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。     

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。     

保山市强制戒毒人员HIV和HCV感染状况及影响因素

目的了解云南省保山市强制戒毒人员艾滋病病毒(HIV)和丙型肝炎(简称丙肝)病毒(HCV)感染现状及相关影响因素,为制定针对吸毒人群的艾滋病和丙肝防控措施提供依据。方法对保山市强制隔离戒毒所吸毒人群开展行为学调查及血清学检测,通过χ2检验和多因素Logistic回归方法分析HIV和HCV感染危险因素。结果800名吸毒者的HIV感染率为2.4%,HCV感染率为27.6%,HIV和HCV合并感染率为1.9%。吸毒人群HIV感染影响因素为与别人共用针具[比值比(OR)=15.669,95%可信区间(CI):3.122～78.615],HCV感染影响因素为使用传统毒品(OR=2.076,95%CI:1.194～3.608)、注射吸毒(OR=17.289,95%CI:8.469～35.295)。结论保山市吸毒人群HIV和HCV感染率较高,共用针具是HIV感染的危险因素。使用传统毒品和注射吸毒是HCV感染的危险因素。     

产生耐多药结核病50例的危险因素分析

目的探讨产生耐多药结核病的危险因素。方法病例组为50例耐多药结核患者,对照组为50例非耐药结核患者,采用卡方检验和非条件Logistic回归进行分析。结果卡方分析有统计学意义(P0.05)的变量有体重指数(BMI)、居住地、饮酒、服药规律性、结核病史、肺结核空洞病灶;非条件logistic回归分析有统计学意义的变量有饮酒、服药规律性、结核病史和肺结核空洞病灶,OR值分别为0.211、0.442、2.468、6.150。结论不规律服药、结核病史和肺结核空洞病灶是产生耐多药结核病的危险因素,应采取相对应措施控制产生耐多药结核病。     

结核菌素皮肤试验诊断结核分枝杆菌潜伏感染学校人群预防性服药临界值的确定

目的: 探寻在学校结核病疫情处置中应用结核菌素皮肤试验(tuberculin skin testing,TST)诊断需要预防性服药的结核分枝杆菌潜伏感染(latent tuberculosis infection,LTBI)者的硬结平均直径临界值。方法: 于2020年10月至2021年10月,选取江苏省发生3例及以上病例学校结核病疫情的2所学校的学生和老师作为研究对象,共纳入163名。对研究对象同时进行TST和QuantiFERON-TB gold in-tube(QFT)检测,以QFT检测结果为参照标准,采用受试者工作特征曲线(receiver operating characteristic curve,ROC)来确定TST检测学校人群中需要预防性服药的LTBI者的硬结平均直径临界值。结果: 163名受试者中,QFT检测阳性者79例(48.5%),QFT检测阴性者84名(51.5%)。TST中度阳性者132名(81.0%),其中,QFT检测阳性者62例,阳性率为47.0%(95%CI:38.3%~55.6%)。在163名研究对象中,以QFT检测结果为参照标准,TST检测硬结平均直径为12.5mm时诊断需要预防性服药的LTBI者的价值最高,敏感度为38.0%(95%CI:27.3%~49.6%),特异度为82.1%(95%CI:72.3%~89.6%),曲线下面积(AUC)为0.621(95%CI:0.542~0.696);在132名TST中度阳性者中,以QFT检测结果为参照标准,TST检测硬结平均直径为12.5mm时诊断需要预防性服药的LTBI者的价值最高,敏感度为25.8%(95%CI:15.5%~38.5%),特异度为87.1%(95%CI:77.0%~93.9%),AUC为0.572(95%CI:0.483~0.657)。结论: 在学校结核病疫情处置中,如果在一个班级发生3例及以上结核病病例或者TST中度阳性率或者强阳性率远高于本地区正常范围时,应该重视TST中度阳性的人群。     

结核分枝杆菌感染检测两步法在学校结核病筛查中的应用价值

目的: 初步评估结核菌素皮肤试验(TST)联合γ-干扰素释放试验(IGRA)(简称“两步法”)检测在学生健康体检中筛查结核分枝杆菌(Mycobacterium tuberculosis,MTB)感染和活动性肺结核的应用价值。方法: 采用横断面研究的方法,选取2017—2021年广东省74358名学生作为研究对象,其中50701(68.18%)名完成了胸部X线摄片(简称“胸片”)筛查,74148名(99.72%)完成了TST筛查;9702(13.08%)名TST检测阳性者进一步完成了IGRA检测。最后对胸片异常、TST和IGRA检测“双阳者”完善肺结核相关检查。结果: 以IGRA检测结果为参照标准,分别以TST检测硬结平均直径为5、10和15mm为阳性临界值,TST与IGRA检测MTB感染的一致率分别为15.97%(1549/9702)、26.63%(2584/9702)、81.11%(7869/9702),Kappa值分别为0.014、0.014和0.112。TST检测MTB感染率[11.67%(8652/74148)]明显高于两步法[1.02%(759/74148)],差异有统计学意义(χ²=7068.423,P<0.001)。对TST中阳和强阳者完善结核病相关检查后的肺结核检出率[0.29%(15/5219)]明显低于对“双阳者”的检出率[1.84%(14/759)],差异有统计学意义(χ²=30.133,P<0.001)。结论: TST和IGRA检测MTB感染的一致性较差,“两步法”可明显提高MTB感染的精准性和肺结核患者筛查效率。     

戒毒所内吸毒人群美沙酮维持治疗参与意愿调查

目的了解戒毒所内吸毒人群对美沙酮维持治疗(MMT)的认识及参与意愿。方法对戒毒所内吸毒人群进行问卷调查,收集吸毒人群的人口学特征、行为学特征、艾滋病(AIDS)知识、对MMT的认识及参与意愿等信息,并抽取3-5mL静脉血检测HIV抗体。结果共调查436名戒毒所内吸毒人员,HIV阳性者62人(14.2%);AIDS知识得分(7.47±1.129)分。236名(54.1%)调查对象表示出戒毒所后若复吸,愿意参与MMT。200名不愿意参加MMT的原因主要有:已经戒除毒瘾无需服用美沙酮(33.5%),美沙酮与海洛因一样有毒(17.5%),美沙酮不能替代海洛因无欣快感(8.5%),美沙酮不良反应多(6%)及不了解MMT(7%)等。单因素分析显示,入所前知道所在地MMT服药点、知道针具交换、文化程度、有自愿戒毒史和强制戒毒三次及以上、AIDS知识得分高、HIV感染等因素与MMT参与意愿相关;多因素Logistic回归分析显示,有自愿戒毒史、HIV感染及AIDS知识得分较高,是吸毒人群参与MMT的有利因素。结论被调查的吸毒人员中,愿意参与MMT的占半数以上,不愿意的原因多是对戒毒与MMT的认识不足,建议加大针对此类人群的MMT及AIDS相关知识宣传。     

196例初治病原学阳性肺结核患者结核感染控制知识知晓情况调查

目的:调查初治病原学阳性肺结核患者结核感染控制知识掌握情况,为有效开展结核感染控制和健康教育工作提供依据。方法:对2019年1月至2023年1月于首都医科大学附属北京胸科医院、北京市昌平区结核病防治所、北京市大兴区结核病预防控制中心纳入的196例初治病原学阳性肺结核患者进行结核感染控制知识知晓情况问卷调查,调查内容包括患者的基本信息、结核感染控制知识问卷、临床信息等;发出问卷196份,有效问卷196份,有效率为100.0%。统计调查对象结核感染控制知识知晓情况,分析影响其结核病防治核心信息知晓情况的因素。结果:196例调查对象结核感染控制知识总知晓率为64.4%(2649/4116)。多因素logistic回归分析结果显示,相对于初中及以下学历,大专/本科及以上学历者结核感染控制知识知晓率达标的可能性更高(OR=6.659,95%CI:1.995～22.220);相对于有结核病接触史者,无结核病接触史者结核感染控制知识知晓率达标的可能性更低(OR=0.218,95%CI:0.054～0.886)。结论:初治病原学阳性肺结核患者结核感染控制知识知晓率尚有待提高,初中及以下文化程度和无结核...     

2018—2021年广州市中学和大学新生结核分枝杆菌潜伏感染情况分析

目的:了解广州市中学和大学新生结核分枝杆菌潜伏感染(latent tuberculosis infection, LTBI)的情况,为广州市学校结核病防控工作和策略制定提供参考依据。方法:选取广州市中学和大学共17所学校作为试点单位,对试点单位2018—2021年共计17 632名入学新生(包括初高中、专科、高等院校的一年级学生)根据知情同意的原则进行结核菌素皮肤试验(tuberculin skin test, TST),对15岁以上学生同时加做胸部X线摄片检查;TST中度及以上阳性者(硬结平均直径≥10 mm)再进一步加做γ-干扰素释放试验(interferon gamma release assay, IGRA);TST和IGRA均为阳性或胸部X线摄片发现肺部异常阴影者,再进行痰涂片、痰培养等结核病辅助诊断检查。使用描述性流行病学方法对筛查结果进行分析。结果:实际筛查学生17 204名,筛查率为97.57%(17 204/17 632)。TST阳性者共4449名,阳性率为25.87%(4449/17 199),一般阳性率为15.98%(2748/17 199),中度阳性率为7.65...     

γ-干扰素释放试验在结核病专科门诊诊断儿童活动性结核病的效能

目的 评价γ-干扰素释放试验(interferon-gamma release assay, IGRA)在结核病专科门诊诊断儿童活动性结核病的效能。方法 回顾性分析2019年1月至2021年12月就诊于西安市胸科医院结核病门诊的268例疑似结核病患儿为研究对象，采用area under the ROC curve (AUC)评估在不同年龄阶段，有无卡痕，有无结核病密切接触史患儿中IGRA诊断活动性结核病的效能。结果 在结核病专科门诊，IGRA诊断儿童活动性结核的敏感度、特异度、阴性预测值、阳性预测值、AUC分别为80.6%、63.6%、48.6%、88.5%、0.74。IGRA诊断儿童结核病AUC(95%CI值),在年龄≤5岁患儿中为0.71(0.62～0.80),低于6～14岁组的0.75(0.70～0.81),两组差异无统计学意义(Z=-0.848,P=0.40);在可见卡痕患儿中为0.72 (0.67～0.78),与未见卡痕组的0.72(0.61～0.83)无统计学差异(Z=0.067,P=0.946);在有密接史组为0.83(0.75～0.91),高于无密接史组的0.72(0....     

Tuberculin reactivity in first‐year schoolchildren in Madagascar

Objective The tuberculin skin test (TST) is an important tool in the diagnosis of tuberculosis infection in children. However, the interpretation of TST may be complicated by prior Bacillus Calmette‐Guerin (BCG) vaccination. We evaluated the effect of vaccination with BCG on TST reactivity in first‐year pupils attending state schools in Antananarivo. Methods STs were performed on 376 first‐year schoolchildren, aged 6 and 7, attending two state primary schools. The relationships between epidemiological information, BCG status (vaccination, BCG scars) and TST reactivity were assessed to compare TST sensitivity between children with and without BCG vaccination and between those with and without a BCG scar. Result The prevalence of positive TST results of ≥5, ≥10 and ≥ 15 mm was 20.2% (76/376), 18.3% (69/376) and 11.4% (43/376), respectively. BCG vaccination was not associated with TST reactivity, whatever the threshold used: ≥5 mm (odds ratio (OR, 1.2; 95% confidence interval (CI), 0.7–2.0); ≥10 mm (OR, 0.9; 95% CI, 0.6–1.7); ≥15 mm (OR, 0.6; 95% CI, 0.3–1.2). Conclusion These results suggest that in Madagascar, a positive TST result indicates TB infection (active or latent) rather than past BCG vaccination. Therefore, high BCG vaccination coverage does not appear to impair the usefulness of the TST as a tool for diagnosing tuberculosis.     

Tuberculin reactivity in a pediatric population with high BCG vaccination coverage.

SETTING: The tuberculin skin test (TST) is often included in diagnostic algorithms for tuberculosis (TB) in children. TST interpretation, however, may be complicated by prior Bacillus Calmette-Guerin (BCG) vaccination. We assessed the prevalence of and risk factors for positive TST reactions in children 3 to 60 months of age in Botswana, a country with high TB rates and BCG coverage of over 90%. METHODS: A multi-stage cluster survey was conducted in one rural and three urban districts. Data collected included demographic characteristics, nutritional indices, vaccination status, and prior TB exposure. Mantoux TSTs were administered and induration measured at 48-72 hours. RESULTS: Of 821 children identified, 783 had TSTs placed and read. Of the 759 children with vaccination cards, 755 (99.5%) had received BCG vaccine. Seventy-nine per cent of children had 0 mm induration, 7% had > or =10 mm induration ('positive' TST), and 2% had > or =15 mm. A positive TST was associated with reported contact with any person with active TB (odds ratio [OR] 1.9; 95% confidence interval [CI] 1.02-3.6), or a mother (OR 5.1; 95% CI 2.1-12.4) or aunt (OR 5.3; 95% CI 2.0-14.0) with active TB. TSTs > or =5 mm (but not > or =10 mm) were associated with presence of a BCG scar. Positive reactions were not associated with age, time since BCG vaccination, clinical signs or symptoms of TB, nutritional status, crowding, or recent measles or polio immunization. CONCLUSION: The TST remains useful in identifying children with tuberculous infection in this setting of high TB prevalence and extensive BCG coverage.     

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.     

Effect of Ascaris Lumbricoides specific IgE on tuberculin skin test responses in children in a high-burden setting: a cross-sectional community-based study

ABSTRACT: BACKGROUND: M.tuberculosis (M.tb) is associated with enhanced T helper cell type 1 (Th1) immune responses while helminth infection is associated with T helper cell type 2 (Th2) immune responses. Our aim was to investigate whether helminth infection could influence the ability to generate an appropriate Th1 immune response that is characterized by a positive tuberculin skin test (TST), in M.tb exposed children. METHODS: We completed a community-based, cross sectional household contact tracing study, using matched enrolment of HIV negative children with and without documented household M.tb exposure. We documented demographics, clinical characteristics, HIV status, M.tb exposure (using a standard contact score) and M.tb infection status (TST > = 10 mm). Ascaris lumbricoides-specific IgE was used as proxy for Ascaris infection/exposure. RESULTS: Of 271 children (median age 4 years (range: 4 months to 15 years)) enrolled, 65 participants (24%) were serum positive for Ascaris IgE. There were 168 (62%) children with a documented household tuberculosis contact and 107 (40%) were (TST) positive overall. A positive TST was associated with increasing age (Odds Ratio (OR) =1.17, p < 0.001), increasing M.tb contact score (OR = 1.17, p < 0.001), previous tuberculosis treatment (OR = 4.8, p = 0.06) and previous isoniazid preventive treatment (OR = 3.16, p = 0.01). A visible bacillus Calmette-Guerin (BCG) scar was associated with reduced odds of being TST positive (OR = 0.42, p = 0.01). Ascaris IgE was not associated with TST status in univariate analysis (OR = 0.9, p = 0.6), but multivariable logistic regression analysis suggested an inverse association between Ascaris IgE status and a positive TST (OR = 0.6, p = 0.08), when adjusted for age, and M.tb contact score. The addition of an age interaction term to the model suggested that the age effect was stronger among Ascaris IgE positive children; the effect of being Ascaris IgE positive significantly reduced the odds of being TST positive amongst younger children while this effect weakened with increasing age. CONCLUSIONS: Our preliminary findings highlight a high prevalence of both Ascaris exposure/infection and M.tb infection in children in an urban setting. Helminth exposure/infection may reduce the immune response following M.tb exposure when controlling for epidemiological and clinical covariates. These findings might be relevant to the interpretation of immunological tests of M.tb infection in children.     

QuantiFERON-TB Gold test for screening latent tuberculosis infection in hemodialysis patients

Hemodialysis patients are at increased risk of latent tuberculosis infection (LTBI) compared with the general population. QuantiFERON-TB Gold (QFT-G) for LTBI detection is more promising than tuberculin skin test (TST) in hemodialysis patients. The aim of this study is to determine whether the QFT-G is more sensitive than the TST in hemodialysis patients in LTBI. Eighty nine hemodialysis patients were evaluated for latent tuberculosis infection with the TST and QFT-G. Blood was obtained for QFT-G, and then TST was administered to all patients. Demographic information, laboratory tests, chest radiography results and BCG vaccination status were collected on standardized patient medical files. Forty patients had positive QFT-G results. 56 patients had TST induration above 5 mm, 28 patients above 10 mm. 61 patients had BCG vaccination scar. Statistically significant correlation was detected between TST and QFT-G (p< 0.05). In the BCG non-vaccinated subgroup, TST was positive in 8 (29%) patients and the QFT-G was positive in 11 (39%). Among the 21 non vaccinated patients with results for both tests, the concordance between the TST and QFT-G was 82%, k= 0.61, p= 0.001. We found good agreement between the TST and QFT-G test for LTBI in non vaccinated hemodialysis patients, whereas we found poor agreement in vaccinated patients. Because BCG vaccination is widely used in our country, the QFT-G test might be more useful for the diagnosis of LTBI than TST in hemodialysis patients who are suspected to have LTBI.     

Increased risk of Mycobacterium tuberculosis infection related to the occupational exposures of health care workers in Chiang Rai, Thailand.

SETTING: Chiang Rai, the northernmost province of Thailand. OBJECTIVE: To evaluate the occupational risk for tuberculous infection of health care workers (HCWs) and the utility of tuberculin skin test (TST) in a developing country setting. DESIGN: A cross-sectional TST survey, including a risk assessment questionnaire, of Chiang Rai Hospital HCWs. RESULTS: Of 911 HCWs tested, 623 (68%) had indurations of > or = 10 mm and 322 (35%) indurations of > or = 15 mm. Factors most predictive for TST positivity, using either cut-off, were employment > 1 year, frequent direct patient contact, and male sex. Moreover, having a bacillus Calmette-Guérin (BCG) scar was predictive of a > or = 10 mm, but not a > or = 15 mm, reaction. CONCLUSIONS: Chiang Rai Hospital HCWs had an increased risk for Mycobacterium tuberculosis infection, which was significantly associated with occupational exposure. Where BCG coverage is high, a TST cut-off of > or = 15 mm may correlate better with M. tuberculosis infection than does a cut-off of > or = 10 mm. Effective, affordable infection control measures are needed for health care facilities in developing countries such as Thailand, where HCWs may be at increased risk for M. tuberculosis infection from occupational exposures.     

Contact tracing using a new T-cell-based test: better correlation with tuberculosis exposure than the tuberculin skin test.

SETTING: Residential institution for alcoholics in Switzerland. OBJECTIVE: To compare the results of the tuberculin skin test (TST) and the new T-cell-based test for tuberculosis infection (T-SPOT.TB) in subjects exposed to a case of smear-positive pulmonary TB (PTB). DESIGN: After the notification of smear-positive PTB in a resident of an institution for alcoholics, contacts underwent TST and determination of Mycobacterium tuberculosis specific T-cells in blood by T-SPOT.TB. Results were analysed according to age, history of BCG vaccination, and level of exposure to the index case. RESULTS: There was no correlation between the level of exposure and the TST results, but the T-SPOT.TB results were significantly correlated with the level of exposure (P = 0.029, OR 5.00, 95%CI 1.05-23.86). Contacts who had been previously BCG-vaccinated were significantly more likely to have a positive TST than unvaccinated contacts (52% vs. 0%, P = 0.0003), but there was no influence of prior BCG vaccination on T-SPOT.TB results. CONCLUSIONS: T-SPOT.TB test results correlated better than TST with level of exposure to M. tuberculosis and were not confounded by prior BCG vaccination. This test allows better selection of contacts who should receive treatment for latent TB infection.     

Tuberculin skin test screening in a military school in Istanbul city center

To investigate the reason of high incidence of annual patients with tuberculosis (TB) in a military school previously known by screening tuberculin skin test (TST) and finding out the proportion of annual infection risk (PAIR), the prevalance of TB infection and the distribution for each grades. Our study is a cross-sectional epidemiologic study made about TB infection. TST were screened for all students in the school. 5 TU PPD was injected to every student and after 72 hours, the results were evaluated by measuring the diameter of enduration. Test was repeated after 10 days for negative reactions. Age, sex, the number of BCG wound, smoking and dwelling for last 5 years were asked from the students and their answers were recorded. More than 10 mm enduration for cases who had no BCG and 15 mm enduration for cases who had BCG were accepted positive. Chest roentgenogram was taken for each student enrolled into the study. Infection prevalance and PAIR were calculated after tests and measurements. The total number of students was 948. Of 917 (96.7%) were male and 31 (3.3%) were female. The mean age was 19.72 +/- 1.25. The mean of TST was 12.79 +/- 5.96 mm for all students. According to the number of BCG scar, the numbers of students, percentage and the mean of TST were like that 70 (7.3%) cases no BCG scar 8.41 +/- 7.87 mm, 393 (41.4%) students one BCG scar, 11.94 +/- 6.26 mm, 343 (36.1%) cases two BCG scars, 13.74 +/- 5.12 mm, 142 (14.9%) students three or more then three scars, 14.97 +/- 4.11 mm. In the students who had no BCG, TST positivity was 50%. TB infection prevalance of entire school and PAIR were 46% and 3.44% (respectively). In this study, we found that increased number of BCG wound associated with the increased diameter of TST enduration. The proportion of unvaccinated students was similar to the same age population in our country but it showed differences in the distribution of regions. The students who started first grade had serious TB infection risk in their first school year. We think that PAIR values derived from TST conversions done in high risky community by screening annual TST could show all aspects of TB infection risk in those community.