Reply #19: TB is a tough nut.....

[Snow]

There is a vaccine, as others have already mentioned, and there's a better vaccine in the works. TB itself requires repeated large doses to pass on - think grandpa living with the family in small quarters that get closed up part of the year when it's cold. And it can hide in your body for decades, maybe even never develop into symptomatic disease, unless conditions for the bug improve. So if your nutritional status goes down or you get worn down by demands of your work, or you get debilitated by a viral infection - then the TB bug can pop back to life. And naturally, something with that much patience requires a lot of time to kill off, which poses a constant challenge to TB control workers. Given that TB patients are often poor, homeless, sometimes literally nomads, how do you keep them taking meds for up to 2 years to get them cured? WHO has come up with some very clever programs, and those work a lot better than some of the old ways of treating (ie, come to the clinic monthly while taking meds - unsupervised - daily for 2 years), but you still can't get around that latency period of decades. In other words, most of 2020's active pulmonary TB cases are probably already walking around infected but invisible to most diagnostic techniques. We'll get it eventually, but when poverty rises, we take quite a few steps backward.