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.