WASHINGTON — In the heart of the Ethiopian community here, a group of friends gathered after work in an office to chew on some dried khat leaves before going home to their wives and children for the night.

Tuberculosis (TB) is a major public health problem in the Horn of Africa with Ethiopia being the most affected where TB cases increase at the rate of 2.6% each year. One of the main contributing factors for this rise is increasing transmission due to large number of untreated patients, serving as reservoirs of the infection within the communities.