Health and medicine
- What is tuberculosis
- What is TB?
- TB epidemiology
- TB pathogenesis
- Primary and Secondary TB
- Pulmonary TB
- Extrapulmonary TB (part 1)
- Extrapulmonary TB (Part 2)
- Mantoux test (aka. PPD or TST)
- Interpreting the PPD
- Diagnosing active TB
- Preventing TB transmission
- Preventing TB using the "4 I's"
- Treatment of Active TB
- Drug-resistant TB
- TB and HIV
Find out how many lives are affected by TB around the world. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Stanford School of Medicine.
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- TB is a bacterium. Are there any bacteriophages that eat it? Also, if bacteriophages take over bacterium, could it make another, more deadly disease?(4 votes)
- Bacteriophages are bacterial virueses and they do not as such eat any bacterium. Alot of diseases are due to the presence of a phage, as with CTXphi and cholera. Whilst one never can say never there are no known phages that would do anything to a Mycobacterium tuberculosis other than killing it off through replication leading to lysis of the cell(6 votes)
- Should we really be stepping in to prevent TB when the countries listed for high TB rates are countries pushing the malthusian limits worldwide. Shouldn't we be attempting for population control, instead?(3 votes)
- Population control is a very slow method. Also, it isn't very effective. Simply controlling population does not mean that people will not get TB and will not spread it. What we need is targeted action to control these diseases.(2 votes)
- Where does Rishi get all the statistics for the number of people who had latent TB infection and the number of all the people who died from this disease?(3 votes)
- He's a pediatric infectious disease physician, so I'm guessing he works with these kinds of statistics on a daily basis, or at least had learned this in university.(2 votes)
- Can't the TB go to the kid if the mom coughs on her hand and then serves him pizza?(2 votes)
- It's possible, but TB is usually spread by coughing. Often, if the bacteria gets onto food, it'll just get swallowed and digested (though TB can rarely start growing in your intestines instead), rather than making it to an area where it thrives, like the lungs.(2 votes)
- At4:43, he says that people die from TB. How?(2 votes)
- when and if you have tuberculoises your brochital trail is inflamed just like if you were to drownd you have no air supply in this case its teh same factor no air is able to be regulated from your aorta to the bronchital trail so you will suffocate.(2 votes)
- So with latent TB, there are the mycobacterium tuberculosis in your body (correct me if I'm wrong). Does this mean you can still spread it?(2 votes)
- The person with latent TB doesn't show the symptoms like a person with active TB. This means no coughing or releasing the bacteria into the air via the respiratory tract thus the next person is not infected.(1 vote)
- Why is TB so geographically skewed?(0 votes)
- Just a quick estimate but about 50% of the world's population is in those countries, so I'm sure that part of it just has to do with how many folks live there. I would also point out that the rest of the map is essentially the "1st world countries" that may have better programs for keeping it under control and the other part are the poorest of the poor "3rd world" countries that likely don't have data or healthcare to take care of disease period, which means higher overall death-rates.(4 votes)
- Why do some people always don't tell people that they have TB and later,the other people get infected!?(1 vote)
- You don't introduce yourself by saying, "Hi, my name is so-and-so and I have TB."
It is not just the infected person's responsibility to stop the spread of the infection, but also the healthy person's. Also, in many societies, people with TB are shunned and humiliated. They need support, empathy and good medical care.(2 votes)
- Can you get TB before you actually know you have it? Like you get the disease but you don't know for a while if that could happen can you infect someone during that time where you don't know you have TB?(1 vote)
- Of course, unless you have latent TB and you don't experience any symptoms. I don't see why you need to know the existence of the disease to be able to spread it or not. Ignorant or not, you still have the active bacteria in your lungs, so you can spread it(1 vote)
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.