TUBERCULOSIS TRANSMISSION AMONG 5 SCHOOL BUS DRIVERS AND STUDENTS IN 2 NEW-YORK COUNTIES

Objective. Between November 1994 and April 1995, more than 3300 studen ts in 49 schools in two counties in New York were potentially exposed to five school bus drivels with tuberculosis. This investigation was c arried out to determine the extent of transmission of Mycobacterium tu berculosis among students. Methods. Components of the epidemiologic in vestigation included tuberculin skin-test screening and collection of demographic information for students exposed to a driver with tubercul osis, chest radiography and medical evaluation of individuals with pos itive skin tests, and DNA fingerprinting of M tuberculosis isolates. A positive skin test was defined as 10 mm induration, and a converter w as an individual with an increase in reaction size of 10 mm in the pas t 2 years. Results. The rates of positive skin tests were 0.8%, 0.3%, 9.9%, 1.1%, and 0.7% among US-born students exposed to drivers 1 throu gh 5, respectively. The relative risk for a positive tuberculin skin t est was significant only for students exposed to driver 3, and the onl y secondary case identified among students was exposed to driver 3. Th e DNA fingerprint patterns of isolates from drivers 3 and 4 matched. C onclusion. There was no clear evidence of transmission of M tuberculos is to students from drivers 1, 2, 4, or 5. However, evidence suggests that driver 3 transmitted M tuberculosis to students and another drive r. Routine annual tuberculin skin-test screening of drivers would not have prevented these tuberculosis exposures.