Structured approaches for the screening and diagnosis of childhood tuberculosis in a high prevalence region of South Africa

Number Needed to Screen for Tuberculosis Disease Among Children: A Systematic Review

CONTEXT

Improving detection of pediatric tuberculosis (TB) is critical to reducing morbidity and mortality among children.

OBJECTIVE

We conducted a systematic review to estimate the number of children needed to screen (NNS) to detect a single case of active TB using different active case finding (ACF) screening approaches and across different settings.

DATA SOURCES

We searched 4 databases (PubMed, Embase, Scopus, and the Cochrane Library) for articles published from November 2010 to February 2020.

STUDY SELECTION

We included studies of TB ACF in children using symptom-based screening, clinical indicators, chest x-ray, and Xpert.

DATA EXTRACTION

We indirectly estimated the weighted mean NNS for a given modality, location, and population using the inverse of the weighted prevalence. We assessed risk of bias using a modified AXIS tool.

RESULTS

We screened 27 221 titles and abstracts, of which we included 31 studies of ACF in children < 15 years old. Symptom-based screening was the most common screening modality (weighted mean NNS: 257 [range, 5-undefined], 19 studies). The weighted mean NNS was lower in both inpatient (216 [18-241]) and outpatient (67 [5-undefined]) settings (107 [5-undefined]) compared with community (1117 [28-5146]) and school settings (464 [118-665]). Risk of bias was low.

LIMITATIONS

Heterogeneity in the screening modalities and populations make it difficult to draw conclusions.

CONCLUSIONS

We identified a potential opportunity to increase TB detection by screening children presenting in health care settings. Pediatric TB case finding interventions should incorporate evidence-based interventions and local contextual information in an effort to detect as many children with TB as possible.

Diagnosis of childhood tuberculosis in Pakistan: Are national guidelines used by private healthcare providers?

BACKGROUND

The National Tuberculosis Control Program (NTP) in Pakistan developed, with the Pakistan Paediatric Association, a pediatric scoring chart to aid diagnosis of childhood tuberculosis (TB). Our study compared the diagnostic practice of private healthcare providers in Pakistan with the NTP guidelines.

METHODS

A cross-sectional study comparing diagnosis of TB in children <15 years by Non-NTP private providers with the NTP's pediatric scoring chart. A generalized linear model was used to determine the difference in adherence by Non-NTP private providers to the NTP guidelines for childhood TB diagnosis by associated factors.

RESULTS

A total of 5193 (79.7% of presumptive childhood TB cases identified in the selected districts during the study) children were diagnosed with TB by Non-NTP private providers. A strong clinical suspicion of TB was present in 17.3%, and chest x-ray was suggestive of TB in 34.3%. The Kappa score between Non-NTP private providers and the NTP guidelines for diagnosing TB was 0.152. Only 47.8% of cases were diagnosed in line with the NTP guidelines. Children <5 years old with a history of TB contact had a higher chance of being diagnosed according to the NTP guidelines.

CONCLUSION

This study indicates a low adherence of NTP guidelines for diagnosing childhood TB by private providers in Pakistan.

Advances in the diagnosis of pulmonary tuberculosis in children

Major challenges still exist in the accurate diagnosis of tuberculosis in children. Algorithms based on clinical and radiological features remain in widespread use despite poor performance. Newer molecular diagnostics allow for rapid identification of TB and detection of drug-resistance in a subset of children, but lack sensitivity. Molecular testing of multiple specimens, including non-traditional specimen types, such as nasopharyngeal aspirates and stool and urine, may improve sensitivity, but the optimal combination of specimens requires further research. Novel tests under development or evaluation include a urine lipoarabinomannan test with improved sensitivity and a range of biomarkers measured from stimulated or unstimulated peripheral blood.

The Impact of Funding on Childhood TB Case Detection in Pakistan

This study is a review of routine programmatically collected data to describe the 5-year trend in childhood case notification in Jamshoro district, Pakistan from January 2013 to June 2018 and review of financial data for the two active case finding projects implemented during this period. The average case notification in the district was 86 per quarter before the start of active case finding project in October 2014. The average case notification rose to 322 per quarter during the implementation period (October 2014 to March 2016) and plateaued at 245 per quarter during the post-implementation period (April 2016 to June 2018). In a specialized chest center located in the district, where active case finding was re-introduced during the post implementation period (October 2016), the average case notification was 218 per quarter in the implementation period and 172 per quarter in the post implementation period. In the rest of the district, the average case notification was 160 per quarter in the implementation period and 78 during the post implementation period. The cost per additional child with TB found ranged from USD 28 to USD 42 during the interventions. A continuous stream of resources is necessary to sustain high notifications of childhood TB.

Joint approach of diffusion- and perfusion-weighted MRI in intra-axial mass like lesions in clinical practice simulation

Although advanced magnetic resonance imaging (MRI) techniques provide useful information for the differential diagnosis of intra-axial mass-like lesions, the specific diagnostic role of multimodal MRI over conventional magnetic resonance imaging (CMRI) alone in the differential diagnosis of mass-like lesions from a large heterogeneous cohort has not been studied. In this study, we aimed to determine the added value of a joint approach of diffusion-weighted imaging (DWI) and dynamic-susceptibility-contrast perfusion imaging (DSC-PWI) for diagnosis of intra-axial mass-like lesions, comparing them with CMRI alone. Furthermore, we performed these evaluations in a manner simulating clinical practice. Our institutional review board approved this retrospective study and waived the requirement for informed consent. A total of 1038 patients with intra-axial mass-like lesions were retrospectively recruited according to their histological and clinico-radiological diagnoses made between January 2005 and December 2014. All patients underwent CMRI, DWI and DSC-PWI. The diagnostic accuracy and confidence in diagnosing each type of intra-axial mass-like lesions, and for differentiating the intra-axial brain tumors from non-neoplastic lesions, were compared according to the MRI protocols. The disease-specific sensitivity of joint approach differed according to specific disease entities in diagnosing each disease category. Joint approach provided the best diagnostic accuracy for discriminating intra-axial brain tumors from non-neoplastic lesions, with high diagnostic accuracy (95.3–96.7%), specificity (82–84.0%), positive-predictive-value (97.0–97.3%), and negative-predictive-value (84.8–92.7%), with the reader’s confidence values being significantly improved over those on CMRI alone (all p-values < 0.001). In conclusion, joint approach of DWI, DSC-PWI to CMRI helps to differentiate non-neoplastic lesions from intra-axial brain tumors, and improves diagnostic confidence compared with CMRI alone. The benefit from the combined imaging differs for each disease category; thus joint approach needs to be customized according to clinical suspicion.

Upfront Xpert MTB/RIF testing on various specimen types for presumptive infant TB cases for early and appropriate treatment initiation

Background

Diagnosis of tuberculosis (TB) in infants is challenging due to non-specific clinical presentations of the disease in this age-group and low sensitivity of widely available TB diagnostic tools, which in turn delays prompt access to TB treatment. Upfront access to Xpert/MTB RIF (Xpert) testing, a highly sensitive and specific rapid diagnostic tool, could potentially address some of these challenges. Under the current project, we assessed the utility and feasibility of applying upfront Xpert for diagnosis of tuberculosis in infants, including for testing of non-sputum specimens.

Methods

A high throughput lab was established in each of the four project cities, and linked to various health care providers across the city, through rapid specimen transportation and electronic reporting linkages. Free Xpert testing was offered to all infant (<2 years of age) presumptive TB cases (both pulmonary and extra-pulmonary) seeking care at public and private health facilities.

Results

A total of 7,994 presumptive infant TB cases were enrolled in the project from April 2014 to October 2016, detecting 465 (5.8%, CI: 5.3–6.4) TB cases. The majority (93.9%; CI: 93.4–94.4) of patient specimens were non-sputum and TB positivity was higher amongst non-sputum specimens. Further, a high proportion (5.6% CI 3.8–8.1) of infant TB cases were found to be rifampicin resistant. Covering large cities with a single lab per city over more than two years, the project demonstrated the feasibility of same-day diagnosis with upfront Xpert testing. This in turn led to prompt treatment initiation, with a two-day median turnaround time to treatment initiation. Case mortality observed in the project cohort of diagnosed TB cases was 11.0% (CI 8.4–14.1), the majority of which was pre- or early treatment mortality, in spite of prompt access to treatment for most diagnosed cases.

Conclusion

The current project demonstrated the feasibility of applying rapid and upfront Xpert testing for presumptive infant TB cases. Rapid TB diagnosis in turn facilitates prompt and appropriate treatment initiation. Further, levels of rifampicin resistance observed in infants TB cases highlight the additional benefit of upfront resistance testing. However, high rates of early case mortality, in spite of prompt diagnosis and treatment initiation, highlight the need for further research in infant patient pathways for overall improvement in TB care for infant populations.

Evaluation of Xpert MTB/RIF assay in children with presumed pulmonary tuberculosis in Papua New Guinea

BACKGROUND

The Gene Xpert MTB/ RIF assay (Xpert) is used for rapid, simultaneous detection of Mycobacterium tuberculosis (MTB) and rifampicin resistance. This study examined the accuracy of Xpert in children with suspected pulmonary tuberculosis (PTB).

METHODS

Children admitted to Port Moresby General Hospital with suspected PTB were prospectively enrolled between September 2014 and March 2015. They were classified into probable, possible and TB-unlikely groups. Sputum or gastric aspirates were tested by Xpert and smear microscopy; mycobacterial culture was undertaken on a subset. Children were diagnosed with TB on the basis of standard criteria which were used as the primary reference standard. Xpert, smear for acid-fast bacilli (AFB) and the Edwards TB score were compared with the primary reference standard.

RESULTS

A total of 93 children ≤14 years with suspected PTB were enrolled; 67 (72%) were classified as probable, 21 (22%) possible and 5 (5.4%) TB-unlikely. Eighty were treated for TB based on the primary reference standard. Xpert was positive in 26/93 (28%) MTB cases overall, including 22/67 (33%) with probable TB and 4/21 (19%) with possible TB. Three (13%) samples identified rifampicin resistance. Xpert confirmed more cases of TB than AFB smear (26 vs 13, p = 0.019). The sensitivity of Xpert, AFB smear and an Edwards TB score of ≥7 was 31% (25/80), 16% (13/80) and 90% (72/80), respectively, and the specificity was 92% (12/13), 100% (13/13) and 31% (4/13), respectively, when compared with the primary reference standard.

CONCLUSION

Xpert sensitivity is sub-optimal and cannot be relied upon for diagnosing TB, although a positive result is confirmatory. A detailed history and examination, standardised clinical criteria, radiographs and available tests remain the most appropriate way of diagnosing TB in children in resource-limited countries. Xpert helps confirm PTB better than AFB smear, and identifies rifampicin resistance. Practical guidelines should be used to identify children who will benefit from an Xpert assay.

Comparative effectiveness of a mnemonic-use approach vs. self-study to interpret a lateral chest X-ray

The chest X-ray is the most commonly performed medical imaging study; however, the lateral chest film intimidates many physicians and medical students. The lateral view is more difficult to interpret than the frontal view but provides important information that is either not visible or not as evident on frontal view, and inability to read it may lead to missed diagnoses and more expensive imaging. The objective of this study was to assess a novel mnemonic-based approach to teaching medical students to proficiently read a lateral film using a prospective pilot study. A clinical faculty radiologist taught two groups of second-year medical students to read a lateral chest X-ray. One group learned a novel mnemonic-based method (MUM), and the other cohort performed directed web-based self-study (STMM). Each cohort was given a pre- and postassessment, and their performance was analyzed. A total of n = 29 students participated with n = 14 being taught the mnemonic method. The MUM group significantly (P = 0.001) improved their score vs. the STMM group This study demonstrates students can quickly and effectively learn to read a lateral chest film using this novel mnemonic.

Tuberculosis exposure, infection and disease in children: a systematic diagnostic approach

The accurate diagnosis of tuberculosis (TB) in children remains challenging. A myriad of common childhood diseases can present with similar symptoms and signs, and differentiating between exposure and infection, as well as infection and disease can be problematic. The paucibacillary nature of childhood TB complicates bacteriological confirmation and specimen collection is difficult. In most instances intrathoracic TB remains a clinical diagnosis. TB infection and disease represent a dynamic continuum from TB exposure with/without infection, to subclinical/incipient disease, to non-severe and severe disease. The clinical spectrum of intrathoracic TB in children is broad, and the classification of clinical, radiological, endoscopic, and laboratory findings into recognized clinical syndromes allows a more refined diagnostic approach in order to minimize both under- and over-diagnosis. Bacteriological confirmation can be improved significantly by collecting multiple, high-quality specimens from the most appropriate source. Mycobacterial testing should include traditional smear microscopy and culture, as well as nucleic acid amplification testing. A systematic approach to the child with recent exposure to TB, or with clinical and radiological findings compatible with this diagnosis, should allow pragmatic classification as TB exposure, infection, or disease to facilitate timely and appropriate management. It is important to also assess risk factors for TB disease progression and to undertake follow-up evaluations to monitor treatment response and ongoing evidence supporting a TB, or alternative, diagnosis.

Diagnostic Test Accuracy in Childhood Pulmonary Tuberculosis: A Bayesian Latent Class Analysis

Evaluation of tests for the diagnosis of childhood pulmonary tuberculosis (CPTB) is complicated by the absence of an accurate reference test. We present a Bayesian latent class analysis in which we evaluated the accuracy of 5 diagnostic tests for CPTB. We used data from a study of 749 hospitalized South African children suspected to have CPTB from 2009 to 2014. The following tests were used: mycobacterial culture, smear microscopy, Xpert MTB/RIF (Cepheid Inc.), tuberculin skin test (TST), and chest radiography. We estimated the prevalence of CPTB to be 27% (95% credible interval (CrI): 21, 35). The sensitivities of culture, Xpert, and smear microscopy were estimated to be 60% (95% CrI: 46, 76), 49% (95% CrI: 38, 62), and 22% (95% CrI: 16, 30), respectively; specificities of these tests were estimated in accordance with prior information and were close to 100%. Chest radiography was estimated to have a sensitivity of 64% (95% CrI: 55, 73) and a specificity of 78% (95% CrI: 73, 83). Sensitivity of the TST was estimated to be 75% (95% CrI: 61, 84), and it decreased substantially among children who were malnourished and infected with human immunodeficiency virus (56%). The specificity of the TST was 69% (95% CrI: 63%, 76%). Furthermore, it was estimated that 46% (95% CrI: 42, 49) of CPTB-negative cases and 93% (95% CrI: 82; 98) of CPTB-positive cases received antituberculosis treatment, which indicates substantial overtreatment and limited undertreatment.

Diagnosis of Pulmonary Tuberculosis in Children: Assessment of the 2012 National Institutes of Health Expert Consensus Criteria

BACKGROUND

The 2012 National Institutes of Health (NIH) consensus criteria for standardized diagnostic categories of pulmonary tuberculosis in children have not been validated. We aimed to assess the NIH diagnostic criteria in children with culture-confirmed pulmonary tuberculosis and those in whom tuberculosis has been excluded.

METHODS

We performed a retrospective analysis of consecutive children hospitalized with suspected pulmonary tuberculosis in Cape Town, South Africa, who were enrolled in a diagnostic study. Children were categorized as definite tuberculosis (culture positive), probable tuberculosis (chest radiograph consistent), possible tuberculosis (chest radiograph inconsistent), or not tuberculosis (improved without tuberculosis treatment). We applied the NIH diagnostic categories to the cohort and evaluated their performance specifically in children with definite tuberculosis and not tuberculosis.

RESULTS

Four hundred sixty-four children (median age, 25.1 months [interquartile range, 13.5-61.5 months]) were included; 96 (20.7%) were HIV infected. Of these, 165 (35.6%) were definite tuberculosis, and 299 (64.4%) were not tuberculosis. If strict NIH symptom criteria were applied, 100 (21.6%) were unclassifiable including 21 (21.0%) with definite pulmonary tuberculosis, as they did not meet the NIH criteria due to short duration of symptoms; 71 (71%) had cough <14 days, 48 (48%) had recent weight loss, and 39 (39%) had fever <7 days. Of 364 classifiable children, there was moderate agreement (κ = 0.48) with 100% agreement for definite tuberculosis and moderate agreement for not tuberculosis (220 [60.4%] vs 89 [24.5%]).

CONCLUSIONS

Entry criteria for diagnostic studies should not be restrictive. Data from this analysis have informed revision of the NIH definitions.

Understanding NIH clinical case definitions for pediatric intrathoracic TB by applying them to a clinical trial

SETTING

Standardized clinical case definitions represent the best option for pediatric tuberculosis (TB) disease diagnosis and classification.

OBJECTIVE

To apply published guidelines for intrathoracic TB classification for use in reporting diagnostic studies with passive case finding to presumed TB patients from International Maternal Pediatric Adolescent AIDS Clinical Trials P1041, a trial of isoniazid prophylaxis in healthy human immunodeficiency virus exposed, bacille Calmette-Guérin vaccinated infants which employed active surveillance to assess a novel application of these guidelines in this setting.

METHODS

P1041 presumed TB patients were retrospectively cross-classified by protocol-defined and National Institutes of Health (NIH) classifications, and agreement was assessed.

RESULTS

Of 219 TB suspects, 166 had signs/symptoms, with 158 considered TB (21 confirmed, 92 probable, 45 possible) and 8 not TB (6 TB unlikely, 2 alternative diagnoses). Weight loss and failure to thrive represented the majority of the observed signs/symptoms. Among those with signs/symptoms, agreement between definitions was poor. Furthermore, 53 TB presumptives were without signs/symptoms, including 33 classified by the P1041 protocol as TB.

CONCLUSION

Poor agreement between P1041 and NIH classifications reflects cases identified through active vs. passive surveillance, the latter reflecting the intended use of NIH definitions. Given the interest in standardized definitions for broader application, future efforts could focus on expanding TB disease classification to presumed TB patients identified through active surveillance.

The Role of Clinical Symptoms in the Diagnosis of Intrathoracic Tuberculosis in Young Children

BACKGROUND

Childhood tuberculosis (TB) is usually Mycobacterium tuberculosis (MTB) culture negative. Furthermore, clinical presentation may be altered by active case finding, isoniazid prophylaxis and early treatment. We aimed to establish the value of presenting symptoms for intrathoracic TB case diagnosis among young children.

METHODS

Healthy, HIV-uninfected, South African infants in an efficacy trial of a novel TB vaccine (MVA85A) were followed for 2 years for suspected TB. When suspected, investigation followed a standardized algorithm comprising symptom history, QuantiFERON Gold-in-Tube, chest radiography (CXR), MTB culture and Xpert MTB/RIF from paired gastric lavage and induced sputa. Adjusted odds ratios and 95% confidence intervals describe the associations between symptoms and positive MTB culture or Xpert MTB/RIF, and CXR compatible with intrathoracic TB.

RESULTS

Persistent cough was present in 172/1017 (16.9%) of the children investigated for TB. MTB culture/Xpert MTB/RIF was positive in 38/1017 children (3.7%); and CXR was positive, that is, compatible with intrathoracic TB, in 131/1017 children (12.9%). Children with persistent cough had more than triple the odds of a positive MTB culture/Xpert MTB/RIF (adjusted odds ratios: 3.3, 95% confidence interval: 1.5-7.0) and positive CXR (adjusted odds ratios: 3.5, 95% confidence interval: 2.2-5.5). Persistent cough was the only symptom that differentiated children with severe (56.5%) from nonsevere intrathoracic TB disease (28.2%; P = 0.001).

CONCLUSION

Persistent cough was the cardinal diagnostic symptom associated with microbiologic and radiologic evidence, and disease severity, of intrathoracic TB. Symptom-based definitions of TB disease for diagnostic, preventive and therapeutic studies should prioritize persistent cough above other symptoms compatible with childhood TB.

A Blueprint to Address Research Gaps in the Development of Biomarkers for Pediatric Tuberculosis

Childhood tuberculosis contributes significantly to the global tuberculosis disease burden but remains challenging to diagnose due to inadequate methods of pathogen detection in paucibacillary pediatric samples and lack of a child-specific host biomarker to identify disease. Accurately diagnosing tuberculosis in children is required to improve case detection, surveillance, healthcare delivery, and effective advocacy. In May 2014, the National Institutes of Health convened a workshop including researchers in the field to delineate priorities to address this research gap. This blueprint describes the consensus from the workshop, identifies critical research steps to advance this field, and aims to catalyze efforts toward harmonization and collaboration in this area.

Integrated Source Case Investigation for Tuberculosis (TB) and HIV in the Caregivers and Household Contacts of Hospitalised Young Children Diagnosed with TB in South Africa: An Observational Study

BACKGROUND

Contact tracing, to identify source cases with untreated tuberculosis (TB), is rarely performed in high disease burden settings when the index case is a young child with TB. As TB is strongly associated with HIV infection in these settings, we used source case investigation to determine the prevalence of undiagnosed TB and HIV in the caregivers and household contacts of hospitalised young children diagnosed with TB in South Africa.

METHODS

Caregivers and household contacts of 576 young children (age ≤7 years) with TB diagnosed between May 2010 and August 2012 were screened for TB and HIV. The primary outcome was the detection of laboratory-confirmed, newly-diagnosed TB disease and/or HIV-infection in close contacts.

RESULTS

Of 576 caregivers, 301 (52·3%) self-reported HIV-positivity. Newly-diagnosed HIV infection was detected in 63 (22·9%) of the remaining 275 caregivers who self-reported an unknown or negative HIV status. Screening identified 133 (23·1%) caregivers eligible for immediate anti-retroviral therapy (ART). Newly-diagnosed TB disease was detected in 23 (4·0%) caregivers. In non-caregiver household contacts (n = 1341), the prevalence of newly-diagnosed HIV infection and TB disease was 10·0% and 3·2% respectively. On average, screening contacts of every nine children with TB resulted in the identification of one case of newly-diagnosed TB disease, three cases of newly diagnosed HIV-infection, and three HIV-infected persons eligible for ART.

CONCLUSION

In high burden countries, source case investigation yields high rates of previously undiagnosed HIV and TB infection in the close contacts of hospitalised young children diagnosed with TB. Furthermore, integrated screening identifies many individuals who are eligible for immediate ART. Similar studies, with costing analyses, should be undertaken in other high burden settings-integrated source case investigation for TB and HIV should be routinely undertaken if our findings are confirmed.

Clinical Predictors of Culture-confirmed Pulmonary Tuberculosis in Children in a High Tuberculosis and HIV Prevalence Area

BACKGROUND

The burden of childhood tuberculosis (TB) remains significant especially in areas of high HIV prevalence. Clinical diagnosis predominates, despite advances in molecular and microbiological diagnostics. The aim of this study is to identify clinical features associated with culture-confirmed pulmonary TB (PTB) in children.

METHODS

Children admitted to hospital were enrolled in a study of novel diagnostics for PTB in South Africa. Standardized clinical, radiological and microbiological data were collected. Definite TB was defined by culture of Mycobacterium tuberculosis from a respiratory specimen. Adjusted odds ratios for definite TB were calculated using a multivariate logistic regression model.

RESULTS

Adjusted odds ratio (AOR) for definite TB increased with a history of fever for more than 1 week [AOR: 8.54, 95% confidence interval (CI): 2.37-30.74], with a chest radiograph (CXR) suggestive of PTB (AOR: 10.0, 95% CI: 3.22-31.2) and with a positive tuberculin skin test (TST; AOR: 64.4, 95% CI: 14.3-290.5). The likelihood ratio of having definite TB if 2 of these factors (CXR and TST) were present compared with having none of them was 17.7. Cough, household contact with TB, HIV status and wheezing were not significantly associated with definite TB.

CONCLUSIONS

Prolonged fever, CXR suggestive of TB or a positive TST were predictive of definite TB and should be considered in composite scoring systems for TB diagnosis in high HIV prevalence settings. Other commonly associated symptoms were not associated with definite TB.

Tuberculosis in the African continent: A comprehensive review

Tuberculosis continues to be a major global health problem, causing an estimated 8.8 million new cases and 1.45 million deaths annually. New drugs in the 1940s made it possible to beat the disease, and consequently, the number of cases reduced drastically. Fast-forward a few decades, drugresistant strains of varied virulence are reported consistently, disease is again on the rise and the treatment has not kept pace. Tuberculosis is the leading cause of death among HIV-infected persons in many resource-constrained settings however, it is curable and preventable. The unprecedented growth of the tuberculosis epidemic in Africa is attributable to several factors, the most important being the HIV epidemic. Analysis of molecular-based data have shown diverse genetic backgrounds among both drug-sensitive and MDR TB isolates in Africa presumably due to underlying genetic and environmental differences. The good news is that there have been important advances recently in TB drugs and diagnostics. Despite the availability of revolutionary tests that allow for faster diagnosis and of new drugs and regimens that offer better and safer treatment it is now becoming clearer that national efforts on TB control should be enhanced and focus on improving the quality of prevention, diagnosis, treatment and care services; strengthening program management, implementation and supervision. This review is an assessment of the trend in TB in Africa.

Patient Reported Delays in Seeking Treatment for Tuberculosis among Adult and Pediatric TB Patients and TB Patients Co-Infected with HIV in Lima, Peru: A Qualitative Study

INTRODUCTION

Tuberculosis (TB) remains a significant public health challenge worldwide, and particularly in Peru with one of the highest incidence rates in Latin America. TB patient behavior has a direct influence on whether a patient will receive timely diagnosis and successful treatment of their illness.

OBJECTIVES

The objective was to understand the complex factors that can impact TB patient health seeking behavior.

METHODS

In-depth interviews were conducted with adult and parents of pediatric patients receiving TB treatment (n = 43), within that group a sub-group was also co-infected with HIV (n = 11).

RESULTS

Almost all of the study participants recognized delays in seeking either their child's or their own diagnosis of their TB symptoms. The principal reasons for treatment-seeking delays were lack of knowledge and confusion of TB symptoms, fear and embarrassment of receiving a TB diagnosis, and a patient tendency to self-medicate prior to seeking formal medical attention.

CONCLUSION

Health promotion activities that target patient delays have the potential to improve individual patient outcomes and mitigate the spread of TB at a community level.

Time to symptom resolution in young children treated for pulmonary tuberculosis

BACKGROUND

Response to treatment may be useful for diagnostic confirmation of childhood tuberculosis (TB). We aimed to evaluate time to symptom resolution in children treated for pulmonary TB.

METHODS

We compared pulmonary TB cases and noncases, classified by a published diagnostic algorithm, in South African children younger than 2. TB treatment was prescribed independently on clinical grounds. We analyzed independent determinants of baseline symptom resolution by Cox regression.

RESULTS

One hundred and ninety-one symptomatic children, median age 12 months, were prescribed for TB treatment. Chest radiograph features of TB were associated with longer time to resolution of cough (adjusted hazard ratio, AHR 0.31), wheeze (AHR 0.26) and failure to thrive (AHR 0.41), (all P < 0.05). However, median duration of baseline cough (63 vs. 70 days, P = 0.98), wheeze (62 vs. 68 days, P = 0.87) and failure to thrive (76 vs. 66 days, P = 0.59) did not differ in TB cases (n = 48) versus noncases (n = 46).

CONCLUSIONS

Baseline symptoms take more than 60 days to resolve in the majority of young children after starting TB treatment. Furthermore, since time to resolution does not differentiate TB cases from noncases; clinical response to treatment is not an appropriate diagnostic criterion for pediatric trials of TB diagnostics, drugs and vaccines.

Diagnosis of childhood tuberculosis and host RNA expression in Africa

BACKGROUND

Improved diagnostic tests for tuberculosis in children are needed. We hypothesized that transcriptional signatures of host blood could be used to distinguish tuberculosis from other diseases in African children who either were or were not infected with the human immunodeficiency virus (HIV).

METHODS

The study population comprised prospective cohorts of children who were undergoing evaluation for suspected tuberculosis in South Africa (655 children), Malawi (701 children), and Kenya (1599 children). Patients were assigned to groups according to whether the diagnosis was culture-confirmed tuberculosis, culture-negative tuberculosis, diseases other than tuberculosis, or latent tuberculosis infection. Diagnostic signatures distinguishing tuberculosis from other diseases and from latent tuberculosis infection were identified from genomewide analysis of RNA expression in host blood.

RESULTS

We identified a 51-transcript signature distinguishing tuberculosis from other diseases in the South African and Malawian children (the discovery cohort). In the Kenyan children (the validation cohort), a risk score based on the signature for tuberculosis and for diseases other than tuberculosis showed a sensitivity of 82.9% (95% confidence interval [CI], 68.6 to 94.3) and a specificity of 83.6% (95% CI, 74.6 to 92.7) for the diagnosis of culture-confirmed tuberculosis. Among patients with cultures negative for Mycobacterium tuberculosis who were treated for tuberculosis (those with highly probable, probable, or possible cases of tuberculosis), the estimated sensitivity was 62.5 to 82.3%, 42.1 to 80.8%, and 35.3 to 79.6%, respectively, for different estimates of actual tuberculosis in the groups. In comparison, the sensitivity of the Xpert MTB/RIF assay for molecular detection of M. tuberculosis DNA in cases of culture-confirmed tuberculosis was 54.3% (95% CI, 37.1 to 68.6), and the sensitivity in highly probable, probable, or possible cases was an estimated 25.0 to 35.7%, 5.3 to 13.3%, and 0%, respectively; the specificity of the assay was 100%.

CONCLUSIONS

RNA expression signatures provided data that helped distinguish tuberculosis from other diseases in African children with and those without HIV infection. (Funded by the European Union Action for Diseases of Poverty Program and others).

Diagnosis of pulmonary tuberculosis

PURPOSE OF REVIEW

This review summarizes the recent literature on the developments in diagnostics for pulmonary tuberculosis (TB).

RECENT FINDINGS

A growing body of literature regarding the Xpert MTB/RIF assay confirms the high diagnostic accuracy in a range of clinical settings, including amongst inpatients, those with HIV coinfection and in children with culture-positive disease. Early experiences with operational implementation are now being reported from South Africa. Initial small-scale evaluations suggest that newer versions of line-probe assays have diagnostic accuracy similar to that of the Xpert MTB/RIF assay. Next-generation fully automated molecular assays that use isothermal amplification may in the future be more readily implemented at the point of care. The first low-cost, lateral-flow (strip-test) assay for lipoarabinomannan in urine shows promise as a rapid point-of-care test for TB amongst HIV-infected patients who have advanced immunodeficiency. A range of other diagnostic tools are also at various stages of development.

SUMMARY

There is continued momentum and optimism regarding the developments in TB diagnostics. However, studies of clinical and programmatic impact and operational research are needed to guide implementation and scale-up of new assays in resource-limited settings. Further concerted efforts are needed to develop point-of-care assays which are desperately needed to accelerate progress in TB control.

Management of children exposed to Mycobacterium tuberculosis: a public health evaluation in West Java, Indonesia

OBJECTIVE

To investigate qualitatively and quantitatively the performance of a programme for managing the child contacts of adult tuberculosis patients in Indonesia.

METHODS

A public health evaluation framework was used to assess gaps in a child contact management programme at a lung clinic. Targets for programme performance indicators were derived from established programme indicator targets, the scientific literature and expert opinion. Compliance with tuberculosis screening, the initiation of isoniazid preventive therapy in children younger than 5 years, the accuracy of tuberculosis diagnosis and adherence to preventive therapy were assessed in 755 child contacts in two cohorts. In addition, 22 primary caregivers and 34 clinic staff were interviewed to evaluate knowledge and acceptance of child contact management. The cost to caregivers was recorded. Gaps between observed and target indicator values were quantified.

FINDINGS

THE GAPS BETWEEN OBSERVED AND TARGET PERFORMANCE INDICATORS WERE: 82% for screening compliance; 64 to 100% for diagnostic accuracy, 50% for the initiation of preventive therapy, 54% for adherence to therapy and 50% for costs. Many staff did not have adequate knowledge of, or an appropriate attitude towards, child contact management, especially regarding isoniazid preventive therapy. Caregivers had good knowledge of screening but not of preventive therapy and had difficulty travelling to the clinic and paying costs.

CONCLUSION

The study identified widespread gaps in the performance of a child contact management system in Indonesia, all of which appear amenable to intervention. The public health evaluation framework used could be applied in other settings where child contact management is failing.

Pulmonary tuberculosis in severely-malnourished or HIV-infected children with pneumonia: a review

Presentation of pulmonary tuberculosis (PTB) as acute pneumonia in severely-malnourished and HIV-positive children has received very little attention, although this is very important in the management of pneumonia in children living in communities where TB is highly endemic. Our aim was to identify confirmed TB in children with acute pneumonia and HIV infection and/or severe acute malnutrition (SAM) (weight-for-length/height or weight-for-age z score <-3 of the WHO median, or presence of nutritional oedema). We conducted a literature search, using PubMed and Web of Science in April 2013 for the period from January 1974 through April 2013. We included only those studies that reported confirmed TB identified by acid fast bacilli (AFB) through smear microscopy, or by culture-positive specimens from children with acute pneumonia and SAM and/or HIV infection. The specimens were collected either from induced sputum (IS), or gastric lavage (GL), or broncho-alveolar lavage (BAL), or percutaneous lung aspirates (LA). Pneumonia was defined as the radiological evidence of lobar or patchy consolidation and/or clinical evidence of severe/ very severe pneumonia according to the WHO criteria of acute respiratory infection. A total of 17 studies met our search criteria but 6 were relevant for our review. Eleven studies were excluded as those did not assess the HIV status of the children or specify the nutritional status of the children with acute pneumonia and TB. We identified only 747 under-five children from the six relevant studies that determined a tubercular aetiology of acute pneumonia in children with SAM and/or positive HIV status. Three studies were reported from South Africa and one each from the Gambia, Ethiopia, and Thailand where 610, 90, 35, and 12 children were enrolled and 64 (10%), 23 (26%), 5 (14%), and 1 (8%) children were identified with active TB respectively, with a total of 93 (12%) children with active TB. Among 610 HIV-infected children in three studies from South Africa and 137 SAM children from other studies, 64 (10%) and 29 (21%) isolates of M. tuberculosis were identified respectively. Children from South Africa were infected with HIV without specification of their nutritional status whereas children from other countries had SAM but without indication of their HIV status. Our review of the existing data suggests that pulmonary tuberculosis may be more common than it is generally suspected in children with acute pneumonia and SAM, or HIV infection. Because of the scarcity of data, there is an urgent need to investigate PTB as one of the potential aetiologies of acute pneumonia in these children in a carefully-conducted larger study, especially outside Africa.

Lessons learnt from the first efficacy trial of a new infant tuberculosis vaccine since BCG

BACKGROUND

New tuberculosis (TB) vaccines are being developed to combat the global epidemic. A phase IIb trial of a candidate vaccine, MVA85A, was conducted in a high burden setting in South Africa to evaluate proof-of-concept efficacy for prevention of TB in infants.

OBJECTIVE

To describe the study design and implementation lessons from an infant TB vaccine efficacy trial.

METHODS

This was a randomised, controlled, double-blind clinical trial comparing the safety and efficacy of MVA85A to Candin control administered to 4-6-month-old, BCG-vaccinated, HIV-negative infants at a rural site in South Africa. Infants were followed up for 15-39 months for incident TB disease based on pre-specified endpoints.

RESULTS

2797 infants were enrolled over 22 months. Factors adversely affecting recruitment and the solutions that were implemented are discussed. Slow case accrual led to six months extension of trial follow up.

CONCLUSION

The clinical, regulatory and research environment for modern efficacy trials of new TB vaccines are substantially different to that when BCG vaccine was first evaluated in infants. Future infant TB vaccine trials will need to allocate sufficient resources and optimise operational efficiency. A stringent TB case definition is necessary to maximize specificity, and TB case accrual must be monitored closely.

Promising directions in the diagnosis of childhood tuberculosis

Estimates of the burden of childhood tuberculosis have been hampered by the lack of a reliable diagnostic test. Clinical scoring systems, radiological findings and tuberculin skin testing (the traditional methods used for diagnosis) are unreliable, particularly in the era of HIV. Microbiologic confirmation using induced sputum is feasible and has become increasingly important to define the burden of disease and to enable appropriate treatment. The availability of a rapid molecular diagnostic test (Xpert® MTB/RIF; Cepheid) is an important advance that can improve case detection in children and enable rapid detection of mycobacterial drug resistance. Xpert testing of two induced sputum specimens detected approximately 75% of children with culture-confirmed disease. Urine lipoarabinomannan has shown promise as a rapid diagnostic in a subgroup of HIV-infected severely immunocompromised adults, but there have been no data in children so far. Further research is needed to develop a rapid point-of-care, reliable and affordable diagnostic test for childhood tuberculosis that can be widely used.

A review of full-body radiography in nontraumatic emergency medicine

This paper reports on the application of full-body radiography to nontraumatic emergency situations. The Lodox Statscan is an X-ray machine capable of imaging the entire body in 13 seconds using linear slit scanning radiography (LSSR). Nontraumatic emergency applications in ventriculoperitoneal (VP) shunt visualisation, emergency room arteriography (ERA), detection of foreign bodies, and paediatric emergency imaging are presented. Reports show that the fast, full-body, and low-dose scanning capabilities of the Lodox system make it well suited to these applications, with the same or better image quality, faster processing times, and lower dose to patients. In particular, the large format scans allowing visualisation of a greater area of anatomy make it well suited to VP shunt monitoring, ERA, and the detection of foreign bodies. Whilst more studies are required, it can be concluded that the Lodox Statscan has the potential for widespread use in these and other nontraumatic emergency radiology applications.

Description of pediatric tuberculosis evaluated in a referral center in istanbul Turkey

PURPOSE

Diagnosis of tuberculosis (TB) in children is more challenging than in adults. This study aimed to describe demographical, clinical and laboratory findings of children diagnosed with tuberculosis in Turkey, including the issues of contact tracing, culture positivity and forms of the disease.

MATERIALS AND METHODS

Clinical and laboratory data of 51 children with a mean age of 8.0±4.6 years who were diagnosed with TB were retrospectively reviewed. Main diagnostic tools included tuberculin skin test, chest X-ray, sputum/gastric aspirate culture with sensitivity testing, and direct microscopy for acid-fast bacilli on available samples. Clinical characteristics and outcomes of the patients were examined.

RESULTS

Thirty-six (70.6%) children were diagnosed with intra-thoracic and 15 (29.4%) with extra-thoracic tuberculosis. Twenty-eight of the patients had a positive Bacillus Calmette-Guérin vaccine scar (28/51, 54.9%) and 23/51 (45.1%) had a positive tuberculin skin test. An adult TB contact was identified in 27 (52.9%) of the cases. On direct microscopy, acid-fast bacilli were found in nine (17.6%) patients and positive culture for Mycobacterium tuberculosis was found in 19 (37.3%). Drug resistance to isoniazid was detected in four (7.8%). One patient with nephrotic syndrome and miliary tuberculosis died during follow-up. All other patients responded well to the treatment.

CONCLUSION

Focusing on active contact tracing among all household contacts of tuberculous cases may be helpful in early identification and controlling childhood disease, even in regions with low disease prevalence. Adopting a suspicious and proactive approach in this particular age group is warranted.

Evaluation of new strategies for the diagnosis of tuberculosis among pediatric contacts of tuberculosis patients

BACKGROUND

In young children, underdiagnosis and diagnostic delay have an adverse effect on morbidity and mortality of tuberculosis (TB). This study evaluated new strategies for early TB diagnosis using an outpatient protocol in children between 0 and 5 years of age, with a recent household TB contact.

METHODS

Case recruitment was performed in Manaus, Amazonas, Brazil, from 2008 to 2009. Epidemiologic and clinical data, tuberculin test, chest radiograph and 2 induced sputum respiratory samples from each participant were obtained. Laboratory diagnosis was based on Lowenstein-Jensen (LJ) culture, mycobacteria growth indicator tube (MGIT) and polymerase chain reaction. We conducted a study of comparison of diagnostic tests and a study of cases and controls to identify the clinical characteristics of the population with positive culture and polymerase chain reaction results.

RESULTS

A total of 102 children were evaluated. Thirty-two fulfilled criteria of suspicion of TB. MGIT was more sensitive (P = 0.035) and faster (P < 0.001) than LJ. Clinical score, MGIT, LJ and polymerase chain reaction presented no concordance or slight concordance. A positive MGIT culture was only associated with a strong tuberculin test reaction (P = 0.026). The combination of MGIT with the clinical score allowed the diagnosis of 33% more cases with little or no symptomatology compared with the exclusive use of the clinical classification.

CONCLUSIONS

The sensitivity and speed of MGIT demonstrate the utility of liquid cultures for the diagnosis in children. Furthermore, these results suggest that the use of MGIT in children presenting recent household TB contact and a strong tuberculin test reaction may be a strategy to improve early TB diagnosis.

Evaluation of tuberculosis diagnostics in children: 1. Proposed clinical case definitions for classification of intrathoracic tuberculosis disease. Consensus from an expert panel

There is a critical need for improved diagnosis of tuberculosis in children, particularly in young children with intrathoracic disease as this represents the most common type of tuberculosis in children and the greatest diagnostic challenge. There is also a need for standardized clinical case definitions for the evaluation of diagnostics in prospective clinical research studies that include children in whom tuberculosis is suspected but not confirmed by culture of Mycobacterium tuberculosis. A panel representing a wide range of expertise and child tuberculosis research experience aimed to develop standardized clinical research case definitions for intrathoracic tuberculosis in children to enable harmonized evaluation of new tuberculosis diagnostic technologies in pediatric populations. Draft definitions and statements were proposed and circulated widely for feedback. An expert panel then considered each of the proposed definitions and statements relating to clinical definitions. Formal group consensus rules were established and consensus was reached for each statement. The definitions presented in this article are intended for use in clinical research to evaluate diagnostic assays and not for individual patient diagnosis or treatment decisions. A complementary article addresses methodological issues to consider for research of diagnostics in children with suspected tuberculosis.

Childhood TB Surveillance: Bridging the Knowledge Gap to Inform Policy

Tuberculosis (TB) is a leading cause of death globally. Natural history studies show that young children are at particularly high risk of progression to active TB and severe, disseminated disease following infection. Despite this, high-quality regional and global surveillance data on the burden of childhood TB are lacking. We discuss the unique aspects of TB in children that make diagnosis and therefore surveillance challenging; the limitations of available surveillance data; other data which provide insights into the true burden of childhood TB. Improved surveillance is among the key research priorities identified for childhood TB, but progress to date has been slow. Recent advances in TB diagnostics, and standardized clinical diagnostic guidelines and case definitions, all provide opportunities for new strategies to improve surveillance. Better-quality data on the burden and trends of childhood TB will inform and improve both public health policy and clinical practice.

Diagnostic features associated with culture of Mycobacterium tuberculosis among young children in a vaccine trial setting

OBJECTIVES

To identify diagnostic features associated with culture of Mycobacterium tuberculosis (MTB), the standard for tuberculosis (TB) diagnosis, to inform clinical end point definitions for new TB vaccine trials.

METHODS

Children <2 years of age (n = 1445) were screened and investigated for TB during a Bacille Calmette Guerin vaccine trial in South Africa. Standardized clinical, radiologic, and microbiologic data were collected, including paired gastric lavage and induced sputum for MTB liquid culture. Adjusted odds ratios (AORs) were calculated using a multivariate logistic regression model.

RESULTS

Adjusted odds of positive MTB culture increased by 90% with history of wheezing (AOR, 1.9) and by 4% with each 1-mm increase in Mantoux diameter (AOR, 1.04). Odds of positive MTB culture doubled if the chest radiograph was suggestive of pulmonary TB (AOR, 2.16) and more than tripled if lower chest retraction was observed clinically (AOR, 3.37). Fever, night sweats, and presence of lymphadenopathy were negatively associated with MTB culture (AOR: 0.5, 0.62, and 0.2, respectively). Persistent cough, weight loss, and failure to thrive were not significantly associated with MTB culture in this study population.

CONCLUSIONS

Wheezing and lower chest retraction, consistent with intrathoracic airway obstruction; chest radiography suggestive of pulmonary tuberculosis; and Mantoux diameter were predictive of positive MTB culture. These variables should be considered for inclusion in composite clinical end point definitions for infant TB vaccine trials. Several clinical features, commonly used for TB diagnosis in older children, were not associated with positive MTB culture among children younger than 2 years.

Advances in the diagnosis of pulmonary tuberculosis in HIV-infected and HIV-uninfected children

The identification of improved diagnostic tests for tuberculosis has been identified as a global research priority. Over the past decade, there has been renewed interest in the development and validation of novel diagnostic tools for pulmonary tuberculosis that are applicable to resource-poor settings. These techniques are aimed primarily at improving detection of the organism or a specific host immune response. Although most studies have focused on determining the accuracy of novel tests in adults, it is likely they will also have the capacity to significantly improve the diagnosis of childhood tuberculosis. Improving the quality of clinical samples obtained from children with suspected tuberculosis remains an important research priority while awaiting validation of novel diagnostic tests. This review will focus on a number of recent developments for the diagnosis of tuberculosis, with a specific emphasis on the application of these new tests to children in settings where tuberculosis is endemic.

Consensus statement on diagnostic end points for infant tuberculosis vaccine trials

BACKGROUND

 Definition of clinical trial end points for childhood tuberculosis is hindered by lack of a standard case definition. We aimed to identify areas of consensus or debate on potential end points for tuberculosis vaccine trials among human immunodeficiency virus-uninfected children.

METHODS

 Thirty-eight opinion leaders participated in a Consensus Workshop at the Second Global Forum on TB Vaccines (Estonia, 2010). Outcomes were categorized as unanimity, modified consensus, or lack of consensus. Individual reservations were noted.

RESULTS

 Modified consensus was achieved on 3 issues: (1) unsuitability of historical BCG trial end points as sole primary end points for modern infant trials; (2) symptomatic, complicated intrathoracic tuberculosis as an uncommon but clinically relevant disease phenotype; (3) primary complex tuberculosis in younger children as a common, high-risk phenotype, with a high rate of spontaneous resolution. Participants agreed that radiologic diagnosis of intrathoracic tuberculosis would be based primarily on hilar lymphadenopathy. Lack of consensus was noted for (1) significance of isolated culture of Mycobacterium tuberculosis and (2) the need for evidence of prior tuberculosis exposure to support a diagnosis of tuberculosis disease. Reservations were expressed regarding use of interferon-γ release assays and the clinical relevance, and potential for misclassification, of primary complex tuberculosis.

CONCLUSIONS

 The Workshop did not achieve consensus on a single primary end-point definition. Tuberculosis disease phenotypes with optimal diagnostic certainty will be uncommon in the study population. Criteria for composite or multiple end points were identified, and we propose a hierarchy of end-point criteria, based on rate of occurrence, clinical relevance, and diagnostic certainty.

Accuracy of the Xpert MTB/RIF test for the diagnosis of pulmonary tuberculosis in children admitted to hospital in Cape Town, South Africa: a descriptive study

BACKGROUND

WHO recommends that Xpert MTB/RIF replaces smear microscopy for initial diagnosis of suspected HIV-associated tuberculosis or multidrug-resistant pulmonary tuberculosis, but no data exist for its use in children. We aimed to assess the accuracy of the test for the diagnosis of pulmonary tuberculosis in children in an area with high tuberculosis and HIV prevalences.

METHODS

In this prospective, descriptive study, we enrolled children aged 15 years or younger who had been admitted to one of two hospitals in Cape Town, South Africa, with suspected pulmonary tuberculosis between Feb 19, 2009, and Nov 30, 2010. We compared the diagnostic accuracy of MTB/RIF and concentrated, fluorescent acid-fast smear with a reference standard of liquid culture from two sequential induced sputum specimens (primary analysis).

RESULTS

452 children (median age 19·4 months, IQR 11·1-46·2) had at least one induced sputum specimen; 108 children (24%) had HIV infection. 27 children (6%) had a positive smear result, 70 (16%) had a positive culture result, and 58 (13%) had a positive MTB/RIF test result. With mycobacterial culture as the reference standard, MTB/RIF tests when done on two induced sputum samples detected twice as many cases (75·9%, 95% CI 64·5-87·2) as did smear microscopy (37·9%, 25·1-50·8), detecting all of 22 smear-positive cases and 22 of 36 (61·1%, 44·4-77·8) smear-negative cases. For smear-negative cases, the incremental increase in sensitivity from testing a second specimen was 27·8% for MTB/RIF, compared with 13·8% for culture. The specificity of MTB/RIF was 98·8% (97·6-99·9). MTB/RIF results were available in median 1 day (IQR 0-4) compared with median 12 days (9-17) for culture (p<0·0001).

INTERPRETATION

MTB/RIF testing of two induced sputum specimens is warranted as the first-line diagnostic test for children with suspected pulmonary tuberculosis.

FUNDING

National Institutes of Health, the National Health Laboratory Service Research Trust, the Medical Research Council of South Africa, and Wellcome Trust.

Xpert® MTB/RIF assay: development, evaluation and implementation of a new rapid molecular diagnostic for tuberculosis and rifampicin resistance

Global TB control efforts have been severely hampered by the lack of diagnostic tests that are accurate, simple to use and can be applied at the point of clinical care. This has been further compounded by the widespread inability to test for drug resistance. The Xpert(®) MTB/RIF assay is a rapid molecular assay that can be used close to the point of care by operators with minimal technical expertise, enabling diagnosis of TB and simultaneous assessment of rifampicin resistance to be completed within 2 h. Moreover, this can be accomplished using unprocessed sputum samples as well as clinical specimens from extrapulmonary sites. We review in detail the development of this assay, its evaluation within the laboratory, its utility among adult and pediatric TB suspects, its use as a screening tool for HIV-associated TB and studies of its implementation at the district and sub-district levels in resource-limited settings. Following endorsement by the WHO in 2010, we consider the next steps in the implementation of the assay and its potential impact in high burden settings.

New specimens and laboratory diagnostics for childhood pulmonary TB: progress and prospects

Childhood pulmonary TB (PTB) is under diagnosed, in part due to difficulties in obtaining microbiological confirmation. However, given the poor specificity of clinical diagnosis, microbiological confirmation and drug susceptibility testing is important in guiding appropriate therapy especially in the context of drug resistant TB. Confirmation is often possible, even in infants and young children, if adequate specimens are collected. Culture yield varies with the severity of illness, specimen type and culture method. Induced sputum is recognised as a safe procedure with a high diagnostic yield. Advances include optimised protocols for smear microscopy and modified culture techniques, such as the Microscopic Observation Drug Susceptibility Assay. Detection of Mycobacterium tuberculosis nucleic acid in respiratory specimens has high specificity but relatively poor sensitivity, particularly for smear negative disease. The recent development of an integrated specimen processing and real-time PCR testing platform for M. tuberculosis and rifampicin resistance is an important advance that requires evaluation in childhood TB.

The use of diagnostic systems for tuberculosis in children

Effective management of tuberculosis (TB) in children and important data of disease burden continue to rely on a clinical approach to diagnosis, as diagnosis of childhood TB is not confirmed in the majority. Many diagnostic scoring systems have been developed to aid with diagnosis. This article reviews the use and evaluation of these approaches. The diagnostic systems are often closely related and all rely on the well-known clinical features associated with TB disease in children. The scoring systems are not well validated and validation is limited by the lack of a gold standard for comparison. When they have been validated, some systems perform reasonably well but may bias to identify the most obvious clinical cases. They perform less well in important sub-groups that pose the greatest diagnostic challenge and are at greatest risk for poor outcome, such as the young, malnourished or HIV-infected. There is marked variation in performance between these diagnostic approaches. The better validated systems may have a role as a screening tool in some settings, but this would need careful consideration as to the most useful and safest approach. More attention is being given to improving diagnosis and management of child TB, including within National TB Programmes. Research with new diagnostics should include children so that there is less reliance on clinical features alone. However, the clinical approach will continue to be relevant and so it is important to strive to improve the diagnostic approach to TB in children, and to validate the approach in different settings.

When to start antiretroviral therapy in children with TB?

The initiation of antiretroviral therapy (ART) after starting TB treatment is complex, involving many variables including treatment tolerance, drug co-toxicities, pharmacokinetic drug interactions and polypharmacy impacts on adherence. Delayed ART potentially allows better determination of a specific cause for a drug side effect, decreasing the severity of paradoxical reactions and adherence difficulties. However, of overriding importance is mortality associated with delayed ART initiation versus mortality associated with immune restoration disease with early ART. While results of adult randomized trials addressing this question are becoming available, there are little data to inform the 'when to start' question for children.