Study: Allergies to Mice Linked to Childhood Asthma

Researchers from Harvard Medical School have determined that allergies to mice are associated with many childhood asthma symptoms.

29 schools tested

The researchers tested 29 schools and over 180 classrooms in Boston area in the fall and spring. They found that mice allergens peak in the springtime in schools and classrooms, and this corresponds with a spike in the children’s asthma symptoms.

The researchers tested the air and furniture/flooring for the allergens. Basements and cafeterias were tested along with classrooms. The schools tested had an average age of 64 years.

The researchers also conducted environmental assessments using surveys and questionnaires in addition to the sampling of each environment.

The researchers found that the mice allergen Mus M1was detected in 97% of the schools and 92% of homes tested. But schools also had significantly greater abundance of these allergens.

Nonetheless, most of the schools and homes tested did not have any signs of mice during the inspections. For example, in the spring, 162 of the environments showed no signs of mice and only 20 showed any signs of mice. Still signs of mice did correlate with greater amounts of mice allergens found.

Other mice-related allergens found were Bla G2 and Der P1. These were found in fewer instances. Bla G2, for example, was found in only 1.2% of the schools and 3% of the children’s homes.

Mice allergens significant among most schools

The study also determined that even with no signs of mice, mice allergen levels were still “significant” among schools, and heightened levels – particularly found in the spring – correlated with heightened asthma symptoms among the children.

Another recent study, this from researchers from John Hopkins University, studied mouse and cockroach allergens among 144 children in Baltimore, Maryland. The researchers collected school samples of allergens and also conducted skin prick testing among the children to determine allergy sensitization.

The researchers found that 41% of the children had immunoglobulins sensitive to mice allergens, and 41% (not necessarily the same children) were sensitive to cockroach allergens.

The researchers found that the mice allergies were associated with greater signs of asthma among the children, while the cockroach allergies were not. This result was clear, as stated by the researchers in their conclusion:

“In a community with high levels of both mouse and cockroach allergens, mouse allergen appears to be more strongly and consistently associated with poor asthma outcomes than cockroach allergen.”

More than half of homes have allergens

A 2008 study also looked specifically at mouse allergens in homes, but among families and children in Los Angeles. The researchers tested 202 families living in inner-city Los Angeles. Their analyses found that 51% of homes had mouse allergens among their kitchen dust.

In this study of the 33 families that reported signs of mice, all had particularly higher levels of mice allergens. This study also found that detached homes had more prevalence of mice allergens than attached housing.

REFERENCES:

Permaul P, Sheehan WJ, Baxi SN, Gaffin JM, Fu C, Petty CR, Gold DR, Phipatanakul W. Predictors of indoor exposure to mouse allergen in inner-city elementary schools. Ann Allergy Asthma Immunol. 2013 Oct;111(4):299-301.e1. doi: 10.1016/j.anai.2013.07.028.

Ahluwalia SK, Peng RD, Breysse PN, Diette GB, Curtin-Brosnan J, Aloe C, Matsui EC. Mouse allergen is the major allergen of public health relevance in Baltimore City. J Allergy Clin Immunol. 2013 Oct;132(4):830-5.e1-2. doi: 10.1016/j.jaci.2013.05.005.

Berg J, McConnell R, Milam J, Galvan J, Kotlerman J, Thorne P, Jones C, Ferdman R, Eggleston P, Rand C, Lewis MA, Peters J, Richardson J. Rodent allergen in Los Angeles inner city homes of children with asthma. J Urban Health. 2008 Jan;85(1):52-61.