Notes: Background As part of a primary prevention of asthma study, we measured the effect of environmental control measures on Der p 1, Fel d 1 and Can f 1 over a 3.5-year period.Methods High-risk infants (both parents atopic) without pets, were randomized to the Active group (n = 142, vinyl flooring in child's room, allergen-impermeable cot mattress, hot-washable toy, mite allergen-impermeable encasings to parental bed and to child's bed when older, high filtration vacuum cleaner, hot-washing of bedding) or the Control group (n = 136, no intervention), in early pregnancy. Dust samples from the parental mattress, living room floor, child's mattress and floor at baseline (pregnancy), birth and at 3 years were analysed for Der p 1, Fel d 1 and Can f 1.Results A total of 278 families completed the baseline visit, 259 the birth visit and 239 the 3-year visit. In the Active group at 3 years, 58% remained compliant with all measures likely to reduce the child's exposure to allergen and 77% of parents still used encasings on their bed. Levels of Der p 1, Fel d 1 and Can f 1 were significantly lower in the Active group in the child's floor and the child's mattress at 3 years compared to the Control group (P 〈 0.001). For the parental mattress, the levels of Der p 1 and Fel d 1 were lower in the Active group (P 〈 0.001) and there was a strong trend towards a lower level for Can f 1. There was no difference in the levels of any of the allergens between the groups in the living room floor. Childrens' bedrooms with no detectable mite, cat or dog allergen were significantly more common in the Active than the Control group (25 vs. 2, P 〈 0.001).Conclusions Environmental control measures are effective in substantially reducing levels of Der p 1, Fel d 1 and Can f 1 in homes without pets in the long term and are acceptable to families. The effect of this environmental manipulation on the development of sensitization and allergic disease remains to be seen.

Notes: Background Mite allergen levels vary enormously between different homes in the same geographical area. No large scale studies of mite levels in Manchester homes has been conducted to identify factors associated with higher levels.Objectives To quantify exposure to mite allergens and to identify characteristics associated with higher Der p 1 levels in a large sample of homes in Manchester, UK.Methods Der p 1 was measured in dust from the living room floor, sofa, bedroom floor and mattress in 564 homes. Data on household characteristics were collected by administering a questionnaire. Univariate and multivariate analyses were performed to identify household characteristics associated with higher mite allergen levels.Results Der p 1 levels were highest in the mattress (GM 1.19 µg/g, 95% CI 0.98–1.45, P 〈 0.001). Two-thirds of homes contained Der p 1 levels 〉 2 µg/g in at least one dust reservoir, and 40.3% contained Der p 1 greater than 10 µg/g. There was a large range in Der p 1 levels between homes (〉 103-fold). Damp and condensation were common findings in homes. In the multivariate analyses, factors associated with higher Der p 1 levels in more than one dust reservoir were older homes, older living room carpets, damp, condensation and mixed glazing. Older mattresses were associated with higher mite allergen levels in the mattress where the age of the mattress was recorded. Twenty-four homes contained no detectable mite allergen, six of which reported damp.Conclusions Mite allergen levels are high enough in two of every three homes to be associated with an increase in the risk of sensitization to mite. Factors such as older homes, carpets and mattresses, damp and condensation are associated with higher mite allergen. However, mite allergen levels are occasionally unpredictably very low in homes with risk factors for high levels.

Notes: Asthma and atopic disorders are the most common chronic diseases in the developed countries. Knowledge of the risk factors for these disorders may facilitate the development of preventive strategies aimed at reducing prevalence rates.To investigate the risk factors for asthma and allergic diseases in a large number of adults who are the parents of children in the National Asthma Campaign Manchester Asthma and Allergy Study.All pregnant women and their partners attending ‘Booking’ antenatal clinics were invited to take part in the study. Questionnaire data were collected including the history of asthma and other atopic diseases, pet ownership and smoking habits, and skin prick tests were performed. The prevalence of atopy and the risk factors for asthma and allergic disorders were investigated in all subjects who completed the questionnaire and underwent skin testing. Statistical analysis was carried out using logistic regression. Initially, risk factors were assessed by univariate analysis to see how each potential explanatory variable affected the probability of having allergic disease. Variables were then tested in a forward stepwise multivariate analysis.In 5687 adult subjects there was a very high (48.2%) prevalence of atopy, and 9.7% of subjects had a diagnosis of asthma. In a multivariate regression analysis sensitization to dust mite, cat, dog and mixed grasses were all independently associated with asthma. The odds ratios for current asthma increased with the increasing number of positive skin tests (any two allergens – OR 4.3, 95% CI 3.3–5.5; any three allergens – OR 7.0 95% CI 5.3–9.3; all four allergens – OR 10.4, 95% CI 7.7–14; P 〈 0.00001). Dog ownership (OR 1.31, 95% CI 1.10–1.57; P = 0.003) and current smoking (OR 1.36, 95% CI 1.15–1.62; P = 0.0004) were significantly and directly associated with ’asthma ever’. Thirteen per cent of participants reported a history of eczema. In the multivariate analysis the strongest independent associate of eczema was sensitization to dog (OR 1.37, 95% CI 1.14–1.63, P 〈 0.0001). Apart from dog, the strength of the association between sensitization to common allergens and eczema appeared to be much lower than in the case of asthma. The prevalence of hay fever was high (20.6%), and in the multivariate analysis the association between sensitization to pollen and hay fever was extremely strong (OR 13.6, 95% CI 11.3–16.3; P 〈 0.0001).The results of the current study emphasize the importance of sensitization to indoor allergens in asthma. However, evidence of a possible direct role of allergen exposure in asthma causation remains unclear.