Predicting the long-term impact of antiretroviral therapy scale-up on population incidence of tuberculosis

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.

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.

The Impact of Anti-Retroviral Therapy on Tuberculosis Detection at the National Level in South Africa

Human immunodeficiency virus/tuberculosis (HIV/TB) coinfection is particularly prevalent in South Africa, where TB has been the leading cause of death for more than a decade. The 2004-2008 national rollout of antiretroviral therapy (ART) provides a unique opportunity to examine the population-level impact of ART on the TB epidemic. We performed longitudinal regression analysis to follow the evolution of TB outcomes before and after the introduction of ART using a large data set from the National Health Laboratory Service. This is the first study to produce estimates of the impact of the ART rollout by exploiting staggered timing and geographic variation in the rollout. After ART became available in a health facility, 3.7% (P < 0.0001) more patients were tested for TB and 3.2% (P < 0.0001) more received repeat testing; however, there was a steep rise in testing before the introduction of ART. Although the number of TB-positive patients increased by 4.3% (P = 0.0002) in the first year post-ART, the TB rate among tested patients fell by 2 percentage points (8%, P = 0.001) after 2 years. Sputum smear testing declined relative to more technologically advanced diagnostics post-ART. Antiretroviral therapy availability increased the attention to TB screening and drew new patients into the health-care system. Small increases in the numbers of repeat patients are indicative of retention in care. The decline in TB rates post-ART suggests that the reduction in TB risk due to improved immune functioning and health-care contact likely outweighed the increased TB risk because of the longer lifespan of ART initiators.

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.

Anti-retroviral therapy scale-up and its impact on sex-stratified tuberculosis notification trends in Uganda

INTRODUCTION

In order to end the tuberculosis (TB) epidemic by 2035, countries must achieve a 10% annual decline in tuberculosis incidence rates by 2025. Provision of antiretroviral therapy (ART) has been associated with population level decreases in TB notification rates. We aimed to assess whether the progressive scale-up of ART provision over the past nine years has had an effect on population level trends of TB notification in Uganda stratified by sex and HIV status.

METHODS

The study area consisted of Kampala and eight surrounding districts. Annual TB notifications and mid-year populations were used to calculate notification rates per 100,000 population from the study area. Numbers alive and retained on ART were used to calculate ART coverage, overall and by sex. TB notification rates (TBNRs) overall and stratified by sex and HIV status were calculated for the period 2009 to 2017. Trends in TBNRs before and after rollout of universal ART for pregnant women in 2013 were examined using Poisson regression models. To gain insight into the trends in CD4+ T-cell counts at ART initiation over the study period, we performed a sub analysis of patient level data from the Infectious Diseases Institute clinic.

RESULTS

From 2009 to 2017, ART coverage increased by 27.6% among men and by 35.4% among women. TBNRs declined during the same period. Overall, the average annual percentage decline in TBNRs was -3.5% (95%CI -3.7% to -3.3%), (-2.3% (95%CI -2.6% to -1.9%) in men and -5.4% (95%CI -5.7% to -5.0%) in women). ART coverage increased after 2013 but this was not associated with an accelerated decline in overall TBNRs among HIV-positive persons -3.6% before 2013 and -5.2% after 2013; p = 0.33. The proportion of patients initiating ART with CD4+ T-cell count ≤ 200 cells/mL did not decrease significantly after 2013 (42.2% to 32.2%, p = 0.05).

CONCLUSIONS

Although ART scale-up was temporally associated with a decline in TB notification rates, the achieved rates of decline are below those required to achieve the End TB Targets. Additional investments in tuberculosis control should include efforts to promote earlier care seeking and ART initiation among HIV-positive persons.

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.

Advances in the understanding of Mycobacterium tuberculosis transmission in HIV-endemic settings

Tuberculosis claims more human lives than any other infectious disease. This alarming epidemic has fuelled the development of novel antimicrobials and diagnostics. However, public health interventions that interrupt transmission have been slow to emerge, particularly in HIV-endemic settings. Transmission of tuberculosis is complex, involving various environmental, bacteriological, and host factors, among which concomitant HIV infection is important. Preventing person-to-person spread is central to halting the epidemic and, consequently, tuberculosis transmission is now being studied with renewed interest. In this Series paper, we review recent advances in the understanding of tuberculosis transmission, from the view of source-case infectiousness, inherent susceptibility of exposed individuals, appending tools for predicting risk of disease progression, the biophysical nature of the contagion, and the environments in which transmission occurs and is sustained in populations. We focus specifically on how HIV infection affects these features with a view to describing novel transmission blocking strategies in HIV-endemic settings.

Incidence of tuberculosis in children on antiretroviral therapy: a retrospective cohort study

Objectives

Be aware of the burden of tuberculosis among high-risk population is important. Three hundred fifty-two children were participated in this study. Survival analysis was conducted. We assessed the incidence of tuberculosis and its predictors in children on ART.

Results

Tuberculosis incidence rate in children on ART was 2.63 per 100 person-years. Those children who were on baseline World Health Organization clinical stages 3 and 4 (AHR (adjusted hazard ratio) = 3.0; 95% CI 1.2–7.7), “fair” and “poor” ART adherence (AHR = 4.0; 95% CI 1.5–10.8), late initiation of ART (AHR = 4.0; 95% CI 1.5–10.6), and less than 6 months duration on ART (AHR = 5.5; 95% CI 1.5–20.6) were more likely to develop tuberculosis infection. The incidence rate of TB in children on ART was high. This study suggests a need to give attention to advanced AIDS stages and improve timely initiation of ART and level of adherence to ART.

HIV and TB co-infection in the ART era: CD4 count distributions and TB case fatality in Cape Town

BACKGROUND

In Cape Town, the roll-out of antiretroviral therapy (ART) has increased over the last decade with an estimated coverage of 63% of HIV- positive patients in 2013. The influence of ART on the characteristics of the population of HIV-positive patients presenting to the primary care TB programme is unknown. In this study, we examined trends in CD4 count distribution, ART usage and treatment outcomes among HIV-positive TB patients in Cape Town from 2009 to 2013.

METHODS

Data from the electronic TB register on all newly registered drug-sensitive TB patients ≥18 years were analyzed retrospectively. Descriptive statistics were used to compare baseline characteristics, the CD4 count distribution and TB treatment outcomes both by year of treatment and ART status at the start of TB treatment. Survival analyses were used to assess the change in mortality risk during TB treatment over time, stratified by ART status at start of TB treatment.

RESULTS

118,989 patients were treated over 5 years. HIV prevalence among TB patients decreased from 50.9% in 2009 to 49.0% in 2013. The absolute number of HIV-positive TB cases declined by 13.2% between 2010 and 2013. More patients entered the TB programme on ART in 2013 compared to 2009 (30.0% vs 9.9%). Among these, the CD4 count distribution showed a year by year shift to higher CD4 counts. In 2013, over 75% of ART-naïve TB patients still had a CD4 count < 350 cells/mm3. ART initiation among ART-naive patients increased from 37.0 to 77.7% and TB case fatality declined from 7.4 to 5.2% (p < 0.001). In multivariate analysis a decrease in TB mortality was most strongly associated with CD4 count (Adjusted HR 0.82 per increase of 50 cells/mm3, 95% CI: 0.81-0.83, p < 001) and the initiation of ART during TB treatment (Adjusted HR 0.39, 95% CI: 0.35-0.42, p < 0.001).

CONCLUSION

Comprehensive changes in the ART and TB treatment programmes resulted in incremental increases in ART coverage for HIV-positive TB patients and a subsequent decrease in TB case fatality due to increased ART uptake in HIV-positive ART-naïve patients. However TB still remained a major presenting opportunistic infection with the majority of cases occurring at low CD4 counts.

Does antiretroviral treatment increase the infectiousness of smear-positive pulmonary tuberculosis?

BACKGROUND

Understanding of the effects of human immunodeficiency virus (HIV) infection and antiretroviral treatment (ART) on Mycobacterium tuberculosis transmission dynamics remains limited. We undertook a cross-sectional study among household contacts of smear-positive pulmonary tuberculosis (TB) cases to assess the effect of established ART on the infectiousness of TB.

METHOD

Prevalence of tuberculin skin test (TST) positivity was compared between contacts of index cases aged 2-10 years who were HIV-negative, HIV-positive but not on ART, on ART for <1 year and on ART for 1 year. Random-effects logistic regression was used to take into account clustering within households.

RESULTS

Prevalence of M. tuberculosis infection in contacts of HIV-negative patients, HIV-positive patients on ART 1 year and HIV-positive patients not on ART/on ART <1 year index cases was respectively 44%, 21% and 22%. Compared to contacts of HIV-positive index cases not on ART or recently started on ART, the odds of TST positivity was similar in contacts of HIV-positive index cases on ART 1 year (adjusted OR [aOR] 1.0, 95%CI 0.3-3.7). The odds were 2.9 times higher in child contacts of HIV-negative index cases (aOR 2.9, 95%CI 1.0-8.2).

CONCLUSIONS

We found no evidence that established ART increased the infectiousness of smear-positive, HIV-positive index cases.

Reduction in extrapulmonary tuberculosis in context of antiretroviral therapy scale-up in rural South Africa

Scale-up of antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection has reduced the incidence of pulmonary tuberculosis (PTB) in South Africa. Despite the strong association of HIV infection with extrapulmonary tuberculosis (EPTB), the effect of ART on the epidemiology of EPTB remains undocumented. We conducted a retrospective record review of patients initiated on treatment for EPTB in 2009 (ART coverage <5%) and 2013 (ART coverage 41%) at four public hospitals in rural Mopani District, South Africa. Data were obtained from TB registers and patients' clinical records. There was a 13% decrease in overall number of TB cases, which was similar for cases registered as EPTB (n = 399 in 2009 vs. 336 in 2013; P < 0·01) and for PTB (1031 vs. 896; P < 0·01). Among EPTB cases, the proportion of miliary TB and disseminated TB decreased significantly (both P < 0·01), TB meningitis and TB of bones increased significantly (P < 0·01 and P = 0·02, respectively) and TB pleural effusion and lymphadenopathy remained the same. This study shows a reduction of EPTB cases that is similar to that of PTB in the context of the ART scale-up. The changing profile of EPTB warrants attention of healthcare workers.

Tradeoffs in Introduction Policies for the Anti-Tuberculosis Drug Bedaquiline: A Model-Based Analysis

BACKGROUND

New drugs for the treatment of tuberculosis (TB) are becoming available for the first time in over 40 y. Optimal strategies for introducing these drugs have not yet been established. The objective of this study was to compare different strategies for introducing the new TB drug bedaquiline based on patients' resistance patterns.

METHODS AND FINDINGS

We created a Markov decision model to follow a hypothetical cohort of multidrug-resistant (MDR) TB patients under different bedaquiline use strategies. The explored strategies included making bedaquiline available to all patients with MDR TB, restricting bedaquiline usage to patients with MDR plus additional resistance and withholding bedaquiline introduction completely. We compared these strategies according to life expectancy, risks of acquired resistance, and the expected number and health outcomes of secondary cases. For our simulated cohort, the mean (2.5th, 97.5th percentile) life expectancy from time of initiation of MDR TB treatment at age 30 was 36.0 y (33.5, 38.7) assuming all patients with MDR TB received bedaquiline, 35.1 y (34.4, 35.8) assuming patients with pre-extensively drug-resistant (PreXDR) and extensively drug-resistant (XDR) TB received bedaquiline, and 34.9 y (34.6, 35.2) assuming only patients with XDR TB received bedaquiline. Although providing bedaquiline to all MDR patients resulted in the highest life expectancy for our initial cohort averaged across all parameter sets, for parameter sets in which bedaquiline conferred high risks of added mortality and only small reductions in median time to culture conversion, the optimal strategy would be to withhold use even from patients with the most extensive resistance. Across all parameter sets, the most liberal bedaquiline use strategies consistently increased the risk of bedaquiline resistance but decreased the risk of resistance to other MDR drugs. In almost all cases, more liberal bedaquiline use strategies reduced the expected number of secondary cases and resulting life years lost. The generalizability of our results is limited by the lack of available data about drug effects among individuals with HIV co-infection, drug interactions, and other sources of heterogeneity, as well as changing recommendations for MDR TB treatment.

CONCLUSIONS

If mortality benefits can be empirically verified, our results provide support for expanding bedaquiline access to all patients with MDR TB. Such expansion could improve patients' health, protect background MDR TB drugs, and decrease transmission, but would likely result in greater resistance to bedaquiline.

Evaluating the potential impact of enhancing HIV treatment and tuberculosis control programmes on the burden of tuberculosis

HIV has fuelled increasing tuberculosis (TB) incidence in sub-Saharan Africa. Better control of TB in this region may be achieved directly through TB programme improvements and indirectly through expanded use of antiretroviral therapy (ART) among those with HIV. We used a mathematical model of TB and HIV in South Africa to examine the potential epidemiological impact in scenarios involving improvements in three dimensions of TB programmes: coverage, diagnosis and treatment effectiveness, as well as expanded ART use through broadened eligibility. We projected the effect of alternative scenarios on TB prevalence, incidence and TB-related mortality over 20 years. Of the three dimensions of TB programme improvement, expanding coverage would produce the greatest reduction in TB burden. Compared with current performance, combined TB programme improvements were projected to decrease TB incidence by 30% over 5 years and 46% over 20 years, and decrease TB-related mortality by 45% over 5 years and 69% over 20 years. Expanded ART eligibility was projected to decrease TB incidence by 22% over 5 years and 45% over 20 years, and TB-related mortality by 22% over 5 years and 50% over 20 years. We found that over a 20-year horizon, TB-specific and HIV-specific programme changes contribute equally to incidence reductions, whereas the TB-specific changes produce a majority of the mortality benefits. An aggressive expansion of ART alongside traditional TB-specific control measures has the potential to greatly reduce TB burden, with the different elements of a combined approach having a synergistic effect in reducing long-term TB incidence and mortality.

Tuberculosis in Cape Town: An age-structured transmission model

BACKGROUND

Tuberculosis (TB) is the leading cause of death in South Africa. The burden of disease varies by age, with peaks in TB notification rates in the HIV-negative population at ages 0-5, 20-24, and 45-49 years. There is little variation between age groups in the rates in the HIV-positive population. The drivers of this age pattern remain unknown.

METHODS

We developed an age-structured simulation model of Mycobacterium tuberculosis (Mtb) transmission in Cape Town, South Africa. We considered five states of TB progression: susceptible, infected (latent TB), active TB, treated TB, and treatment default. Latently infected individuals could be re-infected; a previous Mtb infection slowed progression to active disease. We further considered three states of HIV progression: HIV negative, HIV positive, on antiretroviral therapy. To parameterize the model, we analysed treatment outcomes from the Cape Town electronic TB register, social mixing patterns from a Cape Town community and used literature estimates for other parameters. To investigate the main drivers behind the age patterns, we conducted sensitivity analyses on all parameters related to the age structure.

RESULTS

The model replicated the age patterns in HIV-negative TB notification rates of Cape Town in 2009. Simulated TB notification rate in HIV-negative patients was 1000/100,000 person-years (pyrs) in children aged <5 years and decreased to 51/100,000 in children 5-15 years. The peak in early adulthood occurred at 25-29 years (463/100,000 pyrs). After a subsequent decline, simulated TB notification rates gradually increased from the age of 30 years. Sensitivity analyses showed that the dip after the early adult peak was due to the protective effect of latent TB and that retreatment TB was mainly responsible for the rise in TB notification rates from the age of 30 years.

CONCLUSION

The protective effect of a first latent infection on subsequent infections and the faster progression in previously treated patients are the key determinants of the age-structure of TB notification rates in Cape Town.

The transmission of Mycobacterium tuberculosis in high burden settings

Unacceptable levels of Mycobacterium tuberculosis transmission are noted in high burden settings and a renewed focus on reducing person-to-person transmission in these communities is needed. We review recent developments in the understanding of airborne transmission. We outline approaches to measure transmission in populations and trials and describe the Wells-Riley equation, which is used to estimate transmission risk in indoor spaces. Present research priorities include the identification of effective strategies for tuberculosis infection control, improved understanding of where transmission occurs and the transmissibility of drug-resistant strains, and estimates of the effect of HIV and antiretroviral therapy on transmission dynamics. When research is planned and interventions are designed to interrupt transmission, resource constraints that are common in high burden settings-including shortages of health-care workers-must be considered.

Benefits of combined preventive therapy with co-trimoxazole and isoniazid in adults living with HIV: time to consider a fixed-dose, single tablet coformulation

Antiretroviral therapy (ART) is the main intervention needed to reduce morbidity and mortality and to prevent tuberculosis in adults living with HIV. However, in most resource-limited countries, especially in sub-Saharan Africa, ART is started too late to have an effect with substantial early morbidity and mortality, and in high tuberculosis burden settings ART does not reduce the tuberculosis risk to that reported in individuals not infected with HIV. Co-trimoxazole preventive therapy started before or with ART, irrespective of CD4 cell count, reduces morbidity and mortality with benefits that continue indefinitely. Isoniazid preventive therapy as an adjunct to ART prevents tuberculosis in high-exposure settings, with long-term treatment likely to be needed to sustain this benefit. Unfortunately, both preventive therapies are underused in low-income and high-burden settings. ART development has benefited from patient-centred simplification with several effective regimens now available as a one per day pill. We argue that co-trimoxazole and isoniazid should also be combined into a single fixed-dose pill, along with pyridoxine (vitamin B6), that would be taken once per day to help with individual uptake and national scale-up of therapies.

Temporal trends in TB notification rates during ART scale-up in Cape Town: an ecological analysis

INTRODUCTION

Although antiretroviral therapy (ART) reduces individual tuberculosis (TB) risk by two-thirds, the population-level impact remains uncertain. Cape Town reports high TB notification rates associated with endemic HIV. We examined population trends in TB notification rates during a 10-year period of expanding ART.

METHODS

Annual Cape Town TB notifications were used as numerators and mid-year Cape Town populations as denominators. HIV-stratified population was calculated using overall HIV prevalence estimates from the Actuarial Society of South Africa AIDS and Demographic model. ART provision numbers from Western Cape government reports were used to calculate overall ART coverage. We calculated rates per 100,000 population over time, overall and stratified by HIV status. Rates per 100,000 total population were also calculated by ART use at treatment initiation. Absolute numbers of notifications were compared by age and sub-district. Changes over time were described related to ART provision in the city as a whole (ART coverage) and by sub-district (numbers on ART).

RESULTS

From 2003 to 2013, Cape Town's population grew from 3.1 to 3.7 million inhabitants, and estimated HIV prevalence increased from 3.6 to 5.2%. ART coverage increased from 0 to 63% in 2013. TB notification rates declined by 16% (95% confidence interval (CI), 14-17%) from a 2008 peak (851/100,000) to a 2013 nadir (713/100,000). Decreases were higher among the HIV-positive (21% (95% CI, 19-23%)) than the HIV-negative (9% (95% CI, 7-11%)) population. The number of HIV-positive TB notifications decreased mainly among 0- to 4- and 20- to 34-year-olds. Total population rates on ART at TB treatment initiation increased over time but levelled off in 2013. Overall median CD4 counts increased from 146 cells/µl (interquartile range (IQR), 66, 264) to 178 cells/µl (IQR 75, 330; p<0.001). Sub-district antenatal HIV seroprevalence differed (10-33%) as did numbers on ART (9-29 thousand). Across sub-districts, infant HIV-positive TB decreased consistently whereas adult decreases varied.

CONCLUSIONS

HIV-positive TB notification rates declined during a period of rapid scale-up of ART. Nevertheless, both HIV-positive and HIV-negative TB notification rates remained very high. Decreases among HIV positives were likely blunted by TB remaining a major entry to the ART programme and occurring after delayed ART initiation.

Tuberculosis prevention in South Africa

Background

South Africa has one of the highest per capita rates of tuberculosis (TB) incidence in the world. In 2012, the South African government produced a National Strategic Plan (NSP) to control the spread of TB with the ambitious aim of zero new TB infections and deaths by 2032, and a halving of the 2012 rates by 2016.

Methods

We used a transmission model to investigate whether the NSP targets could be reached if immediate scale up of control methods had happened in 2014. We explored the potential impact of four intervention portfolios; 1) “NSP” represents the NSP strategy, 2) “WHO” investigates increasing antiretroviral therapy eligibility, 3) “Novel Strategies” considers new isoniazid preventive therapy strategies and HIV “Universal Test and Treat” and 4) “Optimised” contains the most effective interventions.

Findings

We find that even with this scale-up, the NSP targets are unlikely to be achieved. The portfolio that achieved the greatest impact was “Optimised”, followed closely by “NSP”. The “WHO” and “Novel Strategies” had little impact on TB incidence by 2050. Of the individual interventions explored, the most effective were active case finding and reductions in pre-treatment loss to follow up which would have a large impact on TB burden.

Conclusion

Use of existing control strategies has the potential to have a large impact on TB disease burden in South Africa. However, our results suggest that the South African TB targets are unlikely to be reached without new technologies. Despite this, TB incidence could be dramatically reduced by finding and starting more TB cases on treatment.