BACKGROUND: The large reservoir of tuberculosis (TB) infections is one of the main reasons for the persistent incidence of TB. Accurate diagnostic tests are crucial to correctly identify and treat people with TB infection, which is vital to eliminate TB globally. The rdESAT-6 and rCFP-10 (Cy-Tb) injection (\'Cy-Tb\'), a TB-specific antigen skin test and STANDARD F TB-Feron FIA (\'Standard F TB\') measuring interferon-gamma by fluorescence immunoassay assay are two novel tools for the diagnosis of TB infection which offer advantages compared with current tests in low-resource settings and reduced costs to both health systems and TB-affected people. The proposed study aims to evaluate the diagnostic accuracy of these two new tests for TB infection diagnosis.
METHODS: This cross-sectional study aims to assess the diagnostic accuracy for TB infection of the Cy-Tb skin test and Standard F TB assay (investigational tests) compared with the QuantiFERON-TB Gold Plus (QFT-Plus) assay as the immunological reference standard. Three different cohorts of study participants will be recruited at the Vietnam National Lung Hospital: adults with bacteriologically confirmed pulmonary TB (n=100), household contacts of people with TB (n=200) and people without TB infection (n=50). All consenting participants will undergo simultaneous testing with Cy-Tb, Standard F TB and QFT-Plus. The primary endpoint is the diagnostic accuracy of the Cy-Tb skin test and Standard F TB assay, expressed as sensitivity and specificity against the reference standard.
BACKGROUND: Ethical approval was granted by the Vietnam National Lung Hospital Institutional Review Board (65/23/CN-HDDD-BVPTU) and the Swedish Ethical Review Authority (Dnr 2023-04271-01). Study results will be disseminated to the scientific community and policymakers through scientific publications.
BACKGROUND: NCT06221735.

BACKGROUND: The interferon-gamma (IFN-γ) release assay (IGRA) is an important laboratory diagnosis for latent Mycobacterium tuberculosis (TB) infection. The TB-IGRA measures the release of IFN-γ from peripheral blood cells, who are exposed to TB antigen (Ag), mitogen (MT), or negative/nil control (NL) in vitro. While, an exceptional higher TB Ag-NL level will reflect an elevation of peripheral lymphocytes released IFN-γ in a same condition. Therefore, we found that the elevated levels of TB Ag-NL could become a new biomarker for the diagnosis and treatment of pediatric systemic lupus erythematosus (SLE) patients.
METHODS: We have analyzed the clinical data of 776 children who are underwent TB-IGRA testing in the Department of Allergy and Rheumatology of Guangzhou Women and Children\'s Medical Center from 2018 to 2020. To investigate the association between TB Ag-NL and SLE, we have analyzed the clinical data of 47 SLE patients and TB Ag-NL testing results, and then evaluated the association between TB Ag-NL and SLE disease activity.
RESULTS: The TB Ag-NL levels were significantly higher in patients with active SLE than those in inactive SLE (p = 0.0002). The TB Ag-NL levels were positively correlated with the SLE disease activity index (SLEDAI) and laboratory diagnosis parameters. The mean value of TB Ag-NL in SLE patients (0.04191 ± 0.07955, IU/mL) were significantly higher than those in patients with juvenile dermatomyositis (JDM) (0.0158 ± 0.0337, IU/mL, p = 0.036), juvenile idiopathic arthritis (JIA) (0.0162 ± 0.0388, IU/mL, p = 0.001), and healthy controls (HC) (0.0001 ± 0.0027, IU/mL, p = 0.0003). Therefore, the elevated TB Ag-NL levels could serve as a potential diagnostic biomarker of SLE, especially for the active SLE.
CONCLUSIONS: The detection of IFN-γ release levels by the TB-IGRA may be useful to assess SLE disease activity in pediatric patients with active SLE.

Currently, interferon-gamma release assay (IGRA) is costly and not included as latent tuberculosis infection (LTBI) screening test strategy in Thailand\'s Universal Coverage Scheme (UCS) benefit package. The objective of this study was to assess the cost-utility of LTBI screening strategies among tuberculosis (TB) contacts in Thailand. A hybrid decision tree and Markov model was developed to compare the lifetime costs and health outcomes of tuberculin skin test (TST) and IGRA, in comparison to no screening, based on a societal perspective. Health outcomes were the total number of TB cases averted and quality-adjusted life years (QALYs), with results presented as an incremental cost-effectiveness ratio (ICER). One-way and probabilistic sensitivity analyses were performed to explore uncertainties in all parameters. The ICER of TST compared with no screening was 27,645 baht per QALY gained, while that of IGRA compared to TST was 851,030 baht per QALY gained. In a cohort of 1000 TB contacts, both TST and IGRA strategies could avert 282 and 283 TB cases, respectively. At the Thai societal willingness-to-pay threshold of 160,000 baht per QALY gained, TST was deemed cost-effective, whereas IGRA would not be cost-effective, unless the cost of IGRA was reduced to 1,434 baht per test.

Background: We aimed to identify the risk factors for impaired cellular and humoral immunity after three doses of the SARS-CoV-2 vaccine. Methods: Six months after the third vaccine dose, T-cell immunity was evaluated using interferon-gamma release assays (IGRAs) in 60 healthy and 139 immunocompromised (IC) individuals, including patients with hematologic malignancy (HM), solid malignancy (SM), rheumatic disease (RD), and kidney transplantation (KT). Neutralizing antibody titers were measured using the plaque reduction neutralization test (PRNT) and surrogate virus neutralization test (sVNT). Results: T-cell immunity results showed that the percentages of IGRA-positive results using wild-type/alpha spike protein (SP) and beta/gamma SP were 85% (51/60) and 75% (45/60), respectively, in healthy individuals and 45.6% (62/136) and 40.4% (55/136), respectively, in IC individuals. IC with SM or KT showed a high percentage of IGRA-negative results. The underlying disease poses a risk for impaired cellular immune response to wild-type SP. The risk was low when all doses were administered as mRNA vaccines. The risk factors for an impaired cellular immune response to beta/gamma SP were underlying disease and monocyte%. In the sVNT using wild-type SP, 12 of 191 (6.3%) individuals tested negative. In the PRNT of 46 random samples, 6 (13%) individuals tested negative for the wild-type virus, and 19 (41.3%) tested negative with omicrons. KT poses a risk for an impaired humoral immune response. Conclusions: Underlying disease poses a risk for impaired cellular immune response after the third dose of the SARS-CoV-2 vaccine; KT poses a risk for impaired humoral immune response, emphasizing the requirement of precautions in patients.

BACKGROUND: With a rapid decrease in tuberculosis (TB) incidence, the significance of latent tuberculosis infection (LTBI) has been underscored in South Korea. Although South Korea does not have a high proportion of immigrants compared to other countries, there is a growing argument that it should actively embrace immigrants as a solution to address issues of low birth rates and population aging. This study aimed to assess TB incidence among immigrants who participated a pilot LTBI screening program in South Korea.
METHODS: Records of immigrants participated in a pilot LTBI screening program in South Korea between 2018 and 2019 were linked with Korean National TB Surveillance System to determine TB development. Participants underwent interferon-gamma release assay (IGRA) and chest X-rays. Standardized incidence ratios (SIRs) stratified by age, country of origin\'s TB burden was calculated with a reference group of general South Korean population.
RESULTS: Of a total of 9,517 participants, 14 TB cases were identified. Participants with positive IGRA results who did not initiate LTBI treatment showed TB incidence of 312.5 per 100,000 person-years, whereas those with negative results showed TB incidence of 34.4 per 100,000 person-years, resulting in an incidence rate ratio of 9.08 (95% confidence interval [CI], 2.50-32.99). SIR of TB among total participants including those with negative IGRA results was 2.60 (95% CI, 1.54-4.38; P < 0.001), whereas SIR among those with positive IGRA results was 5.86 (95% CI, 3.15-10.89; P < 0.001). In the calculation of SIR among participants with positive IGRA results, those aged under 35 from high TB-burden countries or intermediate TB-burden countries showed a high SIR (18.08; 95% CI, 2.55-128.37; P = 0.004), and 11.30 (95% CI, 2.82-45.16; P < 0.001), respectively). Contrary to previous reports that suggest the majority of elderly population with a positive IGRA result were due to remote infection and had a lower TB risk compared to younger ages, SIR among those aged 65 or over from intermediate TB-burden countries was 6.15 (95% CI, 0.87-43.69; P = 0.069), which was comparable to that in younger participants aged between 35 and 49 (SIR, 4.87; 95% CI, 1.22-19.49; P = 0.025) or those aged between 50 and 64 (SIR, 4.62; 95% CI, 1.73-12.31; P = 0.002).
CONCLUSIONS: Young immigrants with positive IGRA results from countries with high or intermediate TB burden showed a relatively high TB risk compared to a general South Korea population. In addition, unexpected high TB risk was observed among elderly immigrants with positive IGRA results. In establishing future policies for LTBI in immigrants in South Korea, screenings should primarily focus on younger age group (who aged under 35). Additionally, further research is needed on the high TB risk observed in elderly immigrants.

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb). Following infection, immune responses to Mtb antigens can be measured using the tuberculin skin test or an interferon-γ release assay. The gain of Mtb immunoreactivity, a change from a negative to a positive tuberculin skin test or interferon-γ release assay result, is called conversion and has long been used as a measure of Mtb exposure. However, the loss of immunoreactivity (reversion; a positive followed by a negative result) has often been overlooked. Instead, in clinical and epidemiological circles, Mtb immunoreactivity is commonly considered to persist lifelong and confer a lifetime of disease risk. We present a critical review, describing the evidence for reversion from cohort studies, ecological studies and studies of TB progression risk. We outline the inconsistent reasons why reversion has been dismissed from common understanding and present evidence demonstrating that, just as conversion predominantly indicates prior exposure to Mtb antigens, so its opposite, reversion, suggests the reduction or absence of exposure (endogenous or exogenous). Mtb immunoreactivity is dynamic in both individuals and populations and this is why it is useful for stratifying short-term TB progression risk. The neglect of reversion has shaped TB research and policy at all levels, influencing clinical management and skewing Mtb infection risk estimation and transmission modelling, leading to an underestimation of the contribution of re-exposure to the burden of TB, a serious oversight for an infectious disease. More than a century after it was first demonstrated, it is time to incorporate reversion into our understanding of the natural history of TB.

BACKGROUND: Tuberculosis (TB) preventive therapy (TPT) reduces the risk of TB disease in people with human immunodeficiency virus (HIV), yet uptake has been suboptimal in many countries. We assessed whether QuantiFERON Gold In-Tube (QGIT) during routine HIV care increased TB infection (TBI) testing and TPT prescriptions.
METHODS: This parallel-arm, 1:1 cluster-randomized controlled trial compared the standard-of-care tuberculin skin test to QGIT in South Africa. We enrolled consenting, TPT-eligible adults diagnosed with HIV ≤30 days prior and used intention-to-treat analyses for the outcomes: proportion of patients with documented TBI results, proportion with documented TPT, and time from enrollment to outcomes.
RESULTS: We enrolled 2232 patients across 14 clinics from November 2014 to May 2017 (58% in intervention clinics). At 24 months of follow-up, more participants in intervention clinics had TBI results (69% vs 2%, P < .001) and TPT prescriptions (45% vs 30%, P = .13) than control clinics. Controlling for baseline covariates, intervention clinics had 60% (95% confidence interval, 51-68; P < .001) more participants with TBI results and 12% (95% confidence interval, -6 to 31; P = .18) more with TPT prescriptions. Among participants with results, those in intervention clinics received results and TPT faster (intervention: median of 6 and 29 days after enrollment vs control: 21 and 54 days, respectively).
CONCLUSIONS: In this setting, QGIT in routine HIV care resulted in more patients with TBI results. Clinicians also initiated more people with HIV on TPT in QGIT intervention clinics, and did so more quickly, than the control arm.
BACKGROUND: NCT02119130.

Interferon-gamma (IFN-γ) release assays play a pivotal role in tuberculosis infection (TBI) diagnosis, with QuantiFERON-TB Gold Plus-an enzyme-linked immunosorbent assay (ELISA)-among the most widely utilized. Newer QuantiFERON-TB platforms with shorter turnaround times were recently released. We aimed to evaluate these platforms\' agreement in the diagnosis of TBI. Blood samples from a prospective cohort of tuberculosis household contacts were collected at baseline and after 12 weeks of follow-up, and tested with LIAISON, an automated chemiluminescence immunoassay (CLIA) system, QIAreach, a lateral flow (QFT-LF) semi-automated immunoassay, and the ELISA QuantiFERON-TB Gold Plus platform. Test concordances were analyzed. ELISA vs CLIA overall agreement was 83.3% for all tested samples (120/144) [Cohen\'s kappa coefficient (κ): 0.66 (95% CI: 0.54-0.77)]. Samples positive with CLIA provided consistently higher IFN-γ levels than with ELISA (P < 0.001). Twenty-four (16.7%) discordant pairs were obtained, all CLIA-positive/ELISA-negative: 15 (62.5%) had CLIA IFN-γ levels within borderline values (0.35-0.99 IU/mL) and 9 (37.5%) >0.99 IU/mL. QFT-LF showed only 76.4% (68/89) overall agreement with ELISA [κ: 0.53 (95% CI: 0.37-0.68)] with 21 (23.6%) discordant results obtained, all QFT-LF-positive/ELISA-negative. Overall concordance between ELISA and CLIA platforms was substantial, and only moderate between ELISA and QFT-LF. The CLIA platform yielded higher IFN-γ levels than ELISA, leading to an almost 17% higher positivity rate. The techniques do not seem interchangeable, and validation against other gold standards, such as microbiologically-confirmed tuberculosis disease, is required to determine whether these cases represent true new infections or whether CLIA necessitates a higher cutoff.
OBJECTIVE: Tuberculosis is an airborne infectious disease caused by Mycobacterium tuberculosis that affects over 10 million people annually, with over 2 billion people carrying an asymptomatic tuberculosis infection (TBI) worldwide. Currently, TBI diagnosis includes tuberculin skin test and the blood-based interferon-gamma (IFN-γ) release assays, with Qiagen QuantiFERON-TB Gold Plus (QFT) being among those most widely utilized. We evaluated Qiagen\'s newer QFT platforms commercially available in a prospective cohort of tuberculosis contacts. A substantial agreement was obtained between the current QFT-enzyme-linked immunosorbent assay (ELISA) and the new QFT-chemiluminescence immunoassay (CLIA) platform, although QFT-CLIA provided higher concentrations of IFN-γ, leading to a 16.6% higher positivity rate. We highlight that both platforms may not be directly interchangeable and that further validation is required.

The World Health Organization End TB strategy aims for a 90% reduction of tuberculosis (TB) incidence by 2035. Systematic testing and treatment of latent TB infection (LTBI) among contacts of active TB patients is recommended as one of the ways to curtail TB incidence. However, there is a shortage of tools to accurately diagnose LTBI. We assessed the appropriateness of whole blood host transcriptomic markers (TM) to diagnose LTBI among household contacts of bacteriologically confirmed index cases compared to HIV negative healthy controls (HC). QuantiFERON-TB Gold Plus Interferon gamma release assay (IGRA) and reverse-transcriptase quantitative PCR were used to determine LTBI and quantify TM expression respectively. Association between TM expression and LTBI was evaluated by logistic regression modelling. A total of 100 participants, 49 TB exposed (TBEx) household contacts and 51 HC, were enrolled. Twenty-five (51%) TBEx individuals tested positive by IGRA, and were denoted as LTBI individuals, and 37 (72.5%) HC were IGRA-negative. Expression of 11 evaluated TM was significantly suppressed among LTBI compared to HC. Out of the 11 TM, ZNF296 and KLF2 expression were strongly associated with LTBI and successfully differentiated LTBI from HC. Paradoxically, 21 (49%) TBEx participants who tested IGRA negative exhibited the same pattern of suppressed TM expression as IGRA positive (LTBI-confirmed individuals). Results suggest that suppression of gene expression underlies LTBI and may be a more sensitive diagnostic biomarker than standard-of-care IGRA.

OBJECTIVE: Patients living with rheumatologic diseases on disease-modifying antirheumatic drugs (DMARD) are at an increased risk of developing tuberculosis (TB). Current guidelines recommend screening for latent tuberculosis infection (LTBI) before initiating DMARD. However, data is lacking on the value of yearly screening for LTBI.
METHODS: A retrospective chart review was conducted on adult patients (≥ 18 years) with rheumatologic disease on DMARD followed longitudinally in the outpatient rheumatology clinics between 2017-2021. Collected data included patient demographics, rheumatologic diagnosis, medications, TB-related risk factors, interferon gamma release assay (IGRA) results, LTBI diagnosis and treatment. Descriptive statistics were performed.
RESULTS: Among 339 patients, 81 (23.9%) were male, 259 (76.4%) were white, and 93 (27.5%) were Latinx. Inflammatory arthritis (84.1%) was the most common rheumatic diagnosis. Common DMARD were JAK inhibitors (19.2%), TNF-alpha inhibitors (18.9%), and IL-17 A inhibitors (18.0%). Only 2 patients at baseline had positive IGRA, and both had a history of treated LTBI. Positive IGRA tests were recorded in 1 (0.7%), 3 (1.8%), 3 (1.3%), and 3 (1.1%) in the years 2018, 2019, 2020, and 2021, respectively. Four patients converted from negative to positive during serial yearly IGRA testing. After reviewing the IGRA test and TB risk factors, only one patient was considered newly diagnosed with LTBI, requiring 4 months of rifampin.
CONCLUSIONS: In a non-endemic area, serial IGRA testing of low-risk patients on DMARD yielded very low rate of newly diagnosed LTBI. A targeted LTBI screening based on TB-related risk factors should be performed prior to IGRA testing rather than universal yearly screening in a non-endemic setting.