Science / Medicine : Dust Mites Linked to Asthma

Exposure to house-dust mites during infancy appears to be an important cause of childhood asthma in places where the climate is humid year-round, researchers reported last week in the New England Journal of Medicine. University of Virginia scientists based the study on a survey of 67 children in humid Poole, England.

The researchers checked for house-dust mites by testing samples of dust from their homes. By age 11, 17 children had asthma. All but one had been exposed to high levels of house-dust mites at age 1.

The work supports the growing belief that a variety of proteins from common household creatures, especially cats and cockroaches, can trigger asthma. It also suggests that modern home construction, including insulation and central heating, is raising the risk of asthma.

The tiny mites are an unseen but common inhabitant of houses everywhere, especially in places with year-round humid climates. In the study, children had an elevated risk if the house dust in their homes contained 500 or more mites per gram. Children whose asthma is triggered by house-dust mites are allergic to a form of a protein found in the mites’ gastrointestinal tracts and droppings.