Risk Of Latent Tuberculosis Infection Research Articles

Rates of Latent Tuberculosis in Health Care Staff in Russia

BackgroundRussia is one of 22 high burden tuberculosis (TB) countries. Identifying individuals, particularly health care workers (HCWs) with latent tuberculosis infection (LTBI), and determining the rate of infection, can assist TB control through chemoprophylaxis and improving institutional cross-infection strategies. The objective of the study was to estimate the prevalence and determine the relative risks and risk factors for infection, within a vertically organised TB service in a country with universal bacille Calmette-Guérin (BCG) vaccination.Methods and FindingsWe conducted a cross-sectional study to assess the prevalence of and risk factors for LTBI among unexposed students, minimally exposed medical students, primary care health providers, and TB hospital health providers in Samara, Russian Federation. We used a novel in vitro assay (for gamma-interferon [IFN-γ]) release to establish LTBI and a questionnaire to address risk factors. LTBI was seen in 40.8% (107/262) of staff and was significantly higher in doctors and nurses (39.1% [90/230]) than in students (8.7% [32/368]) (relative risk [RR] 4.5; 95% confidence interval [CI] 3.1–6.5) and in TB service versus primary health doctors and nurses: respectively 46.9% (45/96) versus 29.3% (34/116) (RR 1.6; 95% CI 1.1–2.3). There was a gradient of LTBI, proportional to exposure, in medical students, primary health care providers, and TB doctors: respectively, 10.1% (24/238), 25.5% (14/55), and 55% (22/40). LTBI was also high in TB laboratory workers: 11/18 (61.1%).ConclusionsIFN-γ assays have a useful role in screening HCWs with a high risk of LTBI and who are BCG vaccinated. TB HCWs were at significantly higher risk of having LTBI. Larger cohort studies are needed to evaluate the individual risks of active TB development in positive individuals and the effectiveness of preventive therapy based on IFN-γ test results.

Latent variable assessment of outcomes in a nurse-managed intervention to increase latent tuberculosis treatment completion in homeless adults.

To assess predictors of latent tuberculosis infection (LTBI) completion by using structural equation modeling (SEM) among homeless adults, a group at great risk for LTBI and active tuberculosis (TB). LTBI therapy is effective in stemming the progression to active TB, yet treatment adherence among homeless persons is difficult to attain. By using SEM, the authors assessed predictors of LTBI completion among a sample of 494 homeless adults in Los Angeles, CA, who received either a nurse case-managed program (NCM) or a usual care program. Latent variables were created with the baseline variables of site type, age, intervention status, dissatisfaction with health care, depression, TB risk assessment, alcohol use, heroin or cocaine use, and TB knowledge. Outcome variables included many of the same baseline variables as well as treatment completion. LTBI treatment completion (100% adherence) was significantly and positively associated with participation in NCM, older age, and less heroin or cocaine use. NCM also predicted greater TB knowledge, greater ease of treatment, and more satisfaction with treatment (NCM completion rate = 64%, control rate = 42%). The culturally competent NCM program, combined with active tracking and incentives, was successful in a difficult-to-treat and highly transient population.

Tuberculosis among Health-Care Workers in Low- and Middle-Income Countries: A Systematic Review

BackgroundThe risk of transmission of Mycobacterium tuberculosis from patients to health-care workers (HCWs) is a neglected problem in many low- and middle-income countries (LMICs). Most health-care facilities in these countries lack resources to prevent nosocomial transmission of tuberculosis (TB).Methods and FindingsWe conducted a systematic review to summarize the evidence on the incidence and prevalence of latent TB infection (LTBI) and disease among HCWs in LMICs, and to evaluate the impact of various preventive strategies that have been attempted. To identify relevant studies, we searched electronic databases and journals, and contacted experts in the field. We identified 42 articles, consisting of 51 studies, and extracted data on incidence, prevalence, and risk factors for LTBI and disease among HCWs. The prevalence of LTBI among HCWs was, on average, 54% (range 33% to 79%). Estimates of the annual risk of LTBI ranged from 0.5% to 14.3%, and the annual incidence of TB disease in HCWs ranged from 69 to 5,780 per 100,000. The attributable risk for TB disease in HCWs, compared to the risk in the general population, ranged from 25 to 5,361 per 100,000 per year. A higher risk of acquiring TB disease was associated with certain work locations (inpatient TB facility, laboratory, internal medicine, and emergency facilities) and occupational categories (radiology technicians, patient attendants, nurses, ward attendants, paramedics, and clinical officers).ConclusionsIn summary, our review demonstrates that TB is a significant occupational problem among HCWs in LMICs. Available evidence reinforces the need to design and implement simple, effective, and affordable TB infection-control programs in health-care facilities in these countries.

SUCCESS OF A TARGETED TUBERCULOSIS TESTING AND TREATMENT PROGRAM IN A FOREIGN-BORN POPULATION, 2000-2004

PURPOSE: The Suffolk County, New York, Department of Health Services, Bureau of Chest Diseases (BCD), Targeted Tuberculosis (TB) Testing and Treatment (TT) Program reached out to foreign-born populations at increased risk for latent tuberculosis infection (LTBI) who accounted for 75 % of TB cases in SC between 2000 and 2004. Of those program participants begun on LTBI treatment, 78.2% completed treatment.

Tuberculin Skin Testing in Children

In 1996, the American Academy of Pediatrics (AAP) recommended targeted tuberculin skin testing (TST) of children while discouraging routine TST of children without risk factors for tuberculosis (TB). Recent studies have provided evidence in support of the targeted TST and recommendations that favor risk assessment over universal screening with TST. While evidence for targeted TB testing exists and benefits of screening programs are clear, administrative logistics could be a greater issue. The challenge for public health and school officials is to develop a screening program that avoids stigmatization of the at-risk group. Until then, pediatric healthcare providers will continue to have a key role in identifying children at risk for latent TB infection by using the AAP-endorsed risk-assessment questionnaire and should screen children with TST only when >1 risk factor is present.

Avoiding the effect of BCG vaccination in detecting Mycobacterium tuberculosis infection with a blood test

Bacille Calmette-Guérin (BCG) vaccination can confound tuberculin skin test (TST) reactions in the diagnosis of latent tuberculosis infection (LTBI). The TST was compared with a Mycobacterium tuberculosis (MTB)-specific enzyme-linked immunospot (ELISPOT) assay during an outbreak of MTB infection at a police academy in Germany. Participants were grouped according to their risk of LTBI in close (n = 36) or occasional (n = 333) contacts to the index case. For the TST, the positive response rate was 53% (19 out of 36) among close and 16% (52 out of 333) among occasional contacts. In total, 56 TST-positive contacts (56 out of 71 = 78.9%) and 27 TST-negative controls (27 out of 298 = 9.1%) underwent ELISPOT testing. The odds ratio (OR) of a positive test result across the two groups was 29.2 (95% confidence interval (CI) 3.5-245.0) for the ELISPOT and 19.7 (95% CI 2.0-190.2) for the TST with a 5 mm cut-off. Of 369 contacts, 158 (42.8%) had previously received BCG vaccination. The overall agreement between the TST and the ELISPOT was low, and positive TST reactions were confounded by BCG vaccination (OR 4.8 (95% CI 1.3-18.0)). In contrast, use of a 10-mm induration cut-off for the TST among occasional contacts showed strong agreement between TST and ELISPOT in nonvaccinated persons. In bacille Calmette-Guérin-vaccinated individuals, the Mycobacterium tuberculosis-specific enzyme-linked immunospot assay is a better indicator for the risk of latent tuberculosis infection than the tuberculin skin test.

High incidence of anergy in inflammatory bowel disease patients limits the usefulness of PPD screening before infliximab therapy

Background & Aims: Reports of tuberculosis (TB) in patients administered infliximab prompted the Food and Drug Administration to recommend that all patients being considered for this therapy be evaluated for the risk for latent TB infection by means of a tuberculin skin test (TST). The aim of this study is to evaluate the utility of a TST as an adequate screen for TB exposure in patients with inflammatory bowel disease (IBD). Methods: Eighty-two consecutive patients with IBD (Crohn’s disease, 70 patients; ulcerative colitis, 4 patients; indeterminate colitis, 8 patients) seen at Cedars-Sinai Medical Center IBD Center (Los Angeles, CA) being treated with or considered for infliximab therapy underwent a standard intradermal purified protein derivative (PPD) TST before or between infusions of infliximab. One or more control antigens ( Candida, tetanus, and/or mumps) were concurrently placed on 69 of these patients. Skin tests were read for induration at 48–72 hours after placement, and results were recorded. Results: None of 82 patients had a positive PPD TST result. Overall, 71% of patients (49 of 69 patients) with controls placed failed to react to any antigen. Eighty-three percent of patients (40 of 48 patients) who were administered corticosteroids and/or immunosuppressive medications, not including infliximab, for at least 1 month were anergic compared with 43% of patients (9 of 21 patients; P < 0.002) who were not administered those medications. Conclusions: Given the high prevalence of anergy, a negative TST result in patients with IBD administered infliximab is an unreliable indicator for TB exposure. Evaluation for TB risks should include not only a TST, but also a detailed history of travel, TB exposures, and such symptoms as chronic cough and weight loss, and a chest radiograph should be considered.

Latent tuberculosis infection: recommendations for preventive therapy in adults in Germany

The immunologic mechanisms of latent tuberculosis (TB) infection are complex and hitherto not completely understood. The lifelong risk of an immunocompetent individual of developing active TB after infection with M. tuberculosis is 5-10 % and highest during the first two years after infection. Various factors may considerably increase the risk of developing active TB, e. g., immunosuppressive disease or immunosuppressive medication. However, the development of active TB may be avoided by preventive chemotherapy, the therapy of choice being isoniazid over a 9-month period. Alternative treatment regimens may be indicated in special cases, but it must be borne in mind that the efficacy of these regimens has not been studied sufficiently while they seem to be less well tolerated than isoniazid monotherapy. The tuberculin skin test is still the only sufficiently documented method to detect latent infection with M. tuberculosis which is also suitable for routine application. This test today should be performed exclusively as described by Mendel and Mantoux. Its sensitivity and specificity depend on the prevalence of tuberculosis infection. It should therefore be restricted to individuals at increased risk of latent TB infection. When interpreting the tuberculin skin test, it is necessary to know whether an individual belongs to one of the defined risk groups or has an elevated risk of developing active TB. Among the risk groups are individuals who may have been infected recently with M. tuberculosis (contacts of contagious TB patients) or in whom other factors increase their risk of developing active TB. The indication for chemotherapy for latent TB infection must be based on a careful individual risk-benefit analysis and, besides patient compliance, requires full information of the patient and careful monitoring during therapy. Before initiating treatment, active TB must always be excluded by the proven methods.

Tuberculin testing and risk of tuberculosis infection among New York City schoolchildren.

To assess adherence to a 1996 health policy change, which discontinued mandatory tuberculin skin testing (TST) of new entrants to NYC primary schools and continued mandatory testing of new entrants to secondary schools. The proportion tested before (1991-1995) and after (1996-1998) the change in health policy was determined. Factors associated with TST positivity and the cost of continued testing were assessed. A total of 76.6% of 551 636 new entrants to primary schools were tested in 1991-1995; slightly fewer, 71.1% of 339 958, were tested in 1996- 1998. Among new entrants to secondary schools, 31.0% of 106 463 were tested in 1991-1995 and 51.4% of 53 762 were tested in 1996-1998. The proportion who were TST-positive continued to decrease after 1996 to 1.2% among primary and 9.7% among secondary schoolchildren in 1998. Older age and birth outside the United States were associated with TST positivity. The estimated minimum cost of continued testing in primary schools was $123 152 per tuberculosis case prevented. An approach aimed at reducing testing of children at low risk for latent tuberculosis infection did not decrease testing of younger children. More important, older children who were more likely to be born in countries of high tuberculosis incidence were not tested. Additional efforts are needed to increase awareness among medical and school personnel to decrease testing among children who do not have risk factors for latent tuberculosis infection and to increase tuberculin testing of children who are entering school for the first time at the secondary level and do have risk factors for tuberculosis infection.

Incentives vs outreach workers for latent tuberculosis treatment in drug users

Background: Drug users are at increased risk for latent tuberculosis infection (LTBI) and also at increased risk for noncompletion of medication regimens for treatment of LTBI or tuberculosis disease. Directly observed therapy (DOT) provided by outreach workers, the use of incentives, or both have been suggested as a means to increase adherence. Objective: To compare the independent and combined effects of monetary incentives and outreach worker provision of DOT for LTBI treatment in a sample of active drug users. Methods: The research design was a randomized controlled trial in a community outreach program setting. Participants consisted of a volunteer sample of 163 active injection drug and crack cocaine users placed on twice weekly DOT. Condition 1 of the interventions consisted of provision of DOT by an outreach worker at a location chosen by the participant (active outreach) and a $5 per visit incentive. Condition 2 was comprised of active outreach with no monetary incentive, and Condition 3, provision of DOT at the study community site and a $5 per visit incentive. The main outcome measures were percentage of medication taken as prescribed and completion of medication regimen. Results: The percentage of prescribed medication taken was higher for those who received incentives, either with (71%) or without (68%) active outreach, compared to those who received active outreach alone (13%). Only 4% of participants assigned to Condition 2 completed treatment, compared to 53% of Condition 1 participants, and 60% of Condition 3 participants. Conclusions: Monetary incentives were clearly superior to active outreach. Active outreach in combination with monetary incentives did not increase adherence over incentives alone.