Subclinical tuberculosis in children: diagnostic strategies for identification reported in a 6-year national prospective surveillance study

Current approaches for diagnosis of subclinical pulmonary tuberculosis, clinical implications and future perspectives: a scoping review

INTRODUCTION

Subclinical tuberculosis (TB) is the presence of TB disease among people who are either asymptomatic or have minimal symptoms.

AREAS COVERED

Currently, there are no accurate diagnostic tools and clear treatment approaches for subclinical TB. In this study, a comprehensive literature search was conducted across major databases. This review aimed to uncover the latest advancements in diagnostic approaches, explore their clinical implications, and outline potential future perspectives. While innovative technologies are in development to enable sputum-free TB tests, there remains a critical need for precise diagnostic tools tailored to the unique characteristics of subclinical TB. Given the complexity of subclinical TB, a multidisciplinary approach involving clinicians, microbiologists, epidemiologists, and public health experts is essential. Further research is needed to establish standardized diagnostic criteria and treatment guidelines specifically tailored for subclinical TB, acknowledging the unique challenges posed by this elusive stage of the disease.

EXPERT OPINION

Efforts are needed for the detection, diagnosis, and treatment of subclinical TB. In this review, we describe the importance of subclinical TB, both from a clinical and public health perspective and highlight the diagnostic and treatment gaps of this stage.

Subclinical tuberculosis: a meta-analysis of prevalence and scoping review of definitions, prevalence and clinical characteristics

BACKGROUND

This scoping review aimed to characterise definitions used to describe subclinical tuberculosis (TB), estimate the prevalence in different populations and describe the clinical characteristics and treatment outcomes in the scientific literature.

METHODS

A systematic literature search was conducted using PubMed. We included studies published in English between January 1990 and August 2022 that defined "subclinical" or "asymptomatic" pulmonary TB disease, regardless of age, HIV status and comorbidities. We estimated the weighted pooled proportions of subclinical TB using a random-effects model by World Health Organization reported TB incidence, populations and settings. We also pooled the proportion of subclinical TB according to definitions described in published prevalence surveys.

RESULTS

We identified 29 prevalence surveys and 71 other studies. Prevalence survey data (2002-2022) using "absence of cough of any duration" criteria reported higher subclinical TB prevalence than those using the stricter "completely asymptomatic" threshold. Prevalence estimates overlap in studies using other symptoms and cough duration. Subclinical TB in studies was commonly defined as asymptomatic TB disease. Higher prevalence was reported in high TB burden areas, community settings and immunocompetent populations. People with subclinical TB showed less extensive radiographic abnormalities, higher treatment success rates and lower mortality, although studies were few.

CONCLUSION

A substantial proportion of TB is subclinical. However, prevalence estimates were highly heterogeneous between settings. Most published studies incompletely characterised the phenotype of people with subclinical TB. Standardised definitions and diagnostic criteria are needed to characterise this phenotype. Further research is required to enhance case finding, screening, diagnostics and treatment options for subclinical TB.

TB or not TB? Diagnostic Sensitivity, Specifity and Interobserver Agreement in the Radiological Diagnosis of Pulmonary Tuberculosis in Children

BACKGROUND

The differentiation between latent tuberculosis infection (LTBI) and tuberculosis (TB) relies on radiological changes. Confirming the diagnosis remains a challenge because typical findings are often missing in children. This study evaluates diagnostic sensitivity, specifity and interobserver agreement on the radiological diagnosis of TB by chest-x-rays in accordance to professional specialization and work experience.

METHODS

Chest x-rays of 120 children with proven tuberculosis infection were independently evaluated by general radiologists, paediatric radiologists and paediatric pulmonologists. Results were compared to a reference diagnosis created by group of experienced paediatric radiologists and paediatric pulmonologists. Primary endpoints were diagnostic sensitivity and specificity and interobserver variability defined as Krippendorfs alpha of thesel groups compared to the reference diagnosis.

RESULTS

Of the 120 chest x-rays 33 (27,5%) were diagnosed as TB by the reference standard . Paediatric pulmonologist had the highest diagnostic sensitivity (90%) but were less specific (71%) whereas general radiologist were less sensitive (68%) but more secific (95%). The best diagnostic accuracy was achieved by pediatric radiologists with a diagnostic sensitivity of 77% and specificity 95% respectively.

CONCLUSIONS

We demonstrated significant interobserver variability and relevant differences in sensitivity and specificity in the radiological diagnosis of TB between the groups. Paediatric radiologists showed the best diagnostic performance. As the diagnosis of pulmonary TB has significant therapeutic consequences for children they should be routinely involved in the diagnostic process.

Tuberculosis Case Detection and Guideline Adherence among Child Contacts in Switzerland: A Retrospective Observational Study

BACKGROUND

Children exposed to a tuberculosis (TB) index case are at risk of TB infection and disease.

OBJECTIVES

The aim of this study was to describe the proportion of child contacts who developed TB infection or disease after exposure and to assess the diagnostic pathways and adherence to current guidelines.

METHODS

Retrospective observational study including children ≤16 years of age who had contact to a TB index case between January 2019 and July 2021. Analysis was stratified by age groups 0-4, 5-11, and 12-16 years.

RESULTS

Of 401 TB-exposed children, data were available for 380 (95%). Of those, 7 (2%) were diagnosed with TB disease and 35 (9%) with TB infection. We identified several deviations in the management compared to recommendations in national Swiss guidelines: In the children aged 0-4 years, only 82% were examined with an immunodiagnostic test or a chest radiography within 2 weeks after last contact. Recommended prophylactic treatment was prescribed in 66% of the children only. In the children aged 5-11 years, 64% were tested with an immunodiagnostic test in a first examination and 75% in a second examination, 2 weeks and 2 months after last contact, respectively.

CONCLUSIONS

Contact investigations of children exposed to a TB index case identified a significant proportion of children with TB infection and disease in a low TB incidence setting. We observed significant deviations from the guidelines in the contact investigations suggesting the need for improved implementation.

Artificial Intelligence in Paediatric Tuberculosis

Tuberculosis (TB) continues to be a leading cause of death in children despite global efforts focused on early diagnosis and interventions to limit the spread of the disease. This challenge has been made more complex in the context of the coronavirus pandemic, which has disrupted the "End TB Strategy" and framework set out by the World Health Organization (WHO). Since the inception of artificial intelligence (AI) more than 60 years ago, the interest in AI has risen and more recently we have seen the emergence of multiple real-world applications, many of which relate to medical imaging. Nonetheless, real-world AI applications and clinical studies are limited in the niche area of paediatric imaging. This review article will focus on how AI, or more specifically deep learning, can be applied to TB diagnosis and management in children. We describe how deep learning can be utilised in chest imaging to provide computer-assisted diagnosis to augment workflow and screening efforts. We also review examples of recent AI applications for TB screening in resource constrained environments and we explore some of the challenges and the future directions of AI in paediatric TB.

Monocyte, Lymphocyte and Neutrophil Ratios - Easy-to-Use Biomarkers for the Diagnosis of Pediatric Tuberculosis

BACKGROUND

The neutrophil-to-lymphocyte-ratio (NLR), neutrophil-to-monocyte-plus-lymphocyte-ratio (NMLR) and monocyte-to-lymphocyte-ratio (MLR) may have diagnostic potential for tuberculosis (TB).

METHODS

Data of two prospective multicenter studies in Switzerland were used, which included children <18 years with TB exposure, infection or disease or with febrile non-TB lower-respiratory-tract infection (nTB-LRTI).

RESULTS

Of the 389 children included 25 (6.4%) had TB disease, 12 (3.1%) TB infection, 28 (7.2%) were healthy TB exposed and 324 (83.3%) nTB-LRTI. Median (IQR) NLR was highest with 2.0 (1.2, 2.2) in children with TB disease compared to TB exposed [0.8 (0.6, 1.3); P = 0.002] and nTB-LRTI [0.3 (0.1, 1.0); P < 0.001]. Median (IQR) NMLR was highest with 1.4 (1.2, 1.7) in children with TB disease compared to healthy exposed [0.7 (0.6, 1.1); P = 0.003] and children with nTB-LRTI [0.2 (0.1, 0.6); P < 0.001). Receiver operating characteristic curves to detect TB disease compared to nTB-LRTI for NLR and NMLR had an area under the curve of 0.82 and 0.86, the sensitivity of 88% and 88%, and specificity of 71% and 76%, respectively.

CONCLUSION

NLR and NMLR are promising, easy-to-obtain diagnostic biomarkers to differentiate children with TB disease from other lower respiratory tract infections. These results require validation in a larger study and in settings with high and low TB endemicity.

Paediatric refugees from Ukraine: guidance for health care providers

BACKGROUND

With the invasion of Ukraine by the Russian Army in February 2022, refugees, the majority of whom are women and children, started fleeing the war to neighbouring countries. Even before the current escalation, the conflict in the eastern part of Ukraine has led to the internal displacement of more than 200,000 children, and many others have experienced attacks, e.g. on schools. This inevitably leads to limitations in health care delivery. During transit, overcrowding, poor shelter and vulnerability may further put refugees at increased risk for infectious diseases. This consensus document aims to provide information and guidance regarding health issues that paediatricians and general practitioners may face when caring for Ukrainian children.

METHODS

Members of the Migrant Health Reference Group of Paediatrics Switzerland and the Paediatric Infectious Disease Group in Switzerland developed this recommendation between March and April 2022 in a modified Delphi process.

RESULTS

A total of 50 recommendations were agreed on with a ≥80% consensus. These include the following topics: i) general aspects, including interpreter services, urgent health needs, personal history and general check-ups; ii) mental health, including how to search for signs of psychological distress without going into traumatic details; iii) vaccinations, including recommendations for evaluation and catch-up; iv) screening for tuberculosis, human immunodeficiency virus, and hepatitis B and C; and v) providing age-appropriate preventive and health service information.

CONCLUSION

This document provides current evidence and guidance when caring for paediatric refugees from Ukraine. The recommendations focus on Switzerland but may well be used in other countries. These are based on current evidence and may need to be adapted to individual situations and once further evidence becomes available.

Towards Accurate Point-of-Care Tests for Tuberculosis in Children

In childhood tuberculosis (TB), with an estimated 69% of missed cases in children under 5 years of age, the case detection gap is larger than in other age groups, mainly due to its paucibacillary nature and children’s difficulties in delivering sputum specimens. Accurate and accessible point-of-care tests (POCTs) are needed to detect TB disease in children and, in turn, reduce TB-related morbidity and mortality in this vulnerable population. In recent years, several POCTs for TB have been developed. These include new tools to improve the detection of TB in respiratory and gastric samples, such as molecular detection of Mycobacterium tuberculosis using loop-mediated isothermal amplification (LAMP) and portable polymerase chain reaction (PCR)-based GeneXpert. In addition, the urine-based detection of lipoarabinomannan (LAM), as well as imaging modalities through point-of-care ultrasonography (POCUS), are currently the POCTs in use. Further to this, artificial intelligence-based interpretation of ultrasound imaging and radiography is now integrated into computer-aided detection products. In the future, portable radiography may become more widely available, and robotics-supported ultrasound imaging is currently being trialed. Finally, novel blood-based tests evaluating the immune response using “omic-“techniques are underway. This approach, including transcriptomics, metabolomic, proteomics, lipidomics and genomics, is still distant from being translated into POCT formats, but the digital development may rapidly enhance innovation in this field. Despite these significant advances, TB-POCT development and implementation remains challenged by the lack of standard ways to access non-sputum-based samples, the need to differentiate TB infection from disease and to gain acceptance for novel testing strategies specific to the conditions and settings of use.

Strengthening Tuberculosis Services for Children and Adolescents in Low Endemic Settings

In low tuberculosis-burden countries, children and adolescents with the highest incidence of tuberculosis (TB) infection or disease are usually those who have immigrated from high-burden countries. It is, therefore, essential that low-burden countries provide healthcare services to immigrant and refugee families, to assure that their children can receive proper testing, evaluation, and treatment for TB. Active case-finding through contact tracing is a critical element of TB prevention in children and in finding TB disease at an early, easily treated stage. Passive case-finding by evaluating an ill child is often delayed, as other, more common infections and conditions are suspected initially. While high-quality laboratory services to detect Mycobacterium tuberculosis are generally available, they are often underutilized in the diagnosis of childhood TB, further delaying diagnosis in some cases. Performing research on TB disease is difficult because of the low number of cases that are spread over many locales, but critical research on the evaluation and treatment of TB infection has been an important legacy of low-burden countries. The continued education of medical providers and the involvement of educational, professional, and non-governmental organizations is a key element of maintaining awareness of the presence of TB. This article provides the perspective from North America and Western Europe but is relevant to many low-endemic settings. TB in children and adolescents will persist in low-burden countries as long as it persists throughout the rest of the world, and these wealthy countries must increase their financial commitment to end TB everywhere.