Temporal trends in the prevalence of Mycobacterium tuberculosis infection in South African adolescents.

South Africa. 1) To measure changes in the adolescent prevalence of latent tuberculous infection (LTBI) between 2005 and 2015, and 2) to evaluate medium-term impact of TB control measures on LTBI prevalence. We compared baseline data from a cohort study (2005-2007) and a vaccine trial (2014-2015) which enrolled adolescents from the same eight South African high schools. LTBI was defined based on QuantiFERON®-TB Gold In-Tube test positivity. We analysed data from 4880 adolescents between 2005 and 2007, and 1968 adolescents between 2014 and 2015, when the average LTBI prevalence was respectively 43.8% (95%CI 28.4-59.1) vs. 48.5% (95%CI 41.1-55.8). Age-specific LTBI prevalence increased between the ages 12 and 18 years by 13% only in lower socio-economic quintile schools, where the average LTBI prevalence was unchanged between the two periods (54% vs. 53%). In the highest socio-economic quintile schools, LTBI prevalence did not increase with age; however, the average LTBI prevalence increased from 20% to 38% between the two periods. Adolescent LTBI prevalence remained high and constant over a decade, suggesting that Mycobacterium tuberculosis transmission to children was not impacted in the medium term by effective TB control efforts. Trends in adolescent LTBI prevalence should be interpreted in the context of the sociodemographic factors that affect the risk of transmission before and during adolescence. .

Comparison of haematology and biochemistry parameters in healthy South African infants with laboratory reference intervals.

OBJECTIVE: Paediatric laboratory reference intervals used in Africa and Asia may be derived from historical intervals of predominantly Caucasian infants in Europe or North America. These intervals may therefore not be compatible with the range of normality for developing country populations. We aimed to compare haematology and biochemistry parameters in healthy South African infants with local laboratory reference intervals. METHODS: We compared the baseline haematology and biochemistry results of 634 (316 male and 318 female) HIV-unexposed infants, aged 3-6 months, living in a rural area of the Western Cape Province, South Africa, against laboratory reference intervals supplied by the South African National Health Laboratory Services (NHLS). We calculated the percentage of observed values out of bound (in terms of lower and upper limits) compared to laboratory reference intervals. RESULTS: Of the 634 healthy infants screened, 316 (49.84%) were male and 318 (50.16%) female. A majority (91.05%) had platelet counts above the laboratory reference interval upper limit (350 × 109 cells/l), while over half, 54.85% and 56.98% had mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values below the lower limits of 77.0-105.0 fl and 26.0-34.0 pg, respectively. A small proportion were outside the reference limits for haematocrit, namely 15.71% below and 7.14% above the normal limits of 0.31-0.38 l/l. For male and female infants, 33.65% and 18.04% of alkaline phosphatase (ALP) values and 7.01% and 14.56% of alanine transaminase (ALT) values were above the upper limits, respectively. For male infants, 10.83% of gamma-glutamyl transferase (GGT) values, and for female infants, 31.11% of GGT values were below the lower limits of 12 U/l for males and 15 U/l for females. We observed no significant deviations (>10% out of bound) from NHLS reference intervals in the remaining haematology and biochemistry parameters measured. CONCLUSIONS: Haematology and biochemistry parameters in apparently healthy South African infants deviate frequently from national laboratory reference intervals, including abnormalities consistent with subclinical hypochromic microcytic anaemia. It is important that clinical laboratory reference intervals for children are derived locally, rather than being adopted from Caucasian norms in developed countries, because clinical trials of vaccines, drugs and diagnostics are increasingly conducted in sub-Saharan Africa.

Impact of Xpert MTB/RIF rollout on management of tuberculosis in a South African community.

BACKGROUND: The Xpert MTB/RIF test shortens the time to microbiological confirmation of pulmonary tuberculosis (TB) under research conditions. OBJECTIVE: To evaluate the field impact of Xpert MTB/RIF rollout on TB diagnostic yield and time to treatment in a South African (SA) community. METHODS: We compared TB investigation outcomes for 6-month calendar periods before and after Xpert MTB/RIF rollout in a semi-rural area of SA. The proportion of adult patients who tested positive by sputum smear microscopy, liquid culture or Xpert MTB/RIF and the proportion of positive sputum smear, liquid culture or Xpert MTB/RIF tests were compared. Secondary outcomes included time to laboratory diagnosis and treatment initiation. Data were collected from the National Health Laboratory Service database and from the Western Cape Provincial Department of Health TB register. RESULTS: Regional rollout of Xpert MTB/RIF testing occurred in 2013. Of the 15 629 patients investigated in the post-rollout period, 7.9% tested positive on GeneXpert, compared with 6.4% of the 10 741 investigated in the pre-rollout period who tested positive by sputum smear microscopy (p<0.001). Median laboratory processing time was <1 day for Xpert MTB/RIF (interquartile range (IQR) 0 - 1) compared with 1 day (IQR 0 - 16) for sputum smear microscopy (p=0.001). The median time to TB treatment initiation was 4 days (IQR 2 - 8) after rollout compared with 5 days (IQR 2 - 14) before (p=0.001). CONCLUSIONS: Patients investigated for suspected pulmonary TB were more likely to be diagnosed after rollout of Xpert MTB/RIF testing, although the benefit to diagnostic yield was modest, and Xpert MTB/RIF testing was associated with a marginal improvement in time to treatment initiation.

Impact of isoniazid preventive therapy on the evaluation of long-term effectiveness of infant MVA85A vaccination.

SETTING: South Africa. OBJECTIVE: To evaluate the long-term effectiveness of infant modified vaccinia Ankara virus-expressing antigen 85A (MVA85A) vaccination against tuberculosis (TB). DESIGN: We analysed data from a double-blind randomised placebo-controlled Phase 2b MVA85A infant TB vaccine trial (2009-2012), with extended post-trial follow-up (2012-2014). Isoniazid preventive therapy (IPT) was provided by public health services according to national guidelines. The primary outcome was curative treatment for TB disease. Survival analysis and Poisson regression were used for study analysis. RESULTS: Total follow-up was 10 351 person-years of observation (pyo). Median follow-up age was 4.8 years (interquartile range 4.4-5.2). There were 328 (12%) TB cases. TB disease incidence was 3.2/100 pyo (95%CI 2.8-3.5) overall, and respectively 3.3 (95%CI 2.9-3.9) and 3.0 (95%CI 2.6-3.5)/100 pyo in the MVA85A vaccine and placebo arms. A total of 304 children (11%) received IPT, with respectively 880 and 9471 pyo among IPT and non-IPT recipients. There were 23 (7.6%) TB cases among 304 IPT recipients vs. 305 (12.9%) among 2374 non-IPT recipients (P = 0.008). IPT effectiveness was 85% (95%CI 76-91). CONCLUSION: Extended follow-up confirms no long-term effectiveness of infant MVA85A vaccination, but a six-fold reduction in TB risk can be attributed to IPT. National TB programmes in high TB burden countries should ensure optimal implementation of IPT for eligible children.

A double-blind, randomised, placebo-controlled, dose-finding trial of the novel tuberculosis vaccine AERAS-402, an adenovirus-vectored fusion protein, in healthy, BCG-vaccinated infants.

BACKGROUND: Several novel tuberculosis vaccines are currently in clinical trials, including AERAS-402, an adenovector encoding a fusion protein of Mycobacterium tuberculosis antigens 85A, 85B, and TB10.4. A multicentred trial of AERAS-402 safety and immunogenicity in healthy infants was conducted in three countries in sub-Saharan Africa, using an adaptive design. METHODS: In a double-blind, randomised, placebo-controlled, dose-finding trial, we enrolled BCG-vaccinated, HIV-uninfected infants aged 16-26 weeks. Infants in the safety/dose-finding phase received two doses of AERAS-402 across three dose levels, or placebo, intramuscularly on days 0 and 28. Infants in the expanded safety phase received three doses of the highest dose level, with the 3rd dose at day 280. Follow up for safety and immunogenicity was for up to two years. RESULTS: We enrolled 206 infants (52 placebo and 154 AERAS-402 recipients) into the dose-finding phase and 281 (141 placebo and 140 AERAS-402 recipients) into the expanded safety phase. Safety data were acceptable across all dose levels. No vaccine-related deaths were recorded. A single serious adverse event of tachypnoea was deemed related to study vaccine. Antibodies directed largely against Ag85A and Ag85B were detected. Low magnitude CD4+ and CD8+ polyfunctional T cell responses were observed at all dose levels. The addition of a third dose of AERAS-402 at the highest dose level did not increase frequency or magnitude of antibody or CD8+ T cell responses. CONCLUSIONS: AERAS-402 has an acceptable safety profile in infants and was well tolerated at all dose levels. Response rate was lower than previously seen in BCG vaccinated adults, and frequency and magnitude of antigen-specific T cells were not increased by a third dose of vaccine.

A controlled trial of sputum induction and routine collection methods for TB diagnosis in a South African community.

The diagnostic yield of pulmonary tuberculosis (TB) by sputum induction (SI) at the first point of contact with health services, conducted in all patients with suspected TB regardless of the ability to expectorate spontaneously, has not been evaluated. We compared the diagnostic yield of SI to routine sputum collection in a South African community setting. Ambulatory patients with suspected TB provided a 'spot' expectorated sputum sample, an SI sample by hypertonic (5 %) saline nebulization, and early morning expectorated sputum sample. The diagnostic yield of sputum smear microscopy and liquid culture (denominator all subjects with any positive Mycobacterium tuberculosis culture), and time-to-positivity of culture were compared between SI and expectorated samples. A total of 555 subjects completed the SI procedure, of whom 132 (24 %) were human immunodeficiency virus (HIV)-infected. One hundred and twenty-nine samples (129, 23 %) were M. tuberculosis culture-positive. The time-to-positivity of Mycobacteria Growth Indicator Tube (MGIT) culture was shorter for SI (median difference 2 days, p = 0.63) and for early morning expectorated sputum (median difference 2 days, p = 0.02) compared to spot expectorated sputum. However, there was no difference in the culture-positive diagnostic yield between SI and spot expectorated sputum [difference +0.7 %; confidence interval (CI) -7.0 to +8.5 %, p = 0.82] or SI and early morning expectorated sputum (difference +4.7 %; CI -3.2 to +12.5 %, p = 0.20) for all subjects or for HIV-infected subjects. SI reduces the time to positive M. tuberculosis culture, but does not increase the rate of positive culture compared to routine expectorated sputum collection. SI cannot be recommended as the routine collection method at first contact among ambulatory patients with suspected TB in high-burden communities.

Vaccine trials in the developing world: operational lessons learnt from a phase IV poliomyelitis vaccine trial in South Africa.

BACKGROUND: Conducting vaccine trials in developing nations is necessary but operationally complex. We describe operational lessons learnt from a phase IV poliomyelitis vaccine trial in a semi-rural region of South Africa. METHODS: We reviewed operational data collected over the duration of the trial with respect to staff recruitment and training, participant recruitment and retention, and cold chain maintenance. RESULTS-LESSONS LEARNT: The recruitment model we used that relied on the 24h physical presence of a team member in the birthing unit was expensive and challenging to manage. Forecasting of enrolment rates was complicated by incomplete baseline data and by the linear nature of forecasts that do not take into account changing variables. We found that analyzing key operational data to monitor progress of the trial enabled us to identify problem areas timeously, and to facilitate a collegial problem-solving process by the extended trial team. Pro-actively nurturing a working relationship with the public sector health care system and the community was critical to our success. Despite the wide geographical area and lack of fixed addresses, we maintained an excellent retention rate through community assistance and the use of descriptive residential information. Training needs of team members were ongoing and dynamic and we discovered that these needs that were best met by an in-house, targeted and systemized training programme. The use of vaccine refrigerators instead of standard frost-free refrigerators is cost-effective and necessary to maintain the cold-chain. CONCLUSION: Operational challenges of a vaccine trial in developing world populations include inexperienced staff, the close liaison required between researchers and public health care services, impoverished participants that require complex recruitment and retention strategies, and challenges of distance and access. These challenges can be overcome by innovative strategies that allow for the unique characteristics of the setting, trial population, and trial team.

Tuberculosis case finding for vaccine trials in young children in high-incidence settings: a randomised trial.

SETTING: A high tuberculosis (TB) burden rural area in South Africa. OBJECTIVE: To compare TB case yield and disease profile among bacille Calmette-Guérin (BCG) vaccinated children using two case-finding strategies from birth until 2 years of age. DESIGN: BCG-vaccinated infants were enrolled within 2 weeks of birth and randomised to 3-monthly home visits for questionnaire-based TB screening plus record surveillance of TB registers, hospital admission and X-ray lists at health facilities for TB suspects and cases (Group 1), or record surveillance (as above) only (Group 2). Both groups received a close-out visit after 2 years. Participants were evaluated for suspected TB disease using standardised investigations. RESULTS: A total of 4786 infants were enrolled: 2392 were randomised to Group 1 and 2394 to Group 2. The case-finding rate was significantly greater in Group 1 (2.2/100 py) than in Group 2 (0.8/100 py), with a case-finding rate ratio of 2.6 (95%CI 1.8-4.0, P < 0.001). Although the proportion of cases with bacteriological confirmation was lower in Group 1, this difference did not reach statistical significance. There was also no significant difference in the proportions with TB symptoms and signs. CONCLUSION: Home visits combined with record surveillance detected significantly more cases than record surveillance with a single study-end visit. The TB case profile did not differ significantly between the two groups.

Sputum induction for the diagnosis of pulmonary tuberculosis: a systematic review and meta-analysis.

Sputum induction (SI) has been proposed as the optimal sample collection method for patients with paucibacillary tuberculosis (TB). Studies reporting the culture of Mycobacterium tuberculosis from SI were reviewed. A random-effects meta-analysis of diagnostic yield (numerator M. tuberculosis SI culture-positive cases; denominator all culture-positive cases) was conducted. Diagnostic yields (95% confidence intervals, CIs) were displayed as Forest plots. Heterogeneity was evaluated using Chi-squared and I-squared tests and meta-regression analysis. Ninety publications were screened, 28 full-text papers reviewed, and 17 analyzed. Collectively, n=627 SI culture-positive cases among n=975 culture-confirmed TB cases were reported. The diagnostic yield of SI ranged from 35 to 95%. The pooled diagnostic yield was 74% (CI 65-81%), with significant heterogeneity (p<0.0001, I2=86%). There were no statistically significant differences in the yield between sub-groups defined by human immunodeficiency virus (HIV) prevalence or age. Univariate analysis demonstrated that the use of fiberoptic bronchoscopy (FOB) as the comparator method was associated with a 22% reduction (CI 2-42%) in the diagnostic yield of SI. However, after adjustment for confounding, the meta-regression analysis showed that FOB usage (p=0.21) and saline concentration (p=0.31) were not independently associated with the diagnostic yield. SI will detect approximately three-quarters of M. tuberculosis culture-positive cases under study conditions. Significant heterogeneity in the diagnostic yield was not explained by HIV prevalence, age, or the use of FOB as the comparator method. The use of a particular nebulized saline concentration for SI cannot be recommended on the basis of this meta-regression analysis.

Safety and tolerability of sputum induction in adolescents and adults with suspected pulmonary tuberculosis.

Sputum induction by the inhalation of hypertonic saline may increase the yield of microbiological diagnosis of pulmonary tuberculosis (TB). This is particularly relevant in paucibacillary TB, such as in children or human immunodeficiency virus (HIV)-infected patients. Sputum induction must be shown to be safe and tolerable in community settings where invasive diagnostic methods are unavailable. The objective of this study was to describe the changes in physiological parameters and adverse events occurring during sputum induction in ambulatory adult and adolescent TB suspects recruited in community clinics. Sputum induction was performed in HIV-infected (n = 35) and HIV-uninfected (n = 67) TB suspects (n = 102). Oxygen saturation (%), blood pressure (mm Hg), heart rate (/minute), respiratory rate (/minute), and adverse events were monitored at baseline, continuously during the salbutamol pre-treatment and saline nebulization phases, and for 30 min afterwards. During nebulization, there was a statistically significant increase in oxygen saturation (1%, p < 0.0001), systolic BP (7 mm Hg, p < 0.0001), and diastolic BP (2 mm Hg, p = 0.008). Post-nebulization decrease in the systolic BP occurred (4 mm Hg, p = 0.016). These changes were not considered to be clinically significant. Eight minor, transitory, self-resolving adverse events occurred (labored breathing, n = 2; chest pain, n = 2; paroxysmal coughing, n = 1; elevated heart rate, n = 1; vomiting, n = 1; hypotension, n = 1), leading to procedure termination in four participants. No serious adverse events occurred. Induced sputum is safe, tolerable, and feasible in adult and adolescent TB suspects in a community healthcare setting.

Analysis of time to regulatory and ethical approval of SATVI TB vaccine trials in South Africa.

BACKGROUND: Tuberculosis (TB) vaccine trials in South Africa must be approved by the Medicines Control Council (MCC) and by a human research ethics committee (HREC). Delays in regulatory and ethical approval may affect operational and budget planning and clinical development of the product. AIM: Our aim was to analyse the time to regulatory and ethical approval for TB vaccine trials conducted by the South African Tuberculosis Vaccine Initiative (SATVI) and to evaluate factors that influence time to final approval. METHOD: Sixteen new TB vaccine clinical trials conducted by SATVI between 2004 and 2012 on infants, children, and adults were included. The period between submission and final approval was determined for protocols submitted to the MCC and the University of Cape Town HREC. RESULTS: Median approval time following first submission to the MCC was 122 days (IQR 112 - 168; range 71 - 350), and for protocol amendments 103 days (interquartile range (IQR) 76 - 141; range 23 - 191; n=30). Median time following first submission for HREC approval was 60 days (IQR 33 - 81; range 18 - 125), and for amendments 6 days (IQR 4 - 13; range 1 - 37; n=30). There was no significant difference in approval time by trial phase, year of submission, revisions required, study population, sample size, or whether a clinical research organisation (CRO) was used. CONCLUSION: The time needed for regulatory and ethics approval was highly variable, but MCC approval for first submissions took twice as long as HREC approval and was the primary determinant of time to final approval. National regulatory capacity should be strengthened to facilitate the conduct of new TB vaccine trials in this country with its high burden of TB.

Risky behaviour and psychosocial correlates in adolescents - is there a link with tuberculosis?

OBJECTIVE: Reasons for the increase in incidence of tuberculosis (TB) in late adolescence are poorly understood. One hypothesis is that psychological and behavioural variables associated with adolescence may increase risk of developing TB. The study aimed to determine whether psychosocial and behavioural variables affect incidence of TB disease in adolescents. METHODS: A case-control study design was used in adolescents who were participants in a TB epidemiological study. Cases were adolescents diagnosed with TB disease. Approximately half of the controls had no TB disease but a positive TST indicative of latent TB. Half had neither TB disease nor latent TB. A self-administered questionnaire was completed by participants. The questionnaire consisted of a combination of standardised psychosocial instruments. RESULTS: Of 292 participants, 62 were cases, 112 had latent TB and 118 neither TB disease nor latent TB. There were no significant differences in instrument scores between cases and controls. There was a trend for certain adverse life events to be more common in the TB-disease group. CONCLUSION: In adolescents, a trend for association between TB incidence and psychosocial and behavioural variables was not statistically significant. Given the trend, research with larger samples, and more comprehensive assessment of the relationship between stressors and TB, is warranted.

Tuberculin skin test and QuantiFERON® assay in young children investigated for tuberculosis in South Africa.

SETTING: Although the literature on interferon-gamma release assays on tuberculosis (TB) in children has increased, data pertaining to young children remain relatively limited. OBJECTIVE: To compare results from the tuberculin skin test (TST) and the QuantiFERON®-TB Gold In-Tube assay (QFT) in children aged <3 years investigated for TB disease. DESIGN: TB suspects were evaluated by medical history and examination, TST, QFT, chest radiography, induced sputum and gastric washings for smear and culture for Mycobacterium tuberculosis. RESULTS: A total of 400 children were enrolled. Among 397 children with both test results, 68 (17%) were QFT-positive and 72 (18%) were TST-positive (≥10 mm). Agreement between the tests was excellent (94%, κ = 0.79, 95%CI 0.69-0.89). TB disease was diagnosed in 52/397 (13%) participants: 3 definite, 35 probable and 14 possible TB. QFT sensitivity and specificity for TB disease were respectively 38% and 81%. TST sensitivity and specificity were respectively 35% and 84%. CONCLUSION: While TST and QFT had excellent concordance in this population, both tests had much lower sensitivity for TB disease than has been reported for other age groups. Our results suggested equivalent performance of QFT and TST in the diagnosis of TB disease in young children in a high-burden setting.

The tuberculin skin test: a comparison of ruler and calliper readings.

BACKGROUND: The Mantoux tuberculin skin test (TST) is widely used to diagnose latent infection with Mycobacterium tuberculosis. TST skin induration may be measured either by a transparent ruler or by a pair of callipers. We hypothesised that the type of instrument used may affect the reading. OBJECTIVE: To determine whether variability in Mantoux TST measurement is affected by the type of reading instrument. METHOD: A TST (Mantoux method) was performed among healthy adolescents. The indurations were read with among ruler and calliper by two independent readers. Limits of agreement and Kappa (κ) scores at TST positivity cut-off points were calculated. A Bland-Altman graph was constructed. RESULTS: The 95% limits of agreement between instruments ranged from -5 mm to 3 mm. The limits of agreement between readers ranged from -5 mm to 4 mm. κ scores between instruments were respectively 0.7 and 0.8 at 15 mm and 10 mm cut-offs. CONCLUSION: The variability between readers of TST indurations is not influenced by changing the reading instrument.

Age-related tuberculosis incidence and severity in children under 5 years of age in Cape Town, South Africa.

SETTING: Limited data are available on the characteristics of tuberculosis (TB) disease in young children, especially in high-burden countries. OBJECTIVE: To assess the incidence and severity of TB in children aged <5 years. METHODS: TB records and chest radiographs of children born in Cape Town in 1999 and diagnosed with TB between 1999 and 2004 were reviewed retrospectively. RESULTS: A total of 1607 cases were registered. The cumulative incidence of definite (bacteriologically confirmed) and probable (radiological evidence and > or =1 TB clinical feature) TB in children aged <5 years was 2.9% and was highest between the ages of 12 and 23 months. Of 1233 children with definite or probable TB, 506 (41%) had severe disease (dissemination, cavities or >1 lobe involved). The under 5 years incidence of disseminated TB was 0.33%. Of 239 (15%) cases that were bacteriologically confirmed, clinical features typical of TB disease were individually present in <60%. The most common combined symptoms were cough for >2 weeks and weight loss, occurring in 43/239 (18%). CONCLUSION: TB incidence was high, and peaked in children aged 12-23 months. Many children experienced severe disease. A fifth of children with microbiologically confirmed disease presented with only one feature typically associated with TB.