METHODS: NYC tuberculosis staff routinely review TB exposures at non-household sites for patients with culture-positive, respiratory TB disease to determine whether a contact investigation is warranted. Contacts are identified, prioritized, and, if eligible, tested with either a tuberculin skin test or an interferon-gamma release assay. Those who test positive are referred for medical evaluation and chest x-ray. Test results are analyzed to assess the likelihood of TB transmission at the site, which informs additional public health intervention. Data about exposure sites, index patients, and contacts were abstracted from the NYC TB registry. Exposures in healthcare facilities and correctional facilities were excluded from this analysis.
RESULTS: Among 656 known exposures in non-household settings, DOHMH conducted investigations for 264 (40%). Transmission was probable at 62 (23%) sites, possible at 15 (6%), unlikely at 151 (57%), and unable to be assessed at 36 (14%). In total, 5,583 contacts were identified, of whom 5,220 (93%) were eligible for testing and 4,479 (86%) were tested. Investigations led to the identification of 15 contacts with TB disease and 578 contacts with latent TB infection (LTBI). Of the latter, 393 (68%) started treatment for LTBI and 251 (64%) completed treatment.
CONCLUSIONS: Non-household contact investigations are an important component of NYC’s TB prevention strategy. Our data indicate that TB transmission regularly occurs in non-household settings. Between October 2010 and December 2014, NYC TB staff identified 15 previously undetected TB cases and nearly 600 contacts with newly-diagnosed latent TB infection through systematic investigations at non-household sites. While the majority of infected contacts started treatment for LTBI, further efforts are warranted to improve treatment initiation and completion in this high-risk group.