Yield of source-case and contact investigations in identifying previously undiagnosed childhood tuberculosis.

OBJECTIVE: To determine the extent to which source-case investigations, in which a child was the index tuberculosis (TB) case, and contact investigations of adult pulmonary cases, identified children and adults with previously undiagnosed TB or latent tuberculosis infection (LTBI).
METHODS: We reviewed records of 111 source-case investigations and 38 contact investigations involving 164 TB cases among children <5 years of age from eight California health jurisdictions with a case rate greater than the state average for this age group (9.6/100000).
RESULTS: In source-case investigations, 141 children <5 years and 113 children 5-14 years of age were evaluated for TB disease and LTBI. Fourteen previously undiagnosed TB cases were found, including seven children <5 years of age. Source-case investigations also identified persons who might benefit from treatment for LTBI (45% had a positive tuberculin reaction). In contact investigations of adult TB cases, 202 children <5 years and 122 children 5-14 years of age were evaluated. In addition to 46 children with TB <5 years of age, the basis on which these contact investigations were selected for study, four children 5-14 years of age and 10 adults were found to have TB disease. A high percentage (41%) of contacts with a positive tuberculin reaction was found, especially among household contacts.
CONCLUSIONS: Source-case investigations and contact investigations are effective for finding previously undiagnosed cases of TB. They are also useful for identifying children and adults who would possibly benefit from treatment for LTBI. Earlier detection and treatment of adults with TB could interrupt transmission and be a step toward eliminating childhood TB.