Asthma and rhinitis symptoms in individuals from different socioeconomic levels in a Brazilian city.

Allergy is considered to be caused by complex interactions between genetic and environmental factors. Socioeconomic status (SES) may be the most important environmental determinant of allergy because it determines the living environment, but few studies have addressed the causal role of SES in allergy. The aim of this study was to compare the prevalence of asthma and rhinitis symptoms in two SES groups in a Brazilian city. History of asthma and rhinitis symptoms was collected using the International Study of Asthma and Allergies in Childhood questionnaire. SES was determined by the Gallup method. Sera from subgroups of the individuals were used to determine total, anti-Dermatophagoides pteronyssinus and anti-Blomia tropicalis IgE. The prevalence of asthma and rhinitis symptoms was higher in the A and B (A&B) SES group than in the C, D, and E (C, D&E) SES group. Individuals with asthma and/or rhinitis were more frequently positive for anti-B. tropicalis and anti-D. pteronyssinus IgE than individuals without these symptoms. A positive association between total IgE levels and asthma and rhinitis symptoms was observed in the A&B SES group but not in the C, D&E SES group. Women reported more respiratory symptoms than men. These results revealed higher prevalence rates ofasthma and rhinitis symptoms in individuals with higher SES and may provide support for the hygiene hypothesis, which attributes the high prevalence of respiratory allergies observed in individuals from developed countries to a low exposure to pathogens. The observed higher prevalence of asthma and rhinitis symptoms in women than in men could be attributed to differences in the perception of these symptoms or in exposures to allergens and protective pathogens.