Factors influencing the clinical picture and the differential sensitization to house dust mites and storage mites.

Sensitization to house dust mites and storage mites has been studied in a number of papers, but several environmental factors and clinical conditions that differently affect sensitization to these mites are still controversial. The purpose of this study was to determine the influence of climatic conditions, occupation and patient age in the differential sensitization to house dust and storage mites, and also to search for possible different symptoms caused by each group of mites. Eighty patients sensitized to mites but not to other inhalant allergens were studied by case history and by skin prick test and serum IgE to Dermatophagoides pteronyssinus. Dermatophagoides farinae, Lepidoglyphus destructor and Tyrophagus putrescentiae. Home conditions, including content of the allergens Der p 1, Der f 1, Lep d 2 and Tp, were determined for all patients. Human activities, such as farming or similar occupations, and humidity are conditions for preferential sensitization to storage mites, while we found no difference between living in rural or urban areas. Mean age for the onset of sensitization was 6.7 years for house dust mites and 18.7 years for storage mites. Conjunctivitis was more frequent in patients allergic to storage mites, whereas perioral syndrome (itching of the tongue and swelling of the lips) was only seen in patients sensitized to T. putrescentiae. We concluded that climatic and damp conditions and human activity, but not urban or rural living environments, influence the differential sensitization to house dust mites and storage mites.