Objective: This study demonstrates the value
of Mycobacterium tuberculosis fingerprinting used in
conjunction with traditional epidemiologic methods to identify
smoldering outbreaks of tuberculosis in endemic areas where background
rates of tuberculosis are high.
IS6110 DNA fingerprinting was performed on isolates of
M tuberculosis from verified cases of tuberculosis in
Alabama from 1994 to 1998. A statewide database groups isolates into“
clusters” and tracks them cumulatively over time. A large cluster
was identified and was secondarily investigated using traditional
Results: Twenty-five isolates
were found to be identical by fingerprinting analysis. Patients were
living within 10 counties across the state, and 12 cases were localized
to a single county. This represented an ongoing, statewide tuberculosis
outbreak previously unrecognized by local and state health officials.
Secondary investigation of the cases revealed the primary sites of
transmission to be a correctional facility and two homeless
Conclusions: Population surveillance using
M tuberculosis fingerprinting was successfully utilized
to detect a significant and smoldering tuberculosis outbreak. Measures
are currently in place to identify and prevent further transmission in
the involved locations.