ISAAC questionnaire-derived symptom prevalences are sufficiently precise for comparisons between populations. Where diagnostic precision at the individual level is important, questionnaires should be validated and potentially modified in those populations beforehand, or a standardized skin examination protocol should be used.

SummaryBackground Several studies have consistently reported inverse associations between exposure to endotoxin in house dust and atopy. With regard to the association between house dust endotoxin and asthma, the results are inconsistent. Objectives To study the association between house dust endotoxin levels and respiratory symptoms and atopy in populations from largely different countries. Methods Data were collected within the International Study on Asthma and Allergies in Childhood Phase Two, a multi-centre cross-sectional study of 840 children aged 9-12 years from six centres in the five countries of Albania, Italy, New Zealand, Sweden and the United Kingdom. Living room floor dust was collected and analysed for endotoxin. Health end-points and demographics were assessed by standardized questionnaires. Atopy was assessed by measurements of allergen-specific IgE against a panel of inhalant allergens. Associations between house dust endotoxin and health outcomes were analysed by logistic regression. Odds ratios (ORs) were presented for an overall interquartile range increase in exposure. Results Many associations between house dust endotoxin in living room floor dust and health outcomes varied between countries. Combined across countries, endotoxin levels were inversely associated with asthma ever [adjusted OR (95% confidence interval (CI)) 0.53 (0.29-0.96) for endotoxin levels per m 2 of living room floor] and current wheeze [adjusted OR (95% CI) 0.77 (0.64-0.93) for endotoxin levels per gram of living room floor dust]. There were inverse associations between endotoxin concentrations and atopy, which were statistically significant in unadjusted analyses, but not after adjustment for gender, parental allergies, cat and house dust mite allergens. No associations were found with dust quantity and between endotoxin exposure and hayfever. Conclusion These findings suggest an inverse association between endotoxin levels in living room floor dust and asthma in children.

Despite the biological plausibility of IgE-related mechanisms in asthma, very few of the tested candidates showed evidence of association with both wheeze and increased IgE levels. We were unable to confirm associations of the positional candidates DPP10 and PHF11 with wheeze, although our study had ample power to detect the expected associations of IL13 variants with IgE and SPINK5 variants with eczema.

Previous studies have suggested that asthma prevalence is generally lower in the Middle East than in more developed countries. The aim of this study was to investigate the prevalence and severity of asthma and asthma symptoms in schoolchildren in the Ramallah District in Palestine.In the autumn of 2000, 3,382 schoolchildren aged 6-12 yrs were surveyed in 12 schools, using the International Study for Asthma and Allergies in Childhood (ISAAC)-phase III, parents-administered translated questionnaire.The crude prevalence rates for "wheezing-ever", "wheezing in the previous 12 months", and "physician-diagnosed asthma" were 17.1, 8.8 and 9.4% respectively, with urban areas having higher prevalence rates than rural areas. Within urban areas, refugee camps had higher prevalence rates than cities. Yet, within the rural areas, the 12-month prevalence was lower in the deprived villages than other residences. Place of residence remained significant for asthma and asthma symptoms, after adjusting for sex, age, and place of birth.To conclude, children from refugee camps appear to be at higher risk of asthma than children from neighbouring villages or cities. The prevalence of asthma and asthma symptoms in Palestine appears to be close to that of Jordan, but it is much lower than Israel, and lower than some other countries in the region, such as Kuwait and Saudi Arabia, and more developed countries. This initial study is a baseline for a study on lifestyle and environmental determinants for asthma among Palestinian children.

Our study confirmed that familial 'atopic' diseases are significant predictors of childhood asthma in Palestinian children. Moreover, indoor environment such as presence of cats and domestic moulds also appear to play a role. Our findings are consistent with studies in Canada, New Zealand, Estonia and Sweden, and show promise to explore further gene-environment interaction in the genesis of asthma.