう「健康」とは

"healthy", someone that's really never seen TB

結核菌にこれまでの人生で一度も感染したことのない状態、

in their life before; "Latent", where you have seen TB

「潜在性」とは過去に結核菌に感染した、

previously, but you don't have any bacteria

でも今は

that are multiplying; and "Active TB infection",

増殖もしていない状態

where you have lots and lots of

「活動性結核感染」は

TB bacteria that are multiplying.

結核菌がたっくさん増殖している状態

Let me make just a little bit more space then.

…もうちょっとだけスペースを使おう

I'm going to focus now on just this final one,

シナリオ4

this multiplying, active TB infection situation.

不幸にもこの息子が

So if, let's say, our son in this case,

ママから結核菌をもらってしまい

gets tuberculosis from mother, from mom,

増殖性の、活動性結核感染の状態になった場合

and let's say unfortunately he has an

これを活動性だと見分ける

active TB infection, what are some clues

手がかりがあるのだろうか？

to tell us that he has an active infection?

本当に活動性の感染症だという手がかり。

If I'm trying to figure out if somebody has TB,

結核菌感染者を書いてみよう

I always think about two key things:

僕はいつも二つのことを頭に入れているんだ

What are their symptoms? What are they sick with?

症状はどんなか？なぜ病気なのか？

That's the first thing.

これが一つ目

And then: How long is it going on for?

二つ目は「罹病期間」と言うんだけど

I'm going to call that "Duration".

どれくらいつづいているか？ということ。

And these two offer really really helpful clues

この二つは結核感染者を理解するのに

to figure out if someone has TB.

とても役に立つ

And with symptoms, I'm going to break it up into

症状については二つのカテゴリーに分けて考える

two categories. The first is "Constitutional",

一つ目は「全身症状」かどうか

and this is constitutional symptoms, and this is

全身症状っていうのは

the things that affect the whole body.

体全部に影響がでているってことだ

The whole body, so I'm going to put a little bracket

全身

on the entire body to remind us of that.

熱とか寒気とかは

And this could be things like fevers or chills,

全身症状だね

you can't really point to one part of your body

体のある部分をさして

and say "This is the part that's having fevers and chills".

ここが熱だ、ここが寒気だ、とは言わないだろう

You'd say just generally "I feel awful".

普通は「具合が良くない」って言うよね

This could be things like night sweats if you wake up

寝汗も全身症状かな。

and your t-shirt is all wet, you might say

起きるとTシャツが

those are night sweats.

びしょびしょだったりする

Another example of a constitutional symptom

他の例だと

is weight loss, particularly when you are not trying

体重が落ちることだ

to lose weight, especially because you are

特に減量していないとか

maybe not eating as much, or you're vomitting.

食べてないとか、吐いているなんてとき

Anything like that...

そんな感じ