TUBERCULOSIS AMONG TIBETAN IMMIGRANTS FROM INDIA AND NEPAL IN MINNESOTA, 1992-1995

Objective.-To study screening outcomes among a group of Tibetan immigr ants at high risk for developing active tuberculosis (TB) after arriva l in Minnesota. Design.-Retrospective cohort study. Participants.-A to tal of 191 Tibetan immigrants undergoing medical screening. Main Outco me Measures.-Occurrence and treatment outcomes of active TB. Setting.- A health maintenance organization and a public TB clinic in Minneapoli s, Minn. Results.-Positive (induration, greater than or equal to 10 mm ) tuberculin skin test results were documented in 98% of Tibetans, com pared with 44% of Vietnamese, 10% of Hmong, and 51% of Russian refugee s in Minnesota (P<.001 for each group). Sixteen active cases (8.4%) we re confirmed by isolation of Mycobacterium tuberculosis; however, 5 (3 1%) were culture-negative on initial screening in Minnesota. Seven cas es (44%) were diagnosed during initial screening efforts, and 9 cases (56%) were diagnosed a mean of 19 months (range, 10-27 months) after t heir initial medical evaluation. Of these 9 cases, 6 (38% of all Tibet an cases) had isolates resistant to 1 or more antituberculous drugs, a nd 3 (19% of all Tibetan cases) were multidrug resistant (MDR TB). All 3 MDR TB cases were culture-negative on initial screening; these case s constituted 75% of the MDR TB isolates in Minnesota in 1994. The pre sence of MDR TB was associated with a known history of active TB in As ia (P<.02), Any abnormality on chest radiograph noted either during th e Immigration and Naturalization Service screening evaluation in India (relative risk [RR], 5.2; P=.006) or on arrival in Minnesota (RR, 6.8 ; P=.005) was associated with an increased risk of subsequent active T B. Conclusions.-Tuberculosis infection is nearly universal among Tibet ans settling in Minnesota, A single screening evaluation failed to det ect the majority of TB cases among Tibetans. Even in the face of negat ive M tuberculosis cultures, persons with a history of active TB requi re particularly close follow-up.