PURPOSE OF THE STUDY.
The goal of this study was to evaluate relationships between exposure to mouse and other perennial allergens and clinical markers of asthma.
A total of 150 Baltimore children (ages 5–17 years) with persistent asthma were followed up for 1 year.
Allergy skin testing was performed to dust mites, mouse, cockroach, cat, dog, and other perennial allergens. Serum-specific IgE levels to those allergens were also measured. Sensitization was defined as a skin test wheal ≥3 mm in diameter more than the negative control subjects. Spirometry with bronchodilator reversibility (≥12% reversibility in forced expiratory volume in 1 second [FEV1] after 2 puffs of albuterol) and fraction of exhaled nitric oxide (FENO) was performed at baseline and every 3 months thereafter. Health care use, asthma symptoms, and mediation use were assessed by using a questionnaire. Levels of major allergens from mouse (Mus m 1), cockroach (Bla g 1), dust mite (Der f 1), cat (Fel d 1), and dog (Can f 1) were measured in dust samples collected from beds and bedroom floors. Exposure was defined as an allergen level greater than thresholds previously determined to be clinically relevant.
The population was predominantly African American, low income, and poorly educated. The most common sensitizations were to cat (64%), cockroach (60%), dust mite (56%), and mouse (51%). The population was divided into those sensitized and exposed to each allergen or not sensitized and not exposed. Twenty-six percent were sensitized and exposed to mouse, 17% to cockroach, 14% to cat, and 9% to dust mite. When sensitization and bed dust exposure were compared with asthma health outcomes, mouse emerged as the most relevant allergen. Statistically significant relationships were identified for acute care visits, FEV1/forced vital capacity (FVC) ratio, and bronchodilator reversibility. No other allergens were associated with such relationships. When bedroom dust was analyzed, mouse exposure was significantly associated with acute care visits, FEV1/FVC ratio, FENO, and bronchodilator reversibility. Cockroach exposure was also significantly related to need for acute care visits. Elevated serum-specific IgE level to mouse but not to cockroach or other allergens was also associated with acute care for asthma visits, FEV1/FVC ratio, FENO, and bronchodilator reversibility. The clinical relationships identified for mouse sensitization/exposure were independent of concurrent sensitization or exposure to other allergens.
In a community with high levels of mouse and cockroach allergens, mouse allergen sensitization and exposure are more strongly associated with poor asthma outcomes than cockroach sensitization and exposure.
Previous inner-city asthma research has focused on cockroach exposure. The present study highlights the important role of another common inner-city pest, the mouse. The implications of this study are not isolated to Baltimore schoolchildren. Mouse has also emerged as a prominent allergen in Boston, and there is no reason to think the same would not be true in other cities. One tricky question is: “What do we do about it?” Decreasing exposure to perennial allergens can be difficult and/or expensive. I look forward to prospective intervention studies to help answer that question. Whatever the solution, I suspect its implementation will require the cooperation of landlords, tenants, and government officials.
- Copyright © 2014 by the American Academy of Pediatrics