Association of prevalence of tuberculin reactions with closeness of contact among household contacts of new smear-positive pulmonary tuberculosis patients.

OBJECTIVES

Among household contacts of newly diagnosed smear-positive pulmonary tuberculosis (TB) patients, to examine the association of apparent tuberculosis transmission with the closeness and duration of contact.

METHODS

Household contacts of newly diagnosed patients with smear-positive pulmonary TB were identified, as well as a healthy population sample. Household contacts were categorized into three groups based on closeness, regularity, and duration of contact with index cases. All subjects underwent tuberculin testing.

RESULTS

Among the household contacts, 47 of 112 (42%) of very close/intimate contacts had positive tuberculin tests, compared to 121 of 356 (34%) close/ regular contacts and 23 of 178 (13%) not close/sporadic contacts and 55 of 355 (16%) of a healthy population sample.

CONCLUSIONS

Even among household contacts of smear-positive pulmonary TB patients, there were major differences in the proximity and duration of contact which were strongly associated with differences in the prevalence of positive tuberculin reactions.