Prevalence Of Tuberculin Skin Test Research Articles

Mycobacterium tuberculosis infection and disease in healthcare workers in a tertiary referral hospital in Bandung, Indonesia.

Healthcare workers (HCWs), especially in high tuberculosis (TB) incidence countries, are at risk of Mycobacterium tuberculosis infection and TB disease, likely due to greater exposure to TB cases and variable implementation of infection control measures. We aimed to estimate the prevalence of tuberculin skin test (TST) positivity, history of TB and to identify associated risk factors in HCWs employed at a tertiary referral hospital in Bandung, Indonesia. A cross-sectional study was conducted from April to August 2018. A stratified sample of the HCWs were recruited, screened by TST, assessed for TB symptoms, history of TB disease and possible risk factors. Prevalence of positive TST included diagnosis with TB after starting work. HCWs with TB disease diagnosed earlier were excluded. Survey weights were used for all analyses. Possible risk factors were examined using logistic regression; adjusted odds ratios and 95% confidence intervals (CI) are presented. Of 455 HCWs recruited, 42 reported a history of TB disease (25 after starting work) and 395 had a TST result. The prevalence of positive TST was 76.9% (95% CI 72.6-80.8%). The odds increased by 7% per year at work (95% CI 3-11%) on average, with a rapid rise in TST positivity up to 10 years of work and then a plateau with around 80% positive. A high proportion of HCWs had a history of TB or were TST positive, increasing with longer duration of work. A package of TB infection control measures is needed to protect HCWs from Mycobacterium tuberculosis infection.

Prevalence Of Tuberculin Skin Test Positivity In Patients Of Early Rheumatoid Arthritis- Study from a tertiary care centre in North India.

Objective: To assess the prevalence of tuberculin skin test (TST) positivity in early rheumatoidarthritis patients (< 6months disease duration) using Tuberculin sensitivity testing in a TB endemiccountry. Method: Included in this cross-sectional study were 200 patients of early rheumatoidarthritis divided into three groups- treatment naïve, patients on methotrexate only andmethotrexate plus low dose corticosteroids. 1TU (0.1ml) of PPD RT-23 with tween 80 was injectedintradermally over the left forearm and the induration measured after 72 hours. For interpretation,Induration >10mm was taken as positive, < 5mm as negative and 5-10mm as indeterminate.Healthy controls were taken for comparison. Results: 200 early RA patients and 60 healthy controlswere included in this study. The median age of the study population was 43 years (IQR 33-51) witha mean disease duration of 3.4 ± 2.1 months. 54 patients (27%) with early RA and 22 healthycontrol (36.7%) had TST positive (p=0.1). The mean TST positivity inpatient cohort was7.25±6.53(mm) and in the control population(mm) was 7.06±6.07.TST was positive in 26 (22.6%)treatment naïve patients (n= 115);22 (37.9%) patients on methotrexate(n=58) and 6 (22.2%)patients on methotrexate and low dose corticosteroids(n=27) (p=0.08). Prior BCG vaccinationstatus, disease activity, a dose of methotrexate and rheumatoid factor seropositivity had nosignificant effect on TST positivity. Conclusion: Tuberculin positivity is low among patients withearly RA as compared to the general population. The use of low dose steroids or methotrexatedoesn’t affect the tuberculin anergy. Further larger studies with augmented tuberculin doses arerequired to assess the factors affecting TST positivity in RA patients.

Prevalence of Tuberculosis in Children After Natural Disasters, Bohol, Philippines.

In 2013, a severe earthquake and typhoon affected Bohol, Philippines. To assess the postdisaster risk for emergence of Mycobacterium tuberculosis infection in children, we conducted a cross-sectional multistage cluster study to estimate the prevalence of tuberculin skin test (TST) positivity and tuberculosis (TB) in children from 200 villages in heavily affected and less affected disaster areas. Of the 5,476 children we enrolled, 355 were TST-positive (weighted prevalence 6.4%); 16 children had active TB. Fourteen (7%) villages had >20% TST-positive prevalence. Although prevalence did not differ significantly between heavily affected and less affected areas, living in a shelter with >25 persons approached significance. TST positivity was independently associated with older age, prior TB treatment, known contact with a person with TB, and living on a geographically isolated island. We found a high TST-positive prevalence, suggesting that national programs should consider the differential vulnerability of children and the role of geographically isolated communities in TB emergence.

Low Prevalence of Tuberculin Skin Test Boosting among Community Residents in Uganda.

Boosted tuberculin skin test (TST) reactions can be misclassified as new latent tuberculosis (TB) infection. To our knowledge, no study has evaluated the prevalence of TST boosting in a population-based sample in high TB burden settings. We determined the prevalence of TST boosting among urban residents in Uganda. We evaluated 99 participants with initial TST < 5 mm and repeated a skin test after 2 weeks. We found that only 2% had boosted TST reactions suggesting that most TST conversions could represent new TB infections in this high-burden setting.

Latent tuberculous infection in household contacts of multidrug-resistant and newly diagnosed tuberculosis.

Differences in the prevalence of latent tuberculous infection (LTBI) and tuberculosis (TB) disease among contacts of patients with multidrug-resistant TB (MDR-TB) and drug-susceptible TB are not well understood. To compare the prevalence of tuberculin skin test (TST) positivity in household contacts of patients with MDR-TB and in contacts of patients never previously treated for TB ('new TB'). Consecutive patients with MDR-TB and their household contacts at nine urban district clinics in Viet Nam were screened for TB and LTBI, and followed up for 6 months. LTBI was defined as a TST result of at least 10 mm. A total of 167 patients with TB and their 337 household contacts were recruited. A total of 167/180 (25.8%) contacts of new TB patients and 60/147 (40.8%) contacts of MDR-TB patients were TST-positive (odds ratio [OR] 2.0, 95%CI 1.3-3.2). Contacts of MDR-TB patients were more likely to have baseline chest radiograph findings consistent with TB (OR 2.6, 95%CI 1.4-5.0). Contacts of MDR-TB patients have a high risk of developing TB. Measures to reduce Mycobacterium tuberculosis transmission and accelerate the detection of disease among high-risk contacts should be prioritised to curb the MDR-TB epidemic.

TUBERCULOSIS IN THE MUNDURUKU INDIGENOUS GROUP IN THE BRAZILIAN AMAZON: A PUBLIC HEALTH CHALLENGE

Os objetivos foram identificar sintomáticos respiratórios e casos de doença ativa, assim como estimar a prevalência de infecção latente por tuberculose (ILTB), fatores associados e descrever as características radiológicas entre pessoas com resultado de prova tuberculínica ?10mm. Trata-se de estudo prospectivo realizado com amostra de conveniência de 1.213 indígenas da etnia Munduruku, do Rio Tapajós, município de Jacareacanga-Pará. Para obtenção dos dados, foram realizados exames diretos e cultura no escarro, prova tuberculínica e radiografias de tórax, o que permitiu a identificação de tuberculose ativa e latente. Para a análise dos dados, valeu-se do softwere Statistical Package for the Social Sciences (SPSS) com os procedimentos estatísticos: teste X2, análises univariadas e multivariadas, nível de significância ?=5% e p valor &lt;0,05, IC 95%. Odds ratio foi utilizado como medida de associação. Foram identificados 70 sintomáticos respiratórios (5,8% da população estudada), obtendo-se a confirmação de Mycobacterium tuberculosis com prevalência pontual de 82,4/100.000. Foram realizados 219 exames radiológicos do tórax, dos quais 40 (18,3%) apresentaram alterações, sendo uma imagem cavitária. Foram realizados 1.213 testes tuberculínicos (PT) e a prevalência de infecção pelo M. tuberculosis (MTB) foi de 22,0% nas reações ?10mm e de 37,4% para o ponto de corte de 5mm. As reações à PT ?10mm mostraram-se associadas com as variáveis aldeia, idade acima de 40 anos, gênero, história de contato e presença de cicatriz vacinal de BCG. São altos os índices de adoecimento quando comparados com a população não indígena. Conclue-se pelos elevados índices que alguns adultos podem ter sido infectados no passado, entretanto a associação de infecção com idade acima de 40 anos indica contato.

What is the effect of antiretroviral treatment on the infectiousness of patients with smear-positive tuberculosis in rural Malawi?

BackgroundSeveral studies have found a lower risk of Mycobacterium tuberculosis infection among household contacts of HIV-positive patients with pulmonary tuberculosis than among patients with HIV-negative pulmonary tuberculosis, suggesting reduced transmission. Our hypothesis is that this association is reversed by antiretroviral therapy (ART). We examined the effect of ART on the prevalence of M tuberculosis infection among child contacts of adults with smear-positive tuberculosis. MethodsA cross-sectional household contact study of smear-positive tuberculosis index cases was conducted in Karonga, Malawi, between Jan 1, 2013, and Dec 31, 2014. Prevalence of tuberculin skin test (TST) positivity was compared between household contacts aged 11 years of index cases (HIV-negative, HIV-positive not on ART, and HIV-positive on ART [HIV status at diagnosis of tuberculosis]). A positive TST was defined as ≥10 mm induration. Data were analysed with a random-effects logistic regression model to account for clustering. FindingsThere were 376 child contacts (148 index cases), of whom 330 (88%) had a TST reading. The proportion of contacts of index cases with the highest mycobacillary burden, with smear-positivity as a proxy, was similar: HIV-negative (78%, 149/191) and HIV-positive index cases on ART (71%, 50/70), compared with HIV-positive index cases not on ART (57%, 39/69). The odds of a positive TST were 60% lower in contacts of HIV-positive patients not on ART (adjusted odds ratio 0·4, 95% CI 0·1–1·0; p=0·04) and 70% lower in contacts of HIV-positive patients on ART (0·3, 0·1–0·8; p=0·02) than in HIV-negative index cases, adjusted for degree of contact and age of index case. The reduction in odds of TST positivity among contacts of HIV-positive patients on ART remained after additionally adjusting for degree of smear-positivity. InterpretationContrary to expectation, we found a reduced prevalence of M tuberculosis infection among contacts of HIV-positive patients with tuberculosis on ART, after adjusting for degree of smear-positivity. This finding is suggestive of decreased transmission from these index cases. This reduction in transmission might be due to earlier diagnosis of tuberculosis in patients who are already engaged in care. FundingWellcome Trust.

Annual risk of tuberculous infection measured using serial skin testing, Orel Oblast, Russia, 1991-2005.

To compare trends in direct annual risk of tuberculous infection (ARTI) during 1991-2005 in relation to tuberculosis (TB) incidence and to indirect estimates of ARTI derived from the prevalence of tuberculin skin test (TST) positivity in schoolchildren in Orel Oblast, Russia. In 2005, we abstracted annual TST results and vaccination histories from a representative sample of schoolchildren in Orel Oblast, Russia, where bacille Calmette-Guerin (BCG) vaccination and annual TST of children are nearly universal. We calculated direct ARTI based on the percentage of children tested with TST conversions each year, excluding conversions following BCG vaccination. We analysed records from 13 206 children, with a median of 10 recorded TST results per child. The ARTI increased from 0.2% in 1991 to 1.6% in 2000, paralleling trends in TB incidence. Similar results were observed when the ARTI was estimated based on prevalence of infection among children aged 3-5 years using a 12 mm cut-off to define TST positivity. Results differed substantially when 10 or 15 mm cut-offs were used or when prevalence was determined among children aged 6-8 years. ARTI measured through TST conversion increased as TB incidence increased in Orel Oblast. ARTI measured through serial TSTs can thus provide an indicator of changing trends in TB incidence.

High prevalence and risk factors associated with latent tuberculous infection in two Colombian prisons.

Two prisons in Medellín and Itagüí, Colombia. To determine the prevalence of tuberculin skin test (TST) positivity in prisoners and the annual risk of tuberculous infection (ARTI), to identify risk factors associated with a positive result, and to describe progression to active disease. Cross-sectional study. Inmates were included if time of incarceration was ⩾1 year and excluded if subjects had had previous or active tuberculosis (TB), or conditions that could hamper TST administration or interpretation. We screened 1014 inmates. The overall prevalence of TST positivity was 77.6%. The first TST administration resulted in 66% positivity, and the second TST an additional 11.6%. In Prison One, the ARTI was 5.09% in high TB incidence cell blocks and 2.72% in low TB incidence blocks. In Prison Two, the ARTI was 2.77%. Risk factors associated with TST positivity were history of previous incarceration and length of incarceration. Among all those included in the study, four individuals developed active pulmonary TB. Prevalence of TST positivity in prisoners and the ARTI were higher than in the general population, but differed between prisons; it is important to apply a second TST to avoid an overestimation of converters during follow-up.

An evaluation of factors associated with taking and responding positive to the tuberculin skin test in individuals with HIV/AIDS

BackgroundThe tuberculin skin test (TST) is still the standard test for detecting latent infection by M tuberculosis (LTBI). Given that the Brazilian Health Ministry recommends that the treatment of latent tuberculosis (LTBI) should be guided by the TST results, the present study sets out to describe the coverage of administering the TST in people living with HIV at two referral health centers in the city of Recife, where TST is offered to all patients. In addition, factors associated with the non-application of the test and with positive TST results were also analyzed.MethodsA cross-sectional study was carried out with HIV patients, aged 18 years or over, attending outpatient clinics at the Correia Picanço Hospital/SES/PE and the Oswaldo Cruz/UPE University Hospital, who had been recommended to take the TST, in the period between November 2007 and February 2010. Univariate and multivariate logistic regression analyses were carried out to establish associations between the dependent variable - taking the TST (yes/no), at a first stage analysis, and the independent variables, followed by a second stage analysis considering a positive TST as the dependent variable. The odds ratio was calculated as the measure of association and the confidence interval (CI) at 95% as the measure of accuracy of the estimate.ResultsOf the 2,290 patients recruited, 1087 (47.5%) took the TST. Of the 1,087 patients who took the tuberculin skin test, the prevalence of TST ≥ 5 mm was 21.6% among patients with CD4 ≥ 200 and 9.49% among those with CD4 < 200 (p = 0.002). The patients most likely not to take the test were: men, people aged under 39 years, people with low educational levels and crack users. The risk for not taking the TST was statiscally different for health service. Patients who presented better immunity (CD4 ≥ 200) were more than two and a half times more likely to test positive that those with higher levels of immunodeficiency (CD4 < 200).ConclusionsConsidering that the TST is recommended by the Brazilian health authorities, coverage for taking the test was very low. The most serious implication of this is that LTBI treatment was not carried out for the unidentified TST-positive patients, who may consequently go on to develop TB and eventually die.

Married to M. tuberculosis: risk of infection and disease in spouses of smear‐positive tuberculosis patients

To quantify the risk of infection and disease in spouses of tuberculosis patients and the extent to which intervention could reduce the risk in this highly exposed group. We compared HIV prevalence, TB prevalence and incidence and tuberculin skin test (TST) results in spouses of TB patients and community controls. HIV-positive spouses were offered isoniazid preventive therapy (IPT), and TST was repeated at 6, 12 and 24 months. We recruited 148 spouses of smear-positive patients ascertained prospectively and 3% had active TB. We identified 203 spouses of previously diagnosed smear-positive patients, 11 had already had TB, and the rate of TB was 2.4 per 100 person years(py) over 2 years (95% CI 1.15-5.09). 116 were found alive and recruited. HIV prevalence was 37% and 39% in the prospective and retrospective spouse groups and 17% in controls. TST was ≥10 mm in 80% of HIV negative and in 57% of HIV-positive spouses ascertained retrospectively; 74% HIV negative and 62% HIV-positive spouses ascertained prospectively, and 48% HIV negative and 26% HIV-positive community controls. Of 54 HIV-positive spouses, 18 completed 6-month IPT. At 2 year follow-up, 87% of surviving spouses had TST ≥10 mm and the rate of TB was 1.1 per 100 py (95% CI 0.34-3.29). Spouses are a high-risk group who should be screened for HIV and active TB. TST prevalence was already high by the time the spouses were approached but further infections were seen to occur. Uptake and adherence to IPT was disappointing, lessening the impact of short-duration therapy.

The prevalence of tuberculin skin test positivity and the effect of BCG vaccinations on tuberculin induration size in the eastern Mediterranean region of Turkey

To evaluate the prevalence of tuberculin skin test (TST) positivity in Kahramanmaraş and interpret the size of purified protein derivative (PPD) induration with respect to the number of Bacillus Calmette-Guerin (BCG) scars and other factors. Materials and methods: A total of 2979 school children between the ages of 7 and 17 years were evaluated. On the basis of socioeconomic levels, 11 schools were selected and categorized into 3 subgroups: schools in the suburbs of the city (Group 1), schools in the city center (Group 2), and private schools (Group 3). Children were injected with 5 TU/0.1 mL of PPD and the sizes of induration were measured after 72 h. The number of BCG scars and the sizes of induration were recorded for each pupil. Results: The TST was positive in 6.3% of the nonvaccinated students and in 7.5% of the vaccinated students (P > 0.05). The number of BCG vaccination scars was 0 in 174 children (5.8%), 1 in 1232 children (41.4%), 2 in 1516 children (50.9%), 3 in 54 children (1.8%), and 4 in 3 children (0.1%). The mean diameter of the size of the PPD induration for 0, 1, 2, 3, and 4 BCG vaccinations was 2.50 ± 4.05 mm, 5.60 ± 5.11 mm, 8.49 ± 5.09 mm, 8.46 ± 4.38 mm, and 7.66 ± 6.80 mm, respectively. The size of the induration was greatest in students vaccinated twice (P < 0.05). The TST positivity rate was highest in children 11-13 years of age (P < 0.05). Conclusion: The BCG vaccination rate was higher in Kahramanmaraş, whereas the TST positivity rate was lower. The factors that affected the size of the PPD induration were the number of vaccination scars and the age of the subject.

Rates of Tuberculosis Transmission to Children and Adolescents in a Community with a High Prevalence of HIV Infection among Adults

Tuberculin skin test surveys are routinely used to test for tuberculosis (TB) infection in communities, but there are few data from tuberculin skin test surveys from countries in which both TB and human immunodeficiency virus (HIV) infection are prevalent. We conducted a tuberculin skin test survey among 831 school-going children aged 5-17 years in a community that was experiencing an increase in the prevalence of TB and HIV infection. Responses to purified protein derivative RT23 were measured 3 days after the test was administered to determine tuberculin skin test results. The prevalence of tuberculin skin test results positive for TB (i.e., an induration >or=10 mm in diameter in response to the skin test) ranged from 26.2% among children aged 5-8 years to 52.5% among children aged 14-17 years. The overall annual risk of infection was 4.1% using a 10-mm cutoff and 2.0% using a 17.4-mm cutoff. Annual risks of infection were constant across age groups. This is consistent with the finding that TB incidence remained the same in children (P= .48) from 1999 through 2005, although total TB incidence and adult TB (determined by sputum smear test) incidence increased in this community during the same period (P<.001). The annual risk of infection is high in the community. It appears that HIV infection-associated TB is not a major influence on the annual risk of infection and that TB transmission from adults to children may be associated with a subset of TB cases in the community. An improved understanding of TB transmission patterns is urgently needed help the implementation of novel strategies for reducing the annual risk of infection in this setting.

Editorial Commentary:On the Risk of Being and Becoming Infected withMycobacterium tuberculosis

In the late 1980s the World Health Organization asked the US Centers for Disease Controls top tuberculosis epidemiologist to review the accumulated reports regarding tuberculin skin test prevalence surveys and to analyze those that were judged to have high scientific merit. The result was an epidemiologic masterpiece that compared the trends in the annual risk of infection in a multitude of countries in the world (excluding industrialized countries). It demonstrated that the risk for a child to become infected or reinfected with Mycobacterium tuberculosis had decreased virtually everywhere albeit to a varying degree over the preceding decades. For the 8 countries in the World Health Organization African region available for analysis (Botswana Burundi Cameroon Ethiopia Gambia Lesotho Nigeria and Tanzania) the risk appeared to have decreased by 1%-5% annually to _2% annually by 1980. No data were available for South Africa at that time. Of the countries considered at that time only Tanzania had a national functional and comprehensive tuberculosis case surveillance system in place and it was capable of providing just an inkling of the impact that the growing epidemic of HIV infection would have on the tuberculosis epidemic. In this issue of Clinical Infectious Diseases Middelkoop et al. present the staggering magnitude of transmission of M. tuberculosis to children in Cape Town South Africa. The annual risk of infection was ~4%. The authors noted that the annual risk of infection was constant across the age groups of the 5-17-year-old participants who were enrolled in the survey. (excerpt)

LOW PREVALENCE AND INCREASED HOUSEHOLD CLUSTERING OF MYCOBACTERIUM TUBERCULOSIS INFECTION IN HIGH ALTITUDE VILLAGES IN PERU

Anecdotal historical evidence suggests that tuberculosis was uncommon at high altitude, but whether transmission is affected by high altitude is not known. To test whether high altitude lowers infection by Mycobacterium tuberculosis, the prevalence of tuberculin skin test (TST) positivity was compared between two high altitude villages (3,340 meters [10,960 feet] and 3,500 meters [11,480 feet]) and three sea-level sites in Peru. High altitude villages had lower TST-positive prevalence rates (5.7% and 6.8%) than sea level areas (25-33%), and the difference remained significant (odds ratio = 4.5-6.0) after adjusting for age, education, bacille Calmette-Guerin vaccination, and contact with tuberculosis patients. The TST-positive individuals clustered within highland families more than within sea level families. These data suggest that prevention and control efforts targeted to families may be more effective at high altitude. The mechanism by which TST-positivity prevalence is decreased at high altitude is unknown, but may reflect relative hypoxia, low humidity, or an increased ultraviolet effect.

Tuberculin Skin Testing of Hospitalized Patients

We sought to define the prevalence of tuberculin skin test (TST) positivity in a group of newly hospitalized patients, to identify risk factors for positive tests, and to examine the impact of testing on infection control practices.Unblinded cohort study over 5 days in July 1992.A 1,000-bed university-affiliated hospital.All patients admitted (excluding obstetric patients and newborns) were interviewed. Patients without a history of tuberculosis (TB) or a positive TST were offered a TST with Candida and tetanus controls.Of 346 patients offered the test, 21 (6%) had a prior history of TB or a positive TST, and 36 (10%) declined to participate; 279 of the remaining 289 completed the study. Anergy was demonstrated in 94 (33.7%) of 279 patients. New positive TSTs were identified in 19 (10.3%) of 185 nonanergic patients. Of the 19 TST-positive patients, 6 (32%) had infiltrates on chest radiographs and were evaluated for active TB. One patient was treated empirically for active TB, and five received isoniazid prophylaxis. Risk factors for a new positive TST included age (odds ratio [OR], 1.56 per decade of life; P = .021), African American race (OR, 4.81; P = .008), alcohol abuse (OR, 5.53; P = .005), and peptic ulcer disease (OR, 4.53; P = .017). Risk factors for anergy included admission to a surgical service (OR, 2.1; P = .006), current use of steroids (OR, 2.65; P = .005), and human immunodeficiency virus (HIV) infection (OR, undefined; P = .034).Despite a high rate of anergy, routine tuberculin skin testing identified a substantial number of patients with TB infection who might otherwise have gone unrecognized.

Tuberculin skin testing of hospitalized patients.

We sought to define the prevalence of tuberculin skin test (TST) positivity in a group of newly hospitalized patients, to identify risk factors for positive tests, and to examine the impact of testing on infection control practices. Unblinded cohort study over 5 days in July 1992. A 1,000-bed university-affiliated hospital. All patients admitted (excluding obstetric patients and newborns) were interviewed. Patients without a history of tuberculosis (TB) or a positive TST were offered a TST with Candida and tetanus controls. Of 346 patients offered the test, 21 (6%) had a prior history of TB or a positive TST, and 36 (10%) declined to participate; 279 of the remaining 289 completed the study. Anergy was demonstrated in 94 (33.7%) of 279 patients. New positive TSTs were identified in 19 (10.3%) of 185 nonanergic patients. Of the 19 TST-positive patients, 6 (32%) had infiltrates on chest radiographs and were evaluated for active TB. One patient was treated empirically for active TB, and five received isoniazid prophylaxis. Risk factors for a new positive TST included age (odds ratio [OR], 1.56 per decade of life; P = .021), African American race (OR, 4.81; P = .008), alcohol abuse (OR, 5.53; P = .005), and peptic ulcer disease (OR, 4.53; P = .017). Risk factors for anergy included admission to a surgical service (OR, 2.1; P = .006), current use of steroids (OR, 2.65; P = .005), and human immunodeficiency virus (HIV) infection (OR, undefined; P = .034). Despite a high rate of anergy, routine tuberculin skin testing identified a substantial number of patients with TB infection who might otherwise have gone unrecognized.