It is very true that people from third world country tend to have Tuberculosis but that's not to say that everyone in third world country has it. Some people whose immune system is strong will not carry the disease while some people whose immune system is weak could easily carry the disease and not know about it. Especially if you wanted to volunteer in a hospital environment, they would ask you to undergo a Tuberculosis Test to make sure that you don't have an active untreated Tuberculosis and then you could easily spread it to everyone working in the hospital. If you do have an inactive form of Tuberculosis, the hospital will allow you to volunteer work for them.
During the Tuberculosis test, the hospital staff would inject a small amount of Tuberculosis Protein under the top layer of skin on your inner forearm. Then you may be asked to come back in two days time. If you have Tuberculosis, a firm red bump will show on the spot where the TB protein was injected. This will confirm whether you have Tuberculosis or not. However, this skin test will not tell if the Tuberculosis is active orr inactive in your body. The hospital staff will want you to go to your family physician and have him ordered a chest X-ray for you. It is only after going through an X-ray inspection then it can be determined if you have an active or inactive Tuberculosis infection.