Mass global movement of people is helping the spread of
Global trade and the number of people travelling by air have increased
dramatically over the years. Passengers and crew can spread TB to
each other. In many industrialized countries, at least one-half of
TB cases are among foreign-born people. In the United States , nearly
40% of TB cases are among foreign-born people.
The number of refugees and displaced people in the world is also
increasing. Untreated TB spreads quickly in crowded refugee camps
and shelters. It is difficult to treat mobile populations, as treatment
takes at least six months and should ideally be supervised.