High prevalence of tuberculosis infection in HIV-1 exposed Kenyan infants

Prevalence and Predictors of Tuberculosis Infection in Children and Adolescents in Rural Uganda: A Cross-sectional Study

BACKGROUND

Much of the latent tuberculosis (TB) reservoir is established in childhood and adolescence. Yet, age-specific data on prevalence and predictors of infection in this population are sparse and needed to guide prevention and case finding.

METHODS

From December 2021 to June 2023, we measured TB infection in children 1-17 years in 25 villages in rural Southwestern Uganda. We defined TB infection as a positive QuantiFERON Gold Plus Test (QFT). We estimated overall and age-stratified population-level prevalence and adjusted risk ratios (aRR) of TB infection for individual, household, and community-based predictors, accounting for age, TB contact, and clustering by household.

RESULTS

Estimated TB infection prevalence was 9.6% [95% confidence interval (CI): 8.7-10.5%] among the 5789 participants, and prevalence varied slightly with age. Household-level risk factors included crowding (aRR: 1.25, 95% CI: 1.03-1.53), indoor cooking (aRR: 1.62, 95% CI: 1.14-2.30), living with ≥2 persons who drink alcohol (aRR: 1.47, 95% CI: 1.04-2.07). The predominant community-based risk factor was child mobility (aRR: 1.67, 95% CI: 1.24-2.26). In age-stratified analyses, household predictors were important in early childhood but not adolescence, where mobility was predominant (aRR: 1.66, 95% CI: 1.13-2.44).

CONCLUSION

We detected a high prevalence of TB infection in children and adolescents in rural Uganda. On a population level, TB risk factors change throughout the early life course, with child mobility a key risk factor in adolescence. Age-specific TB case finding and prevention strategies that address both household and extra-household risk factors are needed to address TB transmission.

Maternal HIV Status and Risk of Infant Mycobacterium tuberculosis Infection as Measured by Tuberculin Skin Test

BACKGROUND

The effect of maternal HIV on infant Mycobacterium tuberculosis (Mtb) infection risk is not well-characterized.

METHODS

Pregnant women with/without HIV and their infants were enrolled in a longitudinal cohort in Kenya. Mothers had interferon gamma-release assays (QFT-Plus) and tuberculin skin tests (TST) at enrollment in pregnancy; children underwent TST at 12 and 24 months of age. We estimated the incidence and correlates of infant TST-positivity using Cox proportional hazards regression.

RESULTS

Among 322 infants, 170 (53%) were HIV-exposed and 152 (47%) were HIV-unexposed. Median enrollment age was 6.6 weeks [interquartile range (IQR): 6.1-10.0]; most received Bacillus Calmette-Guerin (320, 99%). Thirty-nine (12%) mothers were TST-positive; 102 (32%) were QFT-Plus-positive. Among HIV-exposed infants, 154 (95%) received antiretrovirals for HIV prevention and 141 (83%) of their mothers ever received isoniazid preventive therapy (IPT). Cumulative 24-month infant Mtb infection incidence was 3.6/100 person-years (PY) [95% confidence interval (CI): 2.4-5.5/100 PY]; 5.4/100 PY in HIV-exposed infants (10%, 17/170) versus 1.7/100 PY in HIV-unexposed infants (3.3%, 5/152) [hazard ratio (HR): 3.1 (95% CI: 1.2-8.5)]. More TST conversions occurred in the first versus second year of life [5.8 vs. 2.0/100 PY; HR: 2.9 (95% CI: 1.0-10.1)]. Infant TST-positivity was associated with maternal TST-positivity [HR: 2.9 (95% CI: 1.1-7.4)], but not QFT-Plus-positivity. Among HIV-exposed children, Mtb infection incidence was similar regardless of maternal IPT.

CONCLUSIONS

Mtb infection incidence (by TST) by 24 months of age was ~3-fold higher among HIV-exposed children, despite high maternal IPT uptake. Overall, more TST conversions occurred in the first 12 months compared to 12-24 months of age, similar in both HIV-exposed and HIV-unexposed children.

T-SPOT.TB Reactivity in Southern African Children With and Without in Utero Human Immunodeficiency Virus Exposure

Infants who are human immunodeficiency virus (HIV)-exposed uninfected (iHEU) experience higher risk of infectious morbidity than infants HIV-unexposed uninfected (iHUU). We compared tuberculosis (TB) infection prevalence in 418 Bacillus Calmette-Guérin vaccinated sub-Saharan African iHEU and iHUU aged 9-18 months using T-SPOT.TB. Prevalence of TB infection was low and did not differ by HIV exposure status.

Timing of maternal isoniazid preventive therapy on tuberculosis infection among infants exposed to HIV in low-income and middle-income settings: a secondary analysis of the TB APPRISE trial

BACKGROUND

Infants born to women with HIV in settings with a high tuberculosis burden are at risk of tuberculosis infection and rapid progression to active disease. Maternal isoniazid preventive therapy might mitigate this risk, but optimal timing of therapy remains unclear. The TB APPRISE trial showed that initiation of isoniazid during pregnancy resulted in more frequent adverse pregnancy outcomes than when initiated postpartum. We aimed to determine the proportion of infants testing positive for tuberculosis infection born to mothers who initiated isoniazid therapy antepartum compared with postpartum using two commonly used tests, the test agreement, and predictors of test positivity.

METHODS

TB APPRISE was a randomised, double-blind, placebo-controlled, non-inferiority trial done at 13 study sites across eight countries (Botswana, Haiti, India, South Africa, Tanzania, Thailand, Uganda, and Zimbabwe). Pregnant women with HIV on antiretroviral therapy were randomly assigned to receive immediate isoniazid preventive therapy (28 weeks isoniazid [300 mg daily], then placebo until week 40 after delivery) or deferred treatment (placebo until week 12 after delivery, then isoniazid [300 mg daily] for 28 weeks). Mother-infant pairs were followed up until 48 weeks after delivery. We included all liveborn infants with a tuberculin skin test or interferon-γ release assay (IGRA) at 44 weeks. The outcomes assessed in this secondary analysis were tuberculosis test positivity by study group, test agreement, and predictors of test positivity. This study was registered with ClinicalTrials.gov, NCT01494038.

FINDINGS

Between Aug 19, 2014, and April 4, 2016, 956 mothers were randomly assigned, and 749 mother-child pairs were included in this secondary analysis. Of 749 infants, 694 (93%) received Bacille Calmette-Guérin (BCG) vaccination, 675 (90%) were born to mothers who had completed isoniazid treatment, 20 (3%) were exposed to tuberculosis, seven (1%) became HIV positive, and one (<1%) developed probable tuberculosis. 43 (6%; 95% CI 4-8]) of 732 infants had a positive IGRA test result and 55 (8%; 6-10) of 727 infants had a positive tuberculin skin test result. Test positivity did not differ by study group (p=0·88 for IGRA; p=0·44 for tuberculin skin test). Test agreement was poor (κ=0·107 [95% CI 0·002-0·212]). Infant tuberculin skin test positivity was associated with breastfeeding (adjusted odds ratio 6·63 [95% CI 1·57-27·9]), BCG vaccination (4·97 [1·50-16·43]), and maternal tuberculin skin test positivity at delivery (3·28 [1·70-6·33]); IGRA positivity was associated with female sex (2·09 [1·06-4·14]).

INTERPRETATION

Deferral of maternal isoniazid preventive therapy to early postpartum had no effect on infant tuberculosis acquisition in our trial population, regardless of the diagnostic test used; however, tuberculosis test agreement is poor during infancy.

FUNDING

US National Institutes of Health.

Pragmatic cluster-randomized trial of home-based preventive treatment for TB in Ethiopia and South Africa (CHIP-TB)

BACKGROUND

Each year, 1 million children develop TB resulting in over 200,000 child deaths. TB preventive treatment (TPT) is highly effective in preventing TB but remains poorly implemented for household child contacts. Home-based child contact management and TPT services may improve access to care. In this study, we aim to evaluate the effectiveness and cost-effectiveness of home-based contact management with TPT initiation in two TB high-burden African countries, Ethiopia and South Africa.

METHODS

This pragmatic cluster randomized trial compares home-based versus facility-based care delivery models for contact management. Thirty-six clinics with decentralized TB services (18 in Ethiopia and 18 in South Africa) were randomized in a 1:1 ratio to conduct either home-based or facility-based contact management. The study will attempt to enroll all eligible close child contacts of infectious drug-sensitive TB index patients diagnosed and treated for TB by one of the study clinics. Child TB contact management, including contact tracing, child evaluation, and TPT initiation and follow-up, will take place in the child's home for the intervention arm and at the clinic for the control arm. The primary outcome is the cluster-level ratio of the number of household child contacts less than 15 years of age in Ethiopia and less than 5 years of age in South Africa initiated on TPT per index patient, comparing the intervention to the control arm. Secondary outcomes include child contact identification and the TB prevention continuum of care. Other implementation outcomes include acceptability, feasibility, fidelity, cost, and cost-effectiveness of the intervention.

DISCUSSION

This implementation research trial will determine whether home-based contact management identifies and initiates more household child contacts on TPT than facility-based contact management.

TRIAL REGISTRATION

NCT04369326 . Registered on April 30, 2020.

Cumulative Mycobacterium tuberculosis Infection Incidence (Measured Primarily by Tuberculin Skin Test) Among Infants With Human Immunodeficiency Virus Exposure: Observational Follow-up of an Isoniazid Prophylaxis Trial

Cumulative 24-month Mycobacterium tuberculosis infection incidence (measured primarily by tuberculin skin test [TST]) was high among human immunodeficiency virus exposed but uninfected infants (8.7 [95% confidence interval, 6.3-11.9] per 100 person-years). Trend for decreased TST positivity among infants at trial end (12 months postenrollment) randomized to isoniazid at 6 weeks of age was not sustained through observational follow-up to 24 months of age.

CLINICAL TRIALS REGISTRATION

NCT02613169.

Biomarkers of Tuberculous Meningitis and Pediatric Human Immunodeficiency Virus on the African Continent

Biomarkers in body fluids are helpful objective tools in diagnosis, prognosis and monitoring of (therapeutic) responses of many neurological diseases. Cerebrospinal fluid (CSF) biomarkers are part of the diagnostic toolbox for infectious neurological diseases. Tuberculous meningitis (TBM) and Human immunodeficiency virus (HIV), are important burdens of disease in Africa and can negatively affect brain health. Two thirds of the world's population of people living with HIV reside in sub-Saharan Africa and 25% of the global burden of tuberculosis (TB) is carried by the African continent. Neuroinflammation and damage of specific neuronal cell types are key constituents in the pathophysiology of these central nervous system (CNS) diseases, and important potential sources of circulating biomarkers. In this review, we summarize current research in the use of biomarkers in TBM and pediatric HIV as case demonstrations for high prevalence neurological diseases in Africa. Inflammatory molecules, primarily when detected in CSF, appear to have diagnostic value in these diseases, especially when measured as profiles. Brain injury molecules, such as S100, Neuron specific enolase and glial fibrillary acidic protein may have prognostic value in TBM, but more studies are needed. There is a need for more cost-economic and high sensitivity technologies to drive further biomarker discoveries and translate into healthcare improvements for these important healthcare problems in a globally fair way.

A Randomized Controlled Trial of Isoniazid to Prevent Mycobacterium tuberculosis Infection in Kenyan Human Immunodeficiency Virus-Exposed Uninfected Infants

BACKGROUND

Human immunodeficiency virus (HIV)-exposed uninfected (HEU) infants in endemic settings are at high risk of tuberculosis (TB). For infants, progression from primary Mycobacterium tuberculosis (Mtb) infection to TB disease can be rapid. We assessed whether isoniazid (INH) prevents primary Mtb infection.

METHODS

We conducted a randomized nonblinded controlled trial enrolling HEU infants 6 weeks of age without known TB exposure in Kenya. Participants were randomized (1:1) to 12 months of daily INH (10 mg/kg) vs no INH. Primary endpoint was Mtb infection at end of 12 months, assessed by interferon-γ release assay (QuantiFERON-TB Gold Plus) and/or tuberculin skin test (TST, added 6 months after first participant exit).

RESULTS

Between 15 August 2016 and 6 June 2018, 416 infants were screened, with 300 (72%) randomized to INH or no INH (150 per arm); 2 were excluded due to HIV infection. Among 298 randomized HEU infants, 12-month retention was 96.3% (287/298), and 88.9% (265/298) had primary outcome data. Mtb infection prevalence at 12-month follow-up was 10.6% (28/265); 7.6% (10/132) in the INH arm and 13.5% (18/133) in the no INH arm (7.0 vs 13.4 per 100 person-years; hazard ratio, 0.53 [95% confidence interval {CI}, .24-1.14]; P = .11]), and driven primarily by TST positivity (8.6% [8/93] in INH and 18.1% [17/94] in no INH; relative risk, 0.48 [95% CI, .22-1.05]; P = .07). Frequency of severe adverse events was similar between arms (INH, 14.0% [21/150] vs no INH, 10.7% [16/150]; P = .38), with no INH-related adverse events.

CONCLUSIONS

Further studies evaluating TB preventive therapy to prevent or delay primary Mtb infection in HEU and other high-risk infants are warranted.

CLINICAL TRIALS REGISTRATION

NCT02613169.

The utility of a modified WHO TB screening tool among children at a Botswana child welfare clinic

Background

In high TB/HIV settings, the increased risk for TB amongst children exposed to HIV has been established through biomedical tests. Screening HIV exposed children for TB can improve early childhood TB detection and treatment.

Objective

This study assessed the utility of a modified World Health Organization (WHO) tool by including HIV variables, to determine TB exposure amongst HIV exposed children presenting to a “Well Child” Clinic (CWC).

Methods

Clinical data were obtained from medical records and/or from the caregivers of children presenting to CWC. Data was analyzed to explore factors associated with positive screening for TB, including being exposed to HIV and current HIV status.

Results

Five percent (55/1100) screened reported a close TB contact and 21% (n=231) had positive TB symptom screen. History of close TB contact was a risk factor for positive screening for TB symptoms (OR 1.89 CI 1.05–3.4) while being HIV negative was protective (OR 0.3, Cl 0.19–0.62). HIV exposure was associated with increased risk of TB exposure (OR 2.9 CI 1.61–5.19).

Conclusion

Integrating HIV variables in the existing WHO screening tool for childhood TB can be useful in early detection and treatment of TB in HIV exposed children in resource limited settings.

Infant TB Infection Prevention Study (iTIPS): a randomised trial protocol evaluating isoniazid to prevent M. tuberculosis infection in HIV-exposed uninfected children

INTRODUCTION

HIV-exposed uninfected (HEU) infants in tuberculosis (TB) endemic settings are at high risk of Mycobacterium tuberculosis (Mtb) infection and TB disease, even in the absence of known Mtb exposure. Because infancy is a time of rapid progression from primary infection to active TB disease, it is important to define when and how TB preventive interventions exert their effect in order to develop effective prevention strategies in this high-risk population.

METHODS AND ANALYSIS

We designed a non-blinded randomised controlled trial to determine efficacy of isoniazid (INH) to prevent primary Mtb infection among HEU children. Target sample size is 300 (150 infants in each arm). Children are enrolled at 6 weeks of age from maternal and child health clinics in Kenya and are randomised to receive 12 months of daily INH ~10 mg/kg plus pyridoxine or no INH. The primary endpoint is Mtb infection, assessed by interferon-gamma release assay QuantiFERON-TB Gold Plus (QFT-Plus) or tuberculin skin test after 12 months post-enrolment. Secondary outcomes include severe adverse events, expanded Mtb infection definition using additional QFT-Plus supernatant markers and determining correlates of Mtb infection. Exploratory analyses include a combined outcome of TB infection, disease and mortality, and sensitivity analyses excluding infants with baseline TB-specific responses on flow cytometry.

ETHICS AND DISSEMINATION

An external and independent Data and Safety Monitoring Board monitors adverse events. Results will be disseminated through peer-reviewed journals, presentations at local and international conferences to national and global policy-makers, the local community and participants.

TRIAL REGISTRATION NUMBER

NCT02613169; Pre-results.

Paediatric tuberculosis transmission outside the household: challenging historical paradigms to inform future public health strategies

Tuberculosis is a major cause of death and disability among children globally, yet children have been neglected in global tuberculosis control efforts. Historically, tuberculosis in children has been thought of as a family disease, and because of this, household contact tracing of children after identification of an adult tuberculosis case has been emphasised as the principal public health intervention. However, the population-level effect of household contact tracing is predicated on the assumption that most paediatric tuberculosis infections are acquired within the household. In this Personal View, we focus on accumulating scientific evidence indicating that the majority of Mycobacterium tuberculosis transmission to children in high-burden settings occurs in the community, outside of households in which a person has tuberculosis. We estimate the population-attributable fraction of M tuberculosis transmission to children due to household exposures to be between 10% and 30%. M tuberculosis transmission from the household was low (<30%) even in children younger than age 5 years. We propose that an effective public health response to childhood tuberculosis requires comprehensive, community-based interventions, such as active surveillance in select settings, rather than contact tracing alone. Importantly, the historical paradigm that most paediatric transmission occurs in households should be reconsidered on the basis of the scientific knowledge presented.

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

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

High Incidence of Tuberculosis Infection in HIV-exposed Children Exiting an Isoniazid Preventive Therapy Trial

Young HIV-exposed children are at high risk for TB infection. We performed QuantiFERON-TB Gold among HIV-exposed children in South Africa at enrolment and 1-year follow-up. The incidence of TB infection was high for HIV+ (11 cases per 100 child-years) and HIV-exposed uninfected children (15 cases per 100 child-years). QuantiFERON-TB Gold may identify HIV-exposed children at risk for TB disease progression.

Integrating tuberculosis screening in Kenyan Prevention of Mother-To-Child Transmission programs

BACKGROUND

Tuberculosis (TB) screening in Prevention of Mother-To-Child Transmission (PMTCT) programs is important to improve TB detection, prevention and treatment.

METHODS

As part of a national PMTCT program evaluation, mother-infant pairs attending 6-week and 9-month immunization visits were enrolled at 141 maternal and child health clinics throughout Kenya. Clinics were selected using population-proportion-to-size sampling with oversampling in a high human immunodeficiency virus (HIV) prevalence region. The World Health Organization (WHO) TB symptom screen was administered to HIV-infected mothers, and associations with infant cofactors were determined.

RESULTS

Among 498 HIV-infected mothers, 165 (33%) had a positive TB symptom screen. Positive maternal TB symptom screen was associated with prior TB (P = 0.04). Women with a positive TB symptom screen were more likely to have an infant with HIV infection (P = 0.02) and non-specific TB symptoms, including cough (P = 0.003), fever (P = 0.05), and difficulty breathing (P = 0.01). TB exposure was reported by 11% of the women, and 15% of the TB-exposed women received isoniazid preventive therapy.

CONCLUSIONS

Postpartum HIV-infected mothers frequently had a positive TB symptom screen. Mothers with a positive TB symptom screen were more likely to have infants with HIV or non-specific TB symptoms. Integration of maternal TB screening and prevention into PMTCT programs may improve maternal and infant outcomes.

Maternal HIV and Paediatric Lung Health

With improved prevention of mother to child transmission of HIV, paediatric HIV disease is less common. However, the number of HIV exposed but uninfected infants is growing. Exposure to maternal HIV impacts infant respiratory health through an increase in known risk factors such as increased preterm birth and low birth weight, suboptimal breastfeeding, increased psychosocial stressors and increased exposure to infective pathogens. Exposure to the HIV virus and altered maternal immune environment result in immunologic changes in the infant that may contribute to respiratory disease risk. HIV exposed infants are at increased risk for severe pneumonia with poorer outcomes compared to unexposed infants. Maternal ART and optimal nutrition, including breastfeeding in high infective disease burden settings, reduce morbidity and mortality in HIV exposed infants and should be prioritized. The impact of exposure to maternal HIV on normal lung growth and risk for chronic respiratory disease is unknown and warrants further investigation.

Tuberculosis Infection in Early Childhood and the Association with HIV-exposure in HIV-uninfected Children in Rural Uganda

BACKGROUND

In high tuberculosis (TB) burden countries, a significant proportion of the latent TB reservoir is established by the age 5 years. There are critical knowledge gaps in our understanding of the age-specific prevalence of TB infection and the influence of HIV exposure on TB infection in the first 5 years of life among HIV-uninfected children in sub-Saharan Africa.

METHODS

We measured TB infection with the Quantiferon Gold-in-Tube (QFT) and tuberculin skin tests (TST) in 447 children ≤60 months and their 284 HIV-infected and IV-uninfected mothers in rural Uganda.

RESULTS

The overall prevalence of TB infection in children ≤60 months by TST was 24% (95% confidence intervals [CI]: 19.9-27.9). The prevalence of TST positivity was highest among children in their first year of life (36%; 95% CI: 26.0-45.9) and declined with age to 19% at 36-60 months of age, χ test for trend P = 0.014. In contrast, 4% (95% CI: 1.9-5.87%) of children had a positive QFT, and there was no trend detected with age, P = 0.576. QFT positivity was detected as early as 5 months. HIV-exposed uninfected children had significantly higher odds of TB infection by QFT (odds ratio [OR]: 21.2; P = 0.008; 95% CI: 2.2-204.7) or positive TST or QFT (OR, 2.4; P = 0.020; 95% CI: 1.2-5.1) compared with HIV-unexposed uninfected children, adjusting for age, BCG vaccination and a positive maternal TST or QFT.

CONCLUSIONS

An appreciable prevalence of TB infection was detected in early childhood. HIV-exposed uninfected children have a higher risk for TB infection compared with children born to HIV-uninfected mothers.

Tuberculosis interferon-gamma responses in the breast milk of human immunodeficiency virus infected mothers

Tuberculosis (TB) cellular immune responses were examined in the breast milk of human immunodeficiency virus infected mothers using the T-SPOT. TB interferon-gamma release assay (IGRA). Positive TB interferon-gamma (IFN-γ) responses were detected in 6 of 8 (75%) valid breast milk assays. Among 7 mothers with paired breast milk and blood assays, TB IFN-γ responses were higher in breast milk than in blood (P = 0.02). The magnitude of TB IFN-γ responses in maternal breast milk and blood were correlated. Elucidating the influence of TB immune responses in breast milk on infant TB susceptibility and immunity may inform future maternal TB vaccine strategies.