TB is such a danger to us because people from the poorest areas of Mexico and other like countries (ie Guatemala, Honduras, El Salvador etc...) are infested. It's also a danger to our schools. Immigrant children and children of immigrants get them from their rather large families, usually many of them sleeping in the same rooms, may living in the same house, as TB is passed to each other.
Once in schools (and being that many public schools are composed by a mass of these children) they pass TB to other kids, namely non-immigrant children. I know someone who got a positive TB result after he worked as a tutor for a public school that was mostly of latino students. Also, he gave it to his younger sister. Luckily, even if their result was positive, it was dormant and not dangerous to them; they never suffered from it.
But this is a danger we have to watch out for...or at least...private or school schools
It is a danger to them unless they are treated - prophylactically - for it.
It remains dormant in their body. It can activate at a later time - say they are immunosupressed.
Yet - the medication for treatment is very harsh. It is a bit of a problem.
I know a very good infectious disease doctor and she believes in treating the positive PPD. Make sure they consult a good infectious disease doctor.