Tuberculosis (TB) caused by mycobacterium tuberculosis is transmitted from person to person through air. In Korea, it remains still one of the serious public health problems of concern, showing 30,892 newly reported TB cases in 2016. To identify secondary cases of active TB and latent TB infection among contacts for effective TB infection control, contact investigations in congregate settings such as schools are an important component of tuberculosis control in Korea. In 2016, 3,502 contact investigations were performed in school settings. This report describes an episode that in September 2016, a case diagnosed with acid-fast bacillus smear-positive TB at a high school was reported to KCDC. After screening of 569 contacts at this school, 3 cases were classified as pulmonary TB with an identical genotype and 37 cases as latent tuberculosis infection (LTBI). Of them, 28 cases started LTBI treatment for preventing progression to TB disease and 25 cases completed their treatments.
It is suggested that to tackle TB transmission effectively, contact investigations should be more strengthened through private-public collaboration.