HOUSE-DUST MITE ALLERGEN (DER-P-I) AND RESPIRATORY SYMPTOMS IN CHILDREN - A CASE-CONTROL STUDY

The association between house dust mite allergen in house dust and chi ldhood respiratory symptoms was investigated in a case-control study o f 259 children with reported chronic respiratory symptoms and 257 cont rol children without reported respiratory symptoms. The Der p I concen tration in floor dust of the living room and bedroom and in mattress d ust was determined using an enzyme immunoassay. Venous blood samples w ere taken from all children for serum IgE determination against house dust mite (Dermatophagoides pteronyssinus) by radioallergosorbent assa y (RAST). A questionnaire was administered to the parents of the child ren to elicit information about the home, about changes made to the ho me in the past in relation to respiratory symptoms, and about a number of risk factors for childhood respiratory disease. In 83% of the dwel lings of cases and 89% of those of controls, Der p I concentrations hi gher than 2000 ng/g were found, and in 54% of the dwellings of cases a nd 57% of those of controls, the concentrations exceeded 10 000 ng/g d ust. In a crude analysis, cases were generally exposed to lower Der p I concentrations than controls. Restriction of the analysis to cases s ensitized to dust mites, and non-sensitized controls, taking the type of floor covering into account, showed not significantly higher Der p I concentrations in bedroom floor dust of cases. However, restriction of the analysis to cases sensitizied to dust mites and cases not sensi tized to house dust mites - adjusting for allergen avoidance measures taken in the past - revealed a positive association between the Derp I concentrations in bedroom floor dust and mattress dust and sensitizat ion. This finding indicates that allergen avoidance measures modify cu rrent exposure to Der p I. This obscures the relationship between the exposure to mite allergens and sensitization, and hampers the estimati on of the association between exposure to house dust mite allergens, s ensitization and the development of respiratory symptoms.