Hot spots of resistant strains are in India and Brazil, and the rates are increasing along the west coast of South America, all of sub-Saharan Africa, Pakistan, India, China, Indonesia, and the former Soviet Union. TB has increased in the United States because of slackened control efforts due to the mistaken belief that drugs developed in the 1940s would control the infection.
People visiting the above countries are at risk, as are anyone who flies on commercial airlines.
A person with active TB on an aircraft can spread airborne particles to other passengers and crew via the air recycling system. This is to protect the country from in-coming cases. However, it may be of more importance to you to have a TB test after returning home to know if you were exposed during travel abroad. The body's natural defense system attempts to resist the disease by walling off the bacteria, usually in the lungs, but other parts of the body are also susceptible. The walling-off process does not actually kill the organisms, and they can become active at any time, particularly if you become weak, ill, undernourished, or immunocompromised.