Family clusters of pulmonary tuberculosis in a suburban area of Japan.

A survey was conducted in a metropolitan suburb to examine family clusters of pulmonary tuberculosis patients and related factors. Firstly, a descriptive study was done based on the review of tuberculosis registration cards over a 11-yr period. Of 1106 cases, 109 (9.9%) were found to occur in households which had already had one or more pulmonary tuberculosis patient during the period. The most affected were four- and eight-member families with infants and adolescents accounting for most of the second or later patients. Secondly, a home visit survey was performed to investigate factors associated with family clusters of phthisis. Results showed that significant variables were the length of patient's delay (interval between perception of physical symptoms and visit to the physician), the number of rooms, and lack of self-motivation to seek treatment. Log-linear analyses revealed interaction among these variables.