Levels of house-dust-mite allergen in homes of nonallergic people in Pavia, Italy

Background: HDM distribution varies between geographic areas and may be affected by housing characteristics. We quantified Der p 1 and Der f 1 and assessed the relationships between their levels and housing characteristics in homes of nonallergic subjects. Methods: Der f 1 and Der p 1 were measured by ELISA in dust samples from living-room floors and mattresses of 44 homes of nonallergic subjects in Pavia. Information about household characteristics was obtained by questionnaire. Results: Der p 1 and Der f 1 concentrations (μg/g dust, median) were 0.34 and 7.8 on mattresses, and 0.15 and 0.83 on living-room floors. Higher Der f 1 levels on mattresses were associated with synthetic pillows (P<0.05), and (only when expressed as μg/m2) with bedding washing temperature of ≤60°C (P<0.05). Der f 1 levels were higher on the living-room floors of homes located on lower (≤first) floors (P<0.05). Good correlations were found between Der p 1 and Der f 1 expressed as μg/g dust and μg/m2 on both mattresses and living-room floors. Conclusions: In homes of nonallergic subjects in northern Italy, Der f 1 exceeded the threshold for sensitization in a high proportion of mattress samples.