Incidence of tuberculosis during highly active antiretroviral therapy in high-income and low-income countries

The genomic epidemiology of shigellosis in South Africa

Shigellosis, a leading cause of diarrhoeal mortality and morbidity globally, predominantly affects children under five years of age living in low- and middle-income countries. While whole genome sequence analysis (WGSA) has been effectively used to further our understanding of shigellosis epidemiology, antimicrobial resistance, and transmission, it has been under-utilised in sub-Saharan Africa. In this study, we applied WGSA to large sub-sample of surveillance isolates from South Africa, collected from 2011 to 2015, focussing on Shigella flexneri 2a and Shigella sonnei. We find each serotype is epidemiologically distinct. The four identified S. flexneri 2a clusters having distinct geographical distributions, and antimicrobial resistance (AMR) and virulence profiles, while the four sub-Clades of S. sonnei varied in virulence plasmid retention. Our results support serotype specific lifestyles as a driver for epidemiological differences, show AMR is not required for epidemiological success in S. flexneri, and that the HIV epidemic may have promoted Shigella population expansion.

Tuberculosis infection and disease in South African adolescents with perinatally acquired HIV on antiretroviral therapy: a cohort study

INTRODUCTION

There are limited data on Tuberculosis (TB) in adolescents with perinatally acquired HIV (APHIV). We examined the incidence and determinants of TB infection and disease in the Cape Town Adolescent Antiretroviral Cohort (CTAAC).

METHODS

Youth between nine and fourteen years on antiretroviral therapy (ART) for more than six months in public sector care, and age-matched HIV-negative adolescents, were enrolled between July 2013 through March 2015 and followed six-monthly. Data were censored on 31 October 2018. Symptom screening, chest radiograph, viral load, CD4 count, QuantiFERON (QFT) and sputum for Xpert MTB/RIF, microscopy, culture and sensitivity were performed annually. TB infection was defined by a QFT of >0.35 IU/mL. TB diagnosis was defined as confirmed (culture or Xpert MTB/RIF positive) or unconfirmed (clinical diagnosis and started on TB treatment). Analyses examined the incidence and determinants of TB infection and disease.

RESULTS

Overall 496 HIV+ and 103 HIV-negative participants (median age at enrolment 12 years (interquartile range, IQR 10.6 to 13.3) were followed for a median of 3.1 years (IQR 3.0 to 3.4); 50% (298/599) were male. APHIV initiated ART at median age 4.4 years (IQR 2.1 to 7.6). At enrolment, 376/496 (76%) had HIV viral load <40 copies/mL, median CD4 count was 713 cells/mm3 and 179/559 (32%) were QFT+, with no difference by HIV status (APHIV 154/468, 33%; HIV negative 25/91, 27%; p = 0.31). The cumulative QFT+ prevalence was similar (APHIV 225/492, 46%; 95%CI 41% to 50%; HIV negative 44/98, 45%; 95% CI 35% to 55%; p = 0.88). APHIV had a higher incidence of all TB disease than HIV-negative adolescents (2.2/100PY, 95% CI 1.6 to 3.1 vs. 0.3/100PY, 95% CI 0.04 to 2.2; IRR 7.36, 95% CI 1.01 to 53.55). The rate of bacteriologically confirmed TB in APHIV was 1.3/100 PY compared to 0.3/100PY for HIV-negative adolescents, suggesting a fourfold increased risk of developing TB disease in APHIV despite access to ART. In addition, a positive QFT at enrolment was not predictive of TB in this population.

CONCLUSIONS

High incidence rates of TB disease occur in APHIV despite similar QFT conversion rates to HIV-negative adolescents. Strategies to prevent TB in this vulnerable group must be strengthened.

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.

Clinical and genetic markers associated with tuberculosis, HIV-1 infection, and TB/HIV-immune reconstitution inflammatory syndrome outcomes

BACKGROUND

Tuberculosis (TB) and AIDS are the leading causes of infectious disease death worldwide. In some TB-HIV co-infected individuals treated for both diseases simultaneously, a pathological inflammatory reaction termed immune reconstitution inflammatory syndrome (IRIS) may occur. The risk factors for IRIS are not fully defined. We investigated the association of HLA-B, HLA-C, and KIR genotypes with TB, HIV-1 infection, and IRIS onset.

METHODS

Patients were divided into four groups: Group 1- TB+/HIV+ (n = 88; 11 of them with IRIS), Group 2- HIV+ (n = 24), Group 3- TB+ (n = 24) and Group 4- healthy volunteers (n = 26). Patients were followed up at INI/FIOCRUZ and HGNI (Rio de Janeiro/Brazil) from 2006 to 2016. The HLA-B and HLA-C loci were typed using SBT, NGS, and KIR genes by PCR-SSP. Unconditional logistic regression models were performed for Protection/risk estimation.

RESULTS

Among the individuals with TB as the outcome, KIR2DS2 was associated with increased risk for TB onset (aOR = 2.39, P = 0.04), whereas HLA-B*08 and female gender were associated with protection against TB onset (aOR = 0.23, P = 0.03, and aOR = 0.33, P = 0.01, respectively). Not carrying KIR2DL3 (aOR = 0.18, P = 0.03) and carrying HLA-C*07 (aOR = 0.32, P = 0.04) were associated with protection against TB onset among HIV-infected patients. An increased risk for IRIS onset was associated with having a CD8 count ≤500 cells/mm3 (aOR = 18.23, P = 0.016); carrying the KIR2DS2 gene (aOR = 27.22, P = 0.032), the HLA-B*41 allele (aOR = 68.84, P = 0.033), the KIR2DS1 + HLA-C2 pair (aOR = 28.58, P = 0.024); and not carrying the KIR2DL3 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), and the KIR2DL1 + HLA-C1/C2 pair (aOR = 43.04, P = 0.034), CONCLUSIONS: These results suggest the participation of these genes in the immunopathogenic mechanisms related to the conditions studied. This is the first study demonstrating an association of HLA-B*41, KIR2DS2, and KIR + HLA-C pairs with IRIS onset among TB-HIV co-infected individuals.

Immunological non-response and low hemoglobin levels are predictors of incident tuberculosis among HIV-infected individuals on Truvada-based therapy in Botswana

Background

There is a high burden of tuberculosis (TB) in HIV antiretroviral programmes in Africa. However, few studies have looked at predictors of incident TB while on Truvada-based combination antiretroviral therapy (cART) regimens.

Methods

We estimated TB incidence among individuals enrolled into an observational cohort evaluating the efficacy and tolerability of Truvada-based cART in Gaborone, Botswana between 2008 and 2011. We used Cox proportional hazards regressions to determine predictors of incident TB.

Results

Of 300 participants enrolled, 45 (15%) had a diagnosis of TB at baseline. During 428 person-years (py) of follow-up, the incidence rate of TB was 3.04/100py (95% CI, 1.69–5.06), with 60% of the cases occurring within 3 months of ART initiation. Incident cases had low baseline CD4+ T cell counts (153cells/mm³ [Q1, Q3: 82, 242]; p = 0.69) and hemoglobin levels (9.2g/dl [Q1, Q3: 8.5,10.1]; p<0.01). In univariate analysis, low BMI (HR = 0.73; 95% CI 0.58–0.91; p = 0.01) and hemoglobin levels <8 g/dl (HR = 10.84; 95%CI: 2.99–40.06; p<0.01) were risk factors for TB. Time to incident TB diagnosis was significantly reduced in patients with poor immunological recovery (p = 0.04). There was no association between baseline viral load and risk of TB (HR = 1.75; 95%CI: 0.70–4.37).

Conclusion

Low hemoglobin levels prior to initiation of ART are significant predictors of incident tuberculosis. Therefore, there is potential utility of iron biomarkers to identify patients at risk of TB prior to initiation on ART. Furthermore, additional strategies are required for patients with poor immunological recovery to reduce excess risk of TB while on ART.

Immunological recovery in tuberculosis/HIV co-infected patients on antiretroviral therapy: implication for tuberculosis preventive therapy

BACKGROUND

Understanding the immune response to combination antiretroviral therapy (cART) is essential for a clear approach to tuberculosis (TB) preventive therapy. We investigated the immunological recovery in cART-treated HIV-infected patients developing TB compared to those who remained free of TB.

METHODS

We extracted data of HIV-infected patients from a multicenter cohort for the HIV clinical surveillance in Germany. No patients included in our study had TB at the beginning of the observation. Using a longitudinal mixed model, we assessed the differences in the mean change of biomarkers (CD4+ cell count, CD8+ cell count, CD4:CD8 ratio and viral load) since cART initiation in patients who remained free of TB vs. those developing TB. To detect the best-fit trajectories of the immunological biomarkers, we applied a multivariable fractional polynomials model.

RESULTS

We analyzed a total of 10,671 HIV-infected patients including 139 patients who developed TB during follow-up. The highest TB incidences were observed during the first two years since cART initiation (0.32 and 0.50 per 100 person-years). In an adjusted multivariable mixed model, we found that the average change in CD4+ cell count recovery was significantly greater by 33 cells/μl in patients who remained free of TB compared with those developing TB. After the initial three months of cART, 65.6% of patients who remaining free of TB achieved CD4+ count of ≥400 cells/μl, while only 11.3% of patients developing TB reached this immunological status after the three months of cART. We found no differences in the average change of CD8+ cell count, CD4:CD8 ratio or viral load between the two-patient groups.

CONCLUSION

All HIV-infected patients responded to cART. However, patients developing TB showed reduced recovery in CD4+ cell count and this might partly explain the incident TB in HIV-infected patients receiving cART. These findings reinforce the importance of adjunctive TB preventive therapy for patients with reduced recovery in CD4+ cell count.

Impact of HIV co-infection on the evolution and transmission of multidrug-resistant tuberculosis

The tuberculosis (TB) epidemic is fueled by a parallel Human Immunodeficiency Virus (HIV) epidemic, but it remains unclear to what extent the HIV epidemic has been a driver for drug resistance in Mycobacterium tuberculosis (Mtb). Here we assess the impact of HIV co-infection on the emergence of resistance and transmission of Mtb in the largest outbreak of multidrug-resistant TB in South America to date. By combining Bayesian evolutionary analyses and the reconstruction of transmission networks utilizing a new model optimized for TB, we find that HIV co-infection does not significantly affect the transmissibility or the mutation rate of Mtb within patients and was not associated with increased emergence of resistance within patients. Our results indicate that the HIV epidemic serves as an amplifier of TB outbreaks by providing a reservoir of susceptible hosts, but that HIV co-infection is not a direct driver for the emergence and transmission of resistant strains.

Prevalence, incidence, and associated risk factors of tuberculosis in children with HIV living in the UK and Ireland (CHIPS): a cohort study

BACKGROUND

Tuberculosis is the most common serious co-infection in people living with HIV worldwide, but little is known about its incidence in HIV-infected children living in high-resource settings with low tuberculosis prevalence. We aimed to assess the incidence and prevalence of tuberculosis in children with HIV living in the UK and Ireland to understand rates, risk factors, and outcomes of the disease in this group.

METHODS

We did an analysis of children enrolled in CHIPS, an observational multicentre cohort of children receiving HIV care in the UK and Ireland. We assessed characteristics and prevalence of tuberculosis at baseline, measured incidence of disease through the follow-up period using the CHIPS database, and calculated associated risk factors in these children with multivariable logistic and Cox regression models.

FINDINGS

Between Jan 1, 1996, to Sept 18, 2014, data for 1848 children with 14 761 years of follow-up were reported to CHIPS. 57 (3%) children were diagnosed with tuberculosis: 29 children had tuberculosis at presentation (prevalent tuberculosis) and 29 had the disease diagnosed during follow-up (incident tuberculosis), including one child with recurrent tuberculosis events. Median age at diagnosis was 9 years (IQR 5-12). 25 (43%) children had pulmonary tuberculosis, 24 (41%) had extrapulmonary tuberculosis with or without pulmonary involvement, and the remainder (n=9; 16%) had unspecified-site tuberculosis. The overall incidence rate for the follow-up period was 196 cases per 100 000 person-years (95% CI 137-283). In our multivariable model, tuberculosis at presentation was associated with more severe WHO immunological stage at baseline (odds ratio 0·25, 95% CI 0·08-0·74; p=0·0331; for none vs severe) and being born abroad (odds ratio 0·28, 0·10-0·73; p=0·0036; for UK and Ireland vs abroad). Incident tuberculosis was associated with time-updated more severe WHO immunological stage (hazard ratio 0·15, 95% CI 0·06-0·41; p=0·0056; for none vs severe) and older age at baseline (1·11, 0·47-2·63; p=0·0027; for age >10 years vs 5-9 years).

INTERPRETATION

Tuberculosis rates in HIV-infected children in the UK and Ireland were higher than those reported in the general paediatric population. Further study is warranted of tuberculosis screening and preventive treatment for children at high-risk of this disease to avoid morbidity and mortality in this population.

FUNDING

NHS England, PENTA Foundation.

Brief Report: The Effect of Antiretroviral Therapy and CD4 Count on Markers of Infectiousness in HIV-Associated Tuberculosis

Clinical features of tuberculosis influence infectiousness. This cross-sectional study examined the effect of combination antiretroviral therapy (cART) and CD4 on sputum smear-positivity (SS+) and pulmonary cavitation among 1589 (1185/1589 HIV-positive) miners in South Africa. Proportions SS+ varied nonlinearly by CD4 with greatest proportions SS+ (55.3%) in the lowest stratum (<100 cells/μL). Adjusted prevalence ratio for SS+; on vs. off cART was 0.90 (95% confidence interval: 0.73 to 1.11). Proportions with cavitation varied linearly with CD4, with no independent cART effect (adjusted prevalence ratio 1.17; 95% confidence interval: 0.80 to 1.71). cART did not independently affect SS+ or cavitation but may increase infectiousness through CD4 recovery.

Very low levels of 25-hydroxyvitamin D are not associated with immunologic changes or clinical outcome in South African patients with HIV-associated cryptococcal meningitis

Vitamin D deficiency may increase susceptibility to opportunistic infections in HIV-infected individuals. We found no evidence that vitamin D deficiency increases risk of cryptococcal meningitis or leads to impaired immune responses or microbiological clearance in HIV-infected patients with cryptococcal meningitis.

Background. Vitamin D deficiency is associated with impaired immune responses and increased susceptibility to a number of intracellular pathogens in individuals infected with human immunodeficiency virus (HIV). It is not known whether such an association exists with Cryptococcus neoformans.

Methods. Levels of 25-hydroxyvitamin D (25[OH]D) were measured in 150 patients with cryptococcal meningitis (CM) and 150 HIV-infected controls in Cape Town, South Africa, and associations between vitamin D deficiency and CM were examined. The 25-hydroxyvitamin D levels and cryptococcal notifications were analyzed for evidence of reciprocal seasonality. Associations between 25(OH)D levels and disease severity, immune responses, and microbiological clearance were investigated in the patients with CM.

Results. Vitamin D deficiency (plasma 25[OH]D ≤50 nmol/L) was present in 74% of patients. Vitamin D deficiency was not associated with CM (adjusted odds ratio, 0.93 [95% confidence interval, .6–1.6]; P = .796). Levels of 25(OH)D showed marked seasonality, but no reciprocal seasonality was seen in CM notifications. No significant associations were found between 25(OH)D levels and fungal burden or levels of tumor necrosis factor α, interferon γ, interleukin 6, soluble CD14, or neopterin in cerebrospinal fluid. Rates of fungal clearance did not vary according to vitamin D status.

Conclusions. Vitamin D deficiency does not predispose to the development of CM, or lead to impaired immune responses or microbiological clearance in HIV-infected patients with CM.

High rates of tuberculosis in patients accessing HAART in rural South Africa

BACKGROUND

The challenge of early tuberculosis (TB) infection among rural patients accessing highly active antiretroviral therapy (HAART) in a resource-limited setting with high HIV and TB burden has not been fully quantified.

METHODS

This is a retrospective study nested within a prospective study of 969 patients consecutively initiated onto HAART at the CAPRISA AIDS Treatment programme in rural KwaZulu-Natal between January 2007 and December 2010. Patients were screened for clinical symptoms consistent with TB using a standardized checklist, and routine clinical investigations that included sputum microscopy and chest x-ray diagnosis.

RESULTS

Of 969 HIV-infected patients initiated on HAART, 173 [17.9%; 95% confidence interval (CI): 15.5 to 20.4] had active TB at HAART initiation. TB incidence rates were 3-fold higher in the first 3 months (early incident TB) after HAART initiation [11.5/100 person-years (py); 95% CI: 7.1 to 17.5] compared with 4-24 months (late incident TB) post-HAART initiation (3.2/100 py; 95% CI: 2.2 to 4.5; incidence rate ratio: 3.6; 95% CI: 2.0 to 6.4; P < 0.001). Immune status of patients at HAART initiation did not impact TB incidence rates in patients with CD4 counts of <50 (5.3/100) and >200 (4.9/100 py; P = 0.81) cells per cubic millimeter. CD4 count gains achieved 12 months post-HAART initiation were significantly different in patients with early incident TB versus late incident TB; P = 0.03.

CONCLUSIONS

Rural HIV treatment programmes in TB-endemic settings experience high rates of TB irrespective of immunologic status of patients at HAART initiation, or duration on HAART.

Development of a clinical scoring system for assessment of immunosuppression in patients with tuberculosis and HIV infection without access to CD4 cell testing--results from a cross-sectional study in Ethiopia

BACKGROUND

Currently, antiretroviral therapy (ART) is recommended for all HIV-positive patients with tuberculosis (TB). The timing of ART during the course of anti-TB treatment is based on CD4 cell counts. Access to CD4 cell testing is not universally available; this constitutes an obstacle for the provision of ART in low-income countries.

OBJECTIVE

To determine clinical variables associated with HIV co-infection in TB patients and to identify correlations between clinical variables and CD4 cell strata in HIV/TB co-infected subjects, with the aim of developing a clinical scoring system for the assessment of immunosuppression.

DESIGN

Cross-sectional study of adults with TB (with and without HIV co-infection) recruited in Ethiopian outpatient clinics. Clinical variables potentially associated with immunosuppression were recorded using a structured questionnaire, and they were correlated to CD4 cell strata used to determine timing of ART initiation. Variables found to be significant in multivariate analysis were used to construct a scoring system. Results : Among 1,116 participants, the following findings were significantly more frequent in 307 HIV-positive patients compared to 809 HIV-negative subjects: diarrhea, odynophagia, conjunctival pallor, herpes zoster, oral candidiasis, skin rash, and mid-upper arm circumference (MUAC) <20 cm. Among HIV-positive patients, conjunctival pallor, MUAC <20 cm, dyspnea, oral hairy leukoplakia (OHL), oral candidiasis, and gingivitis were significantly associated with <350 CD4 cells/mm(3). A scoring system based on these variables had a negative predictive value of 87% for excluding subjects with CD4 cell counts <100 cells/mm(3); however, the positive predictive value for identifying such individuals was low (47%).

CONCLUSIONS

Clinical variables correlate with CD4 cell strata in HIV-positive patients with TB. The clinical scoring system had adequate negative predictive value for excluding severe immunosuppression. Clinical scoring systems could be of use to categorize TB/HIV co-infected patients with regard to the timing of ART initiation in settings with limited access to laboratory facilities.

Prognostic significance of the interval between the initiation of antiretroviral therapy and the initiation of anti-tuberculosis treatment in HIV/tuberculosis-coinfected patients: results from the TREAT Asia HIV Observational Database

OBJECTIVES

We evaluated the effect of the time interval between the initiation of antiretroviral therapy (ART) and the initiation of tuberculosis (TB) treatment on clinical outcomes in HIV/TB-coinfected patients in an Asian regional cohort.

METHODS

Adult HIV/TB-coinfected patients in an observational HIV-infected cohort database who had a known date of ART initiation and a history of TB treatment were eligible for study inclusion. The time interval between the initiation of ART and the initiation of TB treatment was categorized as follows: TB diagnosed while on ART, ART initiated ≤ 90 days after initiation of TB treatment ('early ART'), ART initiated > 90 days after initiation of TB treatment ('delayed ART'), and ART not started. Outcomes were assessed using survival analyses.

RESULTS

A total of 768 HIV/TB-coinfected patients were included in this study. The median CD4 T-cell count at TB diagnosis was 100 [interquartile range (IQR) 40-208] cells/μL. Treatment outcomes were not significantly different between the groups with early ART and delayed ART initiation. Kaplan-Meier analysis indicated that mortality was highest for those diagnosed with TB while on ART (3.77 deaths per 100 person-years), and the prognoses of other groups were not different (in deaths per 100 person-years: 2.12 for early ART, 1.46 for delayed ART, and 2.94 for ART not started). In a multivariate model, the interval between ART initiation and TB therapy initiation did not significantly impact all-cause mortality.

CONCLUSIONS

A negative impact of delayed ART in patients coinfected with TB was not observed in this observational cohort of moderately to severely immunosuppressed patients. The broader impact of earlier ART initiation in actual clinical practice should be monitored more closely.

Tuberculosis after one year of combination antiretroviral therapy in Nigeria: a retrospective cohort study

Our objective was to determine tuberculosis (TB) incidence and evaluate TB risk in adults after one or more years of use of combination antiretroviral therapy (cART) through a retrospective cohort study in Jos, Nigeria. We studied a cohort of HIV-infected adults treated with ART for at least 1 year. Based on immunologic and virologic responses to ART, patients were categorized into four groups: CD4 T cell count ≥350 cells/mm(3) and HIV-1 RNA level ≤400 copies/ml (group 1), CD4 T cell count ≥350 cells/mm(3) and HIV-1 RNA level >400 copies/ml (group 2), CD4 T cell count <350 cells/mm(3) and HIV-1 RNA level ≤400 copies/ml (group 3), and CD4 T cell count <350 cells/mm(3) and HIV-1 RNA level >400 copies/ml (group 4). Time to incident TB for the four groups was analyzed using the Kaplan-Meier method. Cox regression models were used to evaluate predictors of incident TB. In this cohort of 5,093 HIV-infected adults, of which 68.4% were female, with a mean age 35.1 years (standard deviation 9.1 years), we observed 98 cases of incident TB during 4 years and 3 months of follow-up. The overall TB incidence rate was 8.7 cases/1,000 patient-years of follow-up. Adjusted hazards for incident TB were 2.11 (95% CI 0.97-4.61), 2.05 (95% CI 1.10-3.79), and 3.65 (95% CI 1.15-5.06) in group 2, 3, and 4 patients, respectively, compared to group 1. Tuberculosis incidence in patients on ART is driven by poor immunologic and/or virologic response. Optimization of HIV treatment should be prioritized to reduce the burden of TB in this high-risk population.

Incidence and risk factors for tuberculosis in HIV-infected patients while on antiretroviral treatment in Cambodia

BACKGROUND

Given the lack of detailed studies on tuberculosis (TB) in patients on antiretroviral treatment (ART) in South-East Asia, we aimed to determine the incidence and risk factors for early (after ≤6 months of ART) and late (after >6 months of ART) incident TB in Cambodia.

METHODS

We conducted a retrospective analysis of all patients started on ART at a non-governmental hospital in Phnom Penh (March 2003-December 2010). TB diagnosis was performed according to WHO algorithms. Risk factor analysis was performed using multivariate Cox regression modeling.

RESULTS

Overall, 2984 patients started ART. The median baseline CD4 count was 89 cells µl(-1) (IQR 25-209), median age 34 years (IQR 29-40). Fifty-three percent of the patients were female. Median follow-up time on ART was 2.4 years. In addition to 932 (31.2%) patients already on TB treatment at ART initiation, 313 (10.5%) developed TB, with an overall incidence rate of 3.9/100 patient-years. Of those developing TB, 179 (6.0%) patients were diagnosed with early TB and 134 (4.5%) with late TB, corresponding with a rate of 13.5 and 2.0 per 100 patient-years respectively. Risk factors for early TB included low body mass index, low baseline CD4 count and low hemoglobin levels. Low on-treatment CD4 counts and hemoglobin levels, being underweight while on ART and prevalent TB were identified as risk factors for late TB.

CONCLUSION

The incidence of early TB was high, and predominantly associated with advanced HIV progression markers. Earlier ART initiation and enhanced TB screening prior to and after ART initiation is warranted. Late TB amounts to almost half of the total TB burden, meriting specific preventive and diagnostic approaches.

Incidence of tuberculosis and early mortality in a large cohort of HIV infected patients receiving antiretroviral therapy in a tertiary hospital in Addis Ababa, Ethiopia

Preceding studies on morbidities and mortalities associated with TB in a cohort of HIV care indicate high incidence of TB development and premature death among patients on highly active antiretroviral treatment (HAART). This study aims to measure the rate of TB, TB mortality, and associated risk factors following commencement of HAART in a cohort of patients attending HIV care in Ethiopia. Patient information was gathered from the hospital register and analysed. TB incidence peaked within six months of HAART initiation, and dropped from 3.3/100 person-years in the first year to 0.4/100 person-years in the fifth year. At baseline, risk factors associated with TB included WHO clinical stage 3 HIV infection (adjusted hazard ratio (AHR) 2.53; 95% CI 1.70-3.70), WHO clinical stage 4 HIV infection (AHR, 3.86; 95% CI 2.54-5.86), and patients who were bed ridden >50% a day (AHR, 1.52; 95% CI 1.13-2.05). The rate of mortality was 6.9% (incidence 2.8 per 100 person-years) and 57% of deaths occurred in the first six months of HAART initiation. Multivariate Cox model indicated WHO clinical stage 4 HIV infection, CD4+ cell count <50 cells/μl, bed ridden >50% a day, and TB after HAART initiation as baseline independent predictors of mortality. Additional evidence shows that regular CD4+monitoring of patients before HAART initiation as well as earlier HAART initiation decreases death, and regular clinical staging decreases TB incidence.

Survival from XDR-TB is associated with modifiable clinical characteristics in rural South Africa

BACKGROUND

Drug-resistant tuberculosis (TB) is a major threat to global public health. Patients with extensively drug-resistant TB (XDR-TB), particularly those with HIV-coinfection, experience high and accelerated mortality with limited available interventions. To determine modifiable factors associated with survival, we evaluated XDR-TB patients from a community-based hospital in rural South Africa where a large number of XDR-TB cases were first detected.

METHODOLOGY/PRINCIPAL FINDINGS

A retrospective case control study was conducted of XDR-TB patients diagnosed from 2005-2008. Survivors, those alive at 180 days from diagnostic sputum collection date, were compared with controls who died within 180 days. Clinical, laboratory and microbiological correlates of survival were assessed in 69 survivors (median survival 565 days [IQR 384-774] and 73 non-survivors (median survival 34 days [IQR 18-90]). Among 129 HIV+ patients, multivariate analyses of modifiable factors demonstrated that negative AFB smear (AOR 8.4, CI 1.84-38.21), a lower laboratory index of routine laboratory findings (AOR 0.48, CI 0.22-1.02), CD4>200 cells/mm(3) (AOR 11.53, 1.1-119.32), and receipt of antiretroviral therapy (AOR 20.9, CI 1.16-376.83) were independently associated with survival from XDR-TB.

CONCLUSIONS/SIGNIFICANCE

Survival from XDR-TB with HIV-coinfection is associated with less advanced stages of both diseases at time of diagnosis, absence of laboratory markers indicative of multiorgan dysfunction, and provision of antiretroviral therapy. Survival can be increased by addressing these modifiable risk factors through policy changes and improved clinical management. Health planners and clinicians should develop programmes focusing on earlier case finding and integration of HIV and drug-resistant TB diagnostic, therapeutic, and preventive activities.

Advances in the Diagnosis, Treatment and Control of HIV Associated Tuberculosis

There has been an increase in the number of published tuberculosis/HIV (TB/HIV) research findings in recent times. The potential impact of these findings on routine care has informed this review which aims at discussing current concepts and practices underpinning TB/HIV care and control. Any HIV infected person with a cough of any duration is currently considered a TB suspect. Preliminary results also show that the diagnostic yield of same day sputum samples (front loading) is comparable to two-day samples. Laboratory diagnosis is shifting from Ziehl-Neelsen (ZN) smear microscopy and solid culture to fluorescent microscopy, molecular tests and liquid culture. Concomitant TB/HIV therapy improves survival and WHO has recommended ART for all TB/HIV patients. Unless CD4 cell counts are less than 50 cells/µl, ART can be deferred until end of intensive phase. Evidence of survival benefit at high CD4 cell counts is still lacking. New TB drugs and treatment shortening studies are underway but so far no new TB drugs has been added to the current arsenal and treatment duration still remains six months or more. WHO has recommended the 31s (intensified TB case finding, isoniazid prophylaxis and infection control) for TB/HIV control in addition to effective therapy, Antiretroviral therapy and TB vaccines. There has been immense progress in TB/HIV research, however optimal management of HIV-Infected TB patients, will require further research and appropriate translation of emerging evidence to policy and practice.

Tuberculosis among HIV-positive patients across Europe: changes over time and risk factors

OBJECTIVE

To describe temporal changes in the incidence rate of tuberculosis (TB) (pulmonary or extrapulmonary) among HIV-positive patients in western Europe and risk factors of TB across Europe.

METHODS

Poisson regression models were used to determine temporal changes in incidence rate of TB among 11,952 patients from western Europe (1994-2010), and to assess risk factors for TB among 12,673 patients from across Europe with follow-up after 2001.

RESULTS

Two hundred and seventy-seven TB events occurred during 84,221 person-years of follow-up (PYFU) in western Europe. The incidence rate declined from 1.91 [95% confidence interval (CI) 1.51-2.37)] in 1994-1995 to 0.12 (0.07-0.21)/100 PYFU in 2002-2003, and remained stable thereafter. After January 2001, 159 TB events were diagnosed; 65 cases in western Europe and 94 cases in eastern Europe; resulting in incidence rates of 0.12 (0.09-0.14) and 0.65 (0.52-0.79)/100 PYFU, respectively. In multivariable analysis, incidence rate of TB was approximately four-fold higher in eastern Europe compared with western Europe [incidence rate ratio (IRR) 4.25 (2.78-6.49), P < 0.001]. There were no significant temporal changes after 2001 and risk factors did not differ significantly between eastern Europe and western Europe. Lower CD4 cell counts, higher HIV-RNA levels, male sex, intravenous drug usage and African origin were all associated with higher risk of TB.

CONCLUSION

Incidence rates of TB in western Europe remained at a very low and stable level since 2001. After 2001, patients in eastern Europe were at substantially higher risk of TB than in western Europe. TB is of great concern in HIV-positive patients, especially in areas with high TB prevalence, high levels of immigration from TB-endemic regions, and with suboptimal access to combination antiretroviral therapy.

5th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention: summary of key research and implications for policy and practice - clinical sciences

Studies in several sub-Saharan African countries demonstrated that the expansion of antiretroviral therapy (ART) access is not only beneficial for people living with HIV, but also results in significant declines in tuberculosis and malaria incidence and prevalence, bolstering arguments for earlier and increased ART access and contributing to a growing understanding of co-epidemic dynamics. Several studies demonstrated that using standard triple-drug ART in resource-limited settings can reduce vertical transmission by as much as less than 1% if continued throughout breastfeeding.

The Nevirapine Resistance Study (NEVEREST) results provided proof of concept that nevirapine could be used as part of a paediatric second-line regimen, despite exposure to nevirapine prophylaxis for vertical transmission, following successful suppression on a lopinavir/ritonavir-based regimen. A South African study found that high pre-treatment levels of inflammatory and coagulation markers were strong predictors of death, reflecting similar findings in high-income countries and reinforcing the shift towards viewing HIV as a chronic, inflammatory disease. An early study of a new integrase inhibitor (S/GSK1349572) indicated strong potency and limited cross-resistance with raltegravir, the only integrase inhibitor currently approved for treatment.

Incident tuberculosis during antiretroviral therapy contributes to suboptimal immune reconstitution in a large urban HIV clinic in sub-Saharan Africa

BACKGROUND

Antiretroviral therapy (ART) effectively decreases tuberculosis (TB) incidence long-term, but is associated with high TB incidence rates in the first 6 months. We sought to determine the incidence and the long-term effects of TB during ART on HIV treatment outcome, and the risk factors for incident TB during ART in a large urban HIV clinic in Uganda.

METHODOLOGY/PRINCIPAL FINDINGS

Routinely collected longitudinal clinical data from all patients initiated on first-line ART was retrospectively analysed. 5,982 patients were included with a median baseline CD4+ T cell count (CD4 count) of 117 cells/mm(3) (interquartile range [IQR]; 42, 182). In the first 2 years, there were 336 (5.6%) incident TB events in 10,710 person-years (py) of follow-up (3.14 cases/100 pyar [95% CI 2.82-3.49]); incidence rates at 0-3, 3-6, 6-12 and 12-24 months were 11.25 (9.58-13.21), 6.27 (4.99-7.87), 2.47 (1.87-3.36) and 1.02 (0.80-1.31), respectively. Incident TB during ART was independently associated with baseline CD4 count of <50 cells/mm(3) (hazard ratio [HR] 1.84 [1.25-2.70], P = 0.002) and male gender (HR 1.68 [1.34-2.11], P<0.001). After two years on ART, the patients who had developed TB in the first 12 months had a significantly lower median CD4 count increase (184 cells/mm(3) [IQR; 107, 258, n = 118] vs 209 cells/mm(3) [124, 309, n = 2166], P = 0.01), a larger proportion of suboptimal immune reconstitution according to two definitions (increase in CD4 count <200 cells/mm(3): 57.4% vs 46.9%, P = 0.03, and absolute CD4 count <200 cells/mm(3): 30.4 vs 19.9%, P = 0.006), and a higher percentage of immunological failure according to the WHO criteria (13.6% vs 6.5%, P = 0.003). Incident TB during ART was independently associated with poor CD4 count recovery and fulfilling WHO immunological failure definitions.

CONCLUSIONS/SIGNIFICANCE

Incident TB during ART occurs most often within 3 months and in patients with CD4 counts less than 50 cells/mm(3). Incident TB during ART is associated with long-term impairment in immune recovery.

HIV-associated tuberculosis and immigration in a high-income country: incidence trends and risk factors in recent years

OBJECTIVE

To examine trends in tuberculosis incidence rates in France during the combination antiretroviral therapy (cART) period.

METHODS

From the French Hospital Database on HIV, we selected 72 580 patients (including 14 491 migrants) with no history of tuberculosis, followed between 1 January 1997 and 31 December 2008. We then examined incidence rates of tuberculosis and its risk factors.

RESULTS

A total of 2625 patients were diagnosed with tuberculosis either at enrollment (N = 932) or during follow-up (N = 1693). During follow-up, the incidence rate of tuberculosis was 0.40/100 patient-years overall, 0.20 among non-migrants and 1.03 among migrants. Adjusted risk of tuberculosis was 2.01 [95% confidence interval (CI) 1.79-2.26] times higher in migrants than in non-migrants. The adjusted incidence rate of tuberculosis significantly increased in both migrants and non-migrants after 2000-2001, with adjusted risks of 2.50 (95% CI 1.54-4.06) and 1.85 (95% CI 1.27-2.69) in 2008 compared with that in 1997, respectively. Other factors independently associated with a higher incidence of tuberculosis were medical follow-up less than or equal to 6 months, no previous antiretroviral therapy, lower CD4 cell count and higher viral load. Non-migrant patients belonging to HIV-transmission groups other than homosexual men, residing in the Paris area or in French West Indies or with AIDS status were at a supplementary risk.

CONCLUSION

The incidence of tuberculosis is increasing among both migrant and non-migrant HIV-infected patients in France. This is partly because sub-Saharan African migrants represent an increasing fraction of the HIV-infected population in France and also because of late access to care. Co-prescribing tuberculosis preventive therapy with cART might benefit selected patients, such as migrants and patients with late access to care.

Short and Long-Term Incidence of Tuberculosis and CD4-Cell Count Dynamic on HAART in Senegal

Objectives:

Estimate tuberculosis (TB) incidence among patients receiving HAART. Compare the dynamic of the CD4-cell count and viral load before notification of the TB with the dynamic among patients remaining free of TB.

Design:

Prospective cohort with ascertainment of TB cases from medical records.

Methods:

The first 404 adults HIV-1 infected patients enrolled in the Senegalese antiretroviral drug access initiative were eligible. CD4-cell and viral load were assessed at baseline and every 6 months. Patients receiving an antituberculosis treatment at HAART initiation were excluded from analysis. Any TB case notified after the first month of HAART was considered as an incident case. Follow-up was censored at death or at the last visit before March 31, 2008. CD4-cell trajectories until TB notification were compared to non-TB developers within two distinct periods: from HAART initiation to 24 months and after.

Results:

Over 404 eligible patients, 352 were included in this analysis. Median follow-up reached 73 months and 1821 person-years were accrued. Half of the 42 incident cases were notified before month 19 of HAART yielding to an overall incident rate of 2.3/100 PY [1.7-3.1]. Annual incidence decreased with duration of HAART (trend in incidence: RR=0.26, p<10^-4). During the first period, CD4-cell count dynamic of most TB patients was identical to the dynamic among patients remaining free of TB. Most cases of the second period occurred in a context of an immunological failure.

Conclusions:

This study provides an estimate of TB incidence among patients on HAART in Senegal and supports two underlying mechanisms.

Mortality from HIV and TB coinfections is higher in Eastern Europe than in Western Europe and Argentina

BACKGROUND AND OBJECTIVES

Tuberculosis (TB) is a leading cause of death in HIV-infected patients worldwide. We aimed to study clinical characteristics and outcome of 1075 consecutive patients diagnosed with HIV/TB from 2004 to 2006 in Europe and Argentina.

METHODS

One-year mortality was assessed in patients stratified according to region of residence, and factors associated with death were evaluated in multivariable Cox models.

RESULTS

At TB diagnosis, patients in Eastern Europe had less advanced immunodeficiency, whereas a greater proportion had a history of intravenous drug use, coinfection with hepatitis C, disseminated TB, and infection with drug-resistant TB (P < 0.0001). In Eastern Europe, fewer patients initiated TB treatment containing at least rifamycin, isoniazid, and pyrazinamide or combination antiretroviral therapy (P < 0.0001). Mortality at 1 year was 27% in Eastern Europe, compared with 7, 9 and 11% in Central/Northern Europe, Southern Europe, and Argentina, respectively (P < 0.0001). In a multivariable model, the adjusted relative hazard of death was significantly lower in each of the other regions compared with Eastern Europe: 0.34 (95% confidence interval 0.17-0.65), 0.28 (0.14-0.57), 0.34 (0.15-0.77) in Argentina, Southern Europe and Central/Northern Europe, respectively. Factors significantly associated with increased mortality were CD4 cell count less than 200 cells/microl [2.31 (1.56-3.45)], prior AIDS [1.74 (1.22-2.47)], disseminated TB [2.00 (1.38-2.85)], initiation of TB treatment not including rifamycin, isoniazid and pyrazinamide [1.68 (1.20-2.36)], and rifamycin resistance [2.10 (1.29-3.41)]. Adjusting for these known confounders did not explain the increased mortality seen in Eastern Europe.

CONCLUSION

The poor outcome of patients with HIV/TB in Eastern Europe deserves further study and urgent public health attention.

New methods for estimating the tuberculosis case detection rate in high-HIV prevalence countries: the example of Kenya

OBJECTIVE

To develop new methods for estimating the sputum smear-positive tuberculosis case detection rate (CDR) in a country where infection with HIV is prevalent.

METHODS

We estimated the smear-positive tuberculosis CDR in HIV-negative and HIV-positive adults, and in all adults in Kenya. Data on time trends in tuberculosis case notification rates and on HIV infection prevalence in adults and in tuberculosis patients were used, along with data on tuberculosis control programme performance.

FINDINGS

In 2006, the estimated smear-positive tuberculosis CDR in HIV-negative adults was 79% (95% confidence interval, CI: 64-94) and in HIV-positive adults, 57% (95% CI: 26-88), giving a weighted mean of 68% (95% CI: 49-87). The separate estimate for all smear-positive tuberculosis cases was 72% (95% CI: 53-91), giving an overall average for the three estimates of 70% (95% CI: 58-82). As the tuberculosis CDR in 1996 was 57% (95% CI: 47-67), the estimated increase by 2006 was 13 percentage points (95% CI: 6-20), or 23%. This increase was accompanied by a more than doubling of the resources devoted to tuberculosis control in Kenya, including facilities and staff.

CONCLUSION

Using three approaches to estimate the tuberculosis CDR in a country where HIV infection is prevalent, we showed that expansion of the tuberculosis control programme in Kenya led to an increase of 23% in the CDR between 1996 and 2006. While the methods developed here can be applied in other countries with a high prevalence of HIV infection, they rely on precise data on trends in such prevalence in the general population and among tuberculosis patients.

Unmasked tuberculosis and tuberculosis immune reconstitution inflammatory disease: a disease spectrum after initiation of antiretroviral therapy

Antiretroviral therapy (ART) has beneficial effects on mortality and lowers the incidence of diseases caused by opportunistic infections, such as tuberculosis (TB). Although ART has sustained long-term benefits, the risk of TB is high during the first 3 months after ART initiation. Among cases of ART-associated TB, we define "unmasked TB" as that which occurs in patients with reactivation disease who develop clinically recognizable TB after ART with the restoration of previously acquired TB antigen-specific functional immune responses. TB cases with clinical evidence of an inflammatory syndrome are a subset of these unmasked cases, which we define as "unmasked TB-immune reconstitution inflammatory syndrome." With more widespread use of ART in areas with a high prevalence of TB, unmasked TB will likely become more common. TB diagnostics with improved sensitivity and specificity are urgently needed to detect subclinical TB before it is unmasked.

Effect of simultaneous use of highly active antiretroviral therapy on survival of HIV patients with tuberculosis

INTRODUCTION

The optimal timing for initiation of highly active antiretroviral therapy (HAART) in patients with AIDS and tuberculosis (TB) is an unresolved question. To assess the effect of HAART on the survival of patients with TB, we designed this study.

METHODS

We selected all HIV patients included in the COMESEM cohort with TB diagnosis after 1996. Clinical and epidemiological data were registered. We compared patients who started HAART at the diagnosis of TB [simultaneous therapy (ST)] or not. Survival was assessed by Cox analysis.

RESULTS

Among the 6934 HIV patients included in the cohort, 1217 patients had TB, 322 of them (26.5%) after 1996. At the time of TB diagnosis, 45% of them started HAART (ST). There were no differences between groups regarding basal characteristics, except for a lower viral load in ST patients. ST therapy was associated with improved survival (hazard ratio 0.38; 95% confidence interval 0.20 to 0.72, P = 0.003). By univariate analysis, survival was also associated with no endovenous drug use and a later year of TB diagnosis. After adjusting for other prognostic variables, by Cox multivariate analysis, ST remained robustly associated with improved survival (hazard ratio 0.37; 95% confidence interval 0.17 to 0.66, P = 0.001).

CONCLUSIONS

Simultaneous HAART and TB treatment in HIV patients with TB is associated with improved survival.

Five-year outcomes of initial patients treated in Botswana's National Antiretroviral Treatment Program

BACKGROUND

Antiretroviral treatment (ART) initiatives have now been established in many sub-Saharan African countries showing early benefits. To date, few results are available concerning long-term clinical outcomes in these treatment programs.

METHODS

Response to ART is described in the first HIV-1C-infected adults enrolled in the Botswana Antiretroviral Treatment Program in 2002. Data analysis was conducted on available longitudinal data up to 1st April 2007.

RESULTS

Six hundred thirty-three severely immunodeficient patients with a median CD4+ cell count of 67 cells/microl were initiated on non-nucleoside reverse transcriptase inhibitor-based combination ART and followed for a median of 41.9 months. The median CD4+ cell count increases were 169, 302, and 337 cells/microl at 1, 3, and 5 years, respectively. The percentages of patients with a viral load of less than 400 copies/ml at 1, 3, and 5 years were 91.3, 90.1, and 98.3%, respectively. Seventy-five percent of patients did not miss a single, or missed only one, monthly ART pickup per year with a mean pickup rate of 92.5%. The Kaplan-Meier survival estimates [95% confidence interval (CI)] at 1, 3, and 5 years were 82.7% (81.2 and 84.3%), 79.3% (77.6 and 81.0%), and 79.0% (77.3 and 80.7%), respectively. At 6 months, the risk of treatment modification for anemia was 6.94% (5.9 and 8.0%) for cutaneous hypersensitivity reactions, 1.3% (0.8 and 1.7%), and 1.1% (0.7 and 1.6%) for hepatotoxicity.

CONCLUSION

This initial group of adults on ART in Botswana had excellent sustained immunologic, virologic, and clinical outcomes for up to 5 years of follow-up with low mortality among those surviving into the second year of ART.

Effects of duration of HIV infection and secondary tuberculosis transmission on tuberculosis incidence in the South African gold mines

BACKGROUND

HIV increases the risk of tuberculosis directly, through immunosuppression, and indirectly, through onward transmission of Mycobacterium tuberculosis from the increased caseload. We assess the contribution of these two mechanisms by time since seroconversion to HIV.

METHODS

The incidence of new pulmonary tuberculosis was estimated in a retrospective cohort study of South African gold miners over 14 years. HIV tests were done in random surveys in 1992-1993, and in clinics. One thousand nine hundred fifty HIV positive men with seroconversion intervals of less than 3 years were identified and linked to medical, demographic and occupational records. They were compared with men who were HIV-negative in a survey, with no later evidence of HIV. Analyses were censored when men were diagnosed with tuberculosis, died or left the mine.

RESULTS

Tuberculosis incidence rose soon after HIV infection, reaching 1.4/100 person-years (95% confidence interval 1.1-1.9) within 2 years, and 10.0/100 person-years (95% confidence interval 6.5-15.5) at 10 or more years. By 11 years from seroconversion, nearly half the men had had tuberculosis. Among 5702 HIV-negative men, tuberculosis incidence was 0.48/100 person-years (95% confidence interval 0.33-0.70) in 1991-1993 and doubled over the period of the study (after adjusting for age). Age-adjusted model estimates suggest that half the increase in tuberculosis incidence by time since HIV infection was attributable to increasing incidence over calendar period--the indirect effect.

CONCLUSION

For the first time, we have shown that the increase in tuberculosis risk by time since seroconversion reflects both direct effects of HIV increasing susceptibility, and indirect effects due to onward transmission. Innovative and sustained public health measures are needed to reduce Mycobacterium tuberculosis transmission.

Immune reconstitution and "unmasking" of tuberculosis during antiretroviral therapy

Tuberculosis (TB) is the most common opportunistic disease in HIV-infected patients during the initial months of antiretroviral therapy (ART) and presents a great challenge to ART programs in resource-limited settings. The mechanisms underlying development of TB in this period are complex. Some cases may represent progression of undiagnosed subclinical disease present before starting ART, emphasizing the importance of careful screening strategies for TB. It has been suggested that progression in such cases is due to immune reconstitution disease-a phenomenon in which dysregulated restoration of pathogen-specific immune responses triggers the presentation of subclinical disease. However, whereas some cases have exaggerated or overtly inflammatory manifestations consistent with existing case definitions for IRD, many others do not. Moreover, since ART-induced immune recovery is a time-dependent process, active TB may develop as a consequence of persisting immunodeficiency. All these mechanisms are likely to be important, representing a spectrum of complex interactions between mycobacterial burden and changing host immune response. We propose that the potential range of effects of ART includes (1) shortening of the time for subclinical TB to become symptomatic (a phenomenon often referred to as "unmasking"), (2) increased rapidity of initial onset of TB symptoms, and (3) heightened intensity of clinical manifestations. We suggest that the term "ART-associated TB" be used to refer collectively to all cases of TB presenting during ART and that "immune reconstitution disease" be used to refer to the subset of ART-associated TB cases in which the effect on disease severity results in exaggerated and overtly inflammatory disease.

New concepts in childhood tuberculosis

PURPOSE OF REVIEW

Childhood tuberculosis has long been neglected in international tuberculosis control efforts. There are, however, many opportunities to prevent childhood tuberculosis that are not being fully employed.

RECENT FINDINGS

Several papers have been published to emphasize the unique nature of childhood tuberculosis and improve tuberculosis control in children. Treatment regimens have been improved and refined. Clinical and radiographic methods have been standardized. While new diagnostic tests are greatly needed, it is also apparent that any new tests--such as the interferon release assays--will need to be studied specifically in infants and children or there is a risk they may be misapplied. The areas of greatest need for research and clinical utility remain better diagnostic tests for tuberculosis infection and disease; shorter and more effective regimens for treating tuberculosis infection; better integration of children into standard tuberculosis control practices; a better understanding of the interaction of human immunodeficiency virus infection and tuberculosis in children; detection and treatment of drug-resistant tuberculosis in children; and a more effective vaccine.

SUMMARY

True progress will require a rethinking of basic tuberculosis control with a commitment to address problems specific to childhood tuberculosis.

Burden of tuberculosis in an antiretroviral treatment programme in sub-Saharan Africa: impact on treatment outcomes and implications for tuberculosis control

OBJECTIVES

To determine burden and risk factors for tuberculosis (TB) in an antiretroviral treatment (ART) programme and its impact on ART outcomes.

DESIGN

Prospective cohort study.

METHODS

Prevalent TB was assessed at baseline and incident TB was ascertained prospectively over 3 years among 944 patients accessing a community-based ART programme in South Africa.

RESULTS

At enrollment, median CD4 cell count was 96 cells/microl and 52% of patients had a previous history of TB. Prevalent TB (current antituberculosis treatment or active TB) was present in 25% and was strongly associated with advanced immunodeficiency. During 782 person-years of ART, 81 cases of TB were diagnosed. The incidence was 22.1/100 person-years during the first 3 months of ART and decreased to an average of 4.5/100 person-years during the second and third years. In multivariate analysis, risk of incident TB during follow-up was only associated with the current absolute CD4 cell count at that time point; an increase of 100 cells/mul was associated with a 25% lower risk (P = 0.007). Although prevalent and incident TB were associated with greater than two-fold increased mortality risk, they did not compromise immunological and virological outcomes among survivors at 48 weeks.

CONCLUSIONS

Late initiation of ART was associated with a major burden of TB in this ART programme. TB reduced survival but did not impair immunovirological outcomes. Reductions in TB incidence during ART were dependent on CD4 cell count; however, after 3 years of treatment, rates were still 5- to 10-fold higher than among non-HIV-infected people. Earlier initiation of ART may reduce this burden of TB.