No, actually we do. If you have TB you're not going to get an immigration visa. I know from personal experience.
How many visa applicants do they test for TB? If you didn't get a visa because you answered the questionaire truthfully, good for you. You are a principled, if lonely, minority. But as a practical matter they do not bar people with TB from coming here. And don't even get me started about the illegals with TB, I used to live in Texas.