Childhood infections and risk of wheezing and allergic sensitisation at age 7-8 years

Background: Childhood atopic disease has been associated with exposure to infections early in life. There is however considerable controversy on this issue, since evidence exists for both protective and adverse effects of infections. Aim of this study was to investigate the association between childhood infections and the occurrence of wheeze and allergic sensitisation in 7–8-year-old Dutch and German children. Methods: A nested case–control study was conducted among German and Dutch children participating in a large longitudinal study on respiratory health. Parents of 510 7–8-year-old children with respiratory complaints and an equal number of children without respiratory complaints were asked to complete a questionnaire. Blood samples were collected for specific serum Immunoglobulin E (IgE) analysis. Data on childhood infections were collected through records of the participating Municipal Health Services. Results: No association was found between recent wheeze and any of the childhood infections investigated. For scarlet fever infection an increased risk of allergic sensitisation (OR: 2.82; 95% CI: 1.40–5.72) and sensitisation against grasses (OR: 3.00; 95% CI: 1.35–6.69) at the age of 7–8 years was found. Varicella infection tended towards increased risk of sensitisation against grasses (OR: 1.88; 95% CI: 0.99–3.58). For allergic sensitisation and sensitisation against grasses the odds ratios increased with increasing number of infections. Conclusions: The results do not lend support to the suggestion that childhood infection protects against wheezing or allergic sensitisation at age 7–8 years. Scarlet fever or varicella infection presented an increased risk of allergic sensitisation.