Background: Tuberculosis in children generally occurs as a direct result of cohabitation with a contagious adult. Objective: To create a profile of a typical adult with contagious tuberculosis (as identified through the public health system) living with a child who has been diagnosed with tuberculosis. Method: Case study. Children younger than 14 years of age who were diagnosed with tuberculosis were included. Parents were interviewed using structured questionnaires. Means and standard deviations were analyzed using the Student's t-test. Fisher's exact test or the Dz test was used for comparisons. Results: Fifty children, representing 96% of those diagnosed with tuberculosis in the Porto Alegre health care system between July 20, 2001 and August 10, 2002, were included. The mean age was 76 months, and 60% were girls. The classic forms of pulmonary presentation (consolidation or cavitation) were seen in 38%. The majority of the children were diagnosed in the hospital and came from homes in which there were (a mean of) 6 cohabitants and a total family income less than 2 times the local minimum wage. Using ELISA, HIV co-infection was identified in 25% (although not all were tested). The children regularly visited places other than their homes. In 78% of cases, the contagious adult was identified. These contagious adults were mostly males (56%), and the mean age was 32. In most cases (79%), the contagious adult was a relative, usually a parent. Within this group of adults with contagious tuberculosis, HIV co-infection was identified in 43% of those tested. Conclusions: Adults with contagious tuberculosis living in the home continue to be the most likely source of tuberculosis infection in children. Co-infection with HIV in these pediatric patients, as well as in the cohabiting adults with contagious tuberculosis, is a significant finding. It must be emphasized that the possibility of contact with contagious individuals in the home should be explored in every diagnosed case of pediatric tuberculosis.

Keywords: Tuberculosis/epidemiology. Children. Communicable diseases/etiology.