TB can be found in many different organ systems in the body. It is infectious to others only if in the lungs. That's why in health care and other professions with positive skin test (PPD) are required to have a chest X-Ray to work. This doesn't mean that the patient is free of TB, but does not present a risk to others. US CDC recommends treating all positive skin tests in US. Treatment in Thailand is probably not recommended because risk of re-exposure to too high. If you doubt this check out the CDC USA web site.
Non respiratory TB can show up later in life especially in joints or kidneys, but also other organs. After treatment positive PPD usually are negative.
I am a licensed Microbiologist.