The prevalence of rat allergen in inner-city homes and its relationship to sensitization and asthma morbidity

Background: Rat allergen has proved to be an important cause of IgE-mediated hypersensitivity in the occupational setting. The prevalence and significance of rat allergen in homes has not been studied. Objective: The purpose of this study was to determine the prevalence of rat allergen in the homes of inner-city children with asthma and to examine the relationship between rat allergen exposure, sensitization, and asthma morbidity. Methods: We developed a new monoclonal-based ELISA to determine the prevalence of rat allergen in dust samples from inner-city homes of the National Cooperative Inner-City Asthma Study population. Home characteristics were evaluated to detect variables that were associated with the presence of rat allergen. Data were also analyzed to assess the relationship between the presence of rat allergen, sensitization, and asthma morbidity. Results: Thirty-three percent of inner-city homes had detectable rat allergen (Rat n 1). The presence of rat allergen was associated with reported rat and mouse infestation, as well as evidence of mouse infestation on home inspection. Twenty-one percent of the participants were sensitized to rat allergen; however, sensitization was not more common when rat allergen was found in the home. The number of hospitalizations, unscheduled medical visits, and days with slowed activity because of asthma were significantly increased in those individuals who were both sensitized and exposed to rat allergen. Conclusions: Rat allergen sensitization and exposure are associated with increased asthma morbidity in inner-city children.