Association between endotoxin and mite allergen exposure with asthma and specific sensitization at age 7 in high-risk children.

The role of endotoxin and house dust mite allergen (HDM) in allergen sensitization and asthma is unclear. The timeframe of exposure and asthma assessment appears critical. We aimed to determine, in children at 7 yr of age, the association between current exposure to endotoxin and HDM and risks of recurrent wheeze, paediatric allergist diagnosed asthma and allergen sensitization. Three hundred and eighty children who had an increased risk of asthma because of family background were assessed at age 7 yr by a questionnaire-standardized interview, allergen skin testing and clinical examination by a paediatric allergist. Dust samples were collected from their homes and analysed for levels of endotoxin and HDM (Der p 1 and Der f 1). Levels of endotoxin in dust samples were associated with protection from paediatric allergist diagnosed asthma with inhaled steroid use (OR 0.69, 95% CI 0.53-0.91) and specific sensitization to dog allergen (OR 0.68, 95% CI 0.51-0.90) at the age of 7 yr; both endotoxin and HDM were associated with decreased risk of sensitization to dog allergen. In high-risk children at age 7, endotoxin levels were associated with decreased sensitization to dog, as well as with decreased asthma.