Exposure to mice increase risk of wheeze in kids

NEW YORK (Reuters Health) - Children whose parents have asthma or allergies and who are exposed to mice, or to the allergens they carry, are at risk for developing wheezing, study findings in the journal Allergy suggest. An association was also observed between early mouse exposure and allergies later in childhood.

"There are few (forward-looking) studies of mouse allergen health effects in young children, write Dr. Wanda Phipatanakul, of Harvard Medical School, Boston, and colleagues, "while recent studies have shown that mouse allergen exposure in homes of children with established asthma are highly prevalent and potentially important in both urban and suburban environments."

Phipatanakul's group examined the association between mouse allergen exposure and wheezing, allergy and asthma in the first 7 years of life. A total of 498 children who had parents with a history of asthma or allergies were followed from birth to age 7.

The parents were surveyed to assess mouse exposure. Dust samples were collected at age 2 to 3 months and were tested for mouse allergen levels. Allergy skin testing was performed at an average age of 7.4 years in 248 children.

Overall, 103 of the infants lived in homes with reported signs of mice during the first year of life. The authors report that mouse allergen was detectable in 31.7 percent of kitchens and 33.3 percent of living rooms.

An association was observed between parents' reports of mouse exposure and transient wheeze, but not with persistent wheeze and late-onset wheeze.

The team notes that early life mouse exposure was not predictive of asthma, eczema, or hayfever at 7 years of age. However, infants who lived in homes with detectable levels of mouse allergen at age 2 to 3 months had a twofold increased risk of having an allergy at school age.

"From these findings, we conclude that exposure to mouse allergen may be important in exacerbating current asthma disease symptoms and general (allergy) later on in life," Phipatanakul and colleagues write.

"It is possible," they add, "that even short-term exposure to mouse allergen influences overall risk of (allergy) if encountered at a vulnerable time in the life cycle (e.g. infancy)."

SOURCE: Allergy, November 2008.