Abstract
BackgroundMore than half of all health care workers (HCWs) in high TB-incidence, low and middle income countries are latently infected with tuberculosis (TB). We determined radiological lesions in a cohort of HCWs with latent TB infection (LTBI) in India, and determined their association with demographic, occupational and T-cell immune response variables.MethodologyWe obtained chest radiographs of HCWs who had undergone tuberculin skin test (TST) and QuantiFERON-TB Gold In Tube (QFT), an interferon-γ release assay, in a previous cross-sectional study, and were diagnosed to have LTBI because they were positive by either TST or QFT, but had no evidence of clinical disease. Two observers independently interpreted these radiographs using a standardized data form and any discordance between them resolved by a third observer. The radiological diagnostic categories (normal, suggestive of inactive TB, and suggestive of active TB) were compared with results of TST, QFT assay, demographic, and occupational covariates.ResultsA total of 330 HCWs with positive TST or QFT underwent standard chest radiography. Of these 330, 113 radiographs (34.2%) were finally classified as normal, 206 (62.4%) had lesions suggestive of inactive TB, and 11 (3.4%) had features suggestive of active TB. The mean TST indurations and interferon-γ levels in the HCWs in these three categories were not significantly different. None of the demographic or occupational covariates was associated with prevalence of inactive TB lesions on chest radiography.Conclusion/SignificanceIn a high TB incidence setting, nearly two-thirds of HCWs with latent TB infection had abnormal radiographic findings, and these findings had no clear correlation with T cell immune responses. Further studies are needed to verify these findings and to identify the causes and prognosis of radiologic abnormalities in health care workers.
Highlights
More than half of all health care workers (HCWs) in the high TBincidence, low and middle income countries (LMICs) are estimated to be latently infected with tuberculosis (TB)[1,2] and this high prevalence is attributable to increased occupational exposure to Mycobacterium tuberculosis, in addition to possible exposure in the community.[1,3]
Many individuals and especially HCWs residing in LMICs have asymptomatic abnormalities on chest radiographs,[12,13] and chest radiography is considered as a cost effective screening tool or them.[14]
We evaluated chest radiographs which were obtained in a study carried out among HCWs at the Mahatma Gandhi Institute of Medical Sciences (MGIMS), Sevagram, a rural, tertiary medical school hospital in central India
Summary
More than half of all health care workers (HCWs) in the high TBincidence, low and middle income countries (LMICs) are estimated to be latently infected with tuberculosis (TB)[1,2] and this high prevalence is attributable to increased occupational exposure to Mycobacterium tuberculosis, in addition to possible exposure in the community.[1,3] In high TB incidence countries such as India, HCWs may be repeatedly exposed to M. tuberculosis; previous studies have shown high prevalence of latent TB infection (LTBI), and high rates of conversions (new infections) among HCWs.[4,5,6] low-income countries often do not routinely screen HCWs for LTBI, nor implement TB infection control programs.In high income countries, tuberculin skin test (TST) or interferon-c release assays (IGRA) are used to screen HCWs for the presence of LTBI.[7,8] A sizeable proportion of these HCWs are trained in high TB-incidence LMICs and have a high probability of having LTBI.[9]. More than half of all health care workers (HCWs) in high TB-incidence, low and middle income countries are latently infected with tuberculosis (TB). We determined radiological lesions in a cohort of HCWs with latent TB infection (LTBI) in India, and determined their association with demographic, occupational and T-cell immune response variables. The radiological diagnostic categories (normal, suggestive of inactive TB, and suggestive of active TB) were compared with results of TST, QFT assay, demographic, and occupational covariates. A total of 330 HCWs with positive TST or QFT underwent standard chest radiography. Of these 330, 113 radiographs (34.2%) were classified as normal, 206 (62.4%) had lesions suggestive of inactive TB, and 11 (3.4%) had features suggestive of active TB. Further studies are needed to verify these findings and to identify the causes and prognosis of radiologic abnormalities in health care workers
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