Houston Chronicle (12.12.11) - Wednesday, December 14, 2011
Passengers on certain bus routes of the Metropolitan Transit Authority of Harris County and Houston were more likely to have TB, according to an analysis of 1995-2004 data. Houston residents with TB were asked detailed questions, including whether they rode public buses and, if so, what routes.
The results showed that people living in different parts of town and infected with the same TB strain were connected by certain bus routes. After controlling for other risk factors such as poverty, drug use, and compromised immune systems, people riding certain bus routes were still more likely to have TB, said Marsha Feske, who analyzed the data as a University of Texas School of Public Health graduate student. One of the routes serves local hospitals, the report says.
Airborne infectious diseases can be spread in any public space, from a doctor's office to a post office, noted Andrew Skabowski, senior vice president for service delivery for the transportation authority. "TB is not widespread," he said. "There are still cases, obviously. Our buses are clean. Our [ventilation] systems are very well-maintained." Officials said the transportation authority is collaborating with Rice University researchers and senior engineering students on improving buses' air filtration systems to reduce bacteria and germs. The Rice team hopes to have a prototype device, which uses ultraviolet light to kill bacteria, on a bus by next spring. A key issue will be placing the UV unit where it has time to kill the bacteria without impeding air flow or energy efficiency.
The full study, "Giving TB Wheels: Public Transportation as a Risk Factor for Tuberculosis Transmission," was published in Tuberculosis (2011;doi:10.1016/j.tube.2011.10.005).