TUBERCULOSIS IN MEXICAN-BORN PERSONS IN SAN-FRANCISCO - REACTIVATION,ACQUIRED INFECTION AND TRANSMISSION

SETTING: San Francisco, California. OBJECTIVE: To determine the relati ve contributions of infection acquired in San Francisco and reactivati on of tuberculous infection acquired elsewhere in Mexican-born persons who developed tuberculosis in San Francisco, and to determine the fre quency of transmission leading to secondary cases of tuberculosis in o ther persons. DESIGN: The study population consisted of all Mexican-bo rn tuberculosis patients reported in San Francisco from 1991 through J une 1995. All patients had positive cultures for Mycobacterium tubercu losis and DNA fingerprinting of isolates using IS6110 with more than t wo bands. Patients were classified as infected in San Francisco or inf ected elsewhere based on pre-defined criteria that included a second D NA fingerprinting technique (polymorphic guanine-cytosine-rich sequenc e), chart reviews, and selected patient interviews. RESULTS: Of the 43 Mexican-born patients studied, nine (21%) met the definition of infec tion acquired in San Francisco and 34 (79%) met the definition of reac tivation of infection acquired elsewhere. Only one of the 43 cases res ulted in two secondary cases in US-born persons, CONCLUSION: One-fifth of the Mexican-born patients who developed tuberculosis in San Franci sco acquired their tuberculous infection in San Francisco; transmissio n from Mexican-born persons leading to tuberculosis in other persons i s uncommon.