[Current state and related factors in examinations of those who have had contact with tuberculosis]

This study investigated the current conditions of identifying tuberculosis contacts and enforcing their examinations in Public Health Centers and examined related factors.

The study subjects were 431 index cases with tuberculosis who were newly registered between 1995 and 1997 at four Public Health Centers in Tokyo and Yokohama. Based on case registration card information and interviews with public health nurses in charge, the data of identification of contacts and enforcement of examination of their contacts were collected.

The proportion of index cases with insufficient identification of contacts was 28.3%, particularly the non-family contact data being insufficient. From logistic regression analysis: index cases aged 20-39 years; contact with many people; "a moderate risk index of infection" cases; and being homeless were factors significantly related to insufficient identification of contacts. The proportion of contacts who were examined in individual contact examinations was 59.1%, that of mass contact examinations was 80.4%. From logistic regression analysis: negative index cases on sputum smear; and no history of routine health examinations for the past 3 years or a complete lack of information were factors significantly related to insufficient enforcement of individual contact examinations. As to mass contact examinations, not interviewing index cases was a factor significantly related to insufficient enforcement. Further individual and mass contact examinations differed in quality according to Public Health Center. The incidence in close contacts with active tuberculosis was 1.0%, and was especially high in members of the same household and friends of the newly diagnosed.

This study showed that the current contact examinations for tuberculosis are insufficient. In addition it was shown that an adequate identification of contacts and a complete enforcement of contact examinations are urgent needs in Japan.