The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One showed large worldwide variations in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema, up to 10 to 20 fold between countries. Ecological analyses were undertaken with ISAAC Phase One data to explore factors that may have contributed to these variations, and are summarised and reviewed here.In ISAAC Phase One the prevalence of symptoms in the past 12 months of asthma, rhinoconjunctivitis and eczema were estimated from studies in 463,801 children aged 13 - 14 years in 155 centres in 56 countries, and in 257,800 children aged 6-7 years in 91 centres in 38 countries. Ecological analyses were undertaken between symptom prevalence and the following: Gross National Product per capita (GNP), food intake, immunisation rates, tuberculosis notifications, climatic factors, tobacco consumption, pollen, antibiotic sales, paracetamol sales, and outdoor air pollution.Symptom prevalence of all three conditions was positively associated with GNP, trans fatty acids, paracetamol, and women smoking, and inversely associated with food of plant origin, pollen, immunisations, tuberculosis notifications, air pollution, and men smoking. The magnitude of these associations was small, but consistent in direction between conditions. There were mixed associations of climate and antibiotic sales with symptom prevalence.The potential causality of these associations warrant further investigation. Factors which prevent the development of these conditions, or where there is an absence of a positive correlation at a population level may be as important from the policy viewpoint as a focus on the positive risk factors. Interventions based on small associations may have the potential for a large public health benefit.

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Abstract.Objective : Bronchiectasis not due to cystic fibrosis is usually a consequence of severe bacterial or tuberculous infection of the lungs, which is commonly seen in children in developing countries. Our aim was to study its functional sequelae and affect on work capacity in children. Methods : Seventeen children (7-17 years of age) with clinical and radiological evidence of bronchiectasis of one or both lungs were studied at the Cardiopulmonaly Unit of the Tuberculosis Research Centre. Pulmonary function tests including spirometry and lung volume measurements were performed. Incremental exercise stress test was done on a treadmill, and ventilatory and cardiac parameters we monitored. Control values were taken from a previous study. Results : Children with bronchiectasis had lower forced vital capacity (FVC) (1.1 + 0.4 L versus 1.5 + 0.4 L, p=0.003) and FEV1 (0.95 ± 0.2 L versus 1.4 ± 0.3 L, p<0.002) compared to age-and sex-matched healthy controls. The patient group had significantly higher residual lung volumes (0.7 ± 0.3 L versus 0.4 + 0.1 L, p<0.02). At maximal exercise, they had lower aerobic capacity (28 ± 6 ml/min/kg versus 38 5 ml/min/kg, p<0.0001) and maximal ventilation (24 ± 8 L/min versus 39 ± 10 L/min, p<0.001). At maximal exercise, while none of the controls desaturated, oxygen saturation fell below 88% in eight of 17 patients. conclusion ;The findings show that children and adolescents with non-cystic fibrosis bronchiectasis have abnormal pulmonary function and reduced exercise capacity. This is likely to interfere with their lie as well as future work capacity. Efforts should be made to minimize lung damage in childhood by ensuring early diagnosis and instituting appropriate treatment of respiratory infections.

Bronchoalveolar lavage is a relatively new technique that is used to study the local cellular, biochemical and immunological changes occurring in the lower respiratory tract. The procedure involves instilling a fixed volume of saline into a lung segment after the flexible fibreoptic bronchoscope is wedged into a distal bronchus. The saline is aspirated back and can be used for microbiological and other studies. Recently, attempts have been made to standardise the procedure in children and obtain data on BAL cellular profile in healthy children. The main indications for BAL are diagnostic, particularly to diagnose unusual infections in immunocompromised children. It is also helpful in the diagnosis of a number on non infectious conditions, based on the cellular profile and other constituents. With the availability of new techniques like flow cytometry, analysis of lymphocyte and other cell subsets has become possible leading to a better understanding of the immunopathogenesis of various respiratory diseases.

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