Risk of developing tuberculosis disease among persons diagnosed with latent tuberculosis infection in the Netherlands

Factors Associated With Discontinuation of Tuberculosis Preventive Treatment: Post Hoc Analysis of 2 Randomized, Controlled Trials

BACKGROUND

Adherence to tuberculosis preventive treatment (TPT) is an important determinant of clinical benefit. We assessed the association of participant behaviors early in TPT with subsequent discontinuation.

METHODS

We used data from a phase 3 randomized trial and the preceding phase 2 trial to compare 4 months of rifampin to 9 months of isoniazid for TPT. We excluded participants whose providers discontinued TPT due to adverse events or tuberculosis disease. We analyzed 4 outcomes: discontinuing TPT within the first month of treatment, discontinuing TPT between the first and second month, discontinuing TPT after the second month, and completing treatment but not per protocol. We analyzed the association of outcomes with regimen and participant characteristics and 4 behavioral predictors of discontinuation recorded at the month 1 and month 2 follow-up visits: reporting symptoms of intolerance, missing >20% of doses, rescheduling appointments, and not bringing their medication bottle.

RESULTS

Overall, 6656 participants were included (phase 3, 5848; phase 2, 808), of whom 4318 (64.9%) completed treatment per protocol. Participant characteristics were inconsistently associated with discontinuation. Phase 3 trial participants with 1, 2, or 3-4 behavioral predictors at the month 1 follow-up had 5.0 (95% confidence interval, 3.6-6.7), 18.6 (13.3-26.1), and 79.4 (38.2-165.0), respectively, higher odds of discontinuing before the second month. The corresponding number of predictors at the month 2 follow-up had 1.8 (1.4-2.2), 4.7 (3.6-6.2), and 7.4 (4.6-11.9) higher odds of discontinuing before completing treatment; phase 2 findings were similar.

CONCLUSIONS

Four behavioral predictors recorded early in therapy were more strongly associated with subsequent discontinuation than participant characteristics, particularly when more than 1 behavioral predictor was recorded. Clinical Trials Registration. NCT00170209; NCT00931736.

A cohort study of the long-term outcome of latent tuberculosis infection among socially marginalized people in a low-incidence country

BACKGROUND

Tuberculosis (TB) prevalence is high among socially marginalized citizens in Denmark, and management of latent TB infection (LTBI) may be part of preventing new cases. Patients with LTBI are offered either preventive treatment (TPT) or follow-up chest x-rays, but knowledge about the long-term outcome in terms of active TB is sparse.

METHODS

We performed a retrospective cohort study investigating the long-term outcomes for socially marginalized citizens who were diagnosed with LTBI or who had a positive interferon-gamma release assay (IGRA) but were lost to follow-up. Information on TB examinations, diagnostics, and treatment along with data on death were gathered from medical records from the date of positive IGRA to February 1, 2021.

RESULTS

We identified 119 patients with LTBI, 18 of which (15.1%) were diagnosed with TB during the follow-up period (mean, 4.5 years). TPT was completed by 36.1% and the TB incidence rate ratio of those completing TPT to those who did not was 0.78 (confidence interval, 0.25-2.17; P =.6). Of the patients with TB, 16 of 18 achieved treatment success.

CONCLUSION

High rates of TB development are found among socially marginalized citizens with LTBI. Overall incidence of TB was not significantly reduced by administration of TPT, although TB did not develop in the first 2 years following TPT.

Recent Advances in Host-Directed Therapies for Tuberculosis and Malaria

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, and malaria, caused by parasites from the Plasmodium genus, are two of the major causes of death due to infectious diseases in the world. Both diseases are treatable with drugs that have microbicidal properties against each of the etiologic agents. However, problems related to treatment compliance by patients and emergence of drug resistant microorganisms have been a major problem for combating TB and malaria. This factor is further complicated by the absence of highly effective vaccines that can prevent the infection with either M. tuberculosis or Plasmodium. However, certain host biological processes have been found to play a role in the promotion of infection or in the pathogenesis of each disease. These processes can be targeted by host-directed therapies (HDTs), which can be administered in conjunction with the standard drug treatments for each pathogen, aiming to accelerate their elimination or to minimize detrimental side effects resulting from exacerbated inflammation. In this review we discuss potential new targets for the development of HDTs revealed by recent advances in the knowledge of host-pathogen interaction biology, and present an overview of strategies that have been tested in vivo, either in experimental models or in patients.

[Latent tuberculosis infection (LTBI): What happens at 5 years of the 155 LTBI recent contacts of tuberculosis with positive microscopic examination?]

INTRODUCTION

Contacts of individuals with tuberculosis are at risk of latent infection (LTBI), which can progress to active tuberculosis. The aim of the study was to determine the incidence of tuberculosis in contacts and its risk factors in subjects with LTBI.

METHODOLOGY

This retrospective study from the tuberculosis control centre in Guadeloupe identified smear-positive tuberculosis cases and their contacts. We estimated the incidence of tuberculosis at 5 years using the Kaplan Meier method and identified risk factors for tuberculosis occurrence among contacts by a Cox model.

RESULTS

We analysed 292 contacts of 73 individuals with smear-positive tuberculosis between 2008 and 2015. Of these, 155 contacts had LTBI and 8 developed tuberculosis. The risk of developing tuberculosis was 11.5% (CI : 4.3%-23.4%) for untreated subjects and 1.9% (CI: 0.23%-6.8) for treated subjects. Risk factors identified for tuberculosis were: bacillary density of the index case (HR: 9.10, CI: 1.7-48.4), previous BCG (HR: 0.06, CI: 0.01-0.34), and treatment of LTBI (HR: 0.08, CI: 0.01-0.49).

CONCLUSIONS

This study confirms the relevance of treating LTBI in the context of recent contagion but also the benefit of a BCG vaccination.

Antigen-Specific T-Cell Activation Distinguishes between Recent and Remote Tuberculosis Infection

Rationale: Current diagnostic tests fail to identify individuals at higher risk of progression to tuberculosis disease, such as those with recent Mycobacterium tuberculosis infection, who should be prioritized for targeted preventive treatment. Objectives: To define a blood-based biomarker, measured with a simple flow cytometry assay, that can stratify different stages of tuberculosis infection to infer risk of disease. Methods: South African adolescents were serially tested with QuantiFERON-TB Gold to define recent (QuantiFERON-TB conversion <6 mo) and persistent (QuantiFERON-TB+ for >1 yr) infection. We defined the ΔHLA-DR median fluorescence intensity biomarker as the difference in HLA-DR expression between IFN-γ⁺ TNF⁺ Mycobacterium tuberculosis-specific T cells and total CD3⁺ T cells. Biomarker performance was assessed by blinded prediction in untouched test cohorts with recent versus persistent infection or tuberculosis disease and by unblinded analysis of asymptomatic adolescents with tuberculosis infection who remained healthy (nonprogressors) or who progressed to microbiologically confirmed disease (progressors). Measurements and Main Results: In the test cohorts, frequencies of Mycobacterium tuberculosis-specific T cells differentiated between QuantiFERON-TB- (n = 25) and QuantiFERON-TB+ (n = 47) individuals (area under the receiver operating characteristic curve, 0.94; 95% confidence interval, 0.87-1.00). ΔHLA-DR significantly discriminated between recent (n = 20) and persistent (n = 22) QuantiFERON-TB+ (0.91; 0.83-1.00); persistent QuantiFERON-TB+ and newly diagnosed tuberculosis (n = 19; 0.99; 0.96-1.00); and tuberculosis progressors (n = 22) and nonprogressors (n = 34; 0.75; 0.63-0.87). However, ΔHLA-DR median fluorescent intensity could not discriminate between recent QuantiFERON-TB+ and tuberculosis (0.67; 0.50-0.84). Conclusions: The ΔHLA-DR biomarker can identify individuals with recent QuantiFERON-TB conversion and those with disease progression, allowing targeted provision of preventive treatment to those at highest risk of tuberculosis. Further validation studies of this novel immune biomarker in various settings and populations at risk are warranted.

Quantifying the rates of late reactivation tuberculosis: a systematic review

The risk of tuberculosis is greatest soon after infection, but Mycobacterium tuberculosis can remain in the body latently, and individuals can develop disease in the future, sometimes years later. However, there is uncertainty about how often reactivation of latent tuberculosis infection (LTBI) occurs. We searched eight databases (inception to June 25, 2019) to identify studies that quantified tuberculosis reactivation rates occurring more than 2 years after infection (late reactivation), with a focus on identifying untreated study cohorts with defined timing of LTBI acquisition (PROSPERO registered: CRD42017070594). We included 110 studies, divided into four methodological groups. Group 1 included studies that documented late reactivation rates from conversion (n=14) and group 2 documented late reactivation rates in LTBI cohorts from exposure (n=11). Group 3 included 86 studies in LTBI cohorts with an unknown exposure history, and group 4 included seven ecological studies. Since antibiotics have been used to treat tuberculosis, only 11 studies have documented late reactivation rates in infected, untreated cohorts from either conversion (group 1) or exposure (group 2); six of these studies lasted at least 4 years and none lasted longer than 10 years. These studies found that tuberculosis rates declined over time, reaching approximately 200 cases per 100 000 person-years or less by the fifth year, and possibly declining further after 5 years but interpretation was limited by decreasing or unspecified cohort sizes. In cohorts with latent tuberculosis and an unknown exposure history (group 3), tuberculosis rates were generally lower than those seen in groups 1 and 2, and beyond 10 years after screening, rates had declined to less than 100 per 100 000 person-years. Reinfection risks limit interpretation in all studies and the effect of age is unclear. Late reactivation rates are commonly estimated or modelled to prioritise tuberculosis control strategies towards tubuculosis elimination, but significant gaps remain in our understanding that must be acknowledged; the relative importance of late reactivation versus early progression to the global burden of tuberculosis remains unknown.

Immune profiling of Mycobacterium tuberculosis-specific T cells in recent and remote infection

BACKGROUND

Recent Mycobacterium tuberculosis (M.tb) infection is associated with a higher risk of progression to tuberculosis disease, compared to persistent infection after remote exposure. However, current immunodiagnostic tools fail to distinguish between recent and remote infection. We aimed to characterise the immunobiology associated with acquisition of M.tb infection and identify a biomarker that can distinguish recent from remote infection.

METHODS

Healthy South African adolescents were serially tested with QuantiFERON-TB Gold to define recent (QuantiFERON-TB conversion <6 months) and persistent (QuantiFERON-TB+ for >1.5 year) infection. We characterised M.tb-specific CD4 T cell functional (IFN-γ, TNF, IL-2, CD107, CD154), memory (CD45RA, CCR7, CD27, KLRG-1) and activation (HLA-DR) profiles by flow cytometry after CFP-10/ESAT-6 peptide pool or M.tb lysate stimulation. We then assessed the diagnostic performance of immune profiles that were differentially expressed between individuals with recent or persistent QuantiFERON-TB+.

FINDINGS

CFP-10/ESAT-6-specific CD4 T cell activation but not functional or memory phenotypes distinguished between individuals with recent and persistent QuantiFERON-TB+. In response to M.tb lysate, recent QuantiFERON-TB+ individuals had lower proportions of highly differentiated IFN-γ+TNF+ CD4 T cells expressing a KLRG-1+ effector phenotype and higher proportions of early differentiated IFN-γ-TNF+IL-2+ and activated CD4 T cells compared to persistent QuantiFERON-TB+ individuals. Among all differentially expressed T cell features CFP-10/ESAT-6-specific CD4 T cell activation was the best performing diagnostic biomarker of recent infection.

INTERPRETATION

Recent M.tb infection is associated with highly activated and moderately differentiated functional M.tb-specific T cell subsets, that can be used as biomarkers to distinguish between recent and remote infection.

FUNDING

US National Institutes of Health (NIH), Bill and Melinda Gates Foundation, South African National Research Foundation, South African Medical Research Council, and Aeras.

Discovery and validation of a personalized risk predictor for incident tuberculosis in low transmission settings

The risk of tuberculosis (TB) is variable among individuals with latent Mycobacterium tuberculosis infection (LTBI), but validated estimates of personalized risk are lacking. In pooled data from 18 systematically identified cohort studies from 20 countries, including 80,468 individuals tested for LTBI, 5-year cumulative incident TB risk among people with untreated LTBI was 15.6% (95% confidence interval (CI), 8.0-29.2%) among child contacts, 4.8% (95% CI, 3.0-7.7%) among adult contacts, 5.0% (95% CI, 1.6-14.5%) among migrants and 4.8% (95% CI, 1.5-14.3%) among immunocompromised groups. We confirmed highly variable estimates within risk groups, necessitating an individualized approach to risk stratification. Therefore, we developed a personalized risk predictor for incident TB (PERISKOPE-TB) that combines a quantitative measure of T cell sensitization and clinical covariates. Internal-external cross-validation of the model demonstrated a random effects meta-analysis C-statistic of 0.88 (95% CI, 0.82-0.93) for incident TB. In decision curve analysis, the model demonstrated clinical utility for targeting preventative treatment, compared to treating all, or no, people with LTBI. We challenge the current crude approach to TB risk estimation among people with LTBI in favor of our evidence-based and patient-centered method, in settings aiming for pre-elimination worldwide.

Tools to implement the World Health Organization End TB Strategy: Addressing common challenges in high and low endemic countries

AIM

The purpose of this viewpoint is to summarize the advantages and constraints of the tools and strategies available for reducing the annual incidence of tuberculosis (TB) by implementing the World Health Organization (WHO) End TB Strategy and the linked WHO TB Elimination Framework, with special reference to Oman.

METHODS

The case-study was built based on the presentations and discussions at an international workshop on TB elimination in low incidence countries organized by the Ministry of Health, Oman, which took place from September 5 to September 7, 2019, and supported by the WHO and European Society of Clinical Microbiology and Infectious Diseases (ESCMID).

RESULTS

Existing tools were reviewed, including the screening of migrants for latent TB infection (LTBI) with interferon-gamma release assays, clinical examination for active pulmonary TB (APTB) including chest X-rays, organization of laboratory services, and the existing centres for mandatory health examination of pre-arrival or arriving migrants, including examination for APTB. The need for public-private partnerships to handle the burden of screening arriving migrants for active TB was discussed at length and different models for financing were reviewed.

CONCLUSIONS

In a country with a high proportion of migrants from high endemic countries, screening for LTBI is of high priority. Molecular typing and the development of public-private partnerships are needed.

Risk of active tuberculosis development in contacts exposed to infectious tuberculosis in congregate settings in Korea

Contact investigation is an important and effective active case-finding strategy, but there is a lack of research on congregate settings in countries with an intermediate incidence. This study determined the incidence of and risk factors for tuberculosis (TB) development after exposure in congregate settings. This retrospective cohort study included 116,742 contacts identified during the investigation of 2,609 TB cases diagnosed from January to December 2015. We searched the Korean National Tuberculosis Surveillance System TB registry to identify contacts that developed active TB during follow-up until May 2018. During the mean observation period of 2.9 years, 499 of 116,742 contacts (0.4%) developed new active TB. From these contacts, 404 (81.0%) developed TB within 2 years after exposure. The 2-year Kaplan-Meier cumulative risk for TB was the highest in contacts aged ≥65 years [1%; 95% confidence interval (CI), 0.8-1.3]. Contacts with LTBI who completed chemoprophylaxis exhibited a lower risk of active TB development than those without chemoprophylaxis (adjusted hazard ratio, 0.16; 95% CI, 0.08-0.29). Aggressive contact investigation is effective for the early detection and prevention of TB in congregate settings. The risk of progression to active TB among contacts with LTBI can be minimised by the completion of chemoprophylaxis.

Tuberculosis Transmission in a Primary School and a Private Language School. An Estimation of Infectivity

Introduction: Belgium is a country with low incidence of tuberculosis (TB) and a very low number of TB cases in children. Children in contact with an adult smear-positive TB case are at high risk of transmission. Early diagnosis is important as young children have a significant predisposition of developing TB disease. In this paper, we describe two outbreaks after exposure to, respectively, two teachers with smear-positive pulmonary TB: one in a primary school, a nursery teacher, and another in a private language school. Methods: An exposure investigation was carried out in both index cases household and school, according to the stone-in-the-pond principle. The tuberculin skin test (TST) was used a screening tool. The time elapsed between TB diagnosis in the index case and contact investigation was, respectively, 1 and 3 weeks. If this initial test was negative, it was repeated after a "window period" of ≥8 weeks. Results: Index cases showed a transmission rate of, respectively, 13 and 40% in their classes at school, defined as casual contacts. The proximity of contact increased the risk of infection. TB disease was observed in, respectively, 4 and 11% of all the casual contacts; all of them were children younger than 5 years old. TB-infected and children with active TB disease had good compliance with recommended treatment. Uptake of chemoprophylaxis during the "window period" was poor, respectively, only 32-42%, in children under 5 years with an initially negative TST. Discussion: The World Health Organization recommends to screen all young children (<5 years old) who have close contact with a person affected by pulmonary TB and to initiate Latent tuberculosis infection treatment even before infection can be demonstrated, after ruling out active TB disease. Despite this knowledge, a small percentage of the children younger than 5 years with no proof of infection was treated with the proposed chemoprophylactic treatment, in both cases. Conclusion: This exposure investigation of two teachers detects high transmission among family contacts and school casual contacts. Recommendations for chemoprophylactic treatment in children <5 years showed low compliance, reflecting the difficulty of communication to staff, parents, and children in a school outbreak. It is essential to develop a new approach for this vulnerable group of patients. This approach could be improved, applied, and evaluated by National TB Control Programs, involving public and private health services. Public health authorities play a role in raising public awareness about the risks of TB for young children.

Prevalence of latent TB infection among asylum seekers in emergency accommodation in Cologne, Germany

∼12% of male asylum seekers from multiple countries were diagnosed with LTBI. Systematic documentation and reporting of LTBI, access to chemopreventive therapy, and early diagnosis of active TB are highly recommended for this vulnerable group. http://ow.ly/dVTp30onmaR.

Building a European database to gather multi-country evidence on active and latent TB screening for migrants

BACKGROUND AND AIM

Screening for active and latent TB among migrants in low TB incidence countries may constitute an important contribution to TB elimination. E-DETECT TB, a European multi-county collaboration, aims to address the present lack of evidence on effectiveness of migrant TB screening by collating data in an international database and perform cross-country pooled and comparative analyses of screening coverage, results and linkage to care.

METHOD

A database was established using migrant TB screening data from participating countries' national screening programs, national screening pilots and local research projects. All partner countries contributed to a common agreed protocol with standardized variables, pooling available numerator and denominator screening data from participating countries and sites.

RESULTS

All collaborating members drafted and agreed upon a data sharing accord as well as a protocol that clearly defined responsibilities and data governance principles. The database has been created and data transfer is ongoing.

CONCLUSION

By persistence and focus the project has overcome considerable administrative, practical and legal challenges. This international collaboration provides greater power of analysis of harmonized data and thereby a unique opportunity to contribute migrant TB screening evidence. E-DETECT TB has started to invite other countries to contribute data to the database.

Should NICE reconsider the 2016 UK guidelines on TB contact tracing? A cost-effectiveness analysis of contact investigations in London

BACKGROUND

In January 2016, clinical TB guidance in the UK changed to no longer recommend screening contacts of non-pulmonary, non-laryngeal (ETB) index cases. However, no new evidence was cited for this change, and there is evidence that screening these contacts may be worthwhile. The objective of this study was to estimate the cost-effectiveness of screening contacts of adult ETB cases and adult pulmonary or laryngeal TB (PTB) cases in London, UK.

METHODS

We carried out a cross-sectional analysis of data collected on TB index cases and contacts in the London TB register and an economic evaluation using a static model describing contact tracing outcomes. Incremental cost-effectiveness ratios (ICERs) were calculated using no screening as the baseline comparator. All adult TB cases (≥15 years old) in London from 2012 to 2015, and their contacts, were eligible (2465/5084 PTB and 2559/6090 ETB index cases were included).

RESULTS

Assuming each contact with PTB infects one person/month, the ICER of screening contacts of ETB cases was £78 000/quality-adjusted life-years (QALY) (95% CI 39 000 to 140 000), and screening contacts of PTB cases was £30 000/QALY (95% CI 18 000 to 50 000). The ICER of screening contacts of ETB cases was £30 000/QALY if each contact with PTB infects 3.4 people/month. Limitations of this study include the use of self-reported symptomatic periods and lack of knowledge about onward transmission from PTB contacts.

CONCLUSIONS

Screening contacts of ETB cases in London was almost certainly not cost-effective at any conventional willingness-to-pay threshold in England, supporting recent changes to National Institute for Health and Care Excellence national guidelines.

New concepts in understanding latent tuberculosis

PURPOSE OF REVIEW

Mycobacterium tuberculosis (M.tb), the etiologic agent of tuberculosis, is a prominent global health threat because of the enormous reservoir of subclinical latent tuberculosis infection (LTBI). Current diagnostic approaches are limited in their ability to predict reactivation risk and LTBI is recalcitrant to antibiotic treatment. The present review summarizes recent advances in our ability to detect, treat and model LTBI as well as our understanding of bacterial physiology during latency.

RECENT FINDINGS

T-cell subsets and circulating proteins have been identified which could serve as biomarkers for LTBI or indicators of reactivation risk. In addition, experimental and in-silico models have enabled discoveries regarding bacterial physiology during latency and the host immune response following infection with latent M.tb.

SUMMARY

Despite recent advances, much more research is needed to bolster our ability to detect, implement treatment and model LTBI. The present work is crucial for the eradication of this global problem.

A highly transmissible tuberculosis outbreak: the importance of bars

The transmission of tuberculosis (TB) in bars is difficult to study. The objective was to describe a large TB outbreak in a company's bar and other leisure settings. A descriptive study of a TB outbreak was carried out. Contacts were studied in the index case's workplace bar (five circles of contacts) and other recreational areas (social network of three bars in the index case's neighbourhood). Chest X-rays were recommended to contacts with positive tuberculin skin tests (TST) (⩾5 mm). The risk of latent tuberculosis infection (LTBI) was determined using an adjusted odds ratio. The dose-response relationship was determined using the chi-square test for linear trend. We studied 316 contacts at the index case's workplace and detected five new cases of TB. The prevalence of LTBI was 57·9% (183/316) and was higher in the first circle, 96·0% (24/25), and lower in the fifth, 46·5% (20/43) (P < 0·0001). Among 58 contacts in the three neighbourhood bars, two TB cases were detected and the LTBI prevalence was 51·7% (30/58). Two children of one secondary TB company patient became ill. Bars may be transmission locations for TB and, as they are popular venues for social events, should be considered as potential areas of exposure.

Incidence of active tuberculosis in individuals with latent tuberculosis infection in rural China: follow-up results of a population-based, multicentre, prospective cohort study

BACKGROUND

The management of latent Mycobacterium tuberculosis infection is a new priority action for the WHO End Tuberculosis (TB) Strategy. However, national guidelines on latent tuberculosis infection testing and treatment have not yet been developed in China. Here, we present the results from the 2-year follow-up of a study that aimed to track the development of active disease in individuals with latent tuberculosis infection, identify priority populations for latent infection management, and explore the most suitable latent infection diagnostic approach.

METHODS

A population-based multicentre prospective study was done in four sites in rural China, between 2013 and 2015. The baseline survey in 2013 measured the prevalence of latent tuberculosis infection using QuantiFERON-TB Gold In-Tube (QFT) and tuberculin skin test (TST) in eligible participants. During the follow-up phase between 2014-15, we assessed individuals who had tuberculosis infection at baseline (QFT-positivity or TST tuberculin reaction size [induration] of ≥10 mm) for the development of active disease through active case finding. Eligible participants included in follow-up survey had a birth date before June 1, 2008 (5 years or older in 2013), and continuous residence at the study site for 6 months or longer in the past year. Participants with current active tuberculosis at baseline survey were excluded.

FINDINGS

Between Sept 1, 2013, and Aug 31, 2015, 7505 eligible participants (aged 5 years or older) were included in tuberculosis infection test positive cohorts (4455 were QFT positive, 6404 had TST induration ≥10 mm, and 3354 were positive for both tests) after baseline examination. During the 2-year follow-up period, 84 incident cases of active tuberculosis were diagnosed. Of participants who developed active tuberculosis, 75 were diagnosed with latent infection by QFT, 62 were diagnosed by TST, and 53 were diagnosed by both tests. An incidence rate of 0·87 (95% CI 0·68-1·07) per 100 person-years was observed for individuals who tested positive with QFT, 0·50 (0·38-0·63) per 100 person-years for those who tested positive with TST (p<0·0001), and 0·82 (0·60-1·04) per 100 person-years for those who tested positive with both tests. Male sex and a history of tuberculosis were significantly associated with increased risk of disease development with adjusted hazard ratios of 2·36 (95% CI 1·30-4·30) for male sex and 5·40 (3·34-8·71) for a history of tuberculosis.

INTERPRETATION

Our results suggest that high-risk populations in communities in rural China, such as individuals at a high risk of disease reactivation from previous tuberculosis, should be targeted for latent infection screening and treatment with an interferon-γ releasing assay rather than a TST.

FUNDING

National Science and Technology Major Project of China, Program for Changjiang Scholars and Innovative Research Team in University of China, CAMS Innovation Fund for Medical Sciences, and Sanming Project of Medicine in Shenzhen.

Immunological characterization of latent tuberculosis infection in a low endemic country

The diagnosis of a latent tuberculosis infection (LTBI) is based on detection of immunity against Mycobacterium tuberculosis (Mtb). The tuberculin skin test (TST), the Quantiferon (QFT) and a prolonged lymphocyte stimulation test using either ESAT-6/CFP-10 (LST-EC) or PPD (LST-PPD) were evaluated in a cohort of 495 individuals, suspected to have LTBI, in a low endemic country. While the TST and LST-PPD were both positive in the majority (75%) of individuals, only one third responded in the LST-EC and in the QFT. The choice for LTBI treatment was significantly associated with ESAT6/CFP10 recognition, however the LST-EC detected considerably more individuals (21%) with immunity against Mtb, who might also be at risk for development of active TB, although none of them did during follow up. Follow-up for 2 years showed 7% conversions and 32% reversions for the QFT. The LST-EC showed higher conversion rates (∼45%), although the percentage of individuals positive in the LST-EC did not change significantly within the follow-up period. LTBI treatment did not alter immune recognition of Mtb antigens. In conclusion, the sensitivity of tests for detection of cellular immunity to Mtb specific antigens depends on test methodology and may vary considerably over time in a low endemic region.

The past decade in bench research into pulmonary infectious diseases: What do clinicians need to know?

Respiratory infections are primarily treated with antibiotics, drugs that are mostly inexpensive and have been widely available since the 1940s and 1950s. Nevertheless, despite antibiotics, the burden of disease in pneumonia, bronchiectasis, cystic fibrosis, COPD and rare respiratory infections remains exceptionally high. There is an urgent need for translational studies to develop new treatments or new biomarkers to improve outcomes in these conditions. The 'translational gaps' between bench science and clinical practice are particularly challenging in respiratory infections. This is partly due to the poor representativeness of animal models of infection to human disease, and a long-term lack of investment into pulmonary infection research. The revolution in genomics and other omics technologies, however, is beginning to unlock clinically important information about the host response to infection, the behaviour of bacterial communities and the development of new antibiotics. It is not possible to review the extensive progress made in the last decade into the pathophysiology of the different respiratory infections and so here, we focus on major technologies that are now changing respiratory infection research, specifically bacterial whole-genome sequencing, the microbiota, personalized medicine with omics technologies, new antibiotic development and host inflammatory cell biology.

Policy and practice of programmatic management of latent tuberculosis infection in The Netherlands

Latent tuberculosis infection (LTBI) screening and preventive treatment is one of the components of the World Health Organization (WHO) End TB strategy, and particularly relevant for low tuberculosis (TB) incidence countries, i.e. less than 100 TB cases per million population. The Netherlands is such a low-incidence country with traditionally a strong emphasis on programmatic management of LTBI, e.g. examining contacts of infectious TB patients by the public health services. Increasingly, curative services are involved in LTBI management of clinical risk groups. The country recently adopted a five-year strategic national plan recommending LTBI screening of high-risk migrants populations. A monitoring and evaluation system is already in place to measure programme performance and guide policy. Research on LTBI screening of migrants is on-going and results should inform future decisions in scaling-up this intervention. Several challenges remain for programmatic LTBI management, such as securing financial resources and the right professional cadre for implementation; availability of screening tests and drugs; collecting additional data for monitoring and evaluation, in line with the WHO indicators for LTBI programmatic management; developing cultural-sensitive and client-centred education for migrants; reducing patient costs for LTBI screening and preventive treatment; and assessing cost-effectiveness and impact on TB epidemiology.