Higher Risk Of Latent Tuberculosis Infection Research Articles

Exposure to bovine livestock and latent tuberculosis infection in children: Investigating the zoonotic tuberculosis potential in a large urban and peri-urban area of Cameroon.

Bovine tuberculosis (bTB), a neglected zoonotic disease, is endemic in cattle in many Sub-saharan African countries, yet its contribution to tuberculosis (TB) burden is understudied. Rapid urbanisation and increase in demand for animal proteins, including dairy products, increases the risk of spill over. This study compared the latent tuberculosis infection (LTBI) risk in children, a proxy-measure for recent TB infection, in children living in high cattle density areas to children from the general population in Cameroon. Cross-sectional study in the Centre Region of Cameroon in 2021, recruiting 160 children aged 2-15 years, stratified by exposure to livestock, people treated for pulmonary TB (PTB) and the general community. Veinous blood was tested for LTBI using QuantiFERON-TB Gold-Plus. Prevalence were calculated and the association to exposure and other risk factors investigated using logistic regression models. The crude LTBI prevalence were 8.2% in the general population, 7.3% in those exposed to cattle and 61% in pulmonary TB household contacts. After adjusting for confounding and sampling design, exposure to cattle and exposure to pulmonary TB were associated with higher risk of LTBI than the general population (respectively odds ratio (OR): 3.56, 95%CI: 0.34 to 37.03; and OR: 10.36, 95%CI: 3.13 to 34.21). Children frequently consuming cow milk had higher risk of LTBI (OR: 3.35; 95%CI 0.18 to 60.94). Despite limited statistical power, this study suggests that children exposed to cattle in a setting endemic for bTB had higher risk of LTBI, providing indirect evidence that Mycobacterium bovis may contribute to TB burden.

Interpreter usage and associations with latent tuberculosis infection treatment acceptance and completion in the USA among non-U.S.-born persons, 2012-2017.

Latent tuberculosis infection (LTBI) screening and treatment interventions that are tailored to optimize acceptance among the non-U.S.-born population are essential for U.S. tuberculosis elimination. We investigated the impact of medical interpreter use on LTBI treatment acceptance and completion among non-U.S.-born persons in a multisite study. The Tuberculosis Epidemiologic Studies Consortium was a prospective cohort study that enrolled participants at high risk for LTBI at ten U.S. sites with 18 affiliated clinics from 2012 to 2017. Non-U.S.-born participants with at least one positive tuberculosis infection test result were included in analyses. Characteristics associated with LTBI treatment offer, acceptance, and completion were evaluated using multivariable logistic regression with random intercepts to account for clustering by enrollment site. Our primary outcomes were whether use of an interpreter was associated with LTBI treatment acceptance and completion. We also evaluated whether interpreter usage was associated treatment offer and whether interpreter type was associated with treatment offer, acceptance, or completion. Among 8,761 non-U.S.-born participants, those who used an interpreter during the initial interview had a significantly greater odds of accepting LTBI treatment than those who did not use an interpreter. There was no association between use of an interpreter and a clinician's decision to offer treatment or treatment completion once accepted. Characteristics associated with lower odds of treatment being offered included experiencing homelessness and identifying as Pacific Islander persons. Lower treatment acceptance was observed in Black and Latino persons and lower treatment completion by participants experiencing homelessness. Successful treatment completion was associated with use of shorter rifamycin-based regimens. Interpreter type was not associated with LTBI treatment offer, acceptance, or completion. We found greater LTBI treatment acceptance was associated with interpreter use among non-U.S.-born individuals.

Latent Tuberculosis Infection Testing Practices in a Large US Integrated Healthcare System.

Tuberculosis (TB) is a public health threat, with >80% of active TB in the United States occurring due to reactivation of latent TB infection (LTBI). We may be underscreening those with high risk for LTBI and overtesting those at lower risk. A better understanding of gaps in current LTBI testing practices in relation to LTBI test positivity is needed. This study, conducted between 1 January 2008 and 31 December 2019 at Kaiser Permanente Southern California, included individuals aged ≥18 years without a history of active TB. We examined factors associated with LTBI testing and LTBI positivity. Among 3 816 884 adults (52% female, 37% White, 37% Hispanic, mean age 43.5 years [standard deviation, 16.1]), 706 367 (19%) were tested for LTBI, among whom 60 393 (9%) had ≥1 positive result. Among 1 211 971 individuals who met ≥1 screening criteria for LTBI, 210 025 (17%) were tested for LTBI. Factors associated with higher adjusted odds of testing positive included male sex (1.32; 95% confidence interval, 1.30-1.35), Asian/Pacific Islander (2.78, 2.68-2.88), current smoking (1.24, 1.20-1.28), diabetes (1.13, 1.09-1.16), hepatitis B (1.45, 1.34-1.57), hepatitis C (1.54, 1.44-1.66), and birth in a country with an elevated TB rate (3.40, 3.31-3.49). Despite being risk factors for testing positive for LTBI, none of these factors were associated with higher odds of LTBI testing. Current LTBI testing practices may be missing individuals at high risk of LTBI. Additional work is needed to refine and implement screening guidelines that appropriately target testing for those at highest risk for LTBI.

Latent tuberculosis infection (LTBI) in health-care workers: a cross-sectional study at a northern Peruvian hospital

BackgroundHealthcare workers (HCWs) have a higher risk of latent tuberculosis infection (LTBI) and active tuberculosis than the general population. In HCWs, the risk of tuberculosis infection depends on the local tuberculosis prevalence, HCWs’ characteristics, the healthcare facility, and prevention and control measures. We aimed to estimate the prevalence and risk factors for LTBI in HCWs at a northern Peruvian hospital.MethodsThis study had two phases: (1) a cross-sectional phase involving recruitment, history taking, and sampling for the Interferon-Gamma Release Assays (IGRA test), and (2) a prospective follow-up of IGRA-positive participants. We enrolled direct and non-direct patient caregivers among HCWs. We defined an LTBI case if the IGRA test was positive and clinical, laboratory, and radiological evaluations for active tuberculosis were negative.ResultsWe recruited 308 participants between November 2022 and May 2023. The mean age was 38.6 ± 8.3 years. Over 75% of the participants were female. The most common job category was technicians (30.5%), physicians (22.7%), nurses (20.5%), and other HCWs groups (17.5%). Most participants worked in hospital wards (28.2%), diagnostics departments (16.9%), and critical care departments (15.6%). The LTBI prevalence among HCWs was 17.86% (95% CI 13.84–22.70). In multivariate analysis, after adjusting for age, time working in our hospital, and family history of tuberculosis, males had a higher risk of LTBI (aPR 1.69, 95% CI 1.01–2.77) than females. Working for more than 10 years increased the risk of LBTI (aPR 2.4, 95% CI 1.44–3.97) compared to working for ≤10 years. Even further, participants who had worked for more than 20 years had an aPR of 4.31 (95% CI 1.09–13.65) compared to those with ≤10 years. Similarly, occupational exposure increased the risk of LTBI (aPR 2.21, 95% CI 1.27–4.08) compared to those HCWs not occupationally exposed.ConclusionThe LTBI prevalence in HCWs at a northern Peruvian hospital was lower compared to other Peruvian cities. Males, more experienced, and occupational exposed HCWs are at higher risk of LTBI. LTBI prevalence in Peruvian HCWs is still high. More studies are needed to address some aspects this study has not examined.

Latent tuberculosis infection testing in a large integrated healthcare system

PurposeTuberculosis (TB) is a public health threat with >80% of active TB in the United States occurring due to reactivation of latent tuberculosis infection (LTBI). We may be under-screening those with high risk for LTBI and over-testing those at lower risk. A better understanding of gaps in current LTBI testing practices, particularly as it relates to LTBI test positivity, is needed. MethodsThis study, conducted between 01/01/2008 and 12/31/2019 at Kaiser Permanente Southern California, included individuals aged ≥18years without history of active TB. We examined factors associated with LTBI testing and LTBI positivity. ResultsAmong 3,816,884 adults (52% female, 37% White, mean age 43.5years [SD 16.1]), 706,367 (19%) were tested for LTBI, among whom 60,393 (9%) had ≥1 positive result. Among 1,211,971 individuals meeting ≥1 screening criteria for LTBI, 210,025 (17%) were tested for LTBI. Factors associated with higher odds of testing positive included male sex (OR:1.32, 95% CI:1.30–1.35), Asian/Pacific Islanders (2.78, 2.68–2.88), current smoking (1.24, 1.20–1.28), diabetes (1.13, 1.09–1.16), hepatitis B (1.45, 1.34–1.57), hepatitis C (1.54, 1.44–1.66), and birth in a TB endemic country (3.40, 3.31–3.49). Despite being risk factors for testing positive for LTBI, none of these factors were associated with higher odds of LTBI testing (Fig. 1). ConclusionsWe identified a mismatch between populations tested for LTBI and populations testing positive. Current LTBI testing practices may be missing individuals at high risk of LTBI. Additional work is needed to develop and implement screening guidelines that appropriately target testing for those at highest risk for LTBI.

Examining Test Cutoffs to Optimize Diagnosis of Latent Tuberculosis Infection in People Born Outside the United States.

Rationale: Detection of latent tuberculosis infection (LTBI) in persons born in high tuberculosis (TB) incidence countries living in low TB incidence countries is key to TB elimination in low-incidence countries. Optimizing LTBI tests is critical to targeting treatment. Objectives: To compare the sensitivity and specificity of tuberculin skin test (TST) and two interferon-γ release assays at different cutoffs and of a single test versus dual testing. Methods: We examined a subset (N = 14,167) of a prospective cohort of people in the United States tested for LTBI. We included non-U.S.-born, human immunodeficiency virus-seronegative people ages 5 years and older with valid TST, QuantiFERON-TB Gold-in-Tube (QFT), and T-SPOT.TB (TSPOT) results. The sensitivity/specificity of different test cutoffs and test combinations, obtained from a Bayesian latent class model, were used to construct receiver operating characteristic (ROC) curves and assess the area under the curve (AUC) for each test. The sensitivity/specificity of dual testing was calculated. Results: The AUC of the TST ROC curve was 0.81 (95% credible interval (CrI), 0.78-0.86), with sensitivity/specificity at cutoffs of 5, 10, and 15 mm of 86.5%/61.6%, 81.7%/71.3%, and 55.6%/88.0%, respectively. The AUC of the QFT ROC curve was 0.89 (95% CrI, 0.86-0.93), with sensitivity/specificity at cutoffs of 0.35, 0.7, and 1.0 IU/mL of 77.7%/98.3%, 66.9%/99.1%, and 61.5%/99.4%. The AUC of the TSPOT ROC curve was 0.92 (95% CrI, 0.88-0.96) with sensitivity/specificity for five, six, seven, and eight spots of 79.2%/96.7%, 76.8%/97.7%, 74.0%/98.6%, and 71.8%/99.5%. Sensitivity/specificity of TST-QFT, TST-TSPOT, and QFT-TSPOT at standard cutoffs were 73.1%/99.4%, 64.8%/99.8%, and 65.3%/100%. Conclusion: Interferon-γ release assays have a better predictive ability than TST in people at high risk of LTBI.

The burden and predictors of latent tuberculosis infection among elder adults in high epidemic rural area of tuberculosis in Zhejiang, China.

Diagnosis and treatment of latent tuberculosis infection (LTBI) is critical to tuberculosis (TB) control. Identifying the risk factors associated with LTBI can contribute to developing an optimized strategy for LTBI management. We conducted a survey of adults aged 65 years and older living in rural areas in Zhejiang Province during July 2021, followed by a one-year follow-up period to determine TB incidence. Participants underwent a physical examination and 5-6 mL of blood was drawn to test for Mycobacterium tuberculosis infection A total of 1856 individuals participated in the study, of whom 50.5% were men and 80.1% were married. Most participants (96.8%) often opened windows for ventilation at home. One-third (33.4%) of participants had abnormal chest radiographs and 34.9% had LTBI. Nine participants (0.5%) developed active TB patients during the one-year follow-up period. People who frequented closed entertainment places such as chess and card rooms had a relatively high percentage of LTBI (39.5%). Factors associated with a higher risk of LTBI in multivariable logistic regression analysis included being male (odds ratio [OR]:1.32; 95% confidence interval [CI] =:1.01-1.72), smoking (OR: 1.43; 95% CI:1.04-1.97), not opening windows for ventilation at home frequently (OR: 1.88; 95% CI: 1.10-3.22), and abnormal chest radiographs (OR; 1.48; 95% CI; 1.20-1.81). LTBI was prevalent among the elder adults living in high-epidemic rural areas of TB in Zhejiang province. Men, people who smoke, and people without the habit of ventilating at home should be targeted for LTBI screening to accelerate the decline of the TB epidemic in Zhejiang Province.

Prevalence and risk factors for latent tuberculosis among diabetes patients in Taiwan: A cross-sectional study.

Diabetes mellitus (DM) is a known risk factor for tuberculosis (TB), leading to an approximate three-fold higher risk of developing active TB. However, epidemiological studies on the prevalence of latent TB infection (LTBI) in DM patients are lacking. In this study, we investigated the presence of LTBI and determined risk factors for LTBI in DM patients. We conducted a cross-sectional study at Taipei Medical University-Shuang Ho Hospital in northern Taiwan. The study population comprised DM patients (aged 20-70 years) attending a metabolism outpatient clinic between February 2011 and February 2013, excluding patients who were suspected or confirmed to have active TB. Venous blood samples were drawn from patients to detect LTBI using the QuantiFERON-TB Gold In-Tube (QFT-GIT) method. We enrolled 1120 patients with DM. The QFT-GIT showed positive results for 241 people (21.5%) and negative results for 879 people (78.5%). The mean age at QFT-GIT positivity was 58.2 years, which was significantly dissimilar to the mean age at QFT-GIT negativity, which was 55.0 years (p < 0.001). Multivariate logistic regression indicated that the trend of QFT-GIT positivity increased after the age of 50 years. Effective glycemic control did not differ significantly between QFT-GIT-positive and -negative patients. Moreover, men were predominant were predominant in both QFT-GIT-positive and -negative patients. More than one-fifth of DM patients have LTBI. Among the DM patients, those older than 50 years may have a higher risk of LTBI. Moreover, effective glycemic control did not differ significantly in patients with LTBI.

Prevalence of latent tuberculosis infection among pre-clinical and clinical medical students using QuantiFERON-TB gold plus and tuberculin skin test at a teaching hospital in Thailand: A cross-sectional study

BackgroundHealthcare workers are considered to be at a higher risk of acquiring tuberculosis (TB) infection than the general population. Clinical medical students are part of the healthcare team and clinical practice are done during their clinical rotation. They could be exposed to similar occupational risks as the healthcare workers. Most students who become infected have latent tuberculosis infection (LTBI) and may not exhibit any clinical symptoms. Some students with LTBI can progress to TB disease during clinical rotations in the hospitals. Therefore, screening for LTBI in this population represents hospital aspect of public health strategy and infection control in medical school in high TB burden countries. ObjectiveWe aimed to determine the prevalence of LTBI among fourth-year medical students and sixth-year medical students by using QuantiFERON-TB Gold Plus (QFT-Plus) and Tuberculin Skin Test (TST). MethodsA cross-sectional study of fourth-year medical students (n = 73) and sixth-year medical students (n = 85) was conducted at the School of Medicine, Chulalongkorn University, Bangkok, Thailand. The medical students (n = 158) who met the eligibility criteria were recruited into the study. LTBI was detected by using QFT-Plus and some of the participants had a tuberculin skin test (TST). The TST was interpreted after 48–72 h. The participants who tested positive by QFT-Plus were considered to have LTBI. Demographic information and data on occupational TB exposure were collected via a questionnaire. A multivariate logistic regression was used to test for associations between independent variables and results of the QFT-Plus. ResultsA total of 158 participants were included in this study. The overall prevalence of LTBI was 6.3% (n = 10) as determined by QFT-Plus. The LTBI prevalence was higher in the sixth-year medical students (9.4%) compared to the fourth-year medical students (2.7%). Higher risk of LTBI was associated with sixth-year medical students (odds ratio, 3.69 [95%CI, 0.75–17.96]), but this was not significant. Moreover, history of occupational TB exposure without PPE yielded an odds ratio of 2.98 [95%CI, 0.68–13.12] but it was not statistically significant due to the small sample size. One hundred thirty-nine (88%) participants were BCG vaccinated as per the national vaccination requirements. No abnormal chest X-rays were found for any of the positive participants. Of the 158 participants, 41 (25.9%) of them had TST. Of the 41 participants, 6 (14.6%) tested positive at a cut-off of ≥ 10 mm for TST, which was concordant with QFT-Plus results. The agreement between the two tests was 0.57 using kappa coefficients. ConclusionThe screening of TB infection in new healthcare workers (HCWs), especially medical students, is essential to reduce future nosocomial TB incidences in the hospitals. This study showed that there was a high prevalence of LTBI among sixth-year medical students compared to fourth-year medical students. Our results suggest that tendency of higher LTBI prevalence might be associated with advanced clinical years, thus tailored public health education strategy and infection control in tertiary care hospitals for new healthcare workers in TB endemic countries may prevent nosocomial TB disease from developing in the future. Therefore, active surveillance should be done for all new HCWs, and TB preventive therapy should be administered to recent converters.

Prevalence of Latent Tuberculous Infection in Patients With Nontuberculous Mycobacterial Lung Disease and Colonization: A Prospective Study in an Intermediate Tuberculosis Burden Country.

BackgroundControlling latent tuberculosis infection (LTBI) is important in eliminating tuberculosis (TB); however, the prevalence of LTBI has rarely been studied in patients with nontuberculous mycobacterial (NTM) lung disease (LD) and colonization (LC).MethodsWe prospectively recruited subjects with NTM isolated from sputum mycobacterial cultures from December 2011 to June 2019. NTM-LD and NTM-LC were defined according to the American Thoracic Society guidelines. Patients with negative cultures were recruited as controls. Patients with a history of active TB or positive TB cultures were excluded. LTBI was confirmed using a QuantiFERON-TB Gold In-tube test. The prevalence and factors associated with LTBI were analyzed.ResultsA total of 406 participants were enrolled, including 171 in the NTM-LD group, 153 in the NTM-LC group, and 82 in the control group. The prevalence of LTBI was higher in the NTM-LD and NTM-LC groups than in the controls (21.6%, 20.9%, and 6.1%; P = .006). Multivariable analysis showed that old age (adjusted odds ratio [aOR], 1.021, per year increment; P = .042), NTM-LD (aOR, 4.030; P = .005), NTM-LC (aOR, 3.610; P = .011, compared with the controls), and pulmonary cavitary lesions (aOR, 3.393; P = .034) were independently associated with LTBI.ConclusionsThe prevalence of LTBI was higher in the patients with NTM-LD and NTM-LC than in the controls. Old age, pulmonary cavitation, and NTM isolated from sputum were associated with a higher risk of LTBI.

Prevalence of latent tuberculosis infection and associated risk factors in prison in East Wollega Zone of western Ethiopia

BackgroundLatent tuberculosis infection (LTBI) is the major source of active TB and is an obstacle to the strategy of World Health Organization to end TB by 2035. In Ethiopia, there are hundreds of prisons and they are conducive settings for the transmission of TB and could serve as the sources of infection to the general public. However, there is little data on the epidemiology of TB in prisons in Ethiopia. The objective of the present study was to estimate the prevalence of LTBI and evaluate associated risk factors in prisons in East Wollega Zone in western Ethiopia.MethodsA cross-sectional design and systematic sampling technique were used to select 352 prisoners from a total of 2620 prisoners during the two months (May and June, 2019). The selected inmates were consented for their willingness to participate in the study. Thereafter, they were interviewed and 2ml of blood sample was collected from each prisoner and screened for LTBI using interferon-gamma release assay (IGRA). The data were analyzed using SPSS version 25 and logistic regression was used to model the likelihood of LTBI occurrence and to identify risk factors associated with LTBI.ResultsThe prevalence of LTBI was 51.2% (95% CI: 46.45–57%) and higher prevalence was recorded in males (53%) than in females (43.5%) although the difference was not significant. Prisoners whose age ≥45 years (AOR = 2.48, 95%CI, 1.04–5.9), who chewed khat (AOR = 2.27; 95% CI, 1.27–4.19), who were prisoned over a year (AOR = 1.81, 95%CI, 1.04–3.18) and who were in overcrowded pens (AOR = 1.91, 95% CI, 1.002–3.65) were at higher risk of LTBI.ConclusionsThe prevalence of LTBI in prisoners in West Wollega Zone of western Ethiopia was high and could serve as sources of infection to the public. Hence optimum handling of prisoners, and regular follow up and treatment of TB cases in prisons were recommended to minimize the burden of TB in the Zone.

Latent tuberculosis infection among health-care workers using Quantiferon-TB Gold-Plus in a country with a low burden for tuberculosis: prevalence and risk factors.

ABSTRACTBACKGROUND: Health-care workers (HCW) are susceptible to latent tuberculosis infection (LTBI). The prevalence of LTBI in HCW in Saudi Arabia has not been reported using the fourth-generation interferon gamma release assay QuantiFERON-TB Gold Plus (QFT-Plus).OBJECTIVE: Determine the prevalence of LTBI in a large heterogeneous HCW population and assess risk factors for LTBI.DESIGN: Cross-sectional and case-control study.SETTING: Tertiary academic hospital, Riyadh, Saudi Arabia.PATIENTS AND METHODS: Medical records of HCWs who had QFT-Plus performed between January to December 2018 were reviewed and included in the cross-sectional study. In a subset analysis, randomly selected positive QFT-Plus cases were compared with controls selected from the same areas of work. Univariate and binary logistic regression analyses were performed to assess the significance of other factors to QFT-PLus positivity.MAIN OUTCOME MEASURES: Prevalence of LTBI in HCWs and potential risk factors for LTBI.SAMPLE SIZE: 3024 HCWs in the cross-sectional analysis; 294 cases and 294 controls in the case-control analysis.RESULTS: Twenty-four percent (n=733) of the HCWs had a positive QFT-Plus. The median (interquartile range) age was 34.0 (31.0-37.1) years, 71% were female, and only 24.8% were of Saudi nationals. Nursing represented 57.7% of HCWs, and 24.7% were working in a non-clinical area. Only 20.3% worked in TB-related departments. A higher risk of LTBI was present in HCWs who were older than 50 years (OR=1.95), from either Philippines (OR=4.7) or the Indian subcontinent (OR=4.1), working as a nurse (OR=2.7), allied health profession (OR=2.1), radiology technician (OR=3.1), or in the emergency room (OR=2.4) or intensive care unit (OR=2.1). In the binary logistic regression, independent predictors for positive QFT-Plus were age group older than 50 years (aOR=2.96), known TB exposure (aOR=1.97), and not receiving BCG at birth (aOR=3.08).LIMITATION: Single-center, retrospective, possible recall bias for BCG vaccination.CONCLUSION: The high prevalence of LTBI among HCW emphasizes the need to continue pre-employment screening, especially for employed personnel from high endemic areas, with targeted annual screening for the same group and other identified high-risk groups. These findings can aid in the development of national screening guidelines for LTBI in HCW.CONFLICT OF INTEREST: None.

High risk for latent tuberculosis infection among medical residents and nursing students in India.

Defining occupational latent tuberculosis infection (LTBI) risk among healthcare workers is needed to support implementation of prevention guidelines. Prospective cohort study of 200 medical residents and nursing students in India was conducted May 2016—December 2017. Tuberculin skin test (TST) and QuantiFERON TB Gold Test-in-tube (QFT-GIT) were performed at study entry and 12 months. Primary outcome was incident LTBI (≥10mm TST induration and/or ≥0.35IU/mL QFT-GIT) at 12 months; secondary outcomes included baseline LTBI prevalence and risk factors for incident and prevalent LTBI using Poisson regression. Among 200, [90 nursing students and 110 medical residents], LTBI prevalence was 30% (95% CI, 24–37); LTBI incidence was 26.8 (95% CI, 18.6–37.2) cases per 100 person-years and differed by testing method (28.7 [95% CI, 20.6–38.9] vs 17.4 [95% CI, 11.5–25.4] cases per 100 person-years using TST and QFT-GIT, respectively). Medical residents had two-fold greater risk of incident LTBI than nursing students (Relative Risk, 2.16; 95% CI, 1.05–4.42). During study period 6 (3%) HCWs were diagnosed with active TB disease. Overall, median number of self-reported TB exposures was 5 (Interquartile Range, 1–15). Of 60 participants with prevalent and incident LTBI who were offered free isoniazid preventive therapy (IPT), only 2 participants initiated and completed IPT. High risk for LTBI was noted among medical residents compared to nursing students. Self-reported TB exposure is underreported, and uptake of LTBI prevention therapy remains low. New approaches are needed to identify HCWs at highest risk for LTBI.

Association between vitamin D and latent tuberculosis infection in the United States: NHANES, 2011-2012.

BackgroundLatent tuberculosis infection (LTBI) is a precursor of active tuberculosis diseases and an important issue in the United States and worldwide. The association between vitamin D deficiency and LTBI is poorly understood.MethodsFrom 2011 to 2012, the National Health and Nutrition Examination Survey (NHANES) assessed LTBI (according to tuberculin skin testing and QuantiFERON®-TB Gold In-Tube) and measured serum levels of vitamin D. We evaluated the association between LTBI and vitamin D using multivariate logistic regression models adjusted for known confounders.ResultsThe LTBI group had a lower 25-hydroxyvitamin D [25(OH)D] level than the non-LTBI group (p=0.0012). The adjusted risk of LTBI was significantly higher among participants with serum 25(OH)D levels <12 ng/ml (adjusted OR [aOR], 2.27; 95% CI, 1.40–3.66) and 12–19 ng/ml (aOR, 1.75; 95% CI, 1.25–2.46) compared to those with a level ≥30 ng/ml. The higher risk of LTBI among the participants with serum 25(OH)D levels <12 ng/ml and 12–19 ng/ml remained unchanged in both male and summer season subgroups.ConclusionsA low serum 25(OH)D level was significantly associated with the risk of LTBI in this US cohort.

754. Prevalence of Latent Tuberculosis Infection Among Healthcare Workers at a Tertiary Care University Hospital

BackgroundWe investigated the prevalence of latent tuberculosis infection (LTBI) among healthcare workers (HCWs) and analyzed its risk factors in a tertiary care university hospital in South Korea in a population with intermediate tuberculosis (TB) burden.MethodsA standard questionnaire regarding the baseline demographics and risk factors for LTBI was given to each participant. QuantiFERON-TB GOLD In-Tube (QFT-GIT) assay and chest radiography were performed to investigate the rate of LTBI.ResultsA total of 1,429 participants, 213 (14.9%) doctors and 988 (69.1%) nurses and 228 (16.0%) others were enrolled. The mean age of the subjects was 33.0 years old, and 1,175 (82.2%) were female. Of the participants, 94.5% had received BCG vaccine. QFT-GIT assays were positive for 156 subjects (10.9%). Of the 213 doctors, 28 (13.1%) were positive by QFT-GIT, and among the 988 nurses, 94 (9.5%) had positive QFT-GIT results. Experience of working in hospital was significantly associated with positive LTBI test results by QFT-GIT assay. Gender and duration of employment as an HCW were significantly associated with having a positive QFT-GIT result in univariate analyses. In multivariate analyses, duration of employment as an HCW (>15 years) (odds ratio, 1.98; 95% confidence interval, 1.14–3.43) was independently associated with increased risk of a positive QFT-GIT result.ConclusionA high prevalence of LTBI was found among our HCWs. Considering the association between the experience of working in hospital and high risk of LTBI. The risk for tuberculosis infection among HCWs was higher than general population, which suggests that stricter preventive strategies against nosocomial tuberculosis infection should be implemented.Disclosures All authors: No reported disclosures.

A Systematic Review of Studies Evaluating the Cost Utility of Screening High-Risk Populations for Latent Tuberculosis Infection.

As tuberculosis screening trends to targeting high-risk populations, knowing the cost effectiveness of such screening is vital to decision makers. The purpose of this review was to compile cost-utility analyses evaluating latent tuberculosis infection (LTBI) screening in high-risk populations that used quality-adjusted life-years (QALYs) as their measure of effectiveness. A literature search of MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Web of Knowledge, and PubMed was performed from database start to November 2014. Studies performed in populations at high risk of LTBI and subsequent reactivation that used the QALY as an effectiveness measure were included. Quality was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Data extracted included tuberculin skin test (TST) and/or interferon-gamma release assay (IGRA) use, economic, screening, treatment, health state, and epidemiologic parameters. Data were summarized in regard to consistency in model parameters and the incremental cost-effectiveness ratio (ICER), with costs adjusted to 2013 US dollars. Of 415 studies identified, ultimately eight studies were included in the review. Most took a societal perspective (n=4), used lifetime time horizons (n=6), and used Markov models (n=8). Screening of adult immigrants was found to be cost effective with a TST in one study, but moderately cost effective with an IGRA in another study; screening immigrants arriving more than 5years prior with an IGRA was moderately cost effective until 44years of age (n=1). Screening HIV-positive patients was highly cost effective with a TST (n=1) and moderately cost effective with an IGRA (n=1). Screening in those with renal diseases (n=2) and diabetes (n=1) was not cost effective. Very few studies used the QALY as their effectiveness measure. Parameter and study design inconsistencies limit the comparability of studies. With validity issues in terms of parameters and assumptions, any conclusion should be interpreted with caution. Despite this, some cautionary recommendations emerged: screening HIV patients with a TST is highly cost effective, while screening adult immigrants with an IGRA is moderately cost effective.

Missed Opportunities for Tuberculosis Screening in Primary Care

To assess how frequently pediatric practitioners perform latent tuberculosis infection (LTBI) screening according to guidelines. We hypothesized that screening occurs less frequently among children whose parents do not speak English as the primary language. We conducted a retrospective cohort study of patients attending well-child visits in an urban academic pediatric primary care clinic between April 1, 2012, and March 31, 2013. We assessed documentation of 3 LTBI screening components and tested the association between parent primary language and tuberculin skin test (TST) placement and documentation of results. During the study period, 387 of 9143 children (4%) had no documentation of screening question responses. Among the other 8756 children, 831 (10%) were identified as at high risk for LTBI. Of these, 514 (62%) did not have documented TST placement in the appropriate time frame. Thirty-nine of 213 children (18%) who had a TST placed did not have documented results. Multivariable regression showed that parent language was not associated with TST placement or documentation of results, but non-Hispanic Black children were more likely to not have a documented test result (aOR, 2.12; 95% CI, 1.07-4.19; P=.03) when adjusting for age, sex, parent primary language, insurance status, day of the week, and study year of TST placement. Parent primary language was not associated with LTBI testing. However, we found substantial gaps in TST placement and documentation of TST results among high-risk children, the latter of which was associated with race/ethnicity. Targeted quality improvement efforts should focus on developing processes to ensure complete screening in high-risk children.

Discordance between Two Interferon-Gamma Release Assays in the Diagnosis of Latent Tuberculosis Infection in Healthcare Workers

Background: Interferon-gamma release assays (IGRAs) more accurately diagnose Mycobacterium tuberculosis (Mtb) infection than the tuberculin skin test. To prevent outbreaks in medical facilities, early detection and treatment of Mtb infection (including latent tuberculosis infection (LTBI)) is important in healthcare workers. Therefore, the IGRAs have considerable utility for Mtb infection control in medical facilities. In Japan, two IGRAs are commercially available, QuantiFERON®-TBGold In-Tube assay (QFT-GIT) and T-SPOT®.TB (T-SPOT). However, it remains unclear if diagnostic yields of LTBI by both IGRAs are equivalent in healthcare workers. Methods: We performed both QFT-GIT and T-SPOT simultaneously in healthcare workers with a high risk of LTBI (excluding active tuberculosis) between December 2012 and February 2013. Results: Among 313 subjects (excluding 2 cases with indeterminate T-SPOT), 6 (1.9 %) and 12 (3.8 %) were QFT-GIT positive and T-SPOT positive, respectively. There was no significant concordance of results between the QFT-GIT and the T-SPOT (p=0.064 and Kappa=0.43, 95% confidence interval 0.082-0.78). Among 10 discordant cases between two IGRAs, 8 cases had IGRAs’ results near the cutoff values. Conclusion: Without a diagnostic gold standard for LTBI, it is difficult for us to further assess which test is more accurate and more suitable for the diagnosis of LTBI. However, to diagnose LTBI of healthcare workers with IGRAs’ results near the cutoff values, we should consider clinical context, such as contact level, as well as the results of IGRAs.

Performance of QuantiFERON-TB Gold In-Tube test and Tuberculin Skin Test for diagnosis of latent tuberculosis infection in BCG vaccinated health care workers

BackgroundTuberculin skin test (TST) has been used for years as an aid in diagnosing latent tuberculosis infection (LTBI) but it suffers from a number of well-documented performance and logistic problems. Quantiferon-TB Gold In Tube test (QFT-GIT) has been reported to have better sensitivity and specifity than TST. In this study, it was aimed to compare the performance of a commercial IFN-γ release assay (QFT-GIT) with TST in the diagnosis of HCWs at risk for latent TB infection in BCG vaccinated population.Material/MethodsHundred healthy volunteer health care workers were enrolled. All were subjected to TST and QFT-GIT. Results were compared among Health Care Workers (HCWs) groups in terms of profession, workplace, working duration.ResultsTST is affected by previous BCG vaccinations and number of cases with QFT-GIT positivity is increased in accordance with the TST induration diameter range. QFT-GIT result was negative in 17 of 32 TST positive (≥15 mm) cases and positive in 4 of 61 cases whose TST diameters are between 6–14 mm, that is attritutable to previous BCG vaccination(s). It was negative in all cases with TST diameters between 0–5 mm.HCWs with positive QFT-GIT results were significantly older than the ones with negative results. Furthermore duration of work was significantly longer in QFT-GIT positive than in negative HCWs.ConclusionsThere was a moderate concordance between QFT-GIT and TST, when TST result was defined as positive with a ≥15 mm diameter of induration. We suggest that QFT-GIT can be used as an alternative to TST for detection of LTBI, especially in groups with high risk of LTBI and in population with routine BCG vaccination program.

Prevalence of latent tuberculosis infection and its risk factors in schoolchildren and adolescents in Shanghai, China

As tuberculosis (TB) infection in childhood contributes to the pool of individuals with latent tuberculosis infection (LTBI) from which future tuberculosis cases arise, this study aimed to determine the prevalence and risk factors associated with LTBI in schoolchildren and adolescents from Shanghai, China. In this cross-sectional study, we administered T-SPOT.TB and TB infection risk factor questionnaire to children and adolescents aged between 10 and 18 years in 2010 in Shanghai. LTBI cases were defined by positive T-SPOT.TB test results and X-ray confirmation. A total of 1106 schoolchildren and adolescents were enrolled, of which 46.1% were male, and 91.8% were vaccinated with Bacille Calmette Guerin (BCG). Overall, 52 (4.7%) children had a positive T-SPOT.TB result, with significant increase in age distribution. However, none of the participants demonstrated TB-related abnormality on X-ray examination. Multivariate analysis showed that LTBI was associated with no BCG vaccination (odds ratio: 2.40; 95% confidence interval: 1.182-5.335) and a history of TB exposure (odds ratio: 6.89; 95% confidence interval: 3.095-15.35). For 46 children and adolescents with history of TB exposure, contact hours per week of TB cases were significantly associated with risk of LTBI. Prevalence of LTBI in schoolchildren and adolescents in Shanghai is relatively low compared with other high epidemic areas of TB. A higher risk of LTBI was observed among children with no BCG vaccination and those with a history of TB exposure, which suggests that the prevalence of LTBI among schoolchildren could be further reduced by strengthening BCG vaccination under the national immunization programme and enhancing contact investigation of active TB patients.