Background: The domestic cockroach has been identified as an important source of indoor aeroallergens worldwide in both temperate and tropical climates. Because cockroach populations are highest in crowded urban areas, some have suggested that the increased asthma morbidity and mortality rates in inner cities could be related in part to cockroach allergen exposure. We have examined cockroach allergen exposure in the homes of children with asthma in both urban and suburban locations and have related the rates of exposure and sensitization to socioeconomic, racial, and demographic factors.
Objective: The study was designed to determine the independent contribution of race, socioeconomic status, and place of residence to the risk of cockroach allergen exposure and sensitization in children with asthma.
Methods: Eighty-seven children with moderate to severe allergic asthma, aged 5 to 17 years, participating in a prospective trial of immunotherapy, were evaluated. Extracted dust samples from three home locations were analyzed by using two-site monoclonal immunoassays for major cockroach allergens (Bla g 1 and Bla g 2). A puncture skin test with a mixed cockroach allergen extract was performed in 81 of the 87 subjects.
Results: In the 87 homes evaluated, 26% of the bedroom dust samples had detectable levels of cockroach allergen. In homes with detectable bedroom cockroach allergen levels, mean Bla g 1 and Bla g 2 concentrations in urban and suburban homes were similar. Over 80% of children with bedroom Bla g 1 or Bla g 2 of 1 U/gm or greater demonstrated skin sensitivity to cockroach allergen. The rate of cockroach sensitization was directly related to the level of bedroom exposure. African-American race was the only factor that was independently associated with cockroach allergen exposure (p = 0.05). Lower socioeconomic status, age greater than 11 years, cockroach exposure, and African-American race were all independently associated with cockroach allergen sensitization on the basis of stepwise multiple linear regression analysis.
Conclusions: African-American race and low socioeconomic status were both independent, significant risk factors for cockroach allergen sensitization in children with atopic asthma. Cockroach allergen is detectable throughout the house, including the critical bedroom environment.