TB epidemiology | Infectious diseases | NCLEX-RN | Khan Academy

Voiceover: Back in 2011, I’m
going to write it down here. Our worlds population
was about 6.9 billion. That’s a pretty large number and sometimes when I’m thinking of big numbers they
all kind of melt into each other. I thought it would be helpful to just
write it out so you could see it. 6.9 billion people and that’s
what I try to represent here with this little black circles,
that’s my best attempt. It’s showing all the people on the planet and you just have to take my word for
it that it’s roughly representative. What I wanted to point
out is that the WHO, the World Health Organization, has
said that about one in three people living on our planet, so you
just divide this number by three. One in three people has
latent TB infection., so this is an enormous number of people. When you read that you
might not think about it but that’s actually 2.3 billion
people with latent TB infection. Remember when I say latent TB infection, what I mean is that the bacteria is
either dormant inside of someone’s lungs or it’s dead but it’s really
hard to tell the difference so we always kind of hedge
on the side of being cautious and we treat them as if they have
dormant bacteria in their lungs. Some of us might even see the term LTBI. Now keep your eye on the map and
what I’m going to do is show you what that would actually look like. So if I actually erased
two-thirds of the people this is what you basically
have left, something like this. This people are the ones that we can
imagine then have latent TB infection. Still a lot of people right? The WHO found that in 2011. There are also about nine million
individuals that had active disease. This is actually people that are
coughing and having chest pain, maybe having bloody sputum, all sorts of signs and
symptoms of active disease. That’s a huge number of people and we know that a lot of those
folks have active disease, they’re actually coming from
this pool of latent TB infection. Now about 10% of these folks
that have latent TB infection will actually go on to get active disease and you can break that down further and say well 5% will be in
the first couple of years after they get the latent TB infection. Another 5% will be over a lifetime,
will be in there lifetime. You can split it up so you can
see that most of that risk, that 10% risk is coming in
the first couple of years. In general if you think about 10%
of that enormous number, 2.3 billion that’s a lot of sick folks, right? Let me actually draw in here what
10% of these people would look like just so you get a visual idea. Maybe this person in Brazil will be
sick, maybe another person out here. Perhaps this person over here,
maybe someone in America. Maybe someone in Mexico. We’ve got five, maybe a Canadian, get six. We got six people over there. Maybe seven, eight,
couple in India nine, ten. A couple of folks in
China 11, 12, 13, 14, 15, I mean it’s a lot of folks, right? 17, 18, maybe a Nigerian, maybe
an Ethiopian, something like this. Let me just make sure I did
the math right really quick. A couple more, let’s just
do one here and one there. This is 10%, that’s what
10% visually looks like, so you get a sense for how many
people are actually going to get sick and have active disease. We know that there are a
couple of other groups of folks that are also going to get active disease. Some would be the folks
that had primary infection because you can get primary
infection then immediately have what we call primary
progressive disease. Or you might have
secondary infection, right? You might have latent TB infection then you get another
person coughing on you and we call that secondary infection. These are the different ways
that you might get to be part of that nine million
who have active disease but I want to point out
that this is a huge pool. This is a large number of people
and so many, many, many people are going to contribute to that
nine million with active disease. Now you might be thinking, “Wait
a second the math doesn’t add up.” Because if you just take
10% of this enormous number that’s actually way more
than nine million people so how does that make sense? Just remember this is a risk in a lifetime or in a couple of years and
this is actually looking
at how many people are sick with active disease in one given year. To extend a little bit further, just
want to make a little bit of space. Those folks are going to go on to actually some of them are
going to go on to die. You’re going to have, in 2011 we had
about 1.4 million people that died. Ultimately that’s really
what we’re trying to avoid. We’re trying to avoid people dying of TB and we want to avoid people
getting active disease because it’s a horrible illness, and so you can see why there’s
such pressure to try to find people that have latent TB infection
and really intervene before they actually go on to get sick. The final thing I want to show
you is actually another picture, I think you’ll find this interesting. This is actually 22 countries
where 80% of the disease is. Go on take a look at this map
we’ve got 22 countries in total. This account for 80% of the cases of TB, so this together account for 80%. The majority of the disease in the
world is coming from this places, so TB cases. It’s actually quite interesting,
you can take a look at this and say okay, you can see that
you’ve got some African countries, you’ve got countries in
Asia, and you’ve got Russia, and you’ve got Brazil out here. These countries combined
make up the majority of where people are sick with TB.


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