TRANSMISSION OF TUBERCULOSIS AMONG THE URBAN HOMELESS

Objective. - To determine the relative frequencies of primary and reac tivation tuberculosis in the urban homeless. Design. - Prospective eva luation of homeless tuberculosis patients. Setting. - Central Los Ange les, Calif. Patients. - Thirty-four homeless patients with culture-pro ven tuberculosis. Interventions. - IS61 10-based restriction fragment length polymorphism (RFLP) analysis was performed on Mycobacterium tub erculosis isolates. If results were inconclusive, pTBN12-based RFLP an alysis was performed. Main Outcome Measure. - Clustering of M tubercul osis isolates. A cluster consisted of two or more isolates with indist inguishable RFLP patterns. Results. - Twenty-four of 34 homeless patie nts had clustered isolates in six clusters. Conclusions. - The minimum percentage of cases due to primary tuberculosis in the homeless was e stimated to be 53%, compared with the traditional estimate of 10% in t he general population. The results suggest that primary tuberculosis c aused the majority of tuberculosis cases in this population of the urb an homeless in central Los Angeles.