Setting: Twenty-nine United States jurisdictions.
Objective: To determine yields of tuberculosis (TB) contact investigations.
Methods: Health departments within the jurisdictions reported counts and outcomes from routine contact investigations for cases reported in 1999.
Results: The 29 jurisdictions reported 9199 TB cases, 51.9% of the US and Puerto Rico 1999 total, and listed 67585 contacts. While 571 (10.6%) of 5405 pulmonary cases confirmed by sputum bacteriology had no contacts listed, 13904 contacts were listed for other cases that were unlikely to be contagious. Diagnostic evaluation was completed for 56100 contacts (83.0%), with 561 TB cases found. Of 13083 contacts found to have latent TB infection, 5746 (44.5%) completed treatment to prevent TB. Loss to follow-up and self-discontinuation of treatment accounted for 70% of reasons why treatment was not completed.
Conclusion: Contact investigations capture substantial numbers of TB cases and latent TB infections, but the impact on prevention is limited by the poor treatment rates for infected contacts. Contacts should be sought for each potentially contagious TB case; why so many contacts are sought for cases who are unlikely to be contagious needs to be determined.