Treatment for latent tuberculosis infection in low- and middle-income countries: progress and challenges with implementation and scale-up

Case Finding Among and Comprehensive Management of Household Contacts of Persons with Pulmonary Tuberculosis: a Pilot Project - Uganda, 2023-2024

To help achieve the End TB Strategy target of a 90% reduction in tuberculosis (TB) incidence by 2030, member states of the United Nations High-Level Meetings on TB called for improving provision of TB preventive treatment (TPT) for household contacts of persons with TB, who are at increased risk for infection and disease. However, TPT use among household contacts worldwide remained at 21% in 2023. The International Union Against Tuberculosis and Lung Disease, the Uganda Ministry of Health, and CDC piloted a comprehensive approach for increasing case finding and TPT coverage among household contacts of persons with TB. During November 1, 2023-September 30, 2024, a total of 521 index patients with TB disease were registered at six health facilities in Uganda. Home visits to index patients identified 1,913 household contacts, 1,739 (91.0%) of whom underwent TB symptom screening at home; 321 (18.5%) reported TB symptoms. Of 309 (96.3%) persons with TB symptoms who were further evaluated, 284 (91.9%) provided a sputum specimen for laboratory testing, including 270 (84.1% of those with symptoms) who did so during the home visit; 214 (69.3%) underwent chest radiography. Overall, 80 TB cases were diagnosed; in 61 (76.3%) persons, the diagnosis was based on radiographic findings. Among 1,496 HHCs eligible for TPT, 1,239 (82.8%) initiated treatment and 1,178 (95.1%) completed it. Global scale-up of this approach might help reach global TB elimination goals.

Redefining Peptide 14D: Substitutional Analysis for Accelerated TB Diagnosis and Enhanced Activity against Mycobacterium tuberculosis

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a predominant cause of mortality, especially in low- and middle-income nations. Recently, antimicrobial peptides have been discovered that at low concentrations could stimulate the growth of M. tuberculosis (hormetic response). In this study, such a peptide was used to investigate the effects on the time to positivity (TTP). A systematic substitution analysis of peptide 14D was synthesized using Spot synthesis technology, resulting in 171 novel peptides. Our findings revealed a spectrum of interactions, with some peptides accelerating M. tuberculosis growth, potentially aiding in faster diagnostics, while others exhibited inhibitory effects. Notably, peptide NH2-wkivfiwrr-CONH2 significantly reduced the TTP by 25 h compared to the wild-type peptide 14D, highlighting its potential in improving TB diagnostics by culture. Several peptides demonstrated potent antimycobacterial activity, with a minimum inhibitory concentration (MIC) of 20 µg/mL against H37Rv and a multidrug-resistant M. tuberculosis strain. Additionally, for two peptides, a strongly diminished formation of cord-like structures was observed, which is indicative of reduced virulence and transmission potential. This study underscores the multifaceted roles of antimicrobial peptides in TB management, from enhancing diagnostic efficiency to offering therapeutic avenues against M. tuberculosis.

Timeliness metrics for screening and preventing TB in household contacts of pulmonary TB patients in Kenya

BACKGROUND

The study assessed whether a "7-1-7" timeliness metric for screening and TB preventive therapy (TPT) could be implemented for household contacts (HHCs) of index patients with bacteriologically confirmed pulmonary TB under routine programmatic settings in Kenya.

METHODS

A longitudinal cohort study conducted among index patients and their HHCs in 12 health facilities, Kiambu County, Kenya.

RESULTS

Between January and June 2023, 95% of 508 index patients had their HHCs line-listed within 7 days of initiating anti-TB treatment ("First 7"). In 68% of 1,115 HHCs, screening outcomes were ascertained within 1 day of line-listing ("Next 1"). In 65% of 1,105 HHCs eligible for further evaluation, anti-TB treatment, TPT or a decision for no drugs was made within 7 days of screening ("Second 7"). Altogether, 62% of screened HHCs started TPT during the "7-1-7" period compared with 58% in a historical cohort. Main barriers to TPT uptake were HHCs not consulting clinicians, HHCs being unwilling to initiate TPT and drug shortages. Healthcare workers felt that a timeliness metric was valuable for streamlining HHC management and proposed "3-5-7" as a workable alternative.

CONCLUSIONS

The national TB programme must generate awareness about TPT, ensure uninterrupted drug supplies and assess whether the "3-5-7" metric can be operationalised.

Uptake and Completion of Tuberculosis Preventive Treatment Using 12-Dose, Weekly Isoniazid-Rifapentine Regimen in Bangladesh: A Community-Based Implementation Study

BACKGROUND

The United Nations high-level meeting (UNHLM) pledged to enroll 30 million in tuberculosis preventive treatment (TPT) by 2022, necessitating TPT expansion to all at tuberculosis (TB) risk. We assessed the uptake and completion of a 12-dose, weekly isoniazid-rifapentine (3HP) TPT regimen.

METHODS

Between February 2018 and March 2019 in Dhaka, community-based TPT using 3HP targeted household contacts of 883 confirmed drug-sensitive pulmonary TB patients. Adhering to World Health Organization guidelines, contacts underwent active TB screening before TPT initiation.

RESULTS

Of 3193 contacts who were advised health facility visits for screening, 67% (n = 2149) complied. Among these, 1804 (84%) received chest X-rays. Active TB was diagnosed in 39 (2%) contacts; they commenced TB treatment. Over 97% of 1216 contacts began TPT, with completion rates higher among females, those with more education and income, non-slum residents, and those without 3HP-related adverse events. Adverse events, mainly mild, occurred in 5% of participants.

CONCLUSIONS

The 3HP regimen, with its short duration, self-administered option, and minimal side effects, achieved satisfactory completion rates. A community-focused TPT approach is feasible, scalable nationally, and aligns with UNHLM targets.

Feasibility, enablers and challenges of using timeliness metrics for household contact tracing and TB preventive therapy in Pakistan

INTRODUCTION

Screening household contacts of TB patients and providing TB preventive therapy (TPT) is a key intervention to end the TB epidemic. Global and timely implementation of TPT in household contacts, however, is dismal. We adapted the 7-1-7 timeliness metric designed to evaluate and respond to infectious disease outbreaks or pandemics, and assessed the feasibility, enablers and challenges of implementing this metric for screening and management of household contacts of index patients with bacteriologically-confirmed pulmonary TB in Karachi city, Pakistan.

METHODS

We conducted an explanatory mixed methods study with a quantitative component (cohort design) followed by a qualitative component (descriptive design with focus group discussions).

RESULTS

From January-June 2023, 92% of 450 index patients had their household contacts line-listed within seven days of initiating anti-TB treatment ("first 7"). In 84% of 1342 household contacts, screening outcomes were ascertained within one day of line-listing ("next 1"). In 35% of 256 household contacts eligible for further evaluation by a medical officer (aged ≤5 years or with chest symptoms), anti-tuberculosis treatment, TPT or a decision for no drugs was made within seven days of symptom screening ("second 7"). The principal reason for not starting anti-tuberculosis treatment or TPT was failure to consult a medical officer: only 129(50%) of 256 contacts consulted a medical officer. Reasons for poor performance in the "second 7" component included travel costs to see a medical officer, loss of daily earnings and fear of a TB diagnosis. Field staff reported that timeliness metrics motivated them to take prompt action in household contact screening and TPT provision and they suggested these be included in national guidelines.

CONCLUSIONS

Field staff found "7-1-7" timeliness metrics to be feasible and useful. Integration of these metrics into national guidelines could improve timeliness of diagnosis, treatment and prevention of TB within households of index patients.

Latent tuberculosis infection treatment completion in Biscay: differences between regimens and monitoring approaches

Introduction

Contact tracing and treatment of latent tuberculosis infection (LTBI) is a key element of tuberculosis (TB) control in low TB incidence countries. A TB control and prevention program has been active in the Basque Country since 2003, including the development of the nurse case manager role and a unified electronic record. Three World Health Organization-approved LTBI regimens have been used: isoniazid for 6 months (6H), rifampicin for 4 months (4R), and isoniazid and rifampicin for 3 months (3HR). Centralized follow-up by a TB nurse case manager started in January 2016, with regular telephone follow-up, telemonitoring of blood test results, and monitoring of adherence by electronic review of drugs dispensed in pharmacies.

Objective

To estimate LTBI treatment completion and toxicity of different preventive treatment regimens in a real-world setting. Secondary objective: to investigate the adherence to different approaches to preventive treatment monitoring.

Methods

A multicentre retrospective cohort study was conducted using data collected prospectively on contacts of patients with TB in five hospitals in Biscay from 2003 to 2022.

Results

A total of 3,066 contacts with LTBI were included. The overall completion rate was 66.8%; 86.5% of patients on 3HR (n = 699) completed treatment vs. 68.3% (n = 1,260) of those on 6H (p < 0.0001). The rate of toxicity was 3.8%, without significant differences between the regimens. A total of 394 contacts were monitored by a TB nurse case manager. In these patients, the completion rate was 85% vs. 67% in those under standard care (p < 0.001). A multivariate logistic regression model identified three independent factors associated with treatment completion: being female, the 3HR regimen, and nurse telemonitoring.

Conclusion

3HR was well tolerated and associated with a higher rate of treatment completion. Patients with nurse telemonitoring follow-up had better completion rates.

Tuberculosis Infection in Children and Adolescents

The burden of tuberculosis (TB) in children and adolescents remains very significant. Several million children and adolescents are infected with TB each year worldwide following exposure to an infectious TB case and the risk of progression from TB infection to tuberculosis disease is higher in this group compared to adults. This review describes the risk factors for TB infection in children and adolescents. Following TB exposure, the risk of TB infection is determined by a combination of index case characteristics, contact features, and environmental determinants. We also present the recently recommended approaches to diagnose and treat TB infection as well as novel tests for infection. The tests for TB infection have limitations and diagnosis still relies on an indirect immunological assessment of cellular immune response to Mycobacterium tuberculosis antigens using immunodiagnostic testing. It is recommended that TB exposed children and adolescents and those living with HIV receive TB preventive treatment (TPT) to reduce the risk of progression to TB disease. Several TPT regimens of similar effectiveness and safety are now available and recommended by the World Health Organisation.

Preventive Treatment for Household Contacts of Drug-Susceptible Tuberculosis Patients

People who live in the household of someone with infectious pulmonary tuberculosis are at a high risk of tuberculosis infection and subsequent progression to tuberculosis disease. These individuals are prioritized for contact investigation and tuberculosis preventive treatment (TPT). The treatment of TB infection is critical to prevent the progression of infection to disease and is prioritized in household contacts. Despite the availability of TPT, uptake in household contacts is poor. Multiple barriers prevent the optimal implementation of these policies. This manuscript lays out potential next steps for closing the policy-to-implementation gap in household contacts of all ages.

Pharmacokinetics of isoniazid and rifapentine in young paediatric patients with latent tuberculosis infection

OBJECTIVES

This study investigated the steady-state pharmacokinetic profiles of 3-month weekly rifapentine plus isoniazid (3HP) in children with latent tuberculosis infection (LTBI). Factors including tablet integrity, food, and pharmacogenetics were also assessed.

METHODS

During the 3HP treatment, blood and urine samples were collected on week 4. Isoniazid and rifapentine levels were measured using a high-performance liquid chromatography technique. Genetic variation of arylamine N-acetyltransferase 2 (NAT2) and arylacetamide deacetylase (AADAC) were assessed by the MassARRAY®. Safety and clinical outcomes at week 48 were monitored.

RESULTS

Twelve LTBI children [age 3.8 (range 2.1-4.9 years old)] completed the treatment [isoniazid and rifapentine dose 25.0 (range 21.7-26.8) and 25.7 (range 20.7-32.1) mg/kg, respectively]. No serious adverse events or active tuberculosis occurred. Tablet integrity was associated with decreased area under the concentration-time curve (91 vs 73 mg.hr/L, p = 0.026) and increased apparent oral clearance of isoniazid (0.27 vs 0.32 L/hr/kg, p = 0.019) and decreased rifapentine's renal clearance (CL_R, 0.005 vs 0.003 L/hr, p = 0.014). Food was associated with increased CL_R of isoniazid (3.45 vs 8.95 L/hr, p = 0.006) but not rifapentine. Variability in NAT2 and AADAC did not affect the pharmacokinetics of both drugs.

CONCLUSIONS

There is high variability in the pharmacokinetic profiles of isoniazid and rifapentine in young LTBI children. The variability was partly influenced by tablet integrity and food, but not pharmacogenetics. Further study in a larger cohort is warranted to display the relationship of these factors to treatment outcomes.

QIAreach™ QuantiFERON®-TB for the diagnosis of infection

Timely diagnosis and treatment to prevent tuberculosis (TB) transmission and the consequent replenishment of the TB infection reservoir are essential for the control and elimination of TB worldwide [1], ultimately contributing the World Health Organization (WHO)'s End TB goals [2].

QIAreach QFT demonstrated a good performance in diagnosing TB infection. This tool may offer technical and operational benefits over more complex IGRA ELISA-based assays, granting timely TB diagnosis in decentralised settings with limited infrastructure.https://bit.ly/3n6Dxll

Assessing usability of QIAreach QuantiFERON-TB platform in a high tuberculosis prevalence, low-resource setting

The World Health Organization (WHO) estimates that 1.8 billion people, close to a quarter of the world's population are infected with Mycobacterium tuberculosis [1]. Despite substantial declines in tuberculosis (TB) incidence over the past decade, Zambia still has the seventh highest TB incidence in sub-Saharan Africa and remains one of the 30 WHO high TB-burden priority countries [2]. In 2019, there were ∼59 000 new individuals with active TB disease in Zambia (incidence rate of 333 per 100 000 per year), which resulted in 15 400 TB-related deaths, of which 62% were among people living with HIV [2].

QIAreach QuantiFERON-TB is a portable IGRA with the potential to improve accessibility of TB infection diagnosis in low-resource settingshttps://bit.ly/3nTzolf

Validation of Differentially Expressed Immune Biomarkers in Latent and Active Tuberculosis by Real-Time PCR

Tuberculosis (TB) remains a major global threat and diagnosis of active TB ((ATB) both extra-pulmonary (EPTB), pulmonary (PTB)) and latent TB (LTBI) infection remains challenging, particularly in high-burden countries which still rely heavily on conventional methods. Although molecular diagnostic methods are available, e.g., Cepheid GeneXpert, they are not universally available in all high TB burden countries. There is intense focus on immune biomarkers for use in TB diagnosis, which could provide alternative low-cost, rapid diagnostic solutions. In our previous gene expression studies, we identified peripheral blood leukocyte (PBL) mRNA biomarkers in a non-human primate TB aerosol-challenge model. Here, we describe a study to further validate select mRNA biomarkers from this prior study in new cohorts of patients and controls, as a prerequisite for further development. Whole blood mRNA was purified from ATB patients recruited in the UK and India, LTBI and two groups of controls from the UK (i) a low TB incidence region (CNTRLA) and (ii) individuals variably-domiciled in the UK and Asia ((CNTRLB), the latter TB high incidence regions). Seventy-two mRNA biomarker gene targets were analyzed by qPCR using the Roche Lightcycler 480 qPCR platform and data analyzed using GeneSpring™ 14.9 bioinformatics software. Differential expression of fifty-three biomarkers was confirmed between MTB infected, LTBI groups and controls, seventeen of which were significant using analysis of variance (ANOVA): CALCOCO2, CD52, GBP1, GBP2, GBP5, HLA-B, IFIT3, IFITM3, IRF1, LOC400759 (GBP1P1), NCF1C, PF4V1, SAMD9L, S100A11, TAF10, TAPBP, and TRIM25. These were analyzed using receiver operating characteristic (ROC) curve analysis. Single biomarkers and biomarker combinations were further assessed using simple arithmetic algorithms. Minimal combination biomarker panels were delineated for primary diagnosis of ATB (both PTB and EPTB), LTBI and identifying LTBI individuals at high risk of progression which showed good performance characteristics. These were assessed for suitability for progression against the standards for new TB diagnostic tests delineated in the published World Health Organization (WHO) technology product profiles (TPPs).

The paradigm shift in the approach to management of latent tuberculosis infection in high tuberculosis burden countries

Introduction: Addressing the reservoir of Latent Tuberculosis Infection (LTBI) is critical to TB elimination because if left untreated LTBI can progress to active TB disease. This additional burden can prevent achieving the global targets of TB elimination. Management of LTBI has been a low priority target for National TB Elimination Programs (NTEP) due to various challenges in the field settings.Areas covered: This article reviews the most recent advances in the field of LTBI management including newer diagnostics, treatments, vaccines, programmatic challenges, and gaps and suggests a way forward that can be adopted by NTEPs for LTBI. We searched the electronic databases of PubMed, Scopus, and Web of Science for studies published between 2010 to 2020 using MeSH terms: Latent TB Diagnosis, TB preventive therapy, Vaccines, LTBI, and HIV/ COVID.Expert opinion: NTEPs of developing countries should offer a better, point-of-care diagnostic, and effective treatment for LTBI to reduce the number of new TB cases arising from people infected with M.tb. Awareness about LTBI should be increased among the health system staff and the public. More funding is needed to advance research as well as implement the newer findings in the NTEP to achieve the End TB targets by 2035.

Pharmacokinetics of antiretroviral and tuberculosis drugs in children with HIV/TB co-infection: a systematic review

INTRODUCTION

Management of concomitant use of ART and TB drugs is difficult because of the many drug-drug interactions (DDIs) between the medications. This systematic review provides an overview of the current state of knowledge about the pharmacokinetics (PK) of ART and TB treatment in children with HIV/TB co-infection, and identifies knowledge gaps.

METHODS

We searched Embase and PubMed, and systematically searched abstract books of relevant conferences, following PRISMA guidelines. Studies not reporting PK parameters, investigating medicines that are not available any longer or not including children with HIV/TB co-infection were excluded. All studies were assessed for quality.

RESULTS

In total, 47 studies met the inclusion criteria. No dose adjustments are necessary for efavirenz during concomitant first-line TB treatment use, but intersubject PK variability was high, especially in children <3 years of age. Super-boosted lopinavir/ritonavir (ratio 1:1) resulted in adequate lopinavir trough concentrations during rifampicin co-administration. Double-dosed raltegravir can be given with rifampicin in children >4 weeks old as well as twice-daily dolutegravir (instead of once daily) in children older than 6 years. Exposure to some TB drugs (ethambutol and rifampicin) was reduced in the setting of HIV infection, regardless of ART use. Only limited PK data of second-line TB drugs with ART in children who are HIV infected have been published.

CONCLUSIONS

Whereas integrase inhibitors seem favourable in older children, there are limited options for ART in young children (<3 years) receiving rifampicin-based TB therapy. The PK of TB drugs in HIV-infected children warrants further research.

The Growing Importance of Tuberculosis Preventive Therapy and How Research and Innovation Can Enhance Its Implementation on the Ground

Ending the tuberculosis (TB) epidemic by 2030 requires two key actions: rapid diagnosis and effective treatment of active TB and identification and treatment of latent TB infection to prevent progression to active disease. We introduce this perspective by documenting the growing importance of TB preventive therapy on the international agenda coupled with global data showing poor implementation of preventive activities in programmatic settings. We follow this with two principal objectives. The first is to examine implementation challenges around diagnosis and treatment of active TB. Within this, we include recent evidence about the continued morbidity and heightened mortality that persists after TB treatment is successfully completed, thus elevating the importance of TB preventive therapy. The second objective is to outline how current TB preventive therapy activities have been shaped and are managed and propose how these can be improved through research and innovation. This includes expanding and giving higher priority to certain high-risk groups including those with fibrotic lung lesions on chest X-ray, showcasing the need to develop and deploy new biomarkers to more accurately predict risk of disease and making shorter treatment regimens, especially with rifapentine-isoniazid, more user-friendly and widely available. Ending the TB epidemic requires not only cure of the disease but preventing it before it even begins.