Arrowhead is right on this one. Most asians, and some caucasians (who were exposed), when tested for TB will appear positive. Unless their resistance really goes down, then it will be full blown TB. But once tested, they can be given medication ( I'm not a doctor and memory is quite foggy on this ) which they need to take for quite some time before they can be given a clean bill of health. They need not have the symptoms of TB to be given such medication, just be positive on the tests.
Now the sad thing here is how management reacted to this situation. Too little, too late.