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
Two deadly diseases, HIV and TB, can often co-exist in the same patient. 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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- does the immune system have a maximum capacity? Is there a maximum load of memory cells one body can hold?(12 votes)
- There are about 2,100 different diseases (give or take one hundred). If each memory cell "memorizes" one disease, that's 2,100 cells of the human bodies 100 trillion cells used up. Now I think that Residuum makes a good point when he/she says that memory cells could wear out with age. Howeverm I'm sure that running out is impossible with 100 trillion cells in your body, some of which are stem cells, which can be anything.(6 votes)
- How was the HIV virus formed and how does it spread?(4 votes)
- The infection is caused by the human immunodeficiency virus (HIV).
After HIV is in the body, it attacks and destroys CD4+ cells, which are the part of the body's immune system that fights infection and disease. When HIV weakens or destroys the immune cells, it may lead to certain illnesses or diseases, such as some types of pneumonia or cancer that are more likely to develop in someone who has a weakened immune system. These conditions are a sign that HIV has progressed to AIDS.
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HIV is spread when blood, semen, or vaginal fluids from an infected person enter another person's body, usually through sexual contact, from sharing needles when injecting drugs, or from mother to baby during birth.
HIV is rarely spread by blood transfusions or organ transplants in the United States because of improved screening procedures.
- how do you get TB or HIV?(1 vote)
- Tuberculosis is a respiratory infection which is spread by what is called airborne pathogens. This means they are spread by being in direct breathing contact with someone with tb usually for an extended period of time. Tb does not rely on droplets of water such as influenza to travel.
There are 5 forms of HIV, without getting too involved into it HIV is spread through: blood, sexual contact, shared needles, contaminated water, fecally.. Are the most common infection methods.(3 votes)
- Why are there so many videos about tuberculosis and not as athsma?(1 vote)
- TB is an infectious disease ,can be transmitted by droplet infection . It is caused by Mycobaterium tuberculus ' human type ' ,and there is another type called ' bovin ' although it affects cattles and sheeps ,it also causes Tuberculosis for human through milk ingestion from an infected animal . So ,as you see Tuberculosis is very dangerous due to its infectious ability . About Asthma ,it is usually caused by a hypersensitivity reaction causing narrowing of bronchi ' mainly ' ,and it confined to the patient ' not transmitted by droplet infection ,it is primarily not bacterial ,viral or fungal ' .(2 votes)
- how can you not feel pain when you do not notice you have TB I mean how could you not know?
Wouldn't you have felt pain? Isn't TB bad itself? So you need to have HIV before knowing you had TB?(1 vote)
- TB doesn't usually hurt, because the insides of your lungs aren't designed to feel pain: they don't have any pain receptors. So if the TB bacteria and your immune system are fighting in your lungs and causing damage, you won't feel anything happening.
Doctors have to look for other signs that you have TB, like losing weight, having a fever, coughing up bits of blood, or having trouble breathing. They can also do tests to try to check if your immune system is fighting the TB or to see where the TB is causing problems.
Most people don't get sick when they have TB: their immune system is able to keep the bacteria from getting out of control. They probably don't even know they have it! But about 10% of people do become sick when the bacteria manage to start spreading.
Remember that HIV attacks and kills your immune cells, so that your body has more and more trouble dealing with infections. If you have TB and HIV, then the HIV hurts your immune system, which makes it easier for the TB bacteria to spread and cause damage.
So you can get sick from TB by itself, but if you have HIV and TB, you'll almost certainly become very ill.(1 vote)
- Did this video about TB and HIV confuse anybody else other than me?(1 vote)
- Mainly he's saying that when you have HIV, it damages the immune system, making the body weaker, making the TB is able to infect more cells. My only problem was that when I went to watch it, it went very blurry, making it hard to read what she's writing.(1 vote)
- Can sharks be infected by HIV ?(1 vote)
- Maybe, but probably not. They are a different species and don't have cells that the HIV virus can enter. That is the HIV virus presents a protein on the outside of it and if the cell that the virus presents the protein to doesn't have a protein that "fits" its protein then the virus will just bounce off and do nothing.
There are countless viruses that humans are exposed to every day in water and air that cannot do anything to us because they don't have the appropriate protein receptors to enter our cells. The same can be said for other animals.(1 vote)
- At2:30, how does TB make HIV worse?(1 vote)
- HIV is a weakened immune system and any infection can make it worse. Your body is unable to fight off infections that attack the blood cells. TB can settle in the lungs causing fluid to build up, and because your body can not fight it off it's worse.(1 vote)
- Does MB cause superinfection as is the case of HIV?
Dose person with latent TB is reinfected with the same strain of MB or it has to be cross infected with a new strain of bacteria?(1 vote)
- Tuberculosis is transmitted through airborne spread of Mycobacterium tuberculosis. When a person with active pulmonary TB coughs, aerosolized droplets containing bacilli can invade the lungs of close contacts. In 90-95% of cases, the infected person's immune system halts growth of the bacteria and active disease does not develop, although skin or serological testing for TB will convert to positive. Once positive, a person's TB test will generally remain positive for life.(1 vote)
- Can someone who has HIV and TB spread both diseases to another person?(1 vote)
- HIV cannot be spread through the air; TB is difficult to transmit through bodily fluids. At the same time, they couldn't spread both diseases, but they are still vectors of both HIV and TB. Make sense?(1 vote)
Charles: This is Charles Prober. Morgan: And this is Morgan Theis. Charles: And now we're going to talk about the interaction between tuberculosis and HIV, human immunodeficiency virus. We're going to talk about this because the two actually commonly occur together in different parts of the world, and one infection makes the other one typically worse. Together, they create what one might refer to as a "perfect storm." The stick figures which you've drawn show nine individuals on a top line, one of whom is colored in a different color. This is meant to depict the roughly nine million people each year who are infected with tuberculosis, one of whom, or about 13%, is co-infected with HIV. That's a very large portion of the population for which this is a problem. It represents over 1 million people. The stick figures beneath are meant to depict death caused by tuberculosis. There are three individuals depicted here that represent the roughly 1.5 million individuals who die each year from tuberculosis. And about 1 in 3 of these individuals is co-infected with HIV. So the combination of HIV and tuberculosis is incredibly important. In very general terms, each infection makes the other one worse. In other words, if you're infected with tuberculosis and you are or become co-infected with HIV, the tuberculosis infection becomes more severe. It is more likely to be disseminated. It is more likely to be associated with severe necrosis of the lungs or miliary TB or TB meningitis. So HIV makes tuberculosis worse. Morgan: So almost in every way. Charles: Almost in every way. Morgan: Right, OK. Charles: And similarly, tuberculosis makes HIV worse. Through mechanisms that are not clear to me at least, being infected with TB makes the HIV virus proliferate more and makes the progression of the HIV infection more severe, so they are mutually bad for each other. Morgan: So this why we call it "the perfect storm." Charles: Precisely. Now clearly, ultimately, you have to treat both infections because they're both bad infections. Morgan: Right. Charles: For tuberculosis, we will be talking about the anti-tuberculose drugs to use in another video, but you do have to use the anti-tuberculose drugs. With HIV, of course, you have to use antiretrovirals in order to control the infection. Morgan: Right. Charles: So it's a given that you have to treat both infections. But another part of the perfect storm is that when you begin to treat, you may have an adverse effect in something called the "immune reconstitution inflammatory syndrome." It's abbreviated IRIS. Morgan: OK. I was going to say that's a big word. Charles: It is a big phrase. IRIS stands for the immune reconstitution inflammatory syndrome. In order to describe the effects of IRIS, I'm going to talk about two hypothetical patients infected with tuberculosis. Morgan: OK. Immune reconstitution inflammatory ... Charles: Syndrome. Let's imagine one patient infected with tuberculosis and it's a latent infection. It's a quiet infection. It's a sub-clinical infection. In those patients, when you get infected, if you're infected with HIV and you recognize the HIV infection and you begin to treat the HIV infection with antiretrovirals, the TB infection may become clinically manifest. It is uncovered. That actually is referred to as "unmasking IRIS." In other words, the treatment of the HIV with antiretrovirals, presumably because you reconstitute the immune system, makes the TB infection become evident. That's called unmasking IRIS. Morgan: OK. So before you had this latent TB infection, you might not have even known you were sick as a patient, you get HIV, you still don't know you have the TB, and then you start treating the HIV, and that's when all of a sudden you realize you have TB. You get this clinical tuberculosis - Charlie: Exactly. Morgan: OK. Charlie: So it's unmasked. You recognize it at that point. You then treat the TB infection, and of course, you're in the meantime still treating the HIV infection. That's one hypothetical patient. Another is a patient known to be infected with tuberculosis. They have clinical disease. Perhaps they have the most common clinical disease, which is pulmonary disease. Then you determine that they also are infected with HIV, so you begin, again, treating the HIV infection with antiretrovirals. Paradoxically, as you treat the HIV infection, the TB infection gets worse. Again, it's thought that that results from when you treat the HIV infection, the immune system becomes more robust, because you're controlling the HIV infection, which was previously tamping down the immune system, so the immune system becomes more robust, and as a result of that robust immune system, temporarily, the TB infection gets worse. That's called "paradoxical IRIS." Morgan: Paradoxical IRIS, OK, so that makes me think maybe we just shouldn't treat the HIV. Charles: And of course, that would be not good thinking, not because you said it, but because you must treat the HIV infection because otherwise, it will progress, and the patient will die of HIV. This is a temporary phenomena where you get transient worsening of the TB infection. Then as you continue to treat the HIV infection and you continue to treat the TB infection, they both eventually settle down, ideally. Morgan: OK. This is more something that is interesting and we watch out for because it can be acutely problematic, but that you wouldn't actually change a treatment for. You would just have to be aware of it and eventually, as you treat the HIV, you treat the TB, hopefully, things will actually move in the correct direction (laughs). Charles: Exactly. Then the final thing that I'd like to mention with regards to this perfect storm, this badness between having both TB and HIV at the same time, is that the drugs used to treat each of those two infections may adversely interact with each other. One that is probably the most important adverse interaction to know about is the effect of rifampin, a key drug for treating tuberculosis, on the different antiretroviral agents. Specifically, rifampin is known to be an inducer of important enzymes in the liver that are responsible for metabolizing a lot of drugs. The enzyme system happens to be called the "cytochrome P450 enzymes." Rifampin induces that enzyme, in other words, makes the enzyme more active. That enzyme is responsible for enhancing the metabolism of many drugs, including antiretrovirals, so you end up, when you give the rifampin, causing the antiretrovirals to be metabolized more quickly and lose their effectiveness more quickly. So you have to be aware of that and other kinds of interactions, of drug interactions so that you can modify and modulate your therapy of the infections accordingly. We'll talk about that at another time.