An attempt to determine the background to pulmonary tuberculosis in adolescent males (based on a military survey)

Abstract

1. A comparative study has been made between the tuberculous contact histories of three groups of soldiers—a healthy group, and groups with primary tuberculosis and post-primary tuberculosis. 2. At 19 to 22 years, there is no significant difference in the contact histories of the healthy soldiers and those with primary tuberculosis. 3. A significant difference exists between the contact histories of the healthy soldiers and those with post-primary tuberculosis. 4. These significant differences remain when allowance is made for the significant difference in the mean ages of the groups. 5. An explanation for these significant differences is revealed, namely that the patients with post-primary tuberculosis entered a tuberculous environment roughly 4 years earlier than the patients with primary tuberculosis. 6. The present series reveals a period of 3 to 4 years when tuberculous contacts are made in increasing numbers, and at the end of which a presumedly tuberculin negative individual acquires his primary infection. 7. The average period between tuberculin conversion and the appearance of post-primary tuberculosis in male adolescents is about 3 years for the period of this survey (1950). During this period, contact with tuberculous persons is continued at the same pace as before the primary infection. 8. The history of known tuberculous contacts, when taken with great thoroughness, yields data which parallel the tuberculin conversion rate fairly closely. 9. Once an index case is discovered, search for other cases should be made among all reasonably close contacts of the previous 6 to 8 years rather than among close contacts of the previous 1 to 2 years, which tends to be the current practice.