Exposure to Mouse Allergen in U.S. Homes Associated with Asthma Symptoms

BACKGROUND Most studies investigating the role of residential mouse allergen exposures in asthma have focused on inner-city populations. OBJECTIVE We examined whether elevated mouse allergen levels were associated with occupants' asthma status in a nationally representative sample of U.S. households. METHODS Data for this study were collected as part of the National Survey of Lead and Allergens in Housing. This cross-sectional study surveyed 831 housing units inhabited by 2,456 individuals in 75 different locations throughout the United States. The survey obtained information on demographics, household characteristics, and occupants' health status by questionnaire and environmental observations. We used a polyclonal immunoassay to assess concentrations of mouse urinary protein (MUP) in vacuumed dust collected from various indoor sites. RESULTS Of the surveyed homes, 82% had detectable levels of MUP, and in 35% of the homes, MUP concentrations exceeded 1.6 microg/g, a level that has been associated with increased mouse allergen sensitization rates. Current asthma, defined as having doctor-diagnosed asthma and asthma symptoms in the preceding 12 months, was positively associated with increased MUP levels. The observed association was modified by atopic status; in allergic individuals, elevated MUP levels (>1.6 microg/g) increased the odds of having asthma symptoms [adjusted OR=1.93; 95% confidence interval (CI), 1.14-3.27], but we found no association in those who did not report allergies (adjusted OR=0.69; 95% CI, 0.33-1.44). CONCLUSIONS In allergic asthma, residential mouse allergen exposure is an important risk factor for asthma morbidity.