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Current time:0:00Total duration:12:27

Video transcript

so I've drawn out for you a mother over here a mom and her son on the right and it turns out that mom has tuberculosis let's assume that and sometimes when you see tuberculosis written out the way I'm writing it out you'll actually see them short-handed or kind of use the the quick way of saying it with just two letters which is TB so let's say mom has TB now this is actually a diagnosis right this is a description of her illness this is telling us what she actually has what she's sick with but we have to remember that tuberculosis is actually caused by an organism right there's actually caused by a bacteria turns out and this bacteria has the name Mike oh my Co bacterium Mycobacterium tuberculosis so this is actually a very easy one to remember because tuberculosis is right here in the name now I should point out Mycobacterium tuberculosis is actually not the only cause of tuberculosis turns out there are a few other kind of related Mycobacterium using this word Mike oh that also cause TB but this one the one I wrote out for you this is definitely the most common around the world and that's the one I'm going to focus on and in fact this Mike oh my co this is actually Greek for the term fungus and the reason that this is here actually kind of tells us a little bit about how this bacteria grows because it grows really slowly like a fungus and that's actually the reason that they use the term Mike oh but nevertheless it is a bacteria and so if we're going to put a little bracket around the diagnosis I also want to put a little bracket around this part to kind of distinguish the two so you can see very clearly TB the diagnosis is caused by a bacteria so now let's talk about how mom who we said already is sick with TB I'm going to actually just sketch out what her lungs might look like assuming that the TB is in her lungs this is actually the the most common place we think of with TB but not the only place but let's say that she's got little red I'm going to draw it in red bacteria here in her lungs causing her to be very very sick with tuberculosis you know she could spread it to her son but what are the different ways that she might spread it one of the most common ways well let me sketch out a few possibilities and we're going to go over whether these possibilities are very likely or unlikely to be a way for her to spread disease to her son so let's say first you know they're sharing this delicious pizza I'm drawing here they're you know let's say they're very into pizza and they you know like to share food and they both you know chow down on this little pizza here that's one way they might potentially you might think of as a way to spread it maybe they're even sharing a drink maybe there's a drink here you know in this drink you know they're sharing again you might also think about you know what's going on in their house maybe they're opening and closing doors and maybe they're touching doorknobs there's another way right maybe they're touching stuff in common maybe she says to him hey here grab these keys and she's been holding the keys all day and then she gives him the keys and he holds the keys you know there's another way right maybe the TV can touch objects in the environment like a doorknob or a key and then there's the most obvious way you might be thinking maybe she's coughing maybe she has a loud coughs you know maybe she's coughing all day and some of these bacteria get in the air right so that's another way that you might imagine that the bacteria could spread from her to her son so different ways right now of these ways I'm going to actually label this one over here let's say this is through the air which are the most common ways to be really concerned about TB spreading and I'm actually going to just put it in green so it really sticks out the most common way is what we call person-to-person through the air so in this case the the first person would be mom because she's sick and it's going to go through the air down to her son in these other ways you know for example food and drink that's really not so common that's really really unlikely to be a way of spreading TB and in fact even this down here is really not likely either so the idea of getting TB by sharing food and drink or touching objects in your environment like the keys or the doorknob or things like that that's really not how TB spreads usually usually it's spread through the air and person the sick person is usually coughing a lot and then the other person might breathe it in so let me make a little bit of space on this canvas and let's talk about what happens next I'm going to draw one alveolus here and then I'm going to copy it a few times just so you can see a few different possibilities in terms of what might happen and these represent the sun's alveoli these are the sun's alveoli of course these are the tiny little air sacs at the very ends of the bronchial tree right so let me make a few copies of this so there we go we have four possibilities right possibility one two three and four I'm basically to go through different scenarios different things that might happen when Mom coughs so maybe she coughs and the first possibility could be that the bacteria you know they just don't get far enough they don't actually make it to the Sun and he never ends up breathing them in so this was the case there would be no bacteria in his alveoli of courses his lungs are nice and clean let me draw his lungs in they look nice and clean with no bacteria and he's feeling great right this is this is our son over here feeling really good and we would say basically in this case in scenario one he's healthy because the bacteria never even got to his lungs all right now scenario two let me actually erase a couple of these let's say that the cough actually was you know very strong and he was close by and he ended up breathing some of these in throws nose or his mouth and they went down into his lungs right so that's another possibility once the bacteria get there let me actually draw them on this little alveoli you know impossibility number two they might actually get picked up by little immune cells so he has little cells that are patrolling the lungs making sure they're nice and clean and healthy and these little immune cells I'm going to label them over here these are macrophages macrophages actually this literally means big eater because phage means to eat and so these immune cells they might kind of come by and gobble up these bacteria and take them in and destroy them that's another possibility so that would be possibility number two so here the bacteria are gone now let's play it out again let's say scenario three also you have a couple of bacteria in here and just as before you get a couple of immune cells that come by and they swallow up these little bacteria these are the macrophages I'm drawing swallowing up the bacteria but let's say that unfortunately in scenario three now these macrophages for whatever reason cannot destroy the bacteria the bacteria are still living and that's why I draw them here as little red dots they're still living still there and now let me draw out the fourth scenario which is again let's say a couple of bacteria get in and let's say that you know the immune cells again they kind of you know get alerted and they kind of come by and pick up one of them maybe this immune cells trying to go after this other one maybes really close by but here the key difference is that these bacteria are actually multiplying so I'm actually going to draw lots of them these bacteria are multiplying and they're filling up this space so this space is filling up with a little tiny red bacteria so the key difference here is that these ones are multiplying and we didn't really talk about the other scenarios having bacteria that are multiplying but now that's that the key new thing here and in this scenario we call it active because you're actually seeing the bacteria surviving we call this active TB infection active TB infection and that goes back to kind of what we would label the other scenarios these ones and these ones together we actually called both of them latent TB infection latent TB infection and the reason I'm putting them together is because it's very hard very hard clinically to distinguish scenario two from scenario three because in both cases the immune system has previous experience with the TB bacteria it's seen the TB bacteria and in both cases you're not seeing lots and lots of tria dividing or multiplying so we lump these together and call them both latent TB infection the real key and this is you know kind of the take-home that I want to point out is that there is a difference then between healthy someone that's really never seen TB in their life before latent where you have seen TB previously but you don't have any bacteria that are multiplying an active TB infection or you have lots and lots of TB bacteria that are multiplying let me make just a little bit more space then I'm going to focus now on just this final one this multiplying active TB infection situation so if let's say our son in this case gets tuberculosis from mother from mom and let's say unfortunately he has an active TB infection what are some clues to tell us that he has an active infection so if I'm trying to figure out if somebody has TB I always think about two key things what are their symptoms what are they sick with that's the first thing and then how long is it going on for and I'm going to call that duration and these two offer really really helpful clues to figuring out if someone has TB and with symptoms I'm going to break it up into two categories the first is constitutional constitutional and this is constitutional symptoms and this is kind of things that affect the whole body the whole body so I'm just going to put a little bracket on the entire body to to remind us of that and this could be things like you know fevers or chills you know you can't say you know you can't really point to one part of your body and say this is the part that's having fevers and chills you just say well just generally I feel awful this could be things like night sweats if you wake up and your t-shirt is all wet you might say well those are night sweats another example of a constitutional symptom is weight loss and particularly when you're not trying to lose weight especially because you're maybe not eating as much or you're vomiting anything like that and now the other category is lower respiratory tract I'm going to say respiratory I'm going to bridge it to just RESP tract and this if I want to draw it in would basically be kind the part I've drawn in blue here so going down from your voice box all the way to the alveoli so this would be your lower respiratory tract and you can think about what sort of symptoms you might have that right so it could be things like coughing right that would be coming from the lungs if you're coughing very hard you might have some blood or some little streaks of red that are blood in your sputum so it could be bloody sputum that would be another one and the sputum of course is just the mucus stuff that you kind of caught up in a lot of people that are coughing this much they might have a trouble breathing or you know chest pain anything like that so these are kind of just some examples of lower respiratory tract symptoms and so I always think in my head okay are they having constitutional symptoms if so I put a check there are they having some lower respiratory tract symptoms if so I put a check there and then how long is it going for and usually with things like active TB infection I'm thinking it's got to be usually more than three weeks so more than three weeks and this is again focusing on TB of the lungs or the pleura which is a space around the lungs generally the symptoms have gone on for a little while so these then become very helpful clues to figure out if someone actually has active TB infection