I live in the Washington DC area. We have a foreign population here composed of the rich and well-born from every country on the planet.
They go home to visit their mommies every now and then.
That's where they pick it up.
The only vector for human beings when it comes to TB is another human being with TB, and you have to stay in close proximity to them for several hours.
Odds are an international air flight is a more likely source than any illegal ~ unless you hang around one of them with TB for several hours.
Let's just say it's a lifestyle choice ~ BTW, we had voluntary TB tests where I worked ~ mostly because we had people who did a lot of international travel working in our headquarters building ~ you could get a test any time you wanted. Over the years several of my friends tested positive for the antibody, but negative to TB. They likely contracted it at work. They'd tell everyone so you'd know to go get a test.
Just like grade school.