Introduction: Identifying and screening close contacts of patients with active tuberculosis (TB) is a TB control strategy that is uncommonly pursued in low-and middle-income countries. We carried out a population-based study to determine risk factors for latent TB infection (LTBI) and active TB among contacts of active TB cases.
Methods: Index patients included all smear-positive pulmonary TB cases diagnosed in Georgia between April-December 2012; eligible contacts included all close contacts identified by regional epidemiologists during household visits. Tuberculin skin tests (TST) were performed on contacts and a positive TST was defined as an induration of >10 mm. Active TB cases among contacts were determined by review of the Georgia National TB Program surveillance database.
Results: Among 896 index patients with active TB, 3133 contacts were identified and 1157 (37%) had a TST performed. Among those tested, 34% were positive. Most contacts (86%) were household contacts and 42.5% were male. Household contacts (OR=1.5, 95%CI 1.1-2.0) and contacts of male index patients (OR=1.5, 95%CI 1.1-2.0) were more likely to have positive TST. In multivariable analyses, household contacts were more likely to have a positive TST result (adjusted OR [aOR]=2.28, 95%CI 1.49-3.49) compared to non-household contacts. Those contacts whose index patient had a TB diagnosis in past and failed treatment (OR=6.4, 95%CI 1.9-21.8) or defaulted (OR=5.0, 95%CI 1.8-14.0) were more likely to have a positive TST compared to those with index cases who were previously cured. Overall, there were 111 active TB cases; the incidence rate was 1101 cases per 100 000 person-years. In multivariable analyses for active TB after 1-year follow-up period, Odds of having TB was significantly higher for household contacts among males (aOR 4.38, 95% CI 1.05-18.22), but it was not significant among females (aOR 0.76, 95%CI 0.35-1.67).
Conclusions: A high prevalence of TB was identified among contacts of active TB cases in Georgia. Contacts of index cases that defaulted or failed TB therapy were at increased risk of LTBI. Efforts aimed at reducing treatment default should enhance TB control efforts and may also decrease LTBI and active TB among contacts.
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About this Master's Thesis
|Committee Chair / Thesis Advisor|
|Risk factors for active and latent tuberculosis (TB) among contacts of smear-positive index TB patients in the country of Georgia ()||2018-08-28||