Context.—Recent studies suggest that one third of tuberculosis cases in urban areas result
from recent transmission. Improved tuberculosis control measures such as uniform
implementation of directly observed therapy might reduce the proportion of cases resulting
from recent transmission. Objective.—To determine patterns of tuberculosis transmission in
Baltimore, Md, after 15 years of community-based directly observed therapy. Design.—A 30-
month (January 1994-June 1996), prospective, city-wide study of all cases of tuberculosis …