Levels of airborne mouse allergen in inner-city homes are often comparable to those seen in animal facilities, new research shows. “We were somewhat surprised at how many homes had detectable levels of airborne mouse allergen,” lead author Dr. Elizabeth C. Matsui noted. In many cases, the allergen had reached levels that would likely trigger asthma symptoms in sensitized individuals.

The study is the first to look at levels of airborne mouse allergen in inner-city homes and to correlate those levels with dust levels of the allergen, Matsui, from Johns Hopkins Hospital in Baltimore, told AMN Health.

The findings, which appear in the Journal of Allergy and Clinical Immunology, are based on allergen skin testing and home inspections for 100 inner-city children with asthma.

Dust samples from all bedrooms tested positive for mouse allergen, and 84 percent of bedrooms also had detectable airborne levels of mouse allergen.

Approximately one quarter of homes had airborne mouse allergen levels that were greater than 0.1 nanograms per cubic meter, which is in the range of levels found in animal facilities and may trigger asthma symptoms.

Factors associated with the presence of detectable airborne mouse allergen included cracks in doors or walls, food remains in the kitchen, and obvious mouse infestation.

“The message for clinicians is to test for allergic sensitization to mice in kids with asthma, especially those living in the inner city,” Matsui said.

For households with mouse-allergic children and evidence of infestation, extermination is indicated, Matsui said. However, she added, “no large-scale studies have determined if extermination is effective in the long run.”

Matsui said her team plans to further study this group of children to see if airborne mouse allergen levels correlate with asthma episodes and to determine if extermination and other measures are effective in decreasing asthma.

SOURCE: Journal of Allergy and Clinical Immunology, February 2005.