Exploring genotype concordance in epidemiologically linked cases of tuberculosis in New York City

A population-based tuberculosis contact investigation in the country of Georgia

Setting: Identification and screening of contacts of patients with active tuberculosis (TB) is infrequent in low- and middle-income countries. Objective: To estimate the incidence, prevalence and risk factors of latent tuberculous infection (LTBI) and active TB among contacts of newly reported smear-positive TB patients. Design: A population-based contact investigation of sputum smear-positive pulmonary TB (PTB) cases diagnosed between April and December 2012 in Georgia was conducted. LTBI was assessed using the tuberculin skin test (TST). Contacts with active TB were identified from the National TB Program surveillance database. Results: Among 896 index patients with active TB, 3133 contacts were identified and 1157 (37%) underwent a TST, 34% of whom were positive. Most contacts were household contacts (86%) and female (58%). Among contacts, the 1-year period prevalence of active TB was 3.3% (95%CI 2.70-3.98); the incidence rate was 1101 per 100 000 person-years (95%CI 822-1443). In multivariable analysis, household contacts were more likely to have LTBI (adjusted OR [aOR] 2.28, 95%CI 1.49-3.49) than close contacts. Conclusions: A high prevalence of both LTBI and active TB was identified among contacts of PTB cases. Efforts aimed at active case finding among TB contacts should improve early case detection and enhance TB control efforts.