Management of asthma in children in low-income countries

Asthma is a common disease in children living in low-income countries. Asthma is diagnosed in children, especially those aged over 2 years, who have wheezing episodes that improve after a bronchodilator is given (bronchodilator response test). Children are classified as having either intermittent or persistent asthma and treated according to the severity of the disease with either an inhaled bronchodilator (reliever) or a combination of an inhaled bronchodilator and inhaled corticosteroid (controller). Treatment is best given by inhalation, and as children under 5 years cannot coordinate their breathing with the multidose inhaler, spacers are required. These can be made locally from plastic bottles. Care givers need to be educated about how to manage asthma and should receive a written management plan on the management of the child's asthma. Children should be examined to see if they are allergic to especially airborne allergens, and if these are present they should be removed from the environment. Adult smoking worsens childhood asthma, and care givers need to be given support with smoking cessation. Regular planned follow-up is needed to ensure that the asthma is well controlled and the lowest dose of inhaled corticosteroid is used. Inhaled bronchodilators and corticosteroids must become freely available and should be inexpensive in low-income countries in order to treat childhood asthma correctly.

Medical interns knowledge of TB in Pakistan

Of 460 interns from five Pakistani teaching hospitals surveyed, only 22% correctly identified the estimated number of new TB cases in Pakistan. The majority (96%) knew that droplet infection was the usual mode of transmission. Only 38% considered sputum smears for acid-fast bacilli as the best test for diagnosis of pulmonary TB and 43.5% for follow-up during TB treatment. The recommended four-drug anti-TB regimen was prescribed by 56.5% in the initiation phase and the recommended two-drug combination in the continuation phase by 52%. Most interns (82%) were unable to identify a single component of directly observed treatment short course (DOTS) strategy. Our study reflects poor awareness of and low compliance to the World Health Organization/National Tuberculosis Programme guidelines among interns. For effective control of TB, immediate action to improve undergraduate and continuing medical education is essential, with special emphasis on national guidelines.

Management of pneumonia in the child aged 0 to 8 weeks

The group of children with the highest mortality from pneumonia is the group aged 8 weeks and younger. This group of infants is more likely to present with non-specific signs of disease, and the pneumonia is caused by a wider spectrum of organisms. For these reasons, infants aged < or = 8 weeks have to be carefully assessed, taking into account the characteristics peculiar to this age. Due to the seriousness of the pneumonia, they are only classified into three categories: very severe pneumonia, severe pneumonia and cough or cold. All infants aged < or = 8 weeks diagnosed with severe or very severe pneumonia must be hospitalised, as they require parenteral antibiotics for at least 8 days and need careful monitoring. The monitoring needs to be adapted, as they are more likely to have problems with body temperature and serum glucose control. Careful plans have to be formulated to ensure that these infants recover fully and are integrated into the well baby clinics. In the triage of sick children, it is those aged < or = 8 weeks who should receive the most urgent attention.

Development and evaluation of a new chest radiograph reading and recording system for epidemiological surveys of tuberculosis and lung disease

OBJECTIVE

The development and evaluation of a new chest radiograph reading and recording system (CRRS) for community surveys of tuberculosis (TB) and lung disease.

DESIGN

An experienced pulmonologist read 2608 chest X-rays (CXRs) performed as part of a TB prevalence survey using the newly developed CRRS. The kappa (kappa) for inter-reader agreement was calculated after a second reader reported on a stratified random sample of 810 (31%) of the 2608 CXRs. The kappa for intra-reader agreement was calculated from the repeated reporting of a stratified random sample of 104 CXRs.

RESULTS

The kappa agreement between the two readers was 0.69 (95%CI 0.64-0.74) for abnormalities consistent with TB and 0.47 (95%CI 0.42-0.53) for any abnormalities. The kappa for intra-reader agreement was 0.90 (95%CI 0.81-0.99) for abnormalities consistent with TB and 0.85 (95%CI 0.74-0.95) for any abnormalities.

CONCLUSION

This standardised method for CXR reading and recording provides satisfactory inter- and intra-reader agreement, making it suitable for surveys of TB and other forms of lung disease in the community. Its use will permit comparisons of results obtained in different surveys.

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.

Management of pneumonia in the child 2 to 59 months of age

The mortality from pneumonia is reduced when children with pneumonia requiring antibiotics are identified and the severity of the pneumonia assessed. Children presenting with a cough or difficult breathing have pneumonia if fast breathing is present. The severity of pneumonia is classified by the presence of chest wall indrawing, inability to drink or feed well, decreased level of consciousness or convulsions, amongst others. Using these easily observed signs, pneumonia can be classified into four grades of severity: no pneumonia (cough or cold), pneumonia, severe pneumonia and very severe pneumonia. The classification into one of these four grades of severity is extremely useful as it identifies which children require antibiotics, which antibiotics and who requires hospitalisation and supplementary oxygen. This simple case management of pneumonia can be successfully taught to any cadre of health care worker, and where implemented has been shown to reduce childhood mortality from pneumonia.

Assessing the child with cough or difficult breathing

In most low-income countries, clinical assessment is the only tool available to distinguish an upper respiratory infection (cough or cold) from pneumonia requiring antibiotics. The severity of the pneumonia, determined from the clinical signs, will determine which patients require more potent antibiotic regimens and supplementary oxygen. Careful assessment of the respiratory rate, chest in-drawing, ability to feed normally, cyanosis and level of consciousness are used to make the diagnosis of pneumonia and determine the severity. Co-morbid disease such as malnutrition, measles, HIV infection and malaria increase mortality due to pneumonia, and signs of these diseases must be looked for so that appropriate treatment can be started. This article carefully describes the signs that should be looked for in children presenting with a cough or difficult breathing to any health care worker.

Association between smoking and tuberculosis infection: a population survey in a high tuberculosis incidence area

BACKGROUND

Associations between smoking and tuberculosis disease including death from tuberculosis have been reported, but there are few reports on the influence of smoking on the risk of developing Mycobacterium tuberculosis infection. The aim of this study was to determine the association between smoking and M tuberculosis infection.

METHODS

In a cross sectional population survey, data on smoking and tuberculin skin test (TST) results of 2401 adults aged > or =15 years were compared.

RESULTS

A total of 1832 (76%) subjects had a positive TST (> or = 10 mm induration). Of 1309 current smokers or ex-smokers, 1070 (82%) had a positive TST. This was significantly higher than for never smokers (unadjusted OR 1.99, 95% confidence interval (CI) 1.62 to 2.45). A positive relationship with pack-years was observed, with those smoking more than 15 pack-years having the highest risk (adjusted OR 1.90, 95% CI 1.28 to 2.81).

CONCLUSION

Smoking may increase the risk of M tuberculosis infection.

Management of the child with cough or difficult breathing

Childhood respiratory disease creates considerable morbidity and mortality, especially amongst children living in low-income countries. Of the more than 10 million children who die annually from preventable diseases, pneumonia is responsible for 18.1%, while in low-income countries this percentage rises to 26%. It is calculated that 90% of these deaths from preventable diseases occur in 42 countries. Even in the face of the human immunodeficiency virus (HIV) epidemic, pneumonia is still responsible for 21% of deaths. HIV-infected children are at greatest risk for developing and dying from pneumonia. By the introduction of low cost standardised case management strategies for the management of pneumonia, increasing immunisation, reducing risk factors such as poor nutrition and environmental smoking and promoting breast-feeding, it is estimated that the death rate from pneumonia can be reduced by 50%. In this series the epidemiology of childhood acute respiratory infections (ARI) and the recognition and management of childhood pneumonia in resource-poor settings will be highlighted as well as the scientific justification for the standard case management of childhood pneumonia. As cases of pneumonia are better managed, other childhood respiratory diseases such as asthma and tuberculosis (TB) will be discovered, which also require a standard approach to management. The management of asthma and TB in resource-poor settings will also be discussed.

Interpreting and reporting results

Creating and disseminating knowledge is the goal of research. This is accomplished through critical analysis of systematically collected and clearly reported information. Critical analysis begins with the simple step of looking at the data collected prior to applying complex statistical analysis to make comparisons. Statistical analysis is approached in a standardised manner, depending on the type of data that has been collected. When a careful, stepwise standardised approach is applied to comparisons needed to address the research question, new knowledge is created and erroneous conclusions avoided. Following careful examination and analysis of the data, critical review is an important additional step to ensure that conclusions are correctly drawn. The process of peer review involved in publishing the research in the scientific literature is an important step to disseminating the new knowledge and ensuring its quality. Research is never complete without submitting it for publication in the peer-reviewed literature.

Conducting research: practical steps

Developing a research protocol and obtaining funding for carrying out the research are only the first steps in doing research. Understanding the means to conduct the research is equally important. As research is a joint effort of a team, a mechanism of collaboration must be developed to engage all those with an interest in the research. This includes the community in which the research is to be undertaken, representatives of those who will participate in the research, the academic community who will be involved in the research, and those who will sponsor the research. These individuals can be formed into a 'steering committee' to guide the development, conduct, analysis and communication of the research. Careful consideration must be given to the benefits and risks of the research. These must be precisely spelled out in the research protocol, and all aspects of the research must be independently evaluated for technical competence, accuracy, communication and liability for injury by an ethics review committee. The research must follow precisely the protocol developed. Administrative procedures, including recruitment and management of staff, outlining standard procedures and quality assurance procedures must be clearly outlined and followed. Carefully handling the information collected in a research project is vital to ensuring the quality and validity of the research.

Two 8-month regimens of chemotherapy for treatment of newly diagnosed pulmonary tuberculosis: international multicentre randomised trial

BACKGROUND

A WHO-recommended 8-month regimen based on ethambutol and isoniazid was evaluated in a randomised clinical trial against a 6-month standard regimen.

METHODS

1355 patients with newly diagnosed smear-positive pulmonary tuberculosis were randomly assigned one of three regimens: daily ethambutol, isoniazid, rifampicin, and pyrazinamide for 2 months, followed by ethambutol and isoniazid for 6 months (2EHRZ/6HE); the same drugs but given three times weekly in the initial intensive phase (2[EHRZ]3/6HE); or the same initial intensive phase as the first regimen, followed by 4 months of daily rifampicin and isoniazid (2EHRZ/4HR). Follow-up was to 30 months after the start of chemotherapy. Sputum was regularly examined by microscopy and culture. Unfavourable outcome was defined as failure during treatment or relapse afterwards. Analyses were by intention to treat.

FINDINGS

At 2 months, a significantly higher proportion of patients assigned the daily intensive phase than of those assigned the three-times-weekly regimen were culture negative (700/828 [85%] vs 333/433 [77%], p=0.001). 12 months after the end of chemotherapy, the proportions of unfavourable outcomes were 36 of 346 (10%) with 2EHRZ/6HE, 48 of 351 (14%) with 2(EHRZ)3/6HE, and 17 of 347 (5%) with 2EHRZ/4HR. Both 8-month regimens were significantly inferior to the control 6-month standard regimen (difference between control and 2EHRZ/6HE 5.5% [95% CI 1.6 to 9.4]; between control and 2(EHRZ)3/6HE 8.8% [4.5 to 13.0]). Adverse effects leading to interruption of treatment for 7 days or longer occurred in 28 patients (12 2EHRZ/6HE, five 2[EHRZ]3/6HE, 11 2EHRZ/4HR).

INTERPRETATION

The results of this study must be taken into account in recommendations on management of new cases of smear-positive tuberculosis.

Measurement in epidemiology

Data (information) are the building blocks of epidemiological research. Careful measurement, recording and handling of information are crucial to the research process. The nature of the data required must be precisely defined and its collection requires the use of reliable tools or instruments. Standardisation of definitions and procedures used in measurement helps to ensure comparability. Care in undertaking measurements and rigorous training of personnel carrying out the measurements help to ensure precision. Special care is necessary to ensure completeness and accuracy in recording the data. Information may be obtained from routine or especially designed forms and evaluated by counting deaths or cases of disease or measures of dysfunction. Questionnaires are a frequently used instrument for collecting information. They should include data identifying the individual being studied, followed by specific questions concerning diseases and determinants. To be useful, such questionnaires must be carefully structured. Diseases are usually compared by calculating 'rates' or 'risks', consisting of numerators (cases, events) and denominators (population). Prevalence and incidence are standard measures of 'risk'. The collection of high quality information (data) and its use to construct estimates of 'risk' or risk ratios form the basis of epidemiology.

Choosing a research study design and selecting a population to study

Epidemiological studies have been standardised into a group of 'designs'. The descriptive study describes disease by time, place and person and can develop hypotheses about associations between disease and possible determinants. The analytic study tests these hypotheses. The cross-sectional study measures the disease and determinants at a single point in time. The cohort study identifies those within a group with or without a determinant, and observes the occurrence of disease in the two groups. The case-control study identifies a group of patients with a disease and selects a group of persons from the same population who do not have the disease, comparing the presence of a determinant in the two groups. The experimental study, a type of cohort study, is one in which the investigator 'assigns' the determinant (a treatment) to one subgroup in a population and compares the occurrence of a disease between those with and those without the determinant. All such studies must ensure that the comparisons made have relevance to a defined population. This is done by selecting a 'representative' sample from that population. Carefully selecting a study design and population facilitates the creation of new knowledge while avoiding, as far as possible, important errors.

Getting started in research: the research protocol

To be efficient and precise, research needs a 'road map', called the 'research protocol', which follows a standard format. It includes an abstract, study description, ethical considerations, significance of the study, the budget and a description of the investigators. Study description spells out the study question, the rationale for the study, including previous studies on the subject, the objectives, hypotheses and aims, design and methods, project management, strengths and limitations and a list of references. The objectives, hypotheses and aims are developed by outlining a general research topic (the objective), developing a hypothesis from the broad objective, translating it into the null hypothesis and then listing the steps by which the null hypothesis will be refuted or accepted (the aims). The design and methods describe the type of study to be undertaken, the population in which the study is carried out, including the sample size and statistical power, the selection of subjects, the methods of data collection, and outline of data management and statistical analysis. The detail of the protocol ensures that the study will be carried out successfully and is essential for all health research.

Research methods for promotion of lung health

The goal of health research is to develop new knowledge for action to improve health. Relevant health research includes study of diseases, their causes and their treatment/prevention as well as structure and utilisation of health services and policies to improve lung health. As resources are not infinite, priorities must be established. These are determined by the relative frequency of a condition, how much dysfunction or disability it produces and whether there are cost-effective means to deal with it. Epidemiology is the discipline used to address these issues. Using it, one can describe the distribution and relative importance of a condition (the descriptive study), identify determinants and define its natural history (the analytical study), assess methods of prevention, cure and amelioration (the experimental study) and evaluate the process and outcome of services (health services or operational research). Epidemiology addresses itself to determining causation among associated variables. Characteristics associated with causation include consistency, strength of association, specificity, dose response, temporal relationship, coherence, and experimental evidence. Epidemiology can truly be described as the 'basic science of public health.' When used strategically, it can create the new knowledge that is the cornerstone for improving the health of the whole population.

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.

Global elimination of tuberculosis: implementation, innovation, investigation

The elimination of a public health menace such as tuberculosis is always an attractive proposition. Is it realistic to consider? Selecting elimination as a target engages commitment, identifies challenges and stimulates critical evaluation. Challenges are numerous, including the large pool of latent infection, the long incubation period, the inadequacy of present tools and strategies, poverty and its relation to tuberculosis, the dependence on declining health services, the negative impact of human immunodeficiency virus infection, and the long-term commitment required with present approaches. Although tuberculosis has a tragic impact in causing death and chronic illness, the target for elimination must remain preventing infection, and the aim to achieve a generation free of infection. Targeting decreased mortality or improved health will not be sufficient to guide the critical reflection required to eliminate the causative organism; this can only be achieved by focusing on preventing and eliminating infection. While we have an international consensus on the strategy for controlling tuberculosis, we must also keep in mind that it is not sufficient. We must improve the current strategy as well as develop new tools on which we can base a new strategy if we hope to achieve the objective of elimination of tuberculosis. Reaching the target will require commitment to implementing what we currently have, improving on it in every way possible and keeping our minds and imaginations open to new ways to approach the fight against tuberculosis.

Risk factors for recent transmission ofMycobacterium tuberculosis

In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries. The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions. Strains from 861 culture-positive cases, diagnosed in Norway in 1994-1999, were analysed by use of restriction fragment length polymorphism (RFLP). A cluster was defined as two or more isolates with identical RFLP patterns. Risk factors for being part of a cluster were identified by univariate and multivariate analysis. A total of 134 patients were part of a cluster. These constituted 5% Asian-born, 18% Norwegian-born, 24% European-born and 29% African-born patients. Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain. Transmission of tuberculosis may be further reduced by improving case management, contact tracing, preventive treatment, screening of immigrants and access to health services for the foreign-born population.

Controlling tuberculosis:we can't do it if we don't find the cases

Thecurrent international strategy for the control of tuberculosis emphasizes two different targets: a high success rate for the treatment of tuberculosis cases with an emphasis on positive sputum smear cases and a high case detection rate. Recent analyses indicate that while progress is being made towards successful treatment, targets for case-finding are not being achieved.

Controlling tuberculosis: we can't do it if we don't find the cases

The current international strategy for the control of tuberculosis emphasizes two different targets: a high success rate for the treatment of tuberculosis cases with an emphasis on positive sputum smear cases and a high case detection rate. Recent analyses indicate that while progress is being made towards successful treatment, targets for case-finding are not being achieved.

Epidemiology of tuberculosis on Gran Canaria: a 4 year population study using traditional and molecular approaches

BACKGROUND

In recent years several population based studies using restriction fragment length polymorphism (RFLP) analysis have shown a higher rate of recent transmission of tuberculosis than previously thought. This study was undertaken to determine the transmission patterns of tuberculosis and the potential causes of recent transmission on the island of Gran Canaria (Spain).

METHODS

The strains of all patients diagnosed with tuberculosis confirmed by culture between 1 January 1993 and 31 December 1996 were typed by RFLP using the insertion sequence IS6110. A cluster was defined as two or more isolates with an identical RFLP pattern. Epidemiological linkage through contact tracing was investigated.

RESULTS

Of the total of 719 patients, 153 (21.3%) were excluded because there was inadequate bacterial DNA for genotyping (n=129) or the isolates of Mycobacterium tuberculosis had less than five copies of IS6110 (n=24). The isolates from 409 patients (72.3%) were grouped into 78 different clusters with an estimated 58.5% of the cases being due to recent transmission. Young age was the only significant predictor of clustering. Only in 147 (35.9%) of the 409 patients belonging to a cluster could an epidemiological link be found. 111 patients (19.6%) were identified as having had previous contact with a tuberculosis patient and 81 of them (72.9%) belonged to a cluster. The three largest clusters included 75, 49 and 20 patients, respectively.

CONCLUSION

Recent transmission is frequent among patients with tuberculosis on Gran Canaria and could be associated with certain aspects of control measures. Some of the clusters described in the study could be due to the prevalence of particular strains of M tuberculosis on the island.