Evaluation of QuantiFERON-TB gold in-tube and tuberculin skin tests among immigrant children being screened for latent tuberculosis infection

US Postarrival Evaluation of Immigrant and Refugee Children with Latent Tuberculosis Infection Diagnosed Overseas, 2007-2019

OBJECTIVE

To assess outcomes from the US postarrival evaluation of newly arrived immigrant and refugee children aged 2-14 years who were diagnosed with latent tuberculosis infection (LTBI) during a required overseas medical examination.

STUDY DESIGN

We compared overseas and US interferon-γ release assay (IGRA)/tuberculin skin test (TST) results and LTBI diagnosis; assessed postarrival LTBI treatment initiation and completion; and evaluated the impact of switching from TST to IGRA to detect Mycobacterium tuberculosis infection overseas.

RESULTS

In total, 73 014 children were diagnosed with LTBI overseas and arrived in the US during 2007-2019. In the US, 45 939 (62.9%) completed, and 1985 (2.7%) initiated but did not complete a postarrival evaluation. Among these 47 924 children, 30 360 (63.4%) were retested for M tuberculosis infection. For 17 996 children with a positive overseas TST, 73.8% were negative when retested by IGRA. For 1051 children with a positive overseas IGRA, 58.0% were negative when retested by IGRA. Overall, among children who completed a postarrival evaluation, 18 544 (40.4%) were evaluated as having no evidence of TB infection, and 25 919 (56.4%) had their overseas LTBI diagnosis confirmed. Among the latter, 17 229 (66.5%) initiated and 9185 (35.4%) completed LTBI treatment.

CONCLUSIONS

Requiring IGRA testing overseas could more effectively identify children who will benefit from LTBI treatment. However, IGRA reversions may occur, highlighting the need for individualized assessment for risk of infection, progression, and poor outcome when making diagnostic and treatment decisions. Strategies are needed to increase the proportions receiving a postarrival evaluation and completing LTBI treatment.

Prevalence of Latent Tuberculosis Infection Among Healthy Young Children and Adolescents and a Two-step Approach for the Diagnosis of Tuberculosis Infection in Chengdu, China

BACKGROUND

China has a high burden of tuberculosis and latent tuberculosis infection (LTBI). The aim of this study was to estimate the prevalence of LTBI among healthy young children and adolescents and test a 2-step approach to explore the threshold for the diagnosis of tuberculosis infection in Chengdu, China.

METHODS

Healthy preschool children and school-going children in Chengdu, Sichuan Province, were screened for LTBI using the tuberculin skin test (TST). Preschool children with TST ≥ 5 mm also underwent interferon-γ release assay (IGRA) to explore the threshold of this 2-step approach.

RESULTS

In total, 5667 healthy young children and adolescents completed TST test between July 2020 and January 2021 and were included in the present analysis. The age of the participants ranged from 2.4 to 18 years (median 7.25 ± 4.514 years), of which 2093 (36.9%) were younger than 5 years. The overall prevalence of LTBI was 6.37% and 6.64% in children younger than 5 years old. Fourteen of the 341 preschool children with TST ≥5 mm were interferon-γ release assay positive, of which 4 showed a TST result of 5-10 mm, and 6 preschool children received preventive treatment for LTBI.

CONCLUSIONS

Healthy young children and adolescents should also be considered as important target populations for LTBI screening. TST can be recommended for first-line screening as part of a 2-step approach for LTBI screening using a positive threshold of 5 mm.

Tuberculosis Infection in Children and Adolescents: Testing and Treatment

Tuberculosis (TB) remains an important problem among children in the United States and throughout the world. There is no diagnostic reference standard for latent tuberculosis infection (also referred to as tuberculosis infection [TBI]). The tuberculin skin test (TST) has many limitations, including difficulty in administration and interpretation, the need for a return visit by the patient, and false-positive results caused by cross-reaction with Mycobacterium bovis-bacille Calmette-Guerin vaccines and many nontuberculous mycobacteria. Interferon-gamma release assays (IGRAs) are blood tests that use antigens specific for M tuberculosis; as a result, IGRAs yield fewer false-positive results than the TST. Both IGRAs and the TST have reduced sensitivity in immunocompromised children, including children with severe TB disease. Both methods have high positive predictive value when applied to children with risk factors for TBI, especially recent contact with a person who has TB disease. The advantages of using IGRAs and diminished experience with the placement and interpretation of the TST favor expanded use of IGRAs in children in the United States. There are now several effective and safe regimens for the treatment of TBI in children. For improved adherence to therapy, the 3 rifamycin-based regimens are preferred because of their short duration. Daily isoniazid can be used if there is intolerance or drug interactions with rifamycins. A TB specialist should be involved when there are questions regarding testing interpretation, selection of an appropriate treatment regimen, or management of adverse effects.

Tuberculosis in Internationally Displaced Children Resettling in Harris County, Texas, USA, 2010-20151

US guidelines have recommended testing children emigrating from high tuberculosis-incidence countries with interferon-gamma release assays (IGRAs) or tuberculin skin tests (TSTs). We describe the Harris County (Texas) Public Health Refugee Health Screening Program's testing results during 2010-2015 for children <18 years of age: 5,990 were evaluated, and 5,870 (98%) were tested. Overall, 364 (6.2%) children had >1 positive test: 143/1,842 (7.8%) were tested with TST alone, 129/3,730 (3.5%) with IGRA alone, and 92/298 (30.9%) with both TST and IGRA. Region of origin and younger age were associated with positive TST or IGRA results. All children were more likely to have positive results for TST than for IGRA (OR 2.92, 95% CI 2.37-3.59). Discordant test results were common (20%) and most often were TST+/IGRA- (95.0%), likely because of bacillus Calmette-Guérin vaccination. Finding fewer false positives supports the 2018 change in US immigration guidelines that recommends using IGRAs for recently immigrated children.

Latent tuberculosis in migrants travelling through the northeast regions of Mexico

Background

Latent tuberculosis infection (LTBI) affects nearly a quarter of the global population. Public health interventions aimed at interrupting tuberculosis transmission do not routinely include systematic screening of migrant populations for LTBI in Mexico, nor other high-income countries. However, early detection and treatment of LTBI in immigrant populations from high-burden countries are recommended by the World Health Organization.

Objective

The objective of this study was to determine the proportion of migrants with LTBI in shelters in northeastern Mexico.

Methods

In this cross-sectional study, blood samples were obtained from 455 migrants living in shelters in northeastern Mexico during January 2017 to October 2019. LTBI was diagnosed using the QuantiFERON®-TB Gold Plus test.

Results

Most of the migrants evaluated in this study were from Honduras; ∼86% were male; the average age was 29 ± 10 years. LTBI was identified in 18.4% of those from Central America. Migrants from El Salvador and Nicaragua were more likely to have LTBI than those from Honduras or Guatemala. Overweight or obese persons and older persons had a higher prevalence of LTBI. We detected no significant differences with respect to LTBI when the results were compared based on gender, education, or marital status.

Conclusion

The LTBI rates amongst migrants from Central America recently screened in shelters in northeastern Mexico appears to be relatively low given recent estimates of LTBI prevalence in Mexico.

Interferon-γ Release Assays for Tuberculosis Infection Diagnosis in Refugees <5 Years Old

BACKGROUND

New guidelines support using interferon-γ release assays (IGRAs) in children ≥2 years for diagnosis of latent tuberculosis infection (LTBI). However, lack of experience in young children and concern that IGRAs are less sensitive than tuberculin skin tests (TSTs) limit their use. Our aim was to identify active tuberculosis (TB) cases among high risk children <5 years and tested for LTBI with an IGRA.

METHODS

. Retrospective review of domestic TB screening data from California's Refugee Health Electronic Information System for children <5 years old who resettled in California between October, 2013 and December, 2016. Children were crossmatched with the California TB registry to identify cases of TB disease between October 2013 and December 2018.

RESULTS

A total of 3371 children <5 years were identified; the majority were born in countries with high TB incidence (>150 cases per 100 000). Half received IGRAs (n = 1878; 56%), a quarter received TSTs (n = 811; 24%); 1.4% of children were IGRA-positive (n = 26) and 13% were TST-positive (n = 106). Twenty-two IGRA results were indeterminate (1.2%). Sixteen children had both tests; 9 were discrepant (positive TST with negative IGRA). No cases of TB disease were identified during 10 797 person-years of follow-up.

CONCLUSIONS

IGRA positivity was less than TST positivity in high risk children <5 years old. Despite fewer LTBI diagnoses in the IGRA-tested population, no cases of TB disease among children who tested negative were identified, suggesting IGRA is valuable tool for identifying LTBI in this population.

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.

Tuberculosis infection in under-2-year-old refugees: Should we be screening? A systematic review and meta-regression analysis

AIM

Refugees are at increased risk of tuberculosis infection due to time spent in crowded camps, decreased nutrition and originating from countries whose own tuberculosis control systems may have been disturbed. In Australia, tuberculosis is screened for in for all refugees aged 11-34 years old and in those aged 2-10 years arriving from high-incidence countries. Our aims were to determine if refugee children aged under 2 years of age should also be screened.

METHODS

A systematic literature review and meta-regression was carried out on studies in refugee children under 18 years old, involving screening for tuberculosis (active or latent tuberculosis infection (LTBI)). Studies were extracted from the last 10 years from a range of bibliographic databases using the search terms 'tuberculosis', 'children', 'screening' and 'refugee', which tested for tuberculosis using the tuberculin skin test (TST) or QuantiFERON-Gold (Interferon Gamma Release Assay (IGRA)).

RESULTS

Of the 15 included studies, prevalence of LTBI in < 2-year-olds was 5% using IGRA and 15% using TST (P < 0.05). Prevalence increased with age (odds ratio 1.12; 95% confidence interval: 1.06-1.17) cumulatively and decreased where IGRA was used for screening compared to TST (odds ratio 0.38; 95% confidence interval: 0.25-0.58). Prevalence of LTBI did not differ between general versus clinic refugee cohorts.

CONCLUSIONS

Refugees are a particularly vulnerable group in their susceptibility to tuberculosis, and LTBI management is a critical part of tuberculosis disease control due to the lifetime risk of developing active tuberculosis. A prevalence of 5-15% for LTBI in the under 2 years age group would support them being included in screening programmes.

Interferon-γ Release Assays in Children <15 Years of Age

OBJECTIVES

The tuberculin skin test (TST) has been preferred for screening young children for latent tuberculosis infection (LTBI) because of concerns that interferon-γ release assays (IGRAs) may be less sensitive in this high-risk population. In this study, we compared the predictive value of IGRAs to the TST for progression to tuberculosis disease in children, including those <5 years old.

METHODS

Children <15 years old at risk for LTBI or progression to disease were tested with TST, QuantiFERON-TB Gold In-Tube test (QFT-GIT), and T-SPOT.TB test (T-SPOT) and followed actively for 2 years, then with registry matches, to identify incident disease.

RESULTS

Of 3593 children enrolled September 2012 to April 2016, 92% were born outside the United States; 25% were <5 years old. Four children developed tuberculosis over a median 4.3 years of follow-up. Sensitivities for progression to disease for TST and IGRAs were low (50%-75%), with wide confidence intervals (CIs). Specificities for TST, QFT-GIT, and T-SPOT were 73.4% (95% CI: 71.9-74.8), 90.1% (95% CI: 89.1-91.1), and 92.9% (95% CI: 92.0-93.7), respectively. Positive and negative predictive values for TST, QFT-GIT, and T-SPOT were 0.2 (95% CI: 0.1-0.8), 0.9 (95% CI: 0.3-2.5), and 0.8 (95% CI: 0.2-2.9) and 99.9 (95% CI: 99.7-100), 100 (95% CI: 99.8-100), and 99.9 (95% CI: 99.8-100), respectively. Of 533 children with TST-positive, IGRA-negative results not treated for LTBI, including 54 children <2 years old, none developed disease.

CONCLUSIONS

Although both types of tests poorly predict disease progression, IGRAs are no less predictive than the TST and offer high specificity and negative predictive values. Results from this study support the use of IGRAs for children, especially those who are not born in the United States.

Latent tuberculosis may be missed by current screening practices: Analysis of interferon-gamma release assay results from a paediatric refugee clinic

AIMS

(i) To determine the prevalence of latent tuberculosis infection (LTBI) and characteristics associated with LTBI in children attending a paediatric refugee clinic and (ii) to determine whether current New South Wales (NSW) Health screening practices could miss LTBI cases.

METHODS

This was a retrospective analysis of tuberculosis (TB) screening data from refugee and asylum seeker children who attended a refugee clinic in a tertiary children's hospital during 2014 and 2015. We determined associations between LTBI and child characteristics at 5% significance levels.

RESULTS

Of 358 children attending the clinic, 235 children (66%) received interferon-gamma release assay (IGRA) testing, of whom 28 (11.9%) had positive results. Of the 28 with positive IGRAs, 12 (42.9%) would have been missed using NSW Health screening guidelines: two because they were younger than 2 years old, one who was born in Australia and 10 because they were not born in high TB incidence countries. IGRA results were not significantly associated with any of the child characteristics examined, including age, gender, travel through transit countries, boat versus plane arrival into Australia, whether the child had been in a detention centre or TB incidence in the source country.

CONCLUSIONS

We identified 12 children with LTBI who would have been missed using current NSW Health Department screening practices. These children are at risk of progression to active disease, particularly the two aged younger than 2 years old. We recommend universal screening.

Risk Factors for Indeterminate Interferon-Gamma Release Assay for the Diagnosis of Tuberculosis in Children-A Systematic Review and Meta-Analysis

Background: Interferon-gamma release assays (IGRA) are well-established immunodiagnostic tests for tuberculosis (TB) in adults. In children these tests are associated with higher rates of false-negative and indeterminate results. Age is presumed to be one factor influencing cytokine release and therefore test performance. The aim of this study was to systematically review factors associated with indeterminate IGRA results in pediatric patients. Methods: Systematic literature review guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) searching PubMed, EMBASE, and Web of Science. Studies reporting results of at least one commercially available IGRA (QuantiFERON-TB, T-SPOT.TB) in pediatric patient groups were included. Random effects meta-analysis was used to assess proportions of indeterminate IGRA results. Heterogeneity was assessed using the I² value. Risk differences were calculated for studies comparing QuantiFERON-TB and T-SPOT.TB in the same study. Meta-regression was used to further explore the influence of study level variables on heterogeneity. Results: Of 1,293 articles screened, 133 studies were included in the final analysis. These assessed QuantiFERON-TB only in 77.4% (103/133), QuantiFERON-TB and T-SPOT.TB in 15.8% (21/133), and T-SPOT.TB only in 6.8% (9/133) resulting in 155 datasets including 107,418 participants. Overall 4% of IGRA results were indeterminate, and T-SPOT.TB (0.03, 95% CI 0.02-0.05) and QuantiFERON-TB assays (0.05, 95% CI 0.04-0.06) showed similar proportions of indeterminate results; pooled risk difference was-0.01 (95% CI -0.03 to 0.00). Significant differences with lower proportions of indeterminate assays with T-SPOT.TB compared to QuantiFERON-TB were only seen in subgroup analyses of studies performed in Africa and in non-HIV-infected immunocompromised patients. Meta-regression confirmed lower proportions of indeterminate results for T-SPOT.TB compared to QuantiFERON-TB only among studies that reported results from non-HIV-infected immunocompromised patients (p < 0.001). Conclusion: On average indeterminate IGRA results occur in 1 in 25 tests performed. Overall, there was no difference in the proportion of indeterminate results between both commercial assays. However, our findings suggest that in patients in Africa and/or patients with immunocompromising conditions other than HIV infection the T-SPOT.TB assay appears to produce fewer indeterminate results.

Interferon-Gamma Release Assay-Based Screening for Pediatric Latent Tuberculosis Infection in an Urban Primary Care Network

OBJECTIVE

To assess outcomes from a QuantiFERON-tuberculosis (TB) Gold (QFT)-based screening for pediatric latent TB infection (LTBI) in the Denver Health Community Health System (CHS), an urban primary-care network in the US.

STUDY DESIGN

We retrospectively analyzed all QFTs (n = 6685) performed on children aged 2-18 years between January 5, 2011, and August 18, 2014. Risk factors for positive testing in the CHS population were identified by logistic regression, and further assessed using a case-control comparison. Results from CHS were compared with higher-TB-risk populations (refugee and TB clinics) in our health system.

RESULTS

Positive QFT occurred in 79 of 3745 (2.1%) CHS patients. Positive rates increased with age (0.3% in age 2-5 years to 4.9% in age 13-18 years). Indeterminate results were uncommon (0.8%) including in children <5 (1.3%). Risk factors for positive tests in the CHS population included non-Medicaid insured/uninsured and non-English/Spanish preferred language. In the case-control analysis, birth/travel to/residence in a TB-endemic country was the only identified risk factor for positive testing (OR 5.2 [95% CI 1.04-25.5]). Rates of positive testing were lower in the CHS population than the refugee/TB clinic populations, including among children age 2-5.

DISCUSSION

QFT-based LTBI screening was successfully introduced in our pediatric primary-care health system, and supported our programmatic goals of identifying LTBI cases while limiting unnecessary LTBI treatment courses. Increasing positive rates with age, and higher rates in the refugee/TB populations compared with CHS, add indirect evidence of adequate test sensitivity, even among young children, for whom data on interferon-gamma release assay performance are limited.

Recommendations for the screening of paediatric latent tuberculosis infection in indigenous communities: a systematic review of screening strategies among high-risk groups in low-incidence countries

Background

Tuberculosis (TB) continues to be a global public health concern. Due to the presence of multiple risk factors such as poor housing conditions and food insecurity in Canadian Indigenous communities, this population is at particularly high risk of TB infection. Given the challenges of screening for latent TB infection (LTBI) in remote communities, a synthesis of the existing literature regarding current screening strategies among high-risk groups in low-incidence countries is warranted, in order to provide an evidence base for the optimization of paediatric LTBI screening practices in the Canadian Indigenous context.

Methods

A literature search of the Embase and Medline databases was conducted, and studies pertaining the evaluation of screening strategies or screening tools for LTBI in paediatric high-risk groups in low-incidence countries were included. Studies focusing on LTBI screening in Indigenous communities were also included, regardless of whether they focused on a paediatric population. Their results were summarized and discussed in the context of their relevance to screening strategies suitable to the Canadian Indigenous setting. Grey literature sources such as government reports or policy briefs were also consulted.

Results

The initial literature search returned 327 studies, with 266 being excluded after abstract screening, and 36 studies being included in the final review (original research studies: n = 25, review papers or policy recommendations: n = 11). In the examined studies, case identification and cost-effectiveness of universal screening were low in low-incidence countries. Therefore, studies generally recommended targeted screening of high-risk groups in low-incidence countries, however, there remains a lack of consensus regarding cut-offs for the incidence-based screening of high-risk communities, as well as regarding the utility and prioritization of individual risk-factor-based screening of high-risk groups. The utility of the TST compared to IGRAs for LTBI detection in the pediatric population also remains contested.

Conclusions

Relevant strategies for targeted screening in the Canadian Indigenous context include community-level incidence-based screening (screening based on geographic location within high-incidence communities), as well as individual risk-factor-based screening, taking into account pertinent risk factors in Indigenous settings, such as poor housing conditions, malnutrition, contact with an active case, or the presence of relevant co-morbidities, such as renal disease.

Interferon-γ Release Assay Performance for Tuberculosis in Childhood

BACKGROUND

Interferon-γ release assays (IGRAs) are important adjunctive tests for diagnosing tuberculosis (TB) disease in children.

METHODS

We analyzed California TB registry data for patients ≤18 years with laboratory-confirmed TB disease during 2010-2015 to identify case characteristics associated with test selection and performance and measure IGRA sensitivity.

RESULTS

In total, 778 cases of TB were reported; 360 were laboratory confirmed. Indeterminate IGRAs were associated with being <1 year old (prevalence rate ratio 9.23; 95% confidence interval 2.87 to 29.8) and having central nervous system disease (prevalence rate ratio 2.69; 95% confidence interval 1.06 to 6.86) on multivariable analysis. Ninety-five children had both an IGRA and tuberculin skin test (TST) performed. Among those, the sensitivity of IGRA in 5- to 18-year-olds was 96% (66 out of 69) vs 83% (57 out of 69) for TST (P = .01); IGRA sensitivity compared with TST in children ages 2 to 4 was 91% (10 out of 11) vs 91% (10 out of 11) (P > .99), and the sensitivity compared with TST in children aged <2 years was 80% (12 out of 15) vs 87% (13 out of 15) (P > .99).

CONCLUSIONS

This is the largest North American analysis of IGRA use and performance among children with TB disease. In children <5 years old, IGRA sensitivity is similar to TST, but sensitivity of both tests are reduced in children <2 years old. Indeterminate results are higher in children <1 year old and in central nervous system disease. In children ≥5 years old with laboratory-confirmed TB, IGRA has greater sensitivity than TST and should be considered the preferred immunodiagnostic test..

Too little too late: Waiting for TB to come

There is a new paradigm that preventing tuberculosis (TB) and addressing the reservoir of latent TB infection in combination with curing all TB cases is essential to accelerate the decline of TB rates and ending TB by 2050. However, complacency and incremental change eludes radical policy transformation needed to meet global targets. This essay explores current attitudes, policy disparities between high and lower burden settings, and what changes are needed to remove the obstacles to progress.

Italian multicentre study found infectious and vaccine-preventable diseases in children adopted from Africa and recommends prompt medical screening

AIM

This study evaluated the prevalence of infectious diseases and immunisation status of children adopted from Africa.

METHODS

We studied 762 African children referred to 11 Italian paediatric centres in 2009-2015. Clinical and laboratory data were retrospectively collected and analysed.

RESULTS

The median age of the children (60.3% males) was 3 years and 6 months, 52.6% came from Ethiopia and 50.1% had at least one infectious disease. Parasitic infections accounted for the majority of the infectious diseases (409 of 715), and the most common were Giardia lamblia (n = 239), Toxocara canis (n = 65) and skin infections (n = 205), notably Tinea capitis/corporis (n = 134) and Molluscum contagiosum (n = 56) Active tuberculosis (TB) was diagnosed in nine children (1.2%). Latent TB infections were diagnosed in 52 (6.8%) children, and only 23 had concordant positive tuberculin skin tests and Quantiferon Gold In-Tube results. Discordant results were associated with Bacille de Calmette-Guérin vaccinations (odd ratio 6.30 and 95% confidence interval of 1.01-39.20, p = 0.011). Nonprotective antitetanus or antihepatitis B antibody titres were documented in 266 (34.9%) and 396 (51.9%) of the 762 children.

CONCLUSION

The prevalence of infectious conditions and not-protective titres for vaccine-preventable diseases observed in our population underlines the need for prompt and complete medical screening of children adopted from Africa.

Interferon-gamma release assay for the diagnosis of latent tuberculosis infection: A latent-class analysis

BACKGROUND

Accurate diagnosis and subsequent treatment of latent tuberculosis infection (LTBI) is essential for TB elimination. However, the absence of a gold standard test for diagnosing LTBI makes assessment of the true prevalence of LTBI and the accuracy of diagnostic tests challenging. Bayesian latent class models can be used to make inferences about disease prevalence and the sensitivity and specificity of diagnostic tests using data on the concordance between tests. We performed the largest meta-analysis to date aiming to evaluate the performance of tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) for LTBI diagnosis in various patient populations using Bayesian latent class modelling.

METHODS

Systematic search of PubMeb, Embase and African Index Medicus was conducted without date and language restrictions on September 11, 2017 to identify studies that compared the performance of TST and IGRAs for LTBI diagnosis. Two IGRA methods were considered: QuantiFERON-TB Gold In Tube (QFT-GIT) and T-SPOT.TB. Studies were included if they reported 2x2 agreement data between TST and QFT-GIT or T-SPOT.TB. A Bayesian latent class model was developed to estimate the sensitivity and specificity of TST and IGRAs in various populations, including immune-competent adults, immune-compromised adults and children. A TST cut-off value of 10 mm was used for immune-competent subjects and 5 mm for immune-compromised individuals.

FINDINGS

A total of 157 studies were included in the analysis. In immune-competent adults, the sensitivity of TST and QFT-GIT were estimated to be 84% (95% credible interval [CrI] 82-85%) and 52% (50-53%), respectively. The specificity of QFT-GIT was 97% (96-97%) in non-BCG-vaccinated and 93% (92-94%) in BCG-vaccinated immune-competent adults. The estimated figures for TST were 100% (99-100%) and 79% (76-82%), respectively. T-SPOT.TB has comparable specificity (97% for both tests) and better sensitivity (68% versus 52%) than QFT-GIT in immune-competent adults. In immune-compromised adults, both TST and QFT-GIT display low sensitivity but high specificity. QFT-GIT and TST are equally specific (98% for both tests) in non-BCG-vaccinated children; however, QFT-GIT is more specific than TST (98% versus 82%) in BCG-vaccinated group. TST is more sensitive than QFT-GIT (82% versus 73%) in children.

CONCLUSIONS

This study is the first to assess the utility of TST and IGRAs for LTBI diagnosis in different population groups using all available data with Bayesian latent class modelling. Our results challenge the current beliefs about the performance of LTBI screening tests, and have important implications for LTBI screening policy and practice. We estimated that the performance of IGRAs is not as reliable as previously measured in the general population. However, IGRAs are not or minimally affected by BCG and should be the preferred tests in this setting. Adoption of IGRAs in settings where BCG is widely administered will allow for a more accurate identification and treatment of LTBI.

Infectious diseases prevalence, vaccination coverage, and diagnostic challenges in a population of internationally adopted children referred to a Tertiary Care Children's Hospital from 2009 to 2015

Infectious diseases are common in internationally adopted children (IAC).With the objective to evaluate infectious diseases prevalence in a large cohort of IAC and to explore possible risk factors for tuberculosis (TB) and parasitic infections, clinical and laboratory data at first screening visit of all IAC (<18 years) consecutively referred to our Center in 2009 to 2015 were collected and analyzed.In total, 1612 children (median age: 5.40 years; interquartile range: 3.00-7.90) were enrolled, 123/1612 (7.60%) having medical conditions included in the special needs definition. The most frequent cutaneous infections were Molluscum contagiosum (42/1612; 2.60%) and Tinea capitis (37/1612; 2.30%). Viral hepatitis prevalence was <1% (hepatitis B virus [HBV]: 13 children, 0.80%; hepatitis C virus: 1 child, 0.10%; hepatitis A virus: 6 children, 0.40%). A parasitic infection was diagnosed in 372/1612 (23.10%) children. No risk factors for parasitosis were evidenced. Active TB was diagnosed in 4/1355 (0.3%) children, latent TB in 222/1355 (16.40%). Only 3.7% (51/1355) children had concordant positive tuberculin skin test (TST) and QuantiFERON-TB-Gold In-Tube (QFT-G-IT) results. Risk factors for TST+/QFT-G-IT- results were previous Bacille de Calmette-Guérin vaccination (adjusted odds ratio [aOR]: 2.18; 96% confidence interval [CI]: 1.26-3.79; P = 0.006), and age ≥5 years (aOR: 1.49; 95% CI: 1.06-2.11; P = 0.02). The proportion of children with nonprotective titers for vaccine-preventable diseases (VPD) ranged from 15.70% (208/1323) for tetanus to 35.10% (469/1337) for HBV.Infectious diseases were commonly observed in our cohort. The high rate of discordant TST/QFT-G results brings up questions regarding the optimal management of these children, and suggests that, at least in children older than 5 years, only QFT-G-IT results may be reliable. The low proportion of children protected for VPD, confirms importance of a timely screening.

Optimizing the management of children with latent tuberculosis infection

INTRODUCTION

The management of latent tuberculosis (LTBI) in children represents an important issue for paediatricians because of the disease burden, the lack of a gold standard for the diagnosis and the high annual risk of progression to active disease. Areas covered: A review of English language articles on LTBI in children, published between the 1st of January 2010 and the 1st of July 2016, was conducted using multiple keywords and standardized terminology in PubMed database. This review provides an updated overview of the available tests for LTBI diagnosis in children, management strategies and treatment options. Expert commentary: Two tests are available for LTBI diagnosis: tuberculin skin test and interferon-gamma release assays, both with a suboptimal specificity and sensitivity, and both with the lack of capability in distinguishing between infection and disease. Several new markers have been identified but further studies are needed. Among all treatment regimes, because of the high safety and efficacy profile showed and to avoid the poor completion rate, the treatment with a three-month course of isoniazid and rifampicin is currently recommended. New vaccines are needed because of the spread of the disease despite BCG vaccination in high risk countries. Currently, 15 new vaccines are in the pipeline.

Usefulness of interferon-γ release assay for the diagnosis of latent tuberculosis infection in young children

Purpose

Latent tuberculosis infection (LTBI) in young children may progress to severe active tuberculosis (TB) disease and serve as a reservoir for future transmission of TB disease. There are limited data on interferon-γ release assay (IGRA) performance in young children, which our research aims to address by investigating the usefulness of IGRA for the diagnosis of LTBI.

Methods

We performed a tuberculin skin test (TST) and IGRA on children who were younger than 18 years and were admitted to Chung-Ang University Hospital during May 2011–June 2015. Blood samples for IGRA were collected, processed, and interpreted according to manufacturer protocol.

Results

Among 149 children, 31 (20.8%) and 10 (6.7%) were diagnosed with LTBI and active pulmonary TB, respectively. In subjects lacking contact history with active TB patients, TST and IGRA results were positive in 41.4% (29 of 70) and 12.9% (9 of 70) subjects, respectively. The agreement (kappa) of TST and IGRA was 0.123. The control group, consisting of non-TB-infected subjects, showed no correlation between age and changes in interferon-γ concentration after nil antigen, TB-specific antigen, or mitogen stimulation in IGRAs (P=0.384, P=0.176, and P=0.077, respectively). In serial IGRAs, interferon-γ response to TB antigen increased in IGRA-positive LTBI subjects, but did not change considerably in initially IGRA-negative LTBI or control subjects.

Conclusion

The lack of decrease in interferon-γ response in young children indicates that IGRA could be considered for this age group. Serial IGRA tests might accurately diagnose LTBI in children lacking contact history with active TB patients.

Interferon-gamma release assays can effectively screen migrants for the tuberculosis infection, but urgent, active cases need clinical recognition

AIM

Increasing numbers of migrants to Sweden are screened for tuberculosis (TB), and a rational approach to screening is required. We evaluated positive tuberculin skin tests (TSTs) and interferon-gamma release assays (IGRAs) on paediatric migrants in relation to the TB incidence in the corresponding foreign-born populations in Stockholm.

METHODS

This study examined the characteristics of migrants under the age of 18 who were referred to a paediatric TB clinic at Karolinska University Hospital from 2008 to 2014 by primary care centres in Stockholm County.

RESULTS

We saw 943 TST-positive children with a median age of 14 years at the TB clinic and performed IGRAs on 557. IGRA positivity ranged from 64% in migrants from Somalia to 20% in those from the former Soviet Union and eastern Europe, with an estimated population level prevalence of 18.8% and 4.2%, respectively. These were significantly correlated to TB incidence in foreign-born Stockholm children. We diagnosed active TB in 20 screened migrants, and advanced, symptomatic TB was diagnosed in 10 recently arrived migrants without screening.

CONCLUSION

IGRAs showed higher specificity than TST in identifying tuberculosis. TB screening should focus on migrants from high-incidence countries, but this may be inadequate to detect advanced TB cases.

Interferon-Gamma Release Assays and Pediatric Public Health Tuberculosis Screening: The San Francisco Program Experience 2005 to 2008

BACKGROUND

Interferon-gamma release assay utilization in pediatric tuberculosis (TB) screening is limited by a paucity of longitudinal experience, particularly in low-TB burden populations.

METHODS

We conducted a retrospective review of QuantiFERON (QFT)-TB Gold results in San Francisco children from 2005 to 2008. Concordance with the tuberculin skin test (TST) was analyzed for a subset of children. Progression to active disease was determined through San Francisco and California TB registry matches.

RESULTS

Of 1092 children <15 years of age, 853 (78%) were foreign-born, and 136 (12%) were exposed to active TB cases (contacts). QuantiFERON tests were positive in 72 of 1092 (7%) children; 15 of 136 (11%) recent contacts; 53 of 807 (7%) foreign-born noncontacts; and 4 of 149 (3%) US-born noncontacts. QuantiFERON-negative/TST-positive discordance was seen more often in foreign-born/bacille Calmette-Guerin (BCG)-vaccinated children <5 years of age (52 of 56, 93%) compared to those ≥ 5 years of age (90 of 123, 73%; P = .003). Foreign-born, BCG-vaccinated children were more than twice as likely to have a discordant (79%) result as US-born, non-BCG-vaccinated children (37%; P < .0001). During 5587 person-years of follow-up of untreated children, including 146 TST-positive/QFT-negative children, no cases of active TB were identified, consistent with a negative predictive value of 100%.

CONCLUSIONS

Our experience supports the use of QFT to evaluate latent TB infection in children, particularly young BCG-vaccinated children. The proportion of QFT-positive results correlated with risk of exposure, and none of the untreated QFT-negative children developed TB. The low QFT-positive rate highlights the need for more selective testing based on current epidemiology and TB exposure risk.

Managing tuberculosis infection in children in the USA: an update

The rate of tuberculosis (TB) disease has steadily declined in the last two decades in the USA, and over two-thirds of all cases now occur in foreign-born persons. Further declines in the incidence of TB will be most impacted by identifying and treating persons with TB infection. However, difficulties in accessing care, poor specificity of diagnostic tests and long courses of therapy historically have led to suboptimal screening of groups at high risk for infection, false-positive test results from cross-reaction with the bacille Calmette-Guérin vaccine and low treatment completion rates, respectively. This article reviews newer testing and treatment strategies for TB infection emphasizing risk and benefits of testing and treating.

High Discordance Between Pre-US and Post-US Entry Tuberculosis Test Results Among Immigrant Children: Is it Time to Adopt Interferon Gamma Release Assay for Preentry Tuberculosis Screening?

BACKGROUND

Since 2007, immigration applicants 2-14 years old with a tuberculin skin test (TST) ≥10 mm and an otherwise negative evaluation for tuberculosis (TB) are assigned a classification for TB infection and instructed to seek domestic evaluation upon arrival in the US in accordance with Centers for Disease Control and Prevention instructions. We examined the characteristics and outcome of domestic evaluation of immigrant children who arrived in California with a positive TST on preimmigration examination to inform the preimmigration TB screening process.

METHODS

Retrospective analysis of the characteristics and results of domestic evaluation of immigrants 2-14 years old who arrived in California with a classification for TB infection during October 1, 2008-September 30, 2013 was performed. TB disease was determined by matching preimmigration records with the California TB registry.

RESULTS

Among a total of 12,544 immigrant children included, 7786 (62%) were evaluated for TB postentry. Of these, 5243 (67%) were tested with TST or interferon gamma release assay (IGRA), and 2371 (45%) had a positive test. Of those tested with IGRA (n = 4035), 914 (23%) were positive. The proportion with positive IGRA increased significantly with age (years): 2-4 (11%), 5-9 (19%), 10-14 (28%), P < 0.0001; was lowest among arrivers from China (6%) and highest among arrivers from Mexico (48%). Nine children (0.07%) had TB disease within 5 years after arrival.

CONCLUSIONS

The majority of immigrant children with a positive preimmigration TST tested negative for TB infection on domestic evaluation using TST or IGRA. Inclusion of IGRA in preimmigration TB screening is likely to reduce subsequent testing, treatment and cost of evaluations among immigrant children to the US.

Health Profiles of Newly Arrived Refugee Children in the United States, 2006-2012

OBJECTIVES

We conducted a large-scale study of newly arrived refugee children in the United States with data from 2006 to 2012 domestic medical examinations in 4 sites: Colorado; Minnesota; Philadelphia, Pennsylvania; and Washington State.

METHODS

Blood lead level, anemia, hepatitis B virus (HBV) infection, tuberculosis infection or disease, and Strongyloides seropositivity data were available for 8148 refugee children (aged < 19 years) from Bhutan, Burma, Democratic Republic of Congo, Ethiopia, Iraq, and Somalia.

RESULTS

We identified distinct health profiles for each country of origin, as well as for Burmese children who arrived in the United States from Thailand compared with Burmese children who arrived from Malaysia. Hepatitis B was more prevalent among male children than female children and among children aged 5 years and older. The odds of HBV, tuberculosis, and Strongyloides decreased over the study period.

CONCLUSIONS

Medical screening remains an important part of health care for newly arrived refugee children in the United States, and disease risk varies by population.