Contact screening and latent TB infection treatment in Singapore correctional facilities.

SETTING: Singapore, a city-state with a tuberculosis (TB) incidence rate of 47 per 100000 population in 2000. OBJECTIVES: 1) To report our experience with contact investigation and latent TB infection (LTBI) treatment in high-risk contacts with unknown human immunodeficiency virus (HIV) status in correctional facilities (CFs) (prisons/drug rehabilitation centres); and 2) to compare the yield of contact screening in this setting with that in the community (household/family) setting. METHODS: The tuberculin skin test (TST) readings of 704 CF contacts screened from 1999 to 2001 were compared with those of 2729 household/family contacts who underwent screening in 2000. RESULTS: Respectively eight (1.1%) and 20 (0.7%) active TB cases were detected among the CF and community contacts. A significantly higher proportion of CF contacts had first (non-conversion) TST readings > or =15 mm (39% vs. 22%, OR 2.3; 95%CI 1.9-2.7; P < 0.001), and 10-14 mm (26% vs. 18%, OR 1.6; 95%CI 1.3-2.0; P < 0.001) and TST conversion (43% vs. 20%, OR 2.9; 95%CI 1.7-4.9; P < 0.001). LTBI treatment was started in 65% of the CF contacts screened; 87% completed treatment. CONCLUSION: We found a high LTBI rate among CF contacts, presenting an opportunity for intervention.     

Community-wide INH treatment of latent TB infection in a BCG-vaccinated population: experience in rural Taiwan.

SETTING: A contiguous four-village bacille Calmette-Guérin (BCG) vaccinated population (n = 1785) in an aboriginal township in Taiwan with a very high tuberculosis (TB) burden. OBJECTIVE: To report our experience in this first community-wide effort in Taiwan to treat latent tuberculosis infection (LTBI) in household contacts of recently diagnosed TB cases. RESULTS: Overall, 71 LTBI cases (88.8%) completed varying case-specific isoniazid treatment courses, accounting for 4.0% of the affected community (village range 2.4-7.5%, P < 0.001). CONCLUSION: LTBI in household contacts was successfully identified and treated in a very high TB burden BCG-vaccinated area in rural Taiwan, complementing standard TB control measures.     

Cost-effectiveness of interferon-gamma release assay screening for latent tuberculosis infection treatment in Germany

OBJECTIVES: To assess the cost-effectiveness of the new QuantiFERON-TB Gold In-Tube (QFT-G) [Cellestis; Carnegie, VIC, Australia] assay for screening and treating of persons who have had close contact with tuberculosis (TB) patients and are suspected of having latent tuberculosis infection (LTBI) [hereafter called close-contacts] in Germany. METHODS: The health and economic outcomes of isoniazid treatment of 20-year-old close-contacts were compared in a Markov model over a period of 20 years, using two different cutoff values for the tuberculin skin test (TST), the QFT-G assay alone, or the QFT-G assay as a confirmatory test for the TST results. RESULTS: QFT-G assay-based treatment led to cost savings of $542.9 and 3.8 life-days gained per LTBI case. TST-based treatment at a 10-mm induration size cutoff gained $177.4 and 2.0 life-days gained per test-positive contact. When the cutoff induration size for the TST was reduced to 5 mm, the incremental cost-effectiveness ratio fell below the willingness-to-pay threshold ($30,170 per life-years gained) but resulted in unnecessary treatment of 77% of contacts owing to false-positive TST results. Combination with the 5-mm induration size TST cutoff value compared to the results of the QFT-G assay alone reduced the total costs per 1,000 contacts by 1.8% to $222,869. The number treated to prevent 1 TB case was 22 for the two QFT-G assay-based procedures, 40 for the TST at a cutoff induration size of 10 mm, and 96 for the TST at a cutoff induration size of 5 mm. When the sensitivity rates of the TST and the QFT-G assay were compounded, the QFT-G assay strategy alone was slightly less costly (0.6%) than the two-step approach. CONCLUSIONS: Using the QFT-G assay, but especially combining the QFT-G assay following the TST screening of close-contacts at a cutoff induration size of 5 mm before LTBI treatment is highly cost-effective in reducing the disease burden of TB.     

监测封闭社区结核病患者接触者结核感染状况二年的结果分析

目的 监测封闭社区(强制隔离戒毒所)中结核病患者接触者(简称“接触者”)的结核感染状况,并初步分析可能对该社区接触者受结核感染的影响因素。方法 采用结核菌素试验(PPD试验),对封闭社区中2016年10—11月确诊的5例结核病患者的所有接触者(共计792名)每6个月进行1次PPD试验,连续观察2年,其中有25名因各种原因未进行PPD试验,接受PPD试验者767名。依据《WS 288—2017 肺结核诊断》,有卡介苗接种卡痕者硬结平均直径≥10mm、无卡痕者硬结平均直径≥5mm判断为接触者结核感染。分析不同接触程度的767名接触者受MTB感染状况的变化情况。并用logistic回归模型进行社区接触者结核感染的危险因素分析。结果 在调查的封闭社区中,接触者第一次PPD试验结果被判断为结核感染者444例,感染率为57.9%(444/767)。在后续2年的结核感染监测中,323名未感染者中有54例(占16.7%,54/323)接触者变为结核感染;2年中社区接触者受结核感染者共498例,感染率64.9%(498/767)。有54名社区接触者在2年中PPD试验硬结直径减小或消失,由受结核感染变为未感染状态,占10.8%(54/498)。年龄(Wald χ ²=10.942,P=0.001,OR=1.04, 95%CI为1.02~1.06)、接种卡介苗(Wald χ ²=4.533,P=0.033,OR=1.41, 95%CI 为1.03~1.93)、与患者密切接触(Wald χ ²=6.343,P=0.012,OR=1.68, 95%CI 为1.12~2.52),是导致社区接触者结核感染风险增加的相关因素。讨论 封闭社区(强制隔离戒毒所)中结核病患者接触者MTB感染率较高,首次PPD试验筛查未感染者中有近1/6的接触者在2年间转为结核感染;有1/10结核感染者在2年间转为未感染状态。年龄增长、接种卡介苗、与结核病患者密切接触者受结核感染的比例增高。     

Outcomes of contact investigations of infectious tuberculosis patients

The objective of this study was to describe outcomes of tuberculosis (TB) contact investigations, factors correlated with those outcomes, and current successes and ways to improve TB contact investigations. We abstracted clinic records of a representative U.S. urban sample of 1,080 pulmonary, sputum-smear(+) TB patients reported to CDC July 1996 through June 1997 and the cohort of their 6,225 close contacts. We found a median of four close contacts per patient. Fewer contacts were identified for homeless patients. A visit to the patient's residence resulted in two additional (especially child) contacts identified. Eighty-eight percent of eligible contacts received tuberculin skin tests (TSTs). Recording the last exposure date to the infectious patient facilitated follow-up TST provision. Thirty-six percent of contacts were TST(+). Household contacts and contacts to highly smear(+) or cavitary TB patients were most likely to be TST(+). Seventy-four percent of TST(+) contacts started treatment for latent TB infection (LTBI), of whom 56% completed. Sites using public health nurses (PHNs) started more high-risk TST(-) contacts on presumptive treatment for LTBI. Using directly observed treatment (DOT) increased the likelihood of treatment completion. We documented outcomes of contact investigation efforts by urban TB programs. We identified several successful practices, as well as suggestions for improvements, that will help TB programs target policies and procedures to enhance contact investigation effectiveness.     

Yield of tuberculin screening among injection drug users.

BACKGROUND: Regardless of their HIV status, injection drug users (IDUs) are at increased risk of developing active tuberculosis (TB) if they have latent TB infection (LTBI). We quantified the prevalence and predictors of LTBI and level of adherence to medical evaluation in a population of IDUs in Montreal. METHODS: Participants were recruited from an ongoing dynamic cohort of IDUs followed for HIV seroconversion risk behaviour. Subjects with a tuberculin skin test (TST) of > or =5 mm were referred to designated TB clinics for medical evaluation. A financial incentive was provided for TST readings. RESULTS: Of the 262 subjects tested, 246 (94%) returned for TST reading. The overall prevalence of positive TSTs was 22% (5% in HIV-positive, 28% in HIV-negative participants). Older age at first injection drug use (OR per 10 year increase in age 1.4, 95%CI 1.2-1.8), duration of injection drug use (OR per 10 year increase 1.6, 9.5%CI 1.5-2.2) and negative HIV status (OR 11.2, 95%CI 3.2-4.0) were independent predictors of a positive TST. Nine per cent of all TST-positive participants completed LTBI treatment. CONCLUSION: TB screening activities with incentives can be successful in detecting TST-positive individuals, but better strategies are needed for medical follow-up in this high-risk group.     

Contribution of a IFN-gamma assay in contact tracing for tuberculosis in a low-incidence, high immigration area

AIMS OF STUDY: to analyse, in contacts exposed to smear+/culture + (S+/C+) or S-/C+ TB, most of whom are foreign-born: 1) correlation between T-SPOT.TB IFN-gamma release assay (Oxford Immunotec, UK), TST and exposure scores; 2) agreement between T-SPOT.TB and TST in Bacillus of Calmette-Guérin (BCG) vaccinated and non-vaccinated subjects, and 3) impact of results of T-SPOT.TB on diagnosis and treatment for latent tuberculosis infection (LTBI). PATIENTS AND METHODS: TST and T-SPOT.TB were performed in 295 contacts (74% foreign-born) 8-12 weeks after exposure. Contacts completed five exposure scores. Data were analysed according to most recent US (ATS/CDC), British (NICE) and Swiss guidelines. RESULTS: T-SPOT.TB was positive in 115 (39%) and indeterminate in 15 subjects (5.1%). Neither TST, nor T-SPOT.TB was significantly related to exposure scores or infectiousness of the index case. In multivariate analysis, incidence of TB in country of origin was the strongest predictor of result of TST or T-SPOT.TB. Agreement between TST and T-SPOT.TB (kappa: 0.19-0.27) was low but improved in non BCG-vaccinated subjects (kappa: 0.28-0.47). According to guidelines referred to, 10-24% of subjects screened were T-SPOT.TB+/TST-: the prognosis of this group is yet undetermined. Another 10-27% were T-SPOT.TB-/TST+: present guidelines recommend withholding treatment for LTBI in these subjects although longitudinal data are still scarce. CONCLUSIONS: The lack of a relationship between T-SPOT.TB and exposure scores probably results from both the variability inherent to the design of this study (ie, multiple contact investigations, exposure in different settings) and limits in the performance of the IGRA tested. Longitudinal data are needed to clarify the risk of TB in T-SPOT.TB+/TST- individuals. Unreliability of diagnosis of LTBI in spite of the present use of IGRA in algorithms is illustrated by the wide variations in identification of LTBI according to different guidelines referred to.     

Contribution of Interferon gamma release assays testing to the diagnosis of latent tuberculosis infection in HIV-infected patients: A comparison of QuantiFERON-TB gold in tube, T-SPOT.TB and tuberculin skin test

ABSTRACT: BACKGROUND: Diagnosis and treatment of latent tuberculosis infection (LTBI) is the most effective strategy to control tuberculosis (TB) among patients with HIV infection. The tuberculin skin test (TST) was the only available method to identify LTBI. The aim of the present work was to evaluate the usefulness of the interferon-gamma release assays (IGRAs): QuantiFERONtuberculosis (TB) Gold-In-Tube test (QFG) and T-SPOT.TB for the diagnosis of LTBI in a diverse cohort of HIV-infected patients. METHODS: A prospective study was carried out in consecutive patients cared for in a single institution in Spain from January 2009 to October 2010. IGRAS and tuberculin skin test (TST) were performed simultaneously. TST induration [greater than or equal to] 5 mm was considered positive. RESULTS: QFG, T-SPOT.TB and TST were performed in 373 subjects. Median CD4 cell count was 470/mul with a median nadir of 150/mul. TST, QFG and T-SPOT.TB were positive in 13.3%, 7.5% and 18.5% cases respectively. Among 277 patients with neither past or current TB nor previous treatment for LTBI and who had TST results, a positive TST result was obtained in 20 (7.2%) cases. When adding QFG results to TST, there were a total of 26 (8.6%) diagnoses of LTBI. When the results of both IGRAs were added, the number of diagnoses increased to 54 (17.9%) (incremental difference: 10.7% [95% confidence interval [CI]:5.3-16.2%] [p <0.001]), and when both IGRAs were added, the number of diagnoses reached 56 (18.5%) (incremental difference: 11.3% [95% CI:5.7%-16.9%] [p < 0.001]). Patients with a CD4 cell count greater than 500 cells/mul and prior stay in prison were more likely to have a diagnosis of LTBI by TST and/or QFG and/or T-SPOT.TB (adjusted odds ratio [aOR]: 3.76; 95% CI, 1.4 - 9.89; and aOR: 3.3; 95% CI, 1.3 - 8.3, respectively). CONCLUSIONS: IGRAs were more sensitive than TST for diagnosis of M. tuberculosis infection in HIVinfected patients. Dual sequential testing with TST and IGRAs may be the optimal approach for LTBI screening in this population.     

Is the T-cell-based interferon-gamma releasing assay feasible for diagnosis of latent tuberculosis infection in an intermediate tuberculosis-burden country?

The diagnosis of active and latent tuberculosis infection (LTBI) remains a challenge, especially in light of the fact that the tuberculin skin test (TST), which has been used to diagnose LTBI for over a century, has many well-known drawbacks. This study aimed to compare the diagnostic performance of the T-cell-based interferon-gamma releasing assay (IGRA) T-SPOT.TB with the TST for the diagnosis of LTBI in an intermediate tuberculosis (TB)-burden country with high BCG coverage. For this purpose, a total of 91 participants, including culture-confirmed TB patients, healthy contacts known to have been exposed to Mycobacterium tuberculosis, and healthy volunteers, selected from a BCG-vaccinated population were recruited. The sensitivities of the T-SPOT.TB and TST were 79.3 and 25.8%, and the specificities were 75.9 and 56.7%, respectively. The negative- and positive-predictive values for T-SPOT.TB and TST were 78.6 and 76.7% and 42.5 and 38.1%, respectively. The diagnostic performance of the TST in LTBI diagnosis is therefore severely diminished in BCG-vaccinated populations, with the sensitivity and specificity of the T-SPOT.TB assay being markedly higher. IGRAs have been reported to have higher diagnostic sensitivity and specificity in low TB-incidence settings than those seen here. Further larger scale studies in high and intermediate TB-incidence settings are therefore warranted.     

Comparison of the interferon- gamma release assay and the tuberculin skin test for contact investigation of tuberculosis in BCG-vaccinated health care workers

Health care workers are at increased risk of Mycobacterium tuberculosis infection. The tuberculin skin test (TST) is frequently false positive in BCG-vaccinated health care workers. QuantiFERON-TB GOLD (QFT-G) is a sensitive and specific interferon-gamma release assay unaffected by BCG vaccination. This study compared TST and QFT-G in the diagnosis of latent TB infection in BCG-vaccinated health care workers. 39 health care workers exposed to a smear-positive TB patient were enrolled. Initial TST was positive in 33 (84.6%) cases, but only 4 (10.2%) cases using QFT-G. TST conversion occurred in 2/6 (33.3%), compared to 4/32(12.5%), cases using QFT-G. A higher proportion of QFT converters was associated with intimate contact, although not reaching statistical significance. Face-to-face contact >1 h was significantly associated with QFT-G conversion >or=0.7 IU/ml (OR 8.63, 95%CI 1.08-69.07, p=0.04). Agreement between TST and QFT-G was 18.0%, (kappa: -0.03). Concordance between TST and QFT (>or=0.35 IU/ml) conversion was 40.0%(kappa=-0.40), and 60.0%(kappa=0.00) if QFT >or=0.7 IU/ml was used. Agreement increased with increasing TST cut-offs. TST is not useful in contact investigation among BCG-vaccinated health care workers, in an area with intermediate burden of TB. QFT may provide additional information for the diagnosis and strategic management of preventive treatment of LTBI in BCG-vaccinated health care workers in a country with intermediate burden of TB.     

Interferon-gamma release assays and TB screening in high-income countries: a cost-effectiveness analysis.

OBJECTIVE: Interferon-gamma release assays (IGRA) are now available alternatives to tuberculin skin testing (TST) for detection of latent tuberculosis infection (LTBI). We compared the cost-effectiveness of TST and IGRA in different populations and clinical situations, and with variation of a number of parameters. METHODS: Markov modelling was used to compare expected TB cases and costs over 20 years following screening for TB with different strategies among hypothetical cohorts of foreign-born entrants to Canada, or contacts of TB cases. The less expensive commercial IGRA, Quanti-FERON-TB Gold (QFT), was examined. Model inputs were derived from published literature. RESULTS: For entering immigrants, screening with chest radiograph (CXR) would be the most and QFT the least cost-effective. Sequential screening with TST then QFT was more cost-effective than QFT alone in all scenarios, and more cost-effective than TST alone in selected subgroups. Among close and casual contacts, screening with TST or QFT would be cost saving; savings with TST would be greater than with QFT, except in contacts who were bacille Calmette-Guérin (BCG) vaccinated after infancy. CONCLUSIONS: Screening for LTBI, with TST or QFT, is cost-effective only if the risk of disease is high. The most cost-effective use of QFT is to test TST-positive persons.     

Tuberculin skin test size and risk of tuberculosis development: a large population-based study in contacts.

SETTING: Contacts of tuberculosis (TB) cases identified from eight Provincial databases in British Columbia, Canada, between 1990 and 2000. OBJECTIVE: To assess the risk of developing TB based on tuberculin skin test (TST) sizes in contacts of TB cases who did not receive treatment for latent TB infection. DESIGN: Retrospective, population-based cohort study with a 12-year follow-up. RESULTS: Among 26,542 contacts, 180 individuals developed TB (TB rate 678/100,000). Household contacts with a TST size 0-4 mm had a TB rate of 1014/100,000, those with 5-9 mm a TB rate of 2162/100,000 and those with 10-14 mm a rate of 4478/100,000. Children aged 0-10 years with 0-4 mm had a TB rate of 806/100,000, those with 5-9 mm a TB rate of 5556/100,000 and those with 10-14 mm a rate of 42,424/100,000. Immunosuppressed contacts with TST sizes 0-4 mm had a TB rate of 630/100,000, those with 5-9 mm a TB rate of 1923/100,000, and those with 10-14 mm a rate of 1770/100,000. CONCLUSIONS: TB rates were high for all TST sizes in household contacts, 0-10 year old contacts and immunosuppressed contacts. These contacts may benefit from treatment for latent TB infection, regardless of the size of their TST.     

Comparison of an interferon-gamma assay with tuberculin skin testing for detection of tuberculosis (TB) infection in patients with rheumatoid arthritis in a TB-endemic population

OBJECTIVE: Tuberculosis (TB) in patients with rheumatoid arthritis (RA) undergoing treatment with anti-tumor necrosis factor (TNF) agents is commonly the result of reactivation of latent TB infection (LTBI); detection and treatment of LTBI is essential before treatment with anti-TNF agents. We reported previously that the tuberculin skin test (TST) is inaccurate for diagnosis of LTBI in patients with RA. Here, we compare the prevalence of LTBI in RA patients and matched controls according to positive TST and QuantiFeron-TB Gold In-Tube version (QFT) results and determine their agreement. METHODS: A cross-sectional study of 101 RA patients and 93 controls was conducted in Lima, Perú, where the prevalence of LTBI in the general population has been estimated to be 68%. Blood was drawn for QFT assay followed by TST using 2-TU of RT 23 purified protein derivative. TST was deemed positive at >or= 5 mm for RA patients and >or= 10 mm for controls. RESULTS: There were no significant differences between RA patients and controls for age, sex, bacillus Calmette-Guérin vaccination, or history of or contact with TB. 88% of patients had active RA disease and 2 (1.9%) patients had indeterminate QFT results. The number of subjects testing positive with the QuantiFeron assay was comparable between patients and controls (44.6% vs 59.1%, respectively), whereas the TST detected significantly less LTBI among RA patients (26.7%) than controls (65.6%). Thus, the rate of LTBI in RA patients represented 75% and 41% of the rate in their controls using QFT or TST, respectively (p = 0.008). Poor agreement between TST and QFT was seen in RA patients, but in controls, good agreement was observed between these tests. CONCLUSION: In a TB-endemic population, the QuantiFeron-TB Gold In-Tube assay seemed to be a more accurate test for detection of LTBI in RA patients compared with the TST, and may potentially improve the targeting of prophylactic therapy before treatment with anti-TNF agents.     

封闭社区结核病患者接触者结核感染状况预测模型

目的 通过监测封闭社区(强制隔离戒毒所)中结核病患者接触者的结核感染状况,分析影响接触者结核感染的可能因素,并构建感染预测模型。方法 采用结核菌素皮肤试验(TST),对封闭社区中2016年10月至2018年11月确诊的13例结核病患者的所有接触者,每6个月进行一次TST,至2019年7月。依据《WS 288—2017 肺结核诊断》相关标准,有卡介苗接种卡痕者硬结平均直径≥10mm、无卡痕者硬结平均直径≥5mm判断为结核病患者接触者(以下简称“接触者”)结核感染。在考虑场所特征(吸毒时间、戒毒次数、首次入本戒毒所)和不考虑场所特征情况下,分别采用Cox回归、条件logistic回归法对年龄、体质量指数(BMI)值、卡介苗接种史、既往结核病史、肺结核可疑症状、接触程度、接触患者分类因素构建感染预测模型,比较各模型对结核感染预测情况及预测值计算的ROC曲线下面积,寻找最优感染预测模型。结果 研究期间共纳入13例结核病患者,以及合格完成TST的检查对象2062名。接触者首次TST阳性而判断为结核感染者1060例,感染率为51.4%(1060/2062)。在后续2年的结核感染监测中,1002名第一次检查未感染者中有267例(26.6%,267/1002)接触者变为感染,其中173例(64.8%,173/267)是在封闭社区中出现新结核病患者后转变为结核感染;2年中社区接触者结核感染者共1327例,感染率64.4%(1327/2062)。使用logistic回归分析,在考虑场所特征情况下,纳入10个因素建立的封闭社区接触者结核感染预测模型为:结核感染=0.041×年龄+0.373×接触程度+0.046×BMI+0.028×吸毒年限-2.285;在不考虑场所特征情况下,纳入7个因素建立的预测模型为:结核感染=0.050×年龄+0.372×接触程度+0.041×BMI-2.282,ROC曲线下面积分别为0.584(95%CI:0.558~0.609)、0.625(95%CI:0.600~0.650),P值均<0.001;对结核感染预测准确率为93.6%(1242/1327)和94.1%(1249/1327)。使用Cox回归分析,在考虑场所特征情况下,建立的结核感染预测模型为:结核感染=0.020×年龄+0.133×接触程度+0.030×BMI+0.013×吸毒年限,ROC曲线下面积为0.633(95%CI:0.608~0.658),P<0.001;不考虑场所特征,建立的预测模型为:结核感染=0.025×年龄+0.135×接触程度+0.028×BMI,ROC曲线下面积为0.625(95%CI:0.600~0.650),P<0.001。结论 不考虑场所特征情况下,封闭社区结核病患者接触者结核感染预测中要考虑的因素包括年龄、BMI值、接触程度,使用两种建模方法的效果接近;如果考虑场所特征,需考虑的因素要增加吸毒年限。在能获得社区接触者随访时间的情况下,使用Cox回归预测效果更好。本研究对封闭社区接触者结核感染预测准确率较高,但尚不完善,亟需探索更多可能的影响因素。     

Achieving TB elimination in India: The role of latent TB management

The elimination of Tuberculosis (TB) in settings with a high dual burden of active and latent TB is one of the most important public health challenges of the 21st century. India has the highest TB burden in the world and nearly 40% of the population being infected with TB. There also exist large often overlapping socially and medically vulnerable populations like the PLHIV, pediatric TB contacts, children with protein-energy malnutrition, homeless people, workers in silica industry and adults with low BMI. A significantly higher risk of progression into active tubercular disease exists in those with compromised immune or nutritional status. It is uncertain if global TB elimination targets can be achieved in the absence of aggressive LTBI treatment strategies for interrupting the chain of transmission of the disease. India hence needs to accelerate and prioritize capacity building in latent TB research. A research agenda is outlined for generating evidence towards the evolution of critical evidence-based policy for LTBI management under Indian health settings.     

Tuberculosis,focussed tools and the right schools: estimated impact and cost of a targeted student screening programme for tuberculosis infection

Background

The World Health Organization (WHO) recommends targeted screening for latent tuberculosis infection (LTBI) among high-risk populations. Recent studies that evaluate targeted school-based programmes in low burden settings are scarce.

Aims

To evaluate a school screening programme for recently arrived migrant students from moderate and high tuberculosis (TB) burden countries and estimate (1) the number of cases of active TB that were prevented and (2) the cost per case of active TB prevented.

Methods

Students were screened with tuberculin skin tests (TST) at schools with a high migrant population intake. Those with positive results were referred for specialist evaluation. Outcomes were retrospectively assessed using 5 years of prospectively collected data. Cost data were collected. Main outcomes measured were the number of children were diagnosed with LTBI who completed treatment, and programme costs.

Results

Of 4728 student screened, 295 (6.2%) were diagnosed with LTBI. Of these, 273 (92.5%) were offered preventive therapy, 242 (82.0%) commenced and 204 (69.2%) completed therapy. The number needed to screen (NNS) was 23 per completed course of preventive treatment for LTBI. Assuming a 10% lifetime risk of reactivation, the NNS was 386 per case of TB disease notification avoided. The cost of screening was A$23 932 per case of TB disease avoided.

Conclusions

This TB strategy is supported by the high rate of TB infection in the student group, the treatment uptake and completion rates. Cost–benefit is linked with lifetime risk of TB reactivation. Targeted school screening programmes represent an important opportunity for TB control in low-burden settings.     

Comparison of mantoux skin test with three generations of a whole blood IFN-gamma assay for tuberculosis infection.

SETTING: A rural town in South Africa. OBJECTIVE: To compare the performance of Quanti-FERON assays with the tuberculin skin test (TST) for identifying latent tuberculosis infection (LTBI) in a high TB burden community. DESIGN: In a cross-sectional study in healthy adults, we applied the TST and took blood for the three generations of QuantiFERON assays. RESULTS: Of 358 participants whose results were analysed, 291 (81%) had a TST result of > or = 10 mm induration, and 187 (52%) > or = 15 mm. QuantiFERON-TB was positive in 215 (60%), QuantiFERON-TB Gold in 137 (38%), and QuantiFERON-TB Gold (In-Tube method) in 201 (56%). There was poor agreement between TST and QuantiFERON tests, and between the different generations of QuantiFERON tests (kappa = 0.12-0.50). Of the subset with TST indurations > or = 15 mm, 30-56% had negative QuantiFERON tests. However, positive Quanti-FERON tests were associated with males, who have a higher incidence of TB in this area. CONCLUSION: We showed poor agreement between TST and the different QuantiFERON tests in diagnosing LTBI. The surprising discordance between the Quanti-FERON TB Gold and QuantiFERON TB Gold (In-Tube method) tests needs to be investigated further.     

Latent tuberculosis infection among undergraduate medical students in Rio de Janeiro State, Brazil.

SETTING: Five medical schools in three cities with different tuberculosis (TB) incidence rates in Rio de Janeiro State, Brazil. OBJECTIVE: To estimate prevalence of and associated factors for latent tuberculosis infection (LTBI) among medical students. DESIGN: A cross-sectional survey was conducted among undergraduate students in pre-clinical, early and late clinical years from schools in cities with low (28/100,000), intermediate (63/100,000) and high (114/100,000) TB incidence rates. Information on socio-demographic profile, previous BCG vaccination, potential TB exposure, co-morbidity and use of respiratory protective masks was obtained. A tuberculin skin test (TST) was performed using the Mantoux technique by an experienced professional. A positive TST, defined as induration > or = 10 mm, was considered LTBI. RESULTS: LTBI prevalence was 6.9% (95%CI 5.4-8.6). In multivariate analysis, male sex (adjusted odds ratio [aOR] 1.8; 95% CI 1.1-3.0), late clinical years (aOR 1.9; 95% CI 1.01-3.5), intermediate TB incidence (aOR 4.3; 95% CI 1.3-14.6) and high TB incidence in the city of medical school (aOR 5.1; 95% CI 1.6-16.8) were significantly associated with LTBI. CONCLUSIONS: The higher prevalence of LTBI in late clinical years suggests that medical students are at increased risk for nosocomial Mycobacterium tuberculosis infection. The implementation of a TB control program may be necessary in medical schools, particularly in cities with higher TB incidence.     

Present activity of BCG and LTBI treatment for infants in Japan

I analyzed the BCG vaccination and treatment of latent tuberculosis infection (LTBI) for infants notified in 2008 in Japan. BCG was not recommended and treatment of LTBI was the main activity for prevention of TB in infants from birth to age 2 months. The majority of notified LTBI cases were detected by contact surveys. Out of the estimated number of TB infected (148), only 2 cases were notified based on the outcome of LTBI treatment for 89 infants. When the infants were 3-5 months old, both BCG vaccination and LTBI treatment were implemented. BCG coverage was 61.5-97.7%, and LTBI treatment for non-vaccinated individuals was applied for a larger number of infants (1.04 to 7.82 times as many) than the estimated number of infants infected with TB. The majority of infants were BCG vaccinated when they were 6-11 months old. Although LTBI treatment coverage was low, only 5 cases developed among those receiving BCG vaccination. During 1-2 year, BCG coverage was high and breakdown rates of BCG-vaccinated children were much lower than those of non-vaccinated children. This difference might be due to not only the preventive effect of BCG but also risk difference of TB infection between BCG-vaccinated and BCG non-vaccinated individuals. The number of notified LTBI treatment cases was lower than the estimated number of children infected with TB during 1-2 year. To prevent infant TB, reinforcement of contact surveys to identify LTBI for treatment, improvement of BCG coverage, and attention to BCG non-vaccinated infants older than 6 months might be effective.     

北京口岸赴美移民人群结核病监测结果分析

目的调查北京口岸移民人群日市结核的发病及感染情况,建立出入境口岸防控结核病科学有效的监测管理体系,防止结核病通过口岸跨境传播。方法对2008年7月至2013年6月期间l5598名赴美移民结核病监测资料进行回顾性分析,2～〈15岁组的2488名儿童均行结核菌素皮肤试验或7下扰素体外释放试验;≥15岁组13110名均摄x线胸片,对所有x线胸片可疑的401例肺结核患者进行痰涂片和痰培养检查,对11例培养阳性菌株进行结核分枝杆菌菌种鉴定和抗结核药物敏感性试验。结果按照美国CIX＂结核病筛查指南要求并参照我国肺结核诊断标准确定：（1）继发（}舌动）性肺结核：≥15岁组13110名x线胸片提示可疑肺结核401例,从中确诊肺结核患者15例（检出率114．42/10万）,其中菌阳11例,菌阴4例（检出率分别为83．91／10万和30．51／10万）;（2）非活动性肺结核：≥15岁组确诊非活动性肺结核386例,检出率2944．32／10万;（3）儿童潜伏结核分枝杆菌感染：2～〈15岁组2488名儿童中共444例确诊为结核分枝杆菌潜伏感染,其中结核菌素试验硬结平均直径≥10mm、者423例,7干扰素体外释放试验阳性者2l例,儿童结核分枝杆菌感染率17845．66／10万,444例x线胸片均未见异常;（4）≥15岁组密切接触者2例;（5）细菌学检测：≥15岁组中X线胸片异常的401例均进行3个痰标本检测。检出涂阳培阳4例、涂阴培阳7例和涂阴培阴390例;1l例菌株均属结核分枝杆菌;药敏试验结果为敏感株9例,耐药株2例（1例为MDKTB,1例为PDRTB）;（6）活动性肺结核以60岁及以上组检出率最高,为371．52／10万（6／1615）;15～〈30岁组次之,检出率为145．88／10万（G／4113）。结论对口岸地区的≥15岁年龄组x线胸片异常者作为肺结核的防控重点人群,2～〈15岁组人群结核菌素试验硬结平均直径≥10mm或γ干扰素体外释放试验阳性者也不容忽视。