So I was exposed to TB

Today I got an email from Occupation Health asking me to contact them about my recent exposure to tuberculosis. From department gossip I learned yesterday that one of the students who rotated through this summer had active TB. Now I find myself thinking about this nagging cough I’ve had for the last couple of weeks. I don’t actually think I have TB. I’ve had none of the other symptoms: fevers, night sweats, weight loss, etc. But still I have this cough…

So I’ll stop by Occupational Health tomorrow and get my annual PPD rather ahead of schedule.

A person can have a latent TB infection (LTBI) and be totally without symptoms. Here the TB is hibernating somewhere in the body, dormant. It may remain this way for decades, or longer.

LTBI is easiest to cure. A dose of INH every day for 9 months generally eradicates the TB bacillus from 96% of people with it. If you wait until TB disease occurs (with signs/symptoms like cough, night sweats, weight loss, lung lesions on chest x-ray, etc), then a 5 drug regimen is usually required, and cure rates are lower.

Granted, LTBI doesn’t often turn into TB disease if you’re otherwise healthy. But it does so often enough that treatment is still recommended. And if a person has HIV or other underlying immunocompromising diseases, then the rate of LTBI developing into TB disease is alarmingly high.

When my patients have a positive TB skin test (TST), I recommend getting a Quantiferon Gold blood test on them. Only if that’s positive do I initiate treatment. If the Quantiferon is negative, I assume the TST was a false positive (which happens very frequently).

I should add that TB is not transmitted very easily through casual contact. Usually one needs to spend a LOT of time with someone who has active TB disease in order to pick it up.

Don’t worry about it. It takes some work to get TB.

When I worked in Cameroon, there were about 100 of us volunteers. We all worked for two years in communities where untreated TB was rampant. We are talking teaching in classrooms that echoed with TB coughs, day after day for years. We all spent tons of time with a huge assortment of people with TB. At the end, only one of us tested positive for exposure, and he was able to treat it easily.

So your chances of testing positive are pretty minuscule, and your chances of that ever causing problems beyond having to take the drugs (which are a pain in the butt- no drinking for 9 months!) are pretty much nil.