Passenger contact investigation associated with a transport driver with pulmonary tuberculosis

In October 2008, pulmonary tuberculosis (TB) was diagnosed in a driver who had transported 762 passengers in the District of Columbia metropolitan area during his infectious period. A passenger contact investigation was conducted by the six public health jurisdictions because of concern that some passengers might be infected with HIV or have other medical conditions that put them at increased risk for developing TB disease if infected.

Authorities evaluated 92 of 100 passengers with at least 90 minutes of cumulative exposure. Passengers with fewer than 90 minutes of cumulative exposure were evaluated if they had contacted the health department after exposure and had a medical condition that increased their risk of TB. A tuberculin skin test (TST) result of at least 5 millimeters induration was considered positive.

Of 153 passengers who completed TST evaluation, 11 (7%) had positive TST results. TST results were not associated with exposure time or high-risk medical conditions. No TB cases were identified in the passengers.

The investigation yielded insufficient evidence that Mycobacterium tuberculosis transmission to passengers had occurred. TB-control programs should consider transportation-related passenger contact investigations low priority unless exposure is repetitive or single-trip exposure is long.