Tuberculosis decline in populations affected by HIV: a retrospective study of 12 countries in the WHO African Region

Impact of Community-Wide Tuberculosis Active Case Finding and Human Immunodeficiency Virus Testing on Tuberculosis Trends in Malawi

BACKGROUND

Tuberculosis case-finding interventions are critical to meeting World Health Organization End TB strategy goals. We investigated the impact of community-wide tuberculosis active case finding (ACF) alongside scale-up of human immunodeficiency virus (HIV) testing and care on trends in adult tuberculosis case notification rates (CNRs) in Blantyre, Malawi.

METHODS

Five rounds of ACF for tuberculosis (1-2 weeks of leafleting, door-to-door enquiry for cough and sputum microscopy) were delivered to neighborhoods ("ACF areas") in North-West Blantyre between April 2011 and August 2014. Many of these neighborhoods also had concurrent HIV testing interventions. The remaining neighborhoods in Blantyre City ("non-ACF areas") provided a non-randomized comparator. We analyzed TB CNRs from January 2009 until December 2018. We used interrupted time series analysis to compare tuberculosis CNRs before ACF and after ACF, and between ACF and non-ACF areas.

RESULTS

Tuberculosis CNRs increased in Blantyre concurrently with start of ACF for tuberculosis in both ACF and non-ACF areas, with a larger magnitude in ACF areas. Compared to a counterfactual where pre-ACF CNR trends continued during ACF period, we estimated there were an additional 101 (95% confidence interval [CI] 42 to 160) microbiologically confirmed (Bac+) tuberculosis diagnoses per 100 000 person-years in the ACF areas in 3 and a half years of ACF. Compared to a counterfactual where trends in ACF area were the same as trends in non-ACF areas, we estimated an additional 63 (95% CI 38 to 90) Bac + diagnoses per 100 000 person-years in the same period.

CONCLUSIONS

Tuberculosis ACF was associated with a rapid increase in people diagnosed with tuberculosis in Blantyre.

Transmission modeling to infer tuberculosis incidence prevalence and mortality in settings with generalized HIV epidemics

Tuberculosis (TB) killed more people globally than any other single pathogen over the past decade. Where surveillance is weak, estimating TB burden estimates uses modeling. In many African countries, increases in HIV prevalence and antiretroviral therapy have driven dynamic TB epidemics, complicating estimation of burden, trends, and potential intervention impact. We therefore develop a novel age-structured TB transmission model incorporating evolving demographic, HIV and antiretroviral therapy effects, and calibrate to TB prevalence and notification data from 12 African countries. We use Bayesian methods to include uncertainty for all TB model parameters, and estimate age-specific annual risks of TB infection, finding up to 16.0%/year in adults, and the proportion of TB incidence from recent (re)infection, finding a mean across countries of 34%. Rapid reduction of the unacceptably high burden of TB in high HIV prevalence settings will require interventions addressing progression as well as transmission.

Impact of interventions for tuberculosis prevention and care in South Africa - a systematic review of mathematical modelling studies

BACKGROUND

Substantial additional efforts are needed to prevent, find and successfully treat tuberculosis (TB) in South Africa (SA). In thepast decade, an increasing body of mathematical modelling research has investigated the population-level impact of TB prevention and careinterventions. To date, this evidence has not been assessed in the SA context.

OBJECTIVE

To systematically review mathematical modelling studies that estimated the impact of interventions towards the World HealthOrganization's End TB Strategy targets for TB incidence, TB deaths and catastrophic costs due to TB in SA.

METHODS

We searched the PubMed, Web of Science and Scopus databases for studies that used transmission-dynamic models of TB in SAand reported on at least one of the End TB Strategy targets at population level. We described study populations, type of interventions andtheir target groups, and estimates of impact and other key findings. For studies of country-level interventions, we estimated average annualpercentage declines (AAPDs) in TB incidence and mortality attributable to the intervention.

RESULTS

We identified 29 studies that met our inclusion criteria, of which 7 modelled TB preventive interventions (vaccination,antiretroviral treatment (ART) for HIV, TB preventive treatment (TPT)), 12 considered interventions along the care cascade for TB(screening/case finding, reducing initial loss to follow-up, diagnostic and treatment interventions), and 10 modelled combinationsof preventive and care-cascade interventions. Only one study focused on reducing catastrophic costs due to TB. The highest impactof a single intervention was estimated in studies of TB vaccination, TPT among people living with HIV, and scale-up of ART. Forpreventive interventions, AAPDs for TB incidence varied between 0.06% and 7.07%, and for care-cascade interventions between 0.05%and 3.27%.

CONCLUSION

We describe a body of mathematical modelling research with a focus on TB prevention and care in SA. We found higherestimates of impact reported in studies of preventive interventions, highlighting the need to invest in TB prevention in SA. However, studyheterogeneity and inconsistent baseline scenarios limit the ability to compare impact estimates between studies. Combinations, rather thansingle interventions, are likely needed to reach the End TB Strategy targets in SA.

The impact of HIV and tuberculosis interventions on South African adult tuberculosis trends, 1990-2019: a mathematical modeling analysis

OBJECTIVES

To quantify the South African adult tuberculosis (TB) incidence and mortality attributable to HIV between 1990 and 2019 and to estimate the reduction in TB incidence due to directly observed therapy, antiretroviral therapy (ART), isoniazid preventive therapy, increased TB screening, and Xpert MTB/RIF.

METHODS

We developed a dynamic TB transmission model for South Africa. A Bayesian approach was used to calibrate the model to South African-specific data sources. Counterfactual scenarios were simulated to estimate TB incidence and mortality attributable to HIV and the impact of interventions on TB incidence.

RESULTS

Between 1990 and 2019, 8.8 million (95% confidence interval [CI] 8.3-9.3 million) individuals developed TB, and 2.1 million (95% CI 2.0-2.2 million) died from TB. A total of 55% and 69% of TB cases and mortality were due to HIV, respectively. Overall, TB screening and ART substantially reduced TB incidence by 28.2% (95% CI 26.4-29.8%) and 20.0% (95% CI 19.2-20.7%), respectively, in 2019; other interventions had minor impacts.

CONCLUSION

HIV has dramatically increased TB incidence and mortality in South Africa. The provision of ART and intensification of TB screening explained most recent declines in TB incidence.

Gender differences among patients with drug resistant tuberculosis and HIV co-infection in Uganda: a countrywide retrospective cohort study

BACKGROUND

Gender differences among patients with drug resistant tuberculosis (DRTB) and HIV co-infection could affect treatment outcomes. We compared characteristics and treatment outcomes of DRTB/HIV co-infected men and women in Uganda.

METHODS

We conducted a retrospective chart review of patients with DRTB from 16 treatment sites in Uganda. Eligible patients were aged ≥ 18 years, had confirmed DRTB, HIV co-infection and a treatment outcome registered between 2013 and 2019. We compared socio-demographic and clinical characteristics and tuberculosis treatment outcomes between men and women. Potential predictors of mortality were determined by cox proportional hazard regression analysis that controlled for gender. Statistical significance was set at p < 0.05.

RESULTS

Of 666 DRTB/HIV co-infected patients, 401 (60.2%) were men. The median (IQR) age of men and women was 37.0 (13.0) and 34.0 (13.0) years respectively (p < 0.001). Men were significantly more likely to be on tenofovir-based antiretroviral therapy (ART), high-dose isoniazid-containing DRTB regimen and to have history of cigarette or alcohol use. They were also more likely to have multi-drug resistant TB, isoniazid and streptomycin resistance and had higher creatinine, aspartate and gamma-glutamyl aminotransferase and total bilirubin levels. Conversely, women were more likely to be unemployed, unmarried, receive treatment from the national referral hospital and to have anemia, a capreomycin-containing DRTB regimen and zidovudine-based ART. Treatment success was observed among 437 (65.6%) and did not differ between the genders. However, mortality was higher among men than women (25.7% vs. 18.5%, p = 0.030) and men had a shorter mean (standard error) survival time (16.8 (0.42) vs. 19.0 (0.46) months), Log Rank test (p = 0.046). Predictors of mortality, after adjusting for gender, were cigarette smoking (aHR = 4.87, 95% CI 1.28-18.58, p = 0.020), an increase in alanine aminotransferase levels (aHR = 1.05, 95% CI 1.02-1.07, p < 0.001), and history of ART default (aHR = 3.86, 95% CI 1.31-11.37, p = 0.014) while a higher baseline CD4 count was associated with lower mortality (aHR = 0.94, 95% CI 0.89-0.99, p = 0.013 for every 10 cells/mm³ increment).

CONCLUSION

Mortality was higher among men than women with DRTB/HIV co-infection which could be explained by several sociodemographic and clinical differences.

Gaps related to screening and diagnosis of tuberculosis in care cascade in selected health facilities in East Africa countries: A retrospective study

Introduction

East Africa countries (Tanzania, Kenya, and Uganda) are among tuberculosis high burdened countries globally. As we race to accelerate progress towards a world free of tuberculosis by 2035, gaps related to screening and diagnosis in the cascade care need to be addressed.

Methods

We conducted a three-year (2015–2017) retrospective study using routine program data in 21 health facilities from East Africa. Data abstraction were done at tuberculosis clinics, outpatient departments (OPD), human immunodeficiency virus (HIV) and diabetic clinics, and then complemented with structured interviews with healthcare providers to identify possible gaps related to integration, screening, and diagnosis of tuberculosis. Data were analyzed using STATA™ Version 14.1.

Results

We extracted information from 49,454 presumptive TB patients who were registered in the 21 facilities between January 2015 and December 2017. A total of 9,565 tuberculosis cases were notified; 46.5% (4,450) were bacteriologically confirmed and 31.5% (3,013) were HIV-infected. Prevalence of tuberculosis among presumptive pulmonary tuberculosis cases was 17.4%. The outcomes observed were as follows: 79.8% (7,646) cured or completed treatment, 6.6% (634) died, 13.3% (1,270) lost to follow-up or undocumented and 0.4% (34) treatment failure. In all countries, tuberculosis screening was largely integrated at OPD and HIV clinics. High patient load, weak laboratory specimen referral system, shortage of trained personnel, and frequent interruption of laboratory supplies were the major cited challenges in screening and diagnosis of tuberculosis.

Conclusion

Screening and diagnostic activities were frequently affected by scarcity of human and financial resources. Tuberculosis screening was mainly integrated at OPD and HIV clinics, with less emphasis on the other health facility clinics. Closing gaps related to TB case finding and diagnosis in developing countries requires sustainable investment for both human and financial resources and strengthen the integration of TB activities within the health system.

Computer-aided X-ray screening for tuberculosis and HIV testing among adults with cough in Malawi (the PROSPECT study): A randomised trial and cost-effectiveness analysis

BACKGROUND

Suboptimal tuberculosis (TB) diagnostics and HIV contribute to the high global burden of TB. We investigated costs and yield from systematic HIV-TB screening, including computer-aided digital chest X-ray (DCXR-CAD).

METHODS AND FINDINGS

In this open, three-arm randomised trial, adults (≥18 years) with cough attending acute primary services in Malawi were randomised (1:1:1) to standard of care (SOC); oral HIV testing (HIV screening) and linkage to care; or HIV testing and linkage to care plus DCXR-CAD with sputum Xpert for high CAD4TBv5 scores (HIV-TB screening). Participants and study staff were not blinded to intervention allocation, but investigator blinding was maintained until final analysis. The primary outcome was time to TB treatment. Secondary outcomes included proportion with same-day TB treatment; prevalence of undiagnosed/untreated bacteriologically confirmed TB on day 56; and undiagnosed/untreated HIV. Analysis was done on an intention-to-treat basis. Cost-effectiveness analysis used a health-provider perspective. Between 15 November 2018 and 27 November 2019, 8,236 were screened for eligibility, with 473, 492, and 497 randomly allocated to SOC, HIV, and HIV-TB screening arms; 53 (11%), 52 (9%), and 47 (9%) were lost to follow-up, respectively. At 56 days, TB treatment had been started in 5 (1.1%) SOC, 8 (1.6%) HIV screening, and 15 (3.0%) HIV-TB screening participants. Median (IQR) time to TB treatment was 11 (6.5 to 38), 6 (1 to 22), and 1 (0 to 3) days (hazard ratio for HIV-TB versus SOC: 2.86, 1.04 to 7.87), with same-day treatment of 0/5 (0%) SOC, 1/8 (12.5%) HIV, and 6/15 (40.0%) HIV-TB screening arm TB patients (p = 0.03). At day 56, 2 SOC (0.5%), 4 HIV (1.0%), and 2 HIV-TB (0.5%) participants had undiagnosed microbiologically confirmed TB. HIV screening reduced the proportion with undiagnosed or untreated HIV from 10 (2.7%) in the SOC arm to 2 (0.5%) in the HIV screening arm (risk ratio [RR]: 0.18, 0.04 to 0.83), and 1 (0.2%) in the HIV-TB screening arm (RR: 0.09, 0.01 to 0.71). Incremental costs were US$3.58 and US$19.92 per participant screened for HIV and HIV-TB; the probability of cost-effectiveness at a US$1,200/quality-adjusted life year (QALY) threshold was 83.9% and 0%. Main limitations were the lower than anticipated prevalence of TB and short participant follow-up period; cost and quality of life benefits of this screening approach may accrue over a longer time horizon.

CONCLUSIONS

DCXR-CAD with universal HIV screening significantly increased the timeliness and completeness of HIV and TB diagnosis. If implemented at scale, this has potential to rapidly and efficiently improve TB and HIV diagnosis and treatment.

TRIAL REGISTRATION

clinicaltrials.gov NCT03519425.

Assessment of the tuberculosis case-finding and prevention cascade among people living with HIV in Zambia - 2018: a cross-sectional cluster survey

BACKGROUND

The Ministry of Health Zambia recommends tuberculosis preventive treatment (TPT) with 6 months daily isoniazid for all people living with human immunodeficiency virus (HIV) after ruling out active tuberculosis disease. We sought to estimate the percentage of people living with HIV who progress through each stage of the tuberculosis case-finding and prevention cascade in two provinces with the highest tuberculosis burden in Zambia.

METHODS

In this cross-sectional survey, we used a two-stage cluster sampling method. We sampled 12 healthcare facilities with probability proportional to size. Patient volume determined facility cluster size. During October 2018, from each facility we systematically sampled medical records of adults and children living with HIV. Our primary outcome of interest was TPT initiation rate among eligible people living with HIV, weighted for complex survey design. The Rao-Scott adjusted chi-square test was used to test for differences in TPT initiation rate and other indicators from the tuberculosis prevention cascade by age group and province of residence. Additionally, we conducted semi-structured interviews with healthcare workers at each facility to assess TPT knowledge and identify challenges to its implementation.

RESULTS

We sampled 482 records of people living with HIV (including 128 children living with HIV). Excluding two people diagnosed with tuberculosis disease before enrollment in HIV care, 93.4% underwent tuberculosis symptom screening. Of those, 4.7% were diagnosed with tuberculosis disease and 95.3% were TPT-eligible, of whom 24.7% initiated TPT. TPT initiation was lower among eligible children (7.7%) compared with adults (25.2%, p = 0.03) and Copperbelt residents (3.1%) compared with Lusaka residents (35.8%, p < 0.01). TPT completion rate was 38.4% among people living with HIV who initiated the 6-month course. Among interviewed healthcare workers, 58.3% (unweighted) incorrectly relayed the number of symptoms needed for a positive tuberculosis symptom screen, 83.3% (unweighted) reported insufficient isoniazid stockpile for completion at the time of TPT initiation, and only 27.3% (unweighted) reported receiving TPT-specific training.

CONCLUSIONS

TPT uptake among people living with HIV in Zambia is challenged by inconsistent tuberculosis screening, lack of TPT training for healthcare workers, and supply chain inefficiencies. Addressing these barriers may increase TPT initiations and improve outcomes among people living with HIV.

Antiretroviral Treatment-Induced Decrease in Immune Activation Contributes to Reduced Susceptibility to Tuberculosis in HIV-1/Mtb Co-infected Persons

Antiretroviral treatment (ART) reduces the risk of developing active tuberculosis (TB) in HIV-1 co-infected persons. In order to understand host immune responses during ART in the context of Mycobacterium tuberculosis (Mtb) sensitization, we performed RNAseq analysis of whole blood-derived RNA from individuals with latent TB infection coinfected with HIV-1, during the first 6 months of ART. A significant fall in RNA sequence abundance of the Hallmark IFN-alpha, IFN-gamma, IL-6/JAK/STAT3 signaling, and inflammatory response pathway genes indicated reduced immune activation and inflammation at 6 months of ART compared to day 0. Further exploratory evaluation of 65 soluble analytes in plasma confirmed the significant decrease of inflammatory markers after 6 months of ART. Next, we evaluated 30 soluble analytes in QuantiFERON Gold in-tube (QFT) samples from the Ag stimulated and Nil tubes, during the first 6 months of ART in 30 patients. There was a significant decrease in IL-1alpha and IL-1beta (Ag-Nil) concentrations as well as MCP-1 (Nil), supporting decreased immune activation and inflammation. At the same time, IP-10 (Ag-nil) concentrations significantly increased, together with chemokine receptor-expressing CD4 T cell numbers. Our data indicate that ART-induced decrease in immune activation combined with improved antigen responsiveness may contribute to reduced susceptibility to tuberculosis in HIV-1/Mtb co-infected persons.

The scale-up of antiretroviral therapy coverage was strongly associated with the declining tuberculosis morbidity in Africa during 2000-2018

OBJECTIVES

Antiretroviral therapy (ART) reduces the risk of tuberculosis (TB). We aimed to examine the association between ART coverage scale-up on the changes in TB incidence in Africa from 2000 to 2018.

STUDY DESIGN

The design of the study is a retrospective ecological study.

METHODS

Data for 54 countries were obtained from several institutional-based sources, including the World Health Organization, the Joint United Nations Programme on HIV/AIDS, and the World Bank. A fixed-effects regression method of longitudinal data analysis was used to estimate the association between ART coverage and changes in TB incidence rate during 2000-2018. Statistical analyses were conducted using STATA 15.0/IC.

RESULTS

The TB incidence declined significantly, by an average of 2.3% per year during 2000-2018. The highest significant declines occurred in eastern and southern Africa. In adjusted analysis, each 1% increase in ART coverage was associated with a 3.97 per 100,000 decline of TB incidence. However, the marginal effects of ART on overall population TB incidence was dependent on the prevalence of human immunodeficiency virus infection.

CONCLUSIONS

Investment in the widespread scale-up of ART may contribute to the control of the TB epidemic in Africa. However, interventions are also needed to augment the effect of ART on population TB incidence.

Activation-Induced Marker Expression Identifies Mycobacterium tuberculosis-Specific CD4 T Cells in a Cytokine-Independent Manner in HIV-Infected Individuals with Latent Tuberculosis

HIV infection is a significant risk factor for reactivation of latent Mycobacterium tuberculosis infection (LTBI) and progression to active tuberculosis disease, yet the mechanisms whereby HIV impairs T cell immunity to M. tuberculosis have not been fully defined. Evaluation of M. tuberculosis–specific CD4 T cells is commonly based on IFN-γ production, yet increasing evidence indicates the immune response to M. tuberculosis is heterogeneous and encompasses IFN-γ–independent responses. We hypothesized that upregulation of surface activation-induced markers (AIM) would facilitate detection of human M. tuberculosis–specific CD4 T cells in a cytokine-independent manner in HIV-infected and HIV-uninfected individuals with LTBI. PBMCs from HIV-infected and HIV-uninfected adults in Kenya were stimulated with CFP-10 and ESAT-6 peptides and evaluated by flow cytometry for upregulation of the activation markers CD25, OX40, CD69, and CD40L. Although M. tuberculosis–specific IFN-γ and IL-2 production was dampened in HIV-infected individuals, M. tuberculosis–specific CD25⁺OX40⁺ and CD69⁺CD40L⁺ CD4 T cells were detectable in the AIM assay in both HIV-uninfected and HIV-infected individuals with LTBI. Importantly, the frequency of M. tuberculosis–specific AIM⁺ CD4 T cells was not directly impacted by HIV viral load or CD4 count, thus demonstrating the feasibility of AIM assays for analysis of M. tuberculosis–specific CD4 T cells across a spectrum of HIV infection states. These data indicate that AIM assays enable identification of M. tuberculosis–specific CD4 T cells in a cytokine-independent manner in HIV-uninfected and HIV-infected individuals with LTBI in a high-tuberculosis burden setting, thus facilitating studies to define novel T cell correlates of protection to M. tuberculosis and elucidate mechanisms of HIV-associated dysregulation of antimycobacterial immunity.

Tuberculosis Antigen-Specific T-Cell Responses During the First 6 Months of Antiretroviral Treatment

The reconstitution of Mycobacterium tuberculosis antigen-specific CD4 T cells in a cohort of HIV-infected persons starting antiretroviral treatment (ART) in a high tuberculosis endemic area is described. Restoration of the antigen-specific CD4 T-cell subsets mirrored the overall CD4 T-cell compartment. Activation (assessed by HLA-DR expression) decreased during ART but remained elevated compared to HIV-uninfected persons. Despite known M. tuberculosis sensitization determined by interferon-γ release assay, 12/23 participants had no M. tuberculosis-specific CD4 T cells detectable by flow cytometry, combined with overall elevated T-cell activation and memory differentiation, suggesting heightened turnover. Our data suggest early ART initiation to maintain polyfunctional immune memory responses.

Trend of tuberculosis case notifications and their determinants in Africa and South-East Asia during 2000-2018: a longitudinal analysis of national data from 58 countries

Background: The World Health Organization (WHO) regions of Africa and South-East Asia are the epicentres of the global tuberculosis (TB) epidemic. This study aimed at examining the trend and determinants of TB case notifications in the two regions during 2000-2018.Methods: This was a retrospective analysis of yearly, new TB cases notified to the WHO. We obtained data on potential determinants for the 58 countries in the two regions during 2000-2018. Multivariable longitudinal fixed-effects regression analysis was used to quantify the association between the determinants and TB notifications.Results: During 2000-2018, TB notifications and incidence declined in Africa. In South-East Asia, case notifications increased while the incidence declined, on average, by 2% per year during the same period. After controlling for health, socioeconomic indicators, country and year fixed-effects, each 1% increase in the antiretroviral therapy (ART) coverage and the TB treatment success was associated with a decrease per 100,000 population in the TB case notification rate of -1.62 (95% CI: -4.93, -1.90; p = .037) and -0.91(95% CI: -1.54, -0.28; p = .005) respectively. Similarly, each 1-year increase in the life expectancy at birth resulted in a decrease in TB case notification rates of -6.64 (95% CI: -12.32, -0.95; p = .037). By contrast, a 1% increase in the unemployment rate resulted in an increase in TB notification rate of 3.49 cases (95% CI: 0.19, 6.79; p = .039).Conclusion: Improving population health and the broad scale-up of ART coverage could complement existing TB treatment coverage and cure programmes to drive down new cases in Africa and South-East Asia.

Prevalence and risk factors for latent tuberculosis infection among household contacts of index cases in two South African provinces: Analysis of baseline data from a cluster-randomised trial

INTRODUCTION

Household contacts of patients with active pulmonary tuberculosis (TB) often have latent TB infection, and are at risk of progression to disease. We set out to investigate whether index TB case HIV status was linked to a higher probability of latent TB infection among household contacts.

MATERIALS AND METHODS

Data were collected prospectively from participants in the intervention arm of a household cluster-randomised trial in two South Africa provinces (Mangaung, Free State, and Capricorn, Limpopo). In intervention group households, TB contacts underwent HIV testing and tuberculin skin testing (TST). TST induration was estimated at two cut-offs (≥5mm, ≥10mm). Multilevel Bayesian regression models estimated posterior distributions of the percentage of household contacts with TST induration ≥5mm and ≥10mm by age group, and compared the odds of latent TB infection by key risk factors including HIV status index case age and study province.

RESULTS

A total of 2,985 household contacts of 924 index cases were assessed, with most 2,725 (91.3%) undergoing TST. HIV prevalence in household contacts was 14% and 10% in Mangaung and Capricorn respectively. Overall, 16.8% (458/2,725) had TST induration of ≥5mm and 13.1% (359/2,725) ≥10mm. In Mangaung, children aged 0-4 years had a high TST positivity prevalence compared to their peers in Capricorn (22.0% vs. 7.6%, and 20.5% vs. 2.3%, using TST thresholds of ≥5mm and ≥10mm respectively). Compared to contacts from Capricorn, household contacts living in Mangaung were more likely to have TST induration ≥5mm (odds ratio [OR]: 3.08, 95% credibility interval [CI]: 2.13-4.58) and ≥10mm (OR: 4.52, 95% CI: 3.03-6.97). There was a 90% and 92% posterior probability that the odds of TST induration ≥5mm (OR: 0.79, 95% CI: 0.56-1.14) and ≥10mm (OR: 0.77, 95% CI: 0.53-1.10) respectively were lower in household contacts of HIV-positive compared to HIV-negative index cases.

CONCLUSIONS

High TST induration positivity, especially among young children and people living in Mangaung indicates considerable TB transmission despite high antiretroviral therapy coverage. Household contact of HIV-positive index TB cases were less likely to have evidence of latent TB infection than contacts of HIV-negative index cases.

Immune Phenotype and Functionality of Mtb-Specific T-Cells in HIV/TB Co-Infected Patients on Antiretroviral Treatment

The performance of host blood-based biomarkers for tuberculosis (TB) in HIV-infected patients on antiretroviral therapy (ART) has not been fully assessed. We evaluated the immune phenotype and functionality of antigen-specific T-cell responses in HIV positive (+) participants with TB (n = 12) compared to HIV negative (-) participants with either TB (n = 9) or latent TB infection (LTBI) (n = 9). We show that the cytokine profile of Mtb-specific CD4+ T-cells in participants with TB, regardless of HIV status, was predominantly single IFN-γ or dual IFN-γ/ TNFα. Whilst ESAT-6/CFP-10 responding T-cells were predominantly of an effector memory (CD27-CD45RA-CCR7-) profile, HIV-specific T-cells were mainly of a central (CD27+CD45RA-CCR7+) and transitional memory (CD27+CD45RA+/-CCR7-) phenotype on both CD4+ and CD8+ T-cells. Using receiving operating characteristic (ROC) curve analysis, co-expression of CD38 and HLA-DR on ESAT-6/CFP-10 responding total cytokine-producing CD4+ T-cells had a high sensitivity for discriminating HIV+TB (100%, 95% CI 70-100) and HIV-TB (100%, 95% CI 70-100) from latent TB with high specificity (100%, 95% CI 68-100 for HIV-TB) at a cut-off value of 5% and 13%, respectively. TB treatment reduced the proportion of Mtb-specific total cytokine+CD38+HLA-DR+ CD4+ T-cells only in HIV-TB (p = 0.001). Our results suggest that co-expression of CD38 and HLA-DR on Mtb-specific CD4+ T-cells could serve as a TB diagnosis tool regardless of HIV status.

The Mtb-HIV syndemic interaction: why treating M. tuberculosis infection may be crucial for HIV-1 eradication

Accelerated tuberculosis and AIDS progression seen in HIV-1 and Mycobacterium tuberculosis (Mtb)-coinfected individuals indicates the important interaction between these syndemic pathogens. The immunological interaction between HIV-1 and Mtb has been largely defined by how the virus exacerbates tuberculosis disease pathogenesis. Understanding of the mechanisms by which pre-existing or subsequent Mtb infection may favor the replication, persistence and progression of HIV, is less characterized. We present a rationale for the critical consideration of ‘latent’ Mtb infection in HIV-1 prevention and cure strategies. In support of this position, we review evidence of the effect of Mtb infection on HIV-1 acquisition, replication and persistence. We propose that ‘latent’ Mtb infection may have considerable impact on HIV-1 pathogenesis and the continuing HIV-1 epidemic in sub-Saharan Africa.

Adolescent tuberculosis

Adolescence is characterised by a substantial increase in the incidence of tuberculosis, a known fact since the early 20th century. Most of the world's adolescents live in low-income and middle-income countries where tuberculosis remains common, and where they comprise a quarter of the population. Despite this, adolescents have not yet been addressed as a distinct population in tuberculosis policy or within tuberculosis treatment services, and emerging evidence suggests that current models of care do not meet their needs. This Review discusses up-to-date information about tuberculosis in adolescence, with a focus on the management of infection and disease, including HIV co-infection and rifampicin-resistant tuberculosis. We outline the progress in vaccine development and highlight important directions for future research.

Decreased risk of HIV-associated TB during antiretroviral therapy expansion in rural Eswatini from 2009 to 2016: a cohort and population-based analysis

OBJECTIVES

This paper assesses patient- and population-level trends in TB notifications during rapid expansion of antiretroviral therapy in Eswatini which has an extremely high incidence of both TB and HIV.

METHODS

Patient- and population-level predictors and rates of HIV-associated TB were examined in the Shiselweni region in Eswatini from 2009 to 2016. Annual population-level denominators obtained from projected census data and prevalence estimates obtained from population-based surveys were combined with individual-level TB treatment data. Patient- and population-level predictors of HIV-associated TB were assessed with multivariate logistic and multivariate negative binomial regression models.

RESULTS

Of 11 328 TB cases, 71.4% were HIV co-infected and 51.8% were women. TB notifications decreased fivefold between 2009 and 2016, from 1341 to 269 cases per 100 000 person-years. The decline was sixfold in PLHIV vs. threefold in the HIV-negative population. Main patient-level predictors of HIV-associated TB were recurrent TB treatment (adjusted odds ratio [aOR] 1.40, 95% confidence interval [CI]: 1.19-1.65), negative (aOR 1.31, 1.15-1.49) and missing (aOR 1.30, 1.11-1.53) bacteriological status and diagnosis at secondary healthcare level (aOR 1.18, 1.06-1.33). Compared with 2009, the probability of TB decreased for all years from 2011 (aOR 0.69, 0.58-0.83) to 2016 (aOR 0.54, 0.43-0.69). The most pronounced population-level predictor of TB was HIV-positive status (adjusted incidence risk ratio 19.47, 14.89-25.46).

CONCLUSIONS

This high HIV-TB prevalence setting experienced a rapid decline in TB notifications, most pronounced in PLHIV. Achievements in HIV-TB programming were likely contributing factors.

Successful expansion of community-based drug-resistant TB care in rural Eswatini - a retrospective cohort study

Objectives

Provision of drug‐resistant tuberculosis (DR‐TB) treatment is scarce in resource‐limited settings. We assessed the feasibility of ambulatory DR‐TB care for treatment expansion in rural Eswatini.

Methods

Retrospective patient‐level data were used to evaluate ambulatory DR‐TB treatment provision in rural Shiselweni (Eswatini), from 2008 to 2016. DR‐TB care was either clinic‐based led by nurses or community‐based at the patient's home with involvement of community treatment supporters for provision of treatment to patients with difficulties in accessing facilities. We describe programmatic outcomes and used multivariate flexible parametric survival models to assess time to adverse outcomes. Both care models were costed in supplementary analyses.

Results

Of 698 patients initiated on DR‐TB treatment, 57% were women and 84% were HIV‐positive. Treatment initiations increased from 27 in 2008 to 127 in 2011 and decreased thereafter to 51 in 2016. Proportionally, community‐based care increased from 19% in 2009 to 77% in 2016. Treatment success was higher for community‐based care (79%) than clinic‐based care (68%, P = 0.002). After adjustment for covariate factors among adults (n = 552), the risk of adverse outcomes (death, loss to follow‐up, treatment failure) in community‐based care was reduced by 41% (adjusted hazard ratio 0.59, 95% CI: 0.39–0.91). Findings were supported by sensitivity analyses. The care provider's per‐patient costs for community‐based (USD13 345) and clinic‐based (USD12 990) care were similar.

Conclusions

Ambulatory treatment outcomes were good, and community‐based care achieved better treatment outcomes than clinic‐based care at comparable costs. Contextualised DR‐TB care programmes are feasible and can support treatment expansion in rural settings.

Space-time clustering of recently-diagnosed tuberculosis and impact of ART scale-up: Evidence from an HIV hyper-endemic rural South African population

In HIV hyperendemic sub-Saharan African communities, particularly in southern Africa, the likelihood of achieving the Sustainable Development Goal of ending the tuberculosis (TB) epidemic by 2030 is low, due to lack of cost-effective and practical interventions in population settings. We used one of Africa’s largest population-based prospective cohorts from rural KwaZulu-Natal Province, South Africa, to measure the spatial variations in the prevalence of recently-diagnosed TB disease, and to quantify the impact of community coverage of antiretroviral therapy (ART) on recently-diagnosed TB disease. We collected data on TB disease episodes from a population-based sample of 41,812 adult individuals between 2009 and 2015. Spatial clusters (‘hotspots’) of recently-diagnosed TB were identified using a space-time scan statistic. Multilevel logistic regression models were fitted to investigate the relationship between community ART coverage and recently-diagnosed TB. Spatial clusters of recently-diagnosed TB were identified in a region characterized by a high prevalence of HIV and population movement. Every percentage increase in ART coverage was associated with a 2% decrease in the odds of recently-diagnosed TB (aOR = 0.98, 95% CI:0.97–0.99). We identified for the first time the clear occurrence of recently-diagnosed TB hotspots, and quantified potential benefit of increased community ART coverage in lowering tuberculosis, highlighting the need to prioritize the expansion of such effective population interventions targeting high-risk areas.