The results of a new study suggest there is an association between exposure to mouse allergen in the home and asthma in "mouse-sensitized" inner-city children.

Inner-city children with asthma, particularly those of African American race, continue to suffer disproportionately from asthma-related illness and death. Although some cases of asthma have been attributed to environmental factors, such as cockroach allergen and tobacco smoke, other environmental factors that are just beginning to be examined may involved.

Dr. Elizabeth C. Matsui and colleagues from Johns Hopkins University, Baltimore, Maryland, examined whether household mouse allergen exposure is a risk factor for asthma illness in 127 largely African American asthmatic preschool-age children from inner-city Baltimore.

They assessed symptoms, medication use, and health care use at baseline, 3 months, and 6 months. Dust samples were collected from the children's homes for analysis of mouse allergen. Outcomes of mouse-sensitized, highly exposed children were compared to other children.

Of the 127 children, 22 were not sensitized to mouse allergen and had lower exposure to rodents; 72 were not sensitized but had high exposure levels; 8 were sensitized and had low exposure levels; and 25 were sensitized and had high exposure levels.

According to the team, the 25 mouse-sensitized, highly exposed children suffered significantly more days with asthma symptoms, days of slowed activity as a result of asthma, days of exercise-induced symptoms, and days of asthma inhaler use, than the other children.

Moreover, mouse-sensitized/highly exposed children were three times more likely to have an unscheduled physician visit, two times more likely to visit the emergency department, and 36 times more likely to be admitted to the hospital than were the other children. These associations remained significant after adjusting for potential confounders, including allergy and cockroach sensitization and exposure.

These findings provide "compelling evidence that household mouse allergen exposure and asthma morbidity are related and underscore the potential impact of mouse allergen exposure on asthma morbidity among inner-city children," they conclude.

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