Latent infections like tuberculosis can reactivate when the immune system is compromised, such as in patients taking biological medications for rheumatoid arthritis.

“Where you have a problem is if you have a situation where your immune system is compromised to give you an example of that practically there are some biological medications that people get when they have rheumatoid arthritis before we would if we get to that point where you have rheumatisms there's an antib body there that's suppressing the immune system so that you don't have the symptoms of rheumatoid arthritis that's actually suppressing your immune system in those patients we'll always check them for tuberculosis because certain people walking in the population will have an inactivated tuberculosis they've infected but their immune system has walled it off then we put put them on a biologic and the tuberculosis pops up”