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Current time:0:00Total duration:11:32

Preventing TB using the "4 I's"

Video transcript

this is Charles prober and I'm Morgan theis and we're going to talk about the prevention of tuberculosis and there are eyes for eyes to consider in preventing TB infections one I stands for intensified case finding we'll come back to that but finding cases of TB we talked about that we'll talk about finding cases of latent TB and what we can do about it and finding cases of active infection and what we can do about it okay the second of the four eyes is eyes and eye acid or INH an important anti-tuberculosis of this video we're going to talk about its use in the treatment of latent TB okay the third eye is isolation and that we're going to talk about in the context of an actively infected patient and infect a patient that may be infectious to others and how we can prevent the spread of their TB to other people this is like a very good infectious disease principle right pretty much with any infection you want to isolate the person from spreading it for many that is absolutely true and then the fourth eye is immunization okay what vaccine we currently have available for the prevention of TB and perhaps which on the horizon okay so starting with the first eye intensified case finding so mentioned at the onset that were either looking for latent lea infected people people with a positive TB skin test for example or looking for cases of active TB well first of all thinking about those who may be latent lea infected with TB or actively infected there are certain high risk populations that we always have to keep in mind for example persons immigrating moving from a country that's got a high level of infection with TB such as in many of the countries in sub-saharan Africa moving to another part of the world that has a low level of TB infections such as North America United States or Canada another high-risk population similar are migrant workers from highly endemic areas another high-risk population are prisoners especially in the United States the homeless population have a high risk of tuberculosis individuals who abuse drugs intravenously IV d you intravenous drug using individuals have a high risk of TV and those Co infected or infected with HIV have a high risk so these would be individuals that we would be screening with tuberculosis kin test for example on a regular basis and if we find them to be positive on that test that is to be latent ly infected with TB this leads us to the second eye which is INH treating these lately infected individuals with eysan eysan is a very effective way of reducing the likelihood that the latent infection will become an active infection INH is about 90% effective in reducing infection the prescription of inh is for a 9 to 12 month period who it is a long time that's correct but with that 9 to 12 months of treatment you reduce infection developing there are some alternatives to inh alone but the alternatives tend to be a little bit more toxic have more side effects but one example of an alternative is to give inh with refampin for four months or ion or refampin with pure as in amide pza for two to three months and these combined therapies seem to be almost as effective as inh alone for 9 to 12 but not quite and they also are more toxic okay so again the second eye is AI na yeah it once you start treating someone who has latent TB with inh how long before they stop being infectious well they're not infectious to begin with so I have latent TB they're not infectious the idea of treating them is so that they don't develop active TB which would be which would be infectious and in fact let's stay with this intensive case finding and go down the active TB pathway so many persons with active TB are infectious for other individuals there are some that are much more infectious than others for example if you've got pulmonary TB the most common site of infection with TB and that pulmonary TB is cavitary so there's a big cavity on the chest x-ray the likelihood is that that's teeming with t v-- organisms that is there's a lot of them and they may spread to other individuals quite readily so with those kinds of infectious individuals they must be isolated which is our third eye right it must be isolated so they cannot spread infection to others what isolation typically means is they're put into a single hospital room with protected airflow and any visitor to that hospital room wears a mask that filters out TB organisms typically called an n95 mask and then of course the person with active TB is treated for their infection and usually in about two weeks three weeks or four weeks they become non-infectious that is their anti tuberculous therapy reduces the amount of TB organisms they have present so they're not infectious anymore so then they can come out of isolation and go back into their regular home life and as this treatment just going to be the same just using AI na sure that's a more intensive regimen it's a more intensive regimen and we're going to have a video or two about different treatment options the other thing to say about those with active TB in terms of the intensified case finding is when you find some new active TB you must do contact evaluation as well so you want to look to all the individuals that they have may have been in contact with before they were diagnosed because in doing so you may discover other cases of active tuberculosis that also need to be managed with treatment isolation and so forth so you're looking for their context sir evaluating exactly you're looking for where they got the infection potentially or to whom they already spread the infection so so that's a very important public health effort to reduce the continued spread of tuberculosis the fourth and final I with TB prevention is immunization okay that would be great when we just immunize everybody against TB and we won't have a problem and that would be great if the vaccine were highly effective which unfortunately the current vaccine available worldwide has some effectiveness but it's limited that vaccine is called B C G all capitals and it's a live attenuated vaccine derived from mycobacterium bovis which is another kind of tuberculous agent M Boba's it's a vaccine which is administered in many parts of the world that have high rates of tuberculosis to try and prevent the spread of try to prevent the individuals from acquiring TB and then spreading it so the immunization is typically given around the time of birth with BCG the degree of effectiveness of the vaccine varies widely from study to study ranging from a low of 0% to a high of about 80% and most use the estimated protective effectiveness of about 50% it turns out that the vaccine is especially effective when it's effective when given to children that's why it's administered around the time of birth okay and the reduction in TB is especially evident for those that for severe disease so it seems to reduce the likelihood of getting very severe disease including TB meningitis and miliary TB so that's important because that's the worst kind of tuberculosis but again its effectiveness is limited as I mentioned now because this vaccine is live and attenuated there are also some risks you can get from vaccinating a large number of individuals so if you inadvertently vaccinate somebody who's got an immunodeficiency their immune system isn't working very well their vaccine site can become quite necrotic and they can even disseminate the BCG so you can have an infection arising from the vaccination that's fortunately not way common but it does occur in just normal individuals that is those who do not have any immunodeficiency it's estimated that somewhere between one and ten percent will get a little ulcer at the vaccine site and you can see sort of this little crater in their arm over a long term and that sort of says oh this person's had BCG vaccine and more less commonly beyond the ulcer you can get some local admin appa the-- so lymph nodes swelling around the area where the vaccines been given for example in the armpit and very rarely maybe one in a million cases you can get osteomyelitis a bone infection from the BCG vaccine these are all quite uncommon a non-balanced BCG vaccine is more useful than not and that's why it's given and then the final thing I mentioned about immunization is there's a lot of interest and work in developing new vaccines for tuberculosis that would be more effective of course and with less side effects and there are probably about 30 new vaccines under development but unfortunately at this point none of them have been found to be so beneficial as to be licensed for widespread use but stay tuned we hope to have a vaccine against tuberculosis that's more effective sometime in the future