Diagnosing diffuse lung disease in children in a middle-income country: the role of open lung biopsy

SETTING

A tertiary care hospital situated in a middle-income country with a high burden of tuberculosis (TB) and human immunodeficiency virus (HIV) infection.

OBJECTIVE

To determine the diagnostic yield of open lung biopsy (OLB) in children with diffuse lung disease (DLD), comparing findings in HIV-infected and non-HIV-infected children.

DESIGN

This 9-year retrospective study included 51 children with DLD (oxygen-dependent or on artificial ventilation), who required an OLB where the diagnosis remained uncertain after extensive investigations.

RESULTS

The median age was 7 months, median body weight was 6.6 kg (61% were severely malnourished) and 30% were HIV-infected (62% on antiretroviral treatment). The diagnostic yield of the OLB was 86% (n = 44) and was significantly higher in HIV-infected (77%) than in non-HIV-infected (48%) children (P = 0.01). Pneumonia was the most common diagnosis (n = 25, 57%), with common agents being cytomegalovirus (CMV), viruses other than CMV, Pneumocystis jiroveci pneumonia and previously undiagnosed TB (10%). Mycobacterium tuberculosis as a cause of DLD was not suspected before the OLB, as all investigations for TB were negative. Non-infectious causes of DLD were established in 10% of cases.

CONCLUSION

The OLB is a useful diagnostic tool to diagnose idiopathic DLD, including TB, in young children.

Mycobacterium tuberculosis, a cause of necrotising pneumonia in childhood: a case series

SETTING

Tertiary care hospital, Western Cape, South Africa.

DESIGN

Retrospective descriptive study of a case series of necrotising pneumonia (NP) in children associated with Mycobacterium tuberculosis presenting over a 4-year period in a country with high human immunodeficiency virus (HIV) and tuberculosis (TB) prevalence.

OBJECTIVE

To describe the clinical and radiological features of, and treatment regimens and outcomes in, children with NP.

RESULTS

Of 32 children (median age 16.5 months, interquartile range 10-33), 8 (25%) (median age 49 months) had NP associated with M. tuberculosis, 6 of whom were HIV-infected. Chest computed tomography (CT) was diagnostic in all cases: no radiological signs were suggestive of TB. There was no difference in the clinical picture, chest radiography or CT scan between M. tuberculosis-associated and bacterial NP. M. tuberculosis was cultured in 75% of cases; pleural fluid acid-fast bacilli was positive in an additional two cases. Surgery was required in 46% of the M. tuberculosis cases. At follow-up, 50% of these cases had complete radiological resolution similar to bacterial NP.

CONCLUSION

This series highlights the fact that M. tuberculosis not only causes acute pneumonia in children, it also results in numerous complications. M. tuberculosis should be considered as a cause of NP in all children, especially HIV-infected children, living in high TB prevalence regions.

Antenatal and early life tobacco smoke exposure in an African birth cohort study

BACKGROUND

Exposure to tobacco smoke in African infants has not been well studied, despite the high burden of childhood respiratory disease in these communities.

OBJECTIVE

To investigate the prevalence of antenatal and early life tobacco smoke exposure and associations with infant birth outcomes in an African birth cohort, the Drakenstein Child Health Study.

METHODS

Self-report questionnaires assessing maternal and household smoking were administered. Maternal and infant urine cotinine testing was conducted antenatally, at birth and at 6-10 weeks of life to measure tobacco smoke exposure. Multivariate regression models explored the associations between exposure to smoke and infant birth outcomes.

RESULTS

Of 789 pregnant women included, 250 (32%) were active smokers on cotinine testing. At birth and at 6-10 weeks of life, respectively 135/241 (56%) and 154/291 (53%) infants had urine cotinine levels indicating tobacco smoke exposure. Household smoking was prevalent and was associated with positive infant cotinine test results. Antenatal maternal smoking was associated with decreased infant birthweight-for-age Z-score (0.3, 95%CI 0.1-0.5).

CONCLUSION

Antenatal and early life tobacco smoke exposure is highly prevalent in this community, and may impact on birth outcomes and subsequent child health. Smoking cessation interventions are urgently needed to reduce tobacco smoke exposure in African communities.

Novel application of NIH case definitions in a paediatric tuberculosis contact investigation study

BACKGROUND

International (National Institutes of Health [NIH]) case definitions have been proposed for paediatric tuberculosis (TB) diagnostic studies. The relevance of these definitions for contact tracing studies is unknown.

METHODS

We developed case definitions for a community-based contact tracing diagnostic study. We compare disease certainty using protocol-defined and NIH case definitions and describe TB disease spectrum and severity.

RESULTS

There were 111 potential disease episodes in 109 (21% human immunodeficiency virus [HIV] infected) of 1093 children enrolled. Based on NIH definitions, there were 8 confirmed, 12 probable, 17 possible and 3 unlikely TB and 2 non-TB episodes. Using protocol case definitions, there were 23 episodes of confirmed, 36 probable, 27 possible and 0 unlikely TB and 21 non-TB. Of 111 potential episodes, 69 were unclassifiable using the NIH definition, while 4 were unclassifiable using the protocol definition. Agreement between definitions was 0.30 (95%CI 0.23-0.38). There were 62 episodes (72%) of non-severe and 24 (28%) of severe TB.

CONCLUSIONS

The NIH definition had limited applicability to household contact studies, despite the wide spectrum of disease observed. Further research is needed to develop case definitions relevant to different research settings, including contact investigation to capture the wide spectrum of paediatric TB in clinical research.

Chest radiograph findings in children with tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is diagnosed based on a combination of clinical, laboratory and radiological findings, including signs suggestive of tuberculosis (TB) on a standard chest X-ray (CXR).

METHODS

We describe the radiological features suggestive of intrathoracic TB in children diagnosed with TBM during a prospective evaluation of TBM suspects seen at Tygerberg Children's Hospital, Cape Town, South Africa.

RESULTS

Of 84 children treated for TBM, 31 (37%) had 'definite' TBM, 45 (55%) 'probable' TBM and 8 (9%) 'possible' TBM. In total, 37 (44%) TBM patients had CXR findings suggestive of TB, 9 (11%) with disseminated (miliary) TB. Only 1 in 4.39 children aged ≤3 years with TBM had suggestive CXR findings. The presence of complicated intrathoracic lymph node disease was significantly higher in children aged ≤3 years (OR 21.69, 95%CI 2.73-172.67, P < 0.01). Among 6 human immunodeficiency virus infected children, 3 (50%) had intrathoracic lymphadenopathy.

CONCLUSION

The majority of the children with TBM, including the very young, did not have signs suggestive of TB on CXR.

Teaching chest X-ray reading for child tuberculosis suspects

SETTING

Cape Town, South Africa.

OBJECTIVE

To improve the reading of chest X-rays (CXRs) in child tuberculosis (TB) suspects.

DESIGN

We designed a reporting and recording form to assist in the diagnosis of childhood TB from CXRs. We then developed an image bank of antero-posterior and lateral CXR pairs, with each image pair assigned to one of four diagnostic categories. Finally, we designed and carried out a 1-day training course to teach clinicians how to read paediatric CXRs, with pre- and post-course assessments.

RESULTS

Of the 27 participants included, 17 (63%) were women. The median age was 38 years (interquartile range [IQR] 32.5-43.5). The median pre-training score was 16.0/30 (IQR 13.0-18.0) and the median post-training score was 17.0 (IQR 13.5-21.0). Sensitivity (P = 0.09) and specificity (P = 0.06) to detect TB did not change as a result of the course; however, the Wilcoxon signed ranks paired-sample test indicated an increase in the participants' overall ability to read CXRs (P = 0.017).

CONCLUSIONS

Teaching clinicians with a 1-day training course using a systematic approach and a standardised form led to a limited improvement in CXR reading ability.

Left main bronchus compression as a result of tuberculous lymphnode compression of the right-sided airways with right lung volume loss in children

RATIONALE

The superior mediastinal space is confined by the sterno-manubrium anteriorly and the vertebral column posterior. An abnormal relationship between the superior mediastinal structures may result in compression of the left main bronchus. In patients with right-sided pneumonectomy an exaggerated compensatory response may lead to stretching and compression of the remainder of the intra-thoracic airway. Lymphobronchial TB mimics pneumonectomy when it causes compression of the bronchus intermedius, between nodal lymphnode groups with resultant volume loss in the right lung and displacement of the mediastinum to the right. The left main bronchus may be at risk of compression due to rotation and displacement of the major vessels.

AIM

To report pediatric cases of right-sided lymphobronchial TB with volume loss, demonstrate the use of angle measurements to quantify mediastinal dynamics and support a pathogenetic theory for left main bronchus compression.

MATERIALS AND METHODS

CT scans in children with TB and right lung volume loss, were compared retrospectively with controls using angle measurements based on descriptions of the aorta-carinal syndrome and the post-pneumonectomy syndrome. The Mann-Whitney U-test was used to compare groups.

RESULTS

The "Pulmonary bifurcation angle" between the main pulmonary arteries reached statistical significance (P = 0.025). The "Pulmonary outflow tract rotation" angle (pulmonary trunk with the mid sagittal plane) approached statistical significance (P = 0.078). The left main bronchus ranged from complete obliteration in two patients to 0.7 cm. In 16 of 30 patients the size was reduced to less than 75% of expected.

CONCLUSION

In children with right lung volume loss from TB, the compression of the contralateral bronchus is due to narrowing of the pulmonary artery bifurcation angle as the main trunk rotates towards the midline. This is comparable to the post-pneumonectomy syndrome.

Diversity of disease in childhood pulmonary tuberculosis

Many factors can influence the dynamic balance that exists between the host and the pathogen (M. tuberculosis), but the host immune response seems to be the most important. This is illustrated by the vulnerability of immune-compromised individuals to develop tuberculosis and by the age-related spectrum of disease witnessed in immune-competent children. This age-related spectrum of disease reflects the ontogeny of the host immune response towards M. tuberculosis. Renewing our focus on the ontogeny of the immune response in children might provide valuable insights to direct future research regarding tuberculosis prevention, vaccine development and treatment.

Well-quantified tuberculosis exposure is a reliable surrogate measure of tuberculosis infection

SETTING

Cape Town, South Africa.

OBJECTIVE

To develop a standardized, reliable measure of household tuberculosis (TB) exposure that considers child-specific risk factors.

DESIGN

We assessed TB exposure in 536 children. Children were considered Mycobacterium tuberculosis infected if two of three tests of infection were positive. Principal component analysis identified a discrete set of components that collectively described exposure and contributed to a composite contact score. Logistic regression assessed the odds of having M. tuberculosis infection given increasing contact score while controlling for age and past TB treatment.

RESULTS

Four components described 68% of data variance: 1) maternal TB and sleep proximity, 2) index case infectivity, 3) duration of exposure, and 4) exposure to multiple index cases. Components were derived from 10 binary questions that contributed to a contact score (range 1-10, median 5, 25th-75th interquartile range [IQR] 4-7). Among children aged 3 months to 6 years with household exposure, the odds of being M. tuberculosis-infected increased by 74% (OR 1.74, 95%CI 1.42-2.12) with each 1-point increase in the contact score.

CONCLUSIONS

Well-quantified TB exposure is a good surrogate measure of M. tuberculosis infection in child household contacts in a high-burden setting, and could guide targeted preventive treatment in children at highest risk of M. tuberculosis infection.

Tuberculosis contact investigation in a high-burden setting: house or household?

SETTING

A high tuberculosis (TB) burden setting, South Africa. Two frequently used definitions for 'household' are 1) 'all dwellings on the same plot of land that share the same residential address'; and 2) 'a group of persons who live together in the same dwelling unit and who have the same eating arrangements'.

OBJECTIVE

To characterise a household and the outcome of investigations in household child contacts using definition 1 compared to definition 2 during a TB contact investigation.

DESIGN

Access to a household (definition 1) was gained via an adult TB case. Children were assessed for TB infection and disease.

RESULTS

Household enumeration indicated 25 members of three families living in a main house and a fourth family living in an adjacent structure. Three children were diagnosed with TB and two referred for isoniazid preventive therapy. Families living in the main house shared the main kitchen, while the yard house family used its own kitchen. This household would have been classified as two separate households if definition 2 had been used, and children with TB disease and infection would have been missed.

CONCLUSION

The definition of household in TB contact investigation should provide a framework that is broad enough to capture the majority of children at risk.

Bacteriologically confirmed tuberculosis in HIV-infected infants: disease spectrum and survival

BACKGROUND

The human immunodeficiency virus (HIV) has resulted in epidemiological shifts with an emergence of tuberculosis (TB) amongst HIV-infected women and infants. There are limited data on the TB disease spectrum and outcome amongst HIV-infected infants.

OBJECTIVES

We describe the clinical characteristics, treatment and survival of HIV-infected infants with culture-confirmed TB.

METHODS

This retrospective hospital-based study from Cape Town, South Africa, used routine laboratory-based surveillance among infants diagnosed with culture-confirmed TB from 1 January 2004 to 31 December 2006. Folder and chest radiographic review were completed and vitality status established. TB was classified as pulmonary, extra-pulmonary or disseminated disease.

RESULTS

Of 52 infants, 37 (71.1%) had pulmonary, 2 (3.9%) extra-pulmonary only, 7 (13.5%) pulmonary and extra-pulmonary and 6 (11.5%) disseminated TB. Forty-six (88.5%) were started anti-tuberculosis therapy; 37 (71.2%) received antiretroviral therapy (ART) and 17 (32.7%) died, 10 (19.2%) of whom never started ART. HIV stage 4 disease was associated with death. TB treatment outcome was poorly documented.

CONCLUSIONS

TB is associated with advanced HIV disease and high mortality in HIV-infected infants. Missed opportunities for initiation of ART were frequent. Although the effects of young age, TB disease spectrum and HIV co-infection are difficult to distinguish, our findings support the initiation of early ART in HIV-infected infants with TB.

Tracheostomy home care: in a resource-limited setting

INTRODUCTION

Home tracheostomy care for children in South Africa dates back to 1989.

OBJECTIVE

This study aimed to describe the tracheostomy home programme at Tygerberg Children's Hospital (TCH), situated in a resource-limited setting in Cape Town, South Africa.

DESIGN

Retrospective descriptive study.

SETTING

Tracheostomy home programme at TCH. The primary care giver is trained by nurses.

RESULTS

Fifty-six children (29 girls) were discharged to the home programme (47 to home and 9 to institutions). The median age at tracheostomy was 3 months, mainly for airway obstruction. The mean duration of home care was 26.6 months. Twenty-seven children (43%) were successfully decannulated. Seven children lived in informal housing. The 56 children generated 745 social work contacts. The overall survival was 82%.

CONCLUSION

Children with tracheostomies can be safely cared for at home, even in a resource-constrained environment, provided training, appropriate technology and social support services are available.

Value of bone marrow biopsy in children with suspected disseminated mycobacterial disease

BACKGROUND

Disseminated tuberculosis (TB) is a severe form of disease that can be difficult to diagnose or exclude. The diagnostic role of bone marrow biopsy and culture in children with suspected disseminated TB is not clearly defined.

METHODOLOGY

In a prospective hospital-based study conducted from November 2007 to October 2008, bone marrow biopsy and culture were performed in all children referred with possible disseminated TB; relevant clinical and laboratory data were reviewed.

RESULTS

Thirty-five children were included in the study. An alternative diagnosis was established in 10 (29%) and mycobacterial disease confirmed or probable in 25 (71%). Among those with mycobacterial disease, multiple respiratory specimens provided the best yield (17/25; 68%). Bone marrow histology and/or culture were positive in 5/25 (20%), but were frequently collected after initiation of TB treatment. Blood cultures were positive in only one patient. Mycobacterium tuberculosis accounted for 16/19 (84%) confirmed cases, M.bovis bacille Calmette-Guérin for one, M. avium complex for one, and one was culture-negative. Histology results were available within 24 hours; TB was confirmed exclusively by bone marrow in two cases.

CONCLUSION

Bone marrow biopsy is a valuable diagnostic procedure in children with suspected disseminated mycobacterial disease. Ideally, patients should be referred prior to treatment initiation.

The diagnostic value and safety of transbronchial needle aspiration biopsy in children with mediastinal lymphadenopathy

INTRODUCTION

Anterior mediastinal masses in children can have different causes which includes, Mycobacterium tuberculosis (MTB) or malignant lymphadenopathy. Transbronchial needle aspiration (TBNA) has been described as a safe and effective diagnostic procedure in adult patients with lung cancer.

AIM

To describe the use of TBNA as a diagnostic test in children with large subcarinal lymphadenopathy and to determine the safety of the procedure in children.

PATIENTS AND METHODS

Prospective descriptive study of children with subcarinal mediastinal lymph nodes who underwent TBNA. The majority of the children were referred due to treatment failure. Children were enrolled if the diagnosis remained unclear after computer tomography of the chest.

RESULTS

Thirty patients were enrolled in this study; TBNA was done in 28 patients. A definitive diagnosis was made by TBNA in 54% (n = 15) of patients; MTB lymphadenopathy (n = 13), metastatic nephroblastoma (n = 1), and fibrosing mediastinitis (n = 1). In seven (25%) cases the TBNA was the sole source of the specimens from which the definitive diagnosis was made. No serious complications were encountered during or after the procedure.

CONCLUSION

TBNA is a safe procedure in children with mediastinal lymphadenopathy of unknown cause resulting in a definitive diagnosis in 57% of cases. TBNA adds additional value to flexible bronchoscopy in the diagnosis of mediastinal lymphadenopathy in children.

CMV pneumonia in HIV-infected ventilated infants

BACKGROUND

The contributing role of cytomegalovirus (CMV) in infants treated for Pneumocystis jiroveci pneumonia (PJP) is unknown. High dose steroids used in the treatment of PJP may further immunocompromise these infants contributing to the development of CMV pneumonia.

AIM

The aim of this study was to determine the role of CMV pneumonia in infants being ventilated for suspected PJP.

METHODS

In this prospective study HIV infected infants being treated with trimethoprim-sulfamethoxazole (TMP/SMX) and ventilated for suspected PJP were included if they had not responded to treatment. Open lung biopsy was performed if there was no improvement in ventilatory requirements.

RESULTS

Twenty-five HIV positive infants with a mean age of 3.3 months were included. Lung biopsy was performed in 17 (68%) and post-mortem lung tissue was obtained in 8 (32%). After evaluation of the histology, immunohistochemistry, and viral cultures from lung tissue, the most likely causes of pneumonia were: CMV and PJP dual infection 36% (n = 9), CMV pneumonia 36% (n = 9), and PJP 24% (n = 6). The pp65 test for CMV antigen was falsely negative in 24%. The mean blood CD4 count was 287/microl. There was an association between the CD4 lymphocyte status and the final diagnosis, with the CMV and PJP group (CD4 110/microl) having the lowest CD4 status (P = 0.0128). Pediatric Intensive Care Unit (PICU) mortality was 72% (n = 18) and in hospital mortality 88%.

CONCLUSION

Of the ventilated infants failing to respond to treatment, 72% had histologically confirmed CMV pneumonia, probably accounting for the high mortality in this cohort. The incidence of CMV disease in HIV infected infants being ventilated for severe pneumonia warrants that ganciclovir is used empirically until CMV disease is excluded. The role of lung biopsy in these circumstances needs to be researched.

Baseline sputum time to detection predicts month two culture conversion and relapse in non-HIV-infected patients

BACKGROUND

Few biomarkers are available to identify tuberculosis (TB) patients at risk of delayed sputum conversion and relapse.

OBJECTIVES

To investigate whether baseline pre-treatment time to detection (TTD) of culture predicted 2-month bacteriological conversion and TB relapse.

METHODS

A total of 263 non-HIV-infected smear-positive previously untreated pulmonary TB patients were prospectively followed from diagnosis until treatment outcome after 6 months' treatment and TB recurrence within 24 months.

RESULTS

The median TTD was 3 days (range 1-17). Of 211 (80.2%) patients with favourable treatment outcome, 22 (10.4%) had recurrence, while 12 (5.7%) had confirmed relapse. Culture conversion at 2 months was associated in univariate analysis with the presence and number of cavities, extensive parenchymal involvement, male sex, sputum smear grading and TTD. In multiple logistic regression, TTD or smear grading and extensive parenchymal involvement both predicted month 2 conversion. Relapse was predicted by TTD, sex, body mass index, smear grading and number of cavities in univariate analysis, and in multivariate regression by TTD and sputum smear grading.

CONCLUSIONS

Baseline TTD and smear grading predicted month 2 culture conversion, relapse and also recurrence. These markers may be useful to identify non-HIV-infected patients at risk of recurrence, and may be relevant in clinical trials.

High prevalence of Mycobacterium tuberculosis infection and disease in children and adolescents with type 1 diabetes mellitus

SETTING

Western Cape Province, South Africa.

OBJECTIVES

To describe the prevalence of tuberculosis (TB) infection and disease in children with type 1 diabetes and to investigate the association between glycaemic control and prevalence of TB infection and disease.

DESIGN

Cross-sectional hospital-based study conducted at two public referral hospitals. All children and adolescents (aged <21 years) with type 1 diabetes underwent a Mantoux tuberculin skin test (>or=10 mm classified as Mycobacterium tuberculosis infection), measurement of glycosylated haemoglobin and a chest radiograph. Patients with symptoms suggestive of TB were investigated using mycobacterial culture. Radiologically and/or bacteriologically confirmed disease was classified as TB disease.

RESULTS

Of 291 eligible patients, 258 (88.7%) were included (58% female). The prevalence of M. tuberculosis infection was 29.8% (95%CI 24.2-35.4); nine patients were diagnosed with prevalent TB disease (point prevalence disease 3488 per 100,000 population). Poor glycaemic control (hazard ratio 1.39, 95%CI 1.18-1.63 per unit increase in glycated haemoglobin [HbA1c]) and contact with a TB source case (P = 0.0011) was associated with prevalent TB disease.

CONCLUSIONS

There is a high prevalence of TB disease in diabetic children and adolescents in this setting. Routine TB screening of children with type 1 diabetes may be indicated in settings highly endemic for TB. Preventive treatment should be considered for diabetic children with proof of TB exposure and/or infection.

Phrenic nerve palsy in children associated with confirmed intrathoracic tuberculosis: diagnosis and clinical course

In this descriptive retrospective cases series of eight cases phrenic nerve palsy in children caused by tuberculosis lymph gland infiltration of the phrenic nerve. The lymph gland enlargement was in all cases caused by culture confirmed Mycobacterium tuberculosis. The phrenic nerve palsy was on the left side in all eight cases with the presenting feature a raised diaphragm on chest radiography that was accompanied by consolidation of the left upper lobe (88%) The diagnosis of phrenic nerve palsy was confirmed by fluoroscopy of the chest. On computer tomography the outstanding features were left sided hilar and paratracheal lymph gland enlargement with displacement of the mediastinum to the right. Mediastinal displacement lead to anterior displacement of the descending aorta, which further compressed the left main bronchus. Two children had accompanying respiratory failure requiring assisted ventilation and in two additional cases the airway compression was so severe that glandular enucleation of the enlarged glands was indicated. Of the eight children five remained symptomatic after completion of TB treatment to which steroids were added for the initial month. Diaphragmatic plication was indicated in all five cases. On clinical follow-up two children had repeated respiratory tract infections secondary to underlying lung damage while the other six remained asymptomatic.

Consensus statement on the revised World Health Organization recommendations for BCG vaccination in HIV-infected infants

This document outlines the consensus agreement from the Union's BCG Working Group regarding BCG vaccination in HIV-infected infants, in response to recently revised World Health Organization (WHO) guidelines, which make HIV infection in infants a full contraindication to bacille Calmette-Guérin (BCG) vaccination. BCG is one of the most widely given vaccines globally and is safe in immunocompetent individuals. Recent evidence shows that HIV-infected infants who were routinely vaccinated with BCG at birth, when asymptomatic, and who later developed AIDS, are at high risk of developing disseminated BCG disease (estimated incidence 407-1300 per 100 000). The document outlines requirements to implement selective BCG vaccination strategies in infants born to HIV-infected women and strategies to reduce the risk of vertical HIV transmission and disseminated BCG disease in infants.

Fibrin glue closure of persistent bronchopleural fistula following pneumonectomy for post-tuberculosis bronchiectasis

We report a case of a persistent bronchopleural fistula following a pneumonectomy for post-tuberculosis bronchiectasis. The patient had two unsuccessful surgical attempts at closing of the fistula. Further surgical attempts were technically were not possible. Bronchoscopic closure was achieved by injecting human fibrin glue into the fistula via a catheter. Closure of the broncho-pleural fistula was confirmed by repeated ventilation scan over a period of 2 months. Endoscopic closure of small bronchopleural fistulae is an attractive option in children with significant underlying lung disease.

The outcome of infants younger than 6 months requiring ventilation for pneumonia caused by Mycobacterium tuberculosis

INTRODUCTION

The outcome of young infants (<6 months) being ventilated for respiratory failure caused by Mycobacterium tuberculosis (MTB) has not been recorded.

PATIENTS AND METHODS

A descriptive study of children <6 months admitted to the PICU from 1 February 1999 to 31 December 2005 with MTB causing respiratory failure.

RESULTS

Seventeen infants were ventilated for respiratory failure caused by MTB: ten had ventilatory respiratory failure and seven had hypoxic failure. An index case was found in 47%. All chest radiographs (CXRs) were highly suggestive of tuberculosis. MTB was cultured in 15 cases. In the other two cases MTB was confirmed by histopathology. The median duration of ventilation was 6 days (range: 1-35 days) with a median PaO2/FiO2 of 85 and ventilatory index of 58. Transthoracic glandular enucleation was required to facilitate extubation in six babies. All the infants survived. At 6-month follow-up 35% had a normal CXR and all were asymptomatic. One child had CXR changes suggestive of bronchiectasis but was asymptomatic.

CONCLUSION

The outcome of infants <6 months ventilated for respiratory failure caused by MTB is very good if TB is recognized timeously and appropriate management started. The diagnosis of TB in these infants can be made with a high index of suspicion and careful evaluation of the CXR.

Esophageal stent improves ventilation in a child with a broncho-esophageal fistula caused by Mycobacterium tuberculosis

The deployment of an esophageal stent to aid in the ventilation of a child who had developed an acquired broncho-esophageal fistula caused by Mycobacterium tuberculosis (MTB) is described. The 12-month-old boy presented with respiratory failure requiring ventilation. The air leak via the fistula led to inadequate mechanical ventilation. The deployment of the stent resulted in successful ventilation, closure of the fistula, and eventual successful treatment.

Respiratory atopic disease, Ascaris-immunoglobulin E and tuberculin testing in urban South African children

BACKGROUND

Epidemiological relation of intestinal helminth infection and atopic disease, both associated with a T-helper (Th) 2 immune response, is controversial, as it has been reported that helminth infection may either suppress or pre-dispose to atopic disease. This relation has not been tested in an area with a high burden of Mycobacterium tuberculosis (MTB) infection, a known Th1-stimulating infection.

OBJECTIVE

To study the association of intestinal helminth infection and atopic disease in a community where helminth infection is endemic and MTB infection is high.

METHODS

Three-hundred and fifty-nine randomly selected children aged 6-14 years from a poor urban suburb were tested with allergy questionnaire, skin prick test (SPT) to common aeroallergens, Ascaris-specific IgE (Ascaris-sIgE), fecal examination for pathogenic intestinal helminths and tuberculin skin testing (TST). Histamine bronchoprovocation was tested in the group of children aged 10 years and older.

RESULTS

were corrected for demographic variables, socioeconomic status, parental allergy, environmental tobacco smoke (ETS) exposure in the household, recent anthelminthic treatment and for clustering in the sampling unit. Results Ascaris-sIgE was elevated in 48% of children, Ascaris eggs were found in 15% and TST was positive in 53%. Children with elevated Ascaris-sIgE had significantly increased risk of positive SPT to aeroallergens, particularly house dust mite, atopic asthma (ever and recent), atopic rhinitis (ever and recent) and increased atopy-related bronchial hyper-responsiveness. In children with negative TST (<10 mm), elevated Ascaris-sIgE was associated with significantly increased risk of atopic symptoms (adjusted odds ratio (OR(adj)) 6.5; 95% confidence interval (CI) 1.9-22.4), whereas in those with positive TST (>/=10 mm) this association disappeared (OR(adj) 0.96; 95% CI 0.4-2.8).

CONCLUSIONS

These results suggest that immune response to Ascaris (Ascaris-sIgE) may be a risk factor of atopic disease in populations exposed to mild Ascaris infection and that MTB infection may be protective against this risk, probably by stimulation of anti-inflammatory networks.

Adherence to isoniazid preventive chemotherapy: a prospective community based study

BACKGROUND

Current international guidelines recommend 6-9 months of isoniazid (INH) preventive chemotherapy to prevent the development of active tuberculosis in children exposed to a susceptible strain of M tuberculosis. However, this is dependent on good adherence and retrospective studies have indicated that adherence to unsupervised INH preventive chemotherapy is poor.

AIM

To prospectively document adherence to six months of unsupervised INH monotherapy and outcome in children with household exposure to an adult pulmonary tuberculosis index case.

METHODS

From February 2003 to January 2005 in two suburbs of Cape Town, South Africa, all children <5 years old in household contact with an adult pulmonary tuberculosis index case were screened for tuberculosis and given unsupervised INH preventive chemotherapy once active tuberculosis was excluded. Adherence and outcome were monitored.

RESULTS

In total, 217 index cases from 185 households were identified; 274 children <5 years old experienced household exposure, of whom 229 (84%) were fully evaluated. Thirty eight children were treated for tuberculosis and 180 received preventive chemotherapy. Of the children who received preventive chemotherapy, 36/180 (20%) completed > or =5 months of unsupervised INH monotherapy. During the subsequent surveillance period six children developed tuberculosis: two received no preventive chemotherapy, and four had very poor adherence.

CONCLUSION

Adherence to six months of unsupervised INH preventive chemotherapy was poor. Strategies to improve adherence, such as using shorter duration multidrug regimens and/or supervision of preventive treatment require further evaluation, particularly in children who are at high risk to progress to disease following exposure.

The spectrum of disease in children treated for tuberculosis in a highly endemic area

BACKGROUND

Children contribute a substantial proportion of the global tuberculosis (TB) caseload, particularly in endemic areas, where little is known about their spectrum of disease.

OBJECTIVE

To document the complete disease spectrum, with relevant age- and HIV-related differences, in children treated for TB in a highly endemic community.

METHODS

A prospective descriptive study was conducted from February 2003 to October 2004 at five primary health care clinics in Cape Town, South Africa, including all children (< 13 years of age) treated for TB.

RESULTS

In total, 439 children received anti-tuberculosis treatment. The spectrum of disease included 85 (19.4%) 'not TB', 307 (86.7%) intra-thoracic TB and 72 (20.3%) extra-thoracic TB (25 [5.7%] with co-existing intra- and extra-thoracic disease were included in both groups). In non-HIV-infected children, disseminated (miliary) disease (9/11, 81.8%) and tuberculous meningitis (TBM) (10/13, 76.9%) were predominantly documented in children < 3 years of age. In HIV-infected children, complicated Ghon focus and disseminated (miliary) disease were significantly more common (6/25, 24.0%) than in non-HIV-infected children (12/414, 2.9%) (OR 10.9, 95% CI 3.2-35.9).

CONCLUSION

This study describes the complete disease spectrum observed in children treated for TB in a highly endemic area. Children suffered significant morbidity, with most severe disease recorded in very young and/or HIV-infected children.

Management of childhood asthma

The guidelines for the management of childhood asthma have evolved from recommendations by experts to being evidence-based as a result of better understanding of the pathophysiology of asthma, awareness of the heterogeneity and early onset of childhood asthma and a new approach to the pharmacological management. While there are reasonably good evidence-based guidelines for the treatment of asthma in children aged over 5 years, there is a paucity of data for preschool children for the most appropriate management. Most guidelines include recommendations on diagnosis of asthma in children and pharmacological treatment according to the severity of the asthma. Environmental control is an important cornerstone of care, and allergen avoidance should be recommended for children with asthma who are known to be sensitised to the allergen. Environmental tobacco smoke remains an important trigger for worsening asthma in all children, and their parents must be encouraged to give up the habit. Educating children with asthma and their care givers on the disease and proper treatment is another vital element in the management of asthma. There remains a major problem with ensuring the implementation of guidelines in most countries. A care gap thus exists between best practice and common practice. The impact on asthma morbidity of developing and implementing guidelines requires appropriate study.

Mycobacterium tuberculosis infection may protect against allergy in a tuberculosis endemic area

BACKGROUND

Epidemiological studies have shown an inverse relation of mycobacterial infection and the frequency of allergic diseases and asthma. Recent evidence suggests that allergic inflammation may be inhibited in the presence of chronic and persistent infections, such as that by Mycobacterium tuberculosis (MTB). The relation of tuberculin skin test (TST) size, an accepted marker of MTB infection and the frequency of allergic disease symptoms has not been reported from an area where MTB infection is endemic.

OBJECTIVE

To investigate the association of TST and allergic disease symptoms, in children living in a tuberculosis (TB) endemic area.

METHODS

In this cross-sectional study, 841 children aged 6-14 years from randomly selected household addresses in two poor communities of Cape Town, South Africa, were investigated with TST and standardized International Study on Asthma and Allergies in Childhood-based questionnaire on allergic disease symptoms.

RESULTS

Children with positive TST (> or =10 mm) were significantly less likely to have allergic disease symptoms, in particular allergic rhinitis (AR) (adjusted odds ratio 0.43; 95% confidence interval 0.24-0.79) than those with negative TST. This association remained significant after adjusting for possible confounders and correcting for the effect of clustering (>1 child per household address) in the sample. There was a significant inverse linear trend in the relation of TST size in millimetre and the frequency of allergic disease symptoms, in particular AR (P<0.001).

CONCLUSIONS

These results of inverse association of strong TST reaction and allergic disease symptoms in children from a TB endemic area are in support of the hypotheses that allergic inflammation may be inhibited by chronic infections, such as MTB.

The bacteriologic yield in children with intrathoracic tuberculosis

This report documents the bacteriologic yield in children who received treatment for intrathoracic tuberculosis in an area where it is highly endemic. A total of 307 children were included in the study, and bacteriologic confirmation was achieved in 122 (62.2%) of 196 children from whom specimens were collected. The lowest bacteriologic yield was recorded for the 69 children with uncomplicated lymph node disease (24 [34.8%] had bacteriologic confirmation). The high overall bacteriologic yield indicates the need to reassess the value of bacteriology-based approaches to diagnosis of intrathoracic tuberculosis in children, particularly in areas of endemicity where they frequently present with advanced disease.

Pasteurella multocida lung and liver abscess in an immune-competent child

We report on a 20-month-old infant with a complicated lung and liver abscess caused by Pasteurella multocida after the child had been in close contact with a domestic cat. Surgical drainage confirmed lung and liver abscesses connected to each other, with involvement of the diaphragm.

The burden of childhood tuberculosis and the accuracy of community-based surveillance data

BACKGROUND

Inadequate surveillance and diagnostic difficulties compromise the quality of epidemiological data on childhood tuberculosis (TB).

OBJECTIVE

To document the incidence of childhood TB and to evaluate the accuracy of community-based surveillance data in a high-burden setting.

METHODS

This prospective observational study was conducted from February 2003 to October 2004 at five primary health care clinics in Cape Town, South Africa. Comprehensive surveillance was done to ensure that all children <13 years of age treated for TB were included.

RESULTS

During the study period, 443 children (<13 years of age) received anti-tuberculosis treatment, of whom 389 (87.8%) were recorded in the TB treatment register. The TB incidence calculated from the TB treatment register was 441/100,000/year amongst children and 845/100,000/year amongst adults. Fifty-four children treated for TB were not recorded in the TB treatment register, including 21/28 (75%) children with severe disease.

DISCUSSION

Children <13 years of age contributed 13.7% of the total TB burden, but experienced more than half (52.2%) the TB incidence recorded in adults. Community-based surveillance data excluded the majority of children with severe disease. The accuracy of surveillance data is an important consideration when describing the epidemiology of childhood TB or measuring the success of public health interventions.

Bacille Calmette-Guérin vaccine-induced disease in HIV-infected and HIV-uninfected children

BACKGROUND

Bacille Calmette-Guérin (BCG)--a live, attenuated vaccine--is routinely given to neonates in settings where tuberculosis is endemic, irrespective of human immunodeficiency virus (HIV) exposure. HIV-infected infants and other immunodeficient infants are at risk of BCG-related complications. We report the presentation, treatment, and mortality of children who develop BCG disease, with emphasis on HIV-infected children. In addition, we present a revised classification of BCG disease in children and propose standard diagnostic and management guidelines.

METHODS

This retrospective, hospital-based study was conducted in the Western Cape Province, South Africa. Mycobacterium tuberculosis complex isolates recovered from children aged <13 years during the period of August 2002 through January 2005 were speciated by polymerase chain reaction to confirm Mycobacterium bovis BCG. Clinical data were collected through medical file review. BCG disease was classified according to standard and revised disease classifications. Mortality was assessed at the end of the study period.

RESULTS

BCG disease was diagnosed in 25 children; 22 (88%) had local disease, and 8 (32%) had distant or disseminated disease; 5 children (20%) had both local and distant or disseminated disease. Seventeen children were HIV infected; 2 children had other immunodeficiencies. All 8 children with distant or disseminated disease were immunodeficient; 6 were HIV infected. The mortality rate was 75% for children with distant or disseminated disease.

CONCLUSIONS

BCG vaccination poses a risk to infants perinatally infected with HIV and to other primary immunodeficient children. The proposed pediatric BCG disease classification reflects clinically relevant disease categories in HIV-infected children. The suggested diagnostic and treatment guidelines should improve existing case management and surveillance. Prospective evaluation of management strategies for BCG disease in HIV-infected and HIV-uninfected children is essential.

Adherence to anti-tuberculosis chemoprophylaxis and treatment in children

SETTING

Limited data exist on adherence to anti-tuberculosis treatment and chemoprophylaxis in children in high-burden settings.

OBJECTIVE

To determine the adherence to anti-tuberculosis chemoprophylaxis and treatment in children evaluated as household contacts of adult pulmonary tuberculosis (PTB) cases.

METHODS

A retrospective study, conducted from January 1996 to September 2003, in suburban Cape Town, South Africa, with a high TB incidence. A folder search was done on all children <5 years of age identified as household contacts of adult PTB cases between 1996 and 2003. Data on screening for TB and adherence to prescribed therapy in child contacts were analysed.

RESULTS

Three hundred and sixty-one contact episodes with 243 adult PTB cases were identified in 335 children. The median age was 25 months. Adherence to anti-tuberculosis treatment was significantly better than adherence to chemoprophylaxis (82.6% vs. 44.2%; OR 6.83; 95%CI 3.6-12.96). Adherence to a 3-month chemoprophylaxis regimen of isoniazid and rifampicin (3HR) was significantly better than adherence to a 6-month chemoprophylaxis regimen of isoniazid only (69.6% vs. 27.6%; OR 4.97; 95%CI 2.40-10.36).

CONCLUSIONS

Although adherence to treatment was good, adherence to unsupervised chemoprophylaxis was poor. We recommend that shorter chemoprophylaxis regimens such as 3HR should be considered to improve adherence, but further studies are required.

The burden of childhood tuberculosis: a public health perspective

The burden of childhood tuberculosis (TB) reflects recent transmission within a community and the level of TB control achieved within the adult (maintenance host) population. Children contribute little to the maintenance of the TB epidemic, but they may suffer severe TB-related morbidity and mortality. This review describes the main determinants of the burden of childhood TB within a particular community. Basic infectious disease principles identify the community, and not the individual, as the central entity that sustains an epidemic. The prevalence of TB is determined by the community's exposure to Mycobacterium tuberculosis, and their vulnerability to developing disease following exposure. The main variables that influence both exposure and vulnerability are discussed. Multiple variables are linked to poverty, and it is their cumulative effect, rather than the exact degree of poverty, that seems most important. Diligent contact tracing and the use of preventive chemotherapy will reduce the TB-related suffering of children. The burden of childhood TB, however, is a reflection of our ability to control the epidemic; this remains the ultimate challenge. Current efforts to control the TB epidemic aim to reduce transmission by treating sputum smear-positive adults, while very little emphasis is placed on reducing the vulnerability of high-burden communities. Successful control of the epidemic is the most effective way to reduce the burden of childhood TB, but this will require a holistic approach that acknowledges the importance of sustainable poverty alleviation.

Criteria used for the diagnosis of childhood tuberculosis at primary health care level in a high-burden, urban setting

BACKGROUND

Children contribute a significant proportion of the total tuberculosis (TB) case load in high-burden settings and present a major diagnostic challenge.

OBJECTIVE

To document the criteria used at primary health care level to diagnose childhood TB in a high-burden, urban setting.

METHODS

This retrospective descriptive study was conducted at two primary health care clinics in Cape Town, South Africa. Information on all children (<15 years of age) entered into the TB register from January 2002 through December 2003 was retrieved for analysis.

RESULTS

During the study period, 1277 cases of TB were entered into the TB register, of which 268 (21.0%) were children. Information on 256 (95.5%) children was available for analysis. The majority (206, 80.5%) had intrathoracic TB, of whom 107 (51.5%) had uncomplicated lymph node disease, 79 (38.3%) complicated lymph node disease, 8 (3.9%) a pleural effusion and 12 (5.8%) adult-type cavitating disease. According to modified WHO criteria, the diagnosis of TB was confirmed in 27 (10.5%), probable in 193 (75.4%) and suspect in 36 (14.1%).

DISCUSSION

The diagnostic criteria used at primary health care level demonstrated good agreement with current guidelines, but depended heavily on chest radiograph interpretation.

Well defined symptoms are of value in the diagnosis of childhood pulmonary tuberculosis

BACKGROUND

The diagnosis of childhood pulmonary tuberculosis presents a major challenge as symptoms traditionally associated with tuberculosis are extremely common in children from endemic areas. The natural history of tuberculosis in children shows that progressive disease is associated with symptoms which have a persistent, non-remitting character. The aims of this study were to investigate whether improved symptom definition is possible in a clinical setting, and whether use of these well defined symptoms has improved value in the diagnosis of childhood pulmonary tuberculosis.

METHODS

A prospective, community based study was conducted in two suburbs of Cape Town, South Africa. All children (<13 years) presenting to the local community clinic with a cough of >2 weeks duration, were referred to the investigator. Parents completed a symptom based questionnaire, whereafter reported symptoms were characterised in a standard fashion.

RESULTS

Of the 151 children enrolled, 21 (15.6%) reported symptoms with a persistent, non-remitting character. Tuberculosis was diagnosed in 16 (10.5%) children, all of whom reported these symptom characteristics. A persistent, non-remitting cough was reported in 15/16 (93.8%) children with tuberculosis and in 2/135 (1.5%) children without tuberculosis, indicating a specificity of 98.5% (135/137). Persistent fatigue of recent onset was also sensitive (13/16, 81.3%) and specific (134/135, 99.3%). Persistent fever and/or chest pain were exclusively reported in children with tuberculosis, but were present in only 4/16 (25.0%) children with tuberculosis.

CONCLUSION

The use of well defined symptoms is feasible, even in resource limited settings, and may offer significantly improved value in the diagnosis of childhood pulmonary tuberculosis.

The prevalence of symptoms associated with pulmonary tuberculosis in randomly selected children from a high burden community

BACKGROUND

Diagnosis of childhood tuberculosis is problematic and symptom based diagnostic approaches are often promoted in high burden settings. This study aimed (i) to document the prevalence of symptoms associated with tuberculosis among randomly selected children living in a high burden community, and (ii) to compare the prevalence of these symptoms in children without tuberculosis to those in children with newly diagnosed tuberculosis.

METHODS

A cross sectional, community based survey was performed on a 15% random sample of residential addresses. A symptom based questionnaire and tuberculin skin test (TST) were completed in all children. Chest radiographs were performed according to South African National Tuberculosis Control Program guidelines.

RESULTS

Results were available in 1415 children of whom 451 (31.9%) were TST positive. Tuberculosis was diagnosed in 18 (1.3%) children. Of the 1397 children without tuberculosis, 253 (26.4%) reported a cough during the preceding 3 months. Comparison of individual symptoms (cough, dyspnoea, chest pain, haemoptysis, anorexia, weight loss, fatigue, fever, night sweats) in children with and without tuberculosis revealed that only weight loss differed significantly (OR = 4.5, 95% CI 1.5 to 12.3), while the combination of cough and weight loss was most significant (OR = 5.4, 95% CI 1.7 to 16.9). Children with newly diagnosed tuberculosis reported no symptoms in 50% of cases.

CONCLUSION

Children from this high burden community frequently reported symptoms associated with tuberculosis. These symptoms had limited value to differentiate children diagnosed with tuberculosis from those without tuberculosis. Improved case definitions and symptom characterisation are required when evaluating the diagnostic value of symptoms.

The association of prolonged breastfeeding and allergic disease in poor urban children

The fact that breastfeeding may protect against allergic disease remains controversial, with hardly any reports from developing countries. This study investigated the association between allergic disease in children and prolonged breastfeeding. Data were collected from a 15% random sample of households from two poor suburbs of Cape Town, South Africa. Parents completed a validated International Study on Asthma and Allergies in Childhood questionnaire on allergic diseases for children aged 6-14 yrs. Other questions included breastfeeding duration, maternal smoking and parental allergy. Results were adjusted for possible confounders and for possible clustering within the household. Out of the 861 children included in the study, allergic disease in general, and hay fever in particular, were significantly less frequent in those with prolonged (> or =6 months) breastfeeding. There was a significant linear inverse association between breastfeeding duration and allergic disease in children without allergic parents, but not in children with an allergic predisposition. In conclusion, these results from a developing country suggest a protective effect of prolonged breastfeeding on the development of allergic disease, particularly hay fever, in children born to nonallergic parents. This protective effect was not found in children with an allergic predisposition.

Inverse association between Mycobacterium tuberculosis infection and atopic rhinitis in children

BACKGROUND

The association between Mycobacterium tuberculosis (MTB) infection and atopy remains controversial.

AIM

To investigate the association between MTB infection and atopic rhinitis in children living in a high TB incidence area.

METHODS

In this cross-sectional study 418 children aged 6-14 years from an established epidemiological research-site in a poor urban community were invited to participate. They were assessed for allergic rhinitis (ISAAC questionnaire) and skin responses to tuberculin and eight environmental allergens. The presence of a BCG scar was documented, intestinal parasites and total and Ascaris lumbricoides-specific IgE levels were measured. Atopic rhinitis was defined, using the new World Allergy Organization (WAO) definition, as reported allergic rhinitis and a positive skin prick test (SPT > or =3 mm) to any allergen.

RESULTS

Among the 337 children enrolled 10.4% had allergic rhinitis, 17.5% a positive SPT and 53% a positive tuberculin skin test (TST > or =10 mm). Children with a positive TST were significantly less likely to have recent atopic rhinitis (OR(adjusted) 0.06; 95% CI 0.007-0.5) than those with a negative TST. SPTs were significantly more common in children with negative TST who had recent allergic rhinitis (OR(adj) 34.0; 95% CI 7.6-152.6), but not in children with positive TST and recent allergic rhinitis (OR(adj) 0.6; 95% CI 0.07-5.2).

CONCLUSIONS

MTB infection seems to reduce the prevalence of atopic rhinitis, and influences SPT reactivity in children with allergic rhinitis from a high TB incidence area.

Expansile pneumonia in children caused by Mycobacterium tuberculosis: clinical, radiological, and bronchoscopic appearances

A cohort of 24 children with expansile pneumonia caused by Mycobacterium tuberculosis is described in mostly HIV-noninfected children (n = 22). The children presented with nonresolving pneumonia and a swinging fever (83%). On chest radiography, they had dense opacification with bulging fissures mainly in the upper lobes (75%). On computed tomography, the lobes are consolidated, with areas of liquefacation. Other features visible are enlarged mediastinal lymph adenopathy with ring enhancement (100%), cavities (63%), and tracheal compression (71%). On bronchoscopy, bronchi were obstructed by more than 75% in 20 (83%) of cases. Lymph gland enucleation was required in 42% of cases. Phrenic nerve palsy was present in 3 children, of whom 2 underwent diaphragmatic plication. The children received standard antituberculous therapy, to which prednisone (2 mg/kg/day) was added for 1 month. The mortality was 4% after 6 months of therapy.

Childhood tuberculosis: clinical research needs

Childhood tuberculosis (TB) is common in the developing world, where over 90% of global TB cases occur, and has increased in human immunodeficiency virus (HIV) endemic regions. Most children with TB are not infectious, and so, from a public health perspective, are not afforded the same priority by TB control programmes as older age groups in settings of limited resources. In addition, the diagnosis of pulmonary TB is particularly difficult in young children. This has resulted in TB being a neglected disease in children, although it causes substantial morbidity and mortality. This review summarises the current knowledge of clinical aspects of childhood TB management, and aims to identify priority areas for future research. The most critical need is for improved capability to confirm diagnosis. This would lead to better management of childhood TB and would greatly enhance our ability to conduct meaningful research in many related areas, including immunological studies which could lead to a more effective vaccine. Also important are a better understanding of risk factors for infection and disease, including the impact of HIV, and operational research to improve treatment outcomes and management of well childhood contacts.

The natural history of childhood intra-thoracic tuberculosis: a critical review of literature from the pre-chemotherapy era

The pre-chemotherapy literature documented the natural history of tuberculosis in childhood. These disease descriptions remain invaluable for guiding public health policy and research, as the introduction of effective chemotherapy radically changed the history of disease. Specific high-risk groups were identified. Primary infection before 2 years of age frequently progressed to serious disease within the first 12 months without significant prior symptoms. Primary infection between 2 and 10 years of age rarely progressed to serious disease, and such progression was associated with significant clinical symptoms. In children aged >3 years the presence of symptoms represented a window of opportunity in which to establish a clinical diagnosis before serious disease progression. Primary infection after 10 years of age frequently progressed to adult-type disease. Early effective intervention in this group will reduce the burden of cavitating disease and associated disease transmission in the community. Although the pre-chemotherapy literature excluded the influence of human immune deficiency virus (HIV) infection, recent disease descriptions in HIV-infected children indicate that immune-compromised children behave in a similar fashion to immune immature children (less than 2 years of age). An important concept deduced from the natural history of tuberculosis in childhood is that of relevant disease. Deciding which children to treat may be extremely difficult in high-prevalence, low-resource settings. The concept of relevant disease provides guidance for more effective public health intervention.

The clinical epidemiology of childhood pulmonary tuberculosis: a critical review of literature from the pre-chemotherapy era

The pre-chemotherapy literature represents an impressive body of evidence that clarifies important epidemiological concepts in childhood tuberculosis. Reports describe the major transitions in tuberculosis, from exposure to infection and from infection to disease (morbidity and mortality), without the influence of chemotherapy. Children with household exposure to a sputum smear-positive source case experienced the greatest risk of becoming infected and of developing subsequent disease. Household exposure to a sputum smear-negative source case or non-household exposure still posed an appreciable, although greatly reduced, risk. Infection in children less than 2 years of age indicated a probable household source case. The majority of older children who were infected did not have a household source identified, and presumably became infected in the community. The annual risk of infection (ARI) was not constant across all ages, but seemed to increase during periods of widening social contact. Infants and adolescents were the groups at highest risk for disease development and death following primary infection.