Because TB was rampart before antibiotics (1946) everybody was exposed to it. My Mom would test positive (skin test) and have to have yearly chest xray to prove she didn’t have it to be able to continue to keep her RN license. Nowadays it’s a problem because people don’t take the medication as prescribed.
Melendez was the only person Peanuts creator Charles M. Schulz trusted to turn his popular comic creations into television specials. https://en.wikipedia.org/wiki/Bill_Melendez
Even now that’s the safe thing to do