Mouse allergy

What it is

Mouse allergen is a set of proteins that mice shed into their surroundings. Like rabbits, hamsters and guinea pigs, mice produce allergens in their urine.¹ The main mouse allergens are known as Mus m 1 and mouse urinary protein.² The EPA counts rodents among the warm-blooded animals that can trigger asthma in people allergic to animal dander, through proteins in skin flakes, urine, droppings, saliva and hair.⁴

An AAAAI work group that reviewed research on pest allergens and inner-city asthma found mouse allergen in both homes and schools, with very high detection rates in some studies.²

Symptoms it causes

Mouse allergen causes symptoms mainly when it is breathed in. Among people who work with animals such as mice, mild reactions can include sneezing and a runny nose. More serious reactions can bring asthma symptoms such as cough, chest tightness, wheezing and shortness of breath.⁵

For children with asthma, mouse allergen is linked with worse asthma. In an inner-city Baltimore study, children who were allergic to mice and had high mouse allergen levels at home were more likely to have unscheduled doctor visits, emergency department visits and hospital stays.² In a study of 284 students with asthma at 37 inner-city elementary schools in the northeastern US, mouse allergen at school was linked with more days with asthma symptoms and lower lung function. Cat and dog allergen at school showed no such link.³

Mice in laboratories cause allergy too. NIOSH reports that about a third of animal handlers have allergy symptoms and about 10% have symptoms of asthma caused by animals, and that rats, mice and rabbits are often linked with asthma that develops at work.⁵

Where it’s found

Mouse allergen is widespread in city homes. In the National Cooperative Inner-City Asthma Study, it was found in at least one room of 95% of homes, with the highest levels in kitchens.² In Baltimore, it could be detected in the bedroom air of 84% of children with asthma.²

Schools can carry even more. In the northeastern schools study, mouse allergen turned up in 441 of 443 school dust samples, and levels were higher at school than in the students’ homes.³

The CDC says the best way to prevent rodents is to remove the food, water and shelter that draw them in, and to seal holes around the home.⁶ Its specific steps include:

• Check for gaps under and behind kitchen cabinets, around pipes under sinks, and around windows and doors. Mice can fit through a hole the width of a pencil.⁷
• Fill small holes with steel wool held in place with caulk or spray foam.⁷
• Store food in thick plastic, metal or glass containers with tight lids, and clean up spilled food promptly.⁷
• Do not leave pet food or water out overnight, and keep indoor trash in containers with tight lids.⁷

For pet rodents, the AAAAI suggests asking a family member without allergies to clean the cage.¹ In a small Boston study, combining hole-filling with copper mesh, vacuuming, cleaning and baited traps cut mouse allergen in kitchens and bedrooms by more than 75%.²