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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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Background The Global Asthma Network (GAN), by using the International Study of Asthma and Allergies in Childhood (ISAAC) methodology, has updated trends in prevalence of symptoms of childhood allergic diseases, including non‐infective rhinitis and conjunctivitis (‘rhinoconjunctivitis’), which is reported here. Methods Prevalence and severity of rhinoconjunctivitis were assessed by questionnaire among schoolchildren in GAN Phase I and ISAAC Phase I and III surveys 15–23 years apart. Absolute rates of change in prevalence were estimated for each centre and modelled by multi‐level linear regression to compare trends by age group, time period and per capita national income. Results Twenty‐seven GAN centres in 14 countries surveyed 74,361 13‐ to 14‐year‐olds (‘adolescents’) and 45,434 6‐ to 7‐year‐olds (‘children’), with average response proportions of 90% and 79%, respectively. Many centres showed highly significant (p < .001) changes in prevalence of rhinoconjunctivitis in the past year (‘current rhinoconjunctivitis’) compared with ISAAC. The direction and magnitude of centre‐level trends varied significantly (p < .001) both within and between countries. Overall, current rhinoconjunctivitis prevalence decreased slightly from ISAAC Phase III to GAN: −1.32% per 10 years, 95% CI [−2.93%, +0.30%] among adolescents; and −0.44% [−1.29%, +0.42%] among children. Together, these differed significantly (p < .001) from the upward trend within ISAAC. Among adolescents, centre‐level trends in current rhinoconjunctivitis were highly correlated with those for eczema symptoms (rho = 0.72, p < .0001) but not with centre‐level trends in asthma symptoms (rho = 0.15, p = .48). Among children, these correlations were positive but not significant. Conclusion Symptoms of non‐infective rhinoconjunctivitis among schoolchildren may no longer be on the increase globally, although trends vary substantially within and between countries.

Sixty-two infants 1-12 months of age were administered five doses of trivalent oral polio vaccine (TOPV) at intervals of 4 weeks. The seroconversion achieved were 88.7, 93.5 and 96.5 per cent for type I, II, and III polioviruses. These seroconversion rates are significantly better when compared to seroconversion achieved after two and three doses of trivalent oral polio vaccine. Factors which were considered in previous studies to be responsible for low seroconversion rates viz. interference by enteroviruses, breast feeding, malnutrition, and age were found to be insignificant when five doses of oral polio vaccine were given. It is possible that these effects were overcome by increasing the number of doses of trivalent oral polio vaccine.