Exposure to mouse allergen in U.S. homes associated with asthma symptoms

Abstract

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.

Keywords: allergy; asthma; exposure; indoor; mouse allergen.

Figure 1

Adjusted ORs and 95% CIs for the association between current asthma and MUP concentration in the household (continuous variable, logistic regression). The house index (mean of site-specific concentrations) and site-specific ORs correspond to a 2-fold increase in MUP concentration adjusting for age, sex, race, education, smoking, and survey season. The ORs for atopic (A) and nonatopic (B) individuals are presented separately (in parentheses) because the observed association was modified by atopic status.

Figure 2

Smoothed plots showing adjusted prevalence of current asthma by MUP concentration for the house index and each sampling location. The estimated prevalence is adjusted for age, sex, race, education, smoking, and survey season.