I tested positive to TB exposure back in 1990. It was a shock to me, but I took the course of INH and went about my life. Now with all the Crohn's meds and the risk of TB, I get chest x-rays every couple of years. I have not been told that I am still at a risk to develop active TB from that initial exposure. But, I could be exposed again, though I've been told it's less likely that I'd get latent TB at all now.
Personally, I have chosen not to worry about TB. I've been on every TNF and immune modulator available for Crohn's. I just keep a watch with chest x-rays and don't worry about it. There is also a new test for TB - TB Gold - that is more specific about the exposure. I haven't researched it in detail, but I believe it can distinguish between an old/treated exposure and a newer exposure. I've never had the test, so I didn't really pay as much attention.
I figure I live with Crohn's everyday. I need to treat the Crohn's... Sorry you are going through this!
--female dx as UC in '04 (1st symptoms in '03), switched to Crohn's in '05, 1 fistula, crohn's colitis, limited to large intestine --rejected (reaction/didn't work): Asacol, AZA, 6-MP, MTX, Remicade, Humira, prednisone, Tysabri
--Prochymal in Phase III study (can't wait til it's approved!)
--currently taking methylprednisolone 40mg-taper. Started Cimzia first dose 2/10/09. Dx Osteoporosis 10/08 started Forteo 1/27/09