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WEDNESDAY, July 16, 2003 (HealthDayNews) -- Impenetrable covers that put a barrier between you and your bed's dust mites do their job well -- but they don't guarantee an end to wheezing or sneezing.
So say two new studies that found the covers reduce exposure to dust mite allergens, yet that alone isn't enough to prevent allergy and asthma flare-ups in people sensitive to the microscopic menaces.
"If you want to do a simple intervention only by [covering] your mattress, pillows and quilts, it won't work," says Dr. Adnan Custovic, an allergist at Wythenshawe Hospital, in Manchester, England, and a co-author of one of the studies.
Custovic and his colleagues looked at whether bedding covers could reduce breathing trouble in adult asthmatics.
The second study, by Dutch researchers, asked the same question in a group of people, mostly adults, suffering from perpetual hay fever.
Both papers appear in the July 17 issue of The New England Journal of Medicine.
In both cases, the bedcovers -- designed to prevent dust mite particles from reaching sleepers -- reduced exposure to allergy-causing proteins. Yet doing so wasn't enough to reduce symptoms in the long run.
Dr. Darryl Zeldin, a dust mite expert at the National Institute of Environmental Health Sciences, says the findings shouldn't discourage people with allergies or asthma from using bedcovers.
"I still think that for mite-sensitive people, mite allergen avoidance measures, which include impermeable covers, make sense as a component of a more comprehensive and intensive intervention," Zeldin says.
Such a program might also involve taking steps to eliminate other allergens, such as cockroaches or pet dander, from the home. It could also include washing bedding frequently in hot water, which has been shown to remove dust mite allergens.
Still, Zeldin believes the new research underscores gaps in what scientists understand about allergies and allergens. "It may be that you get rid of one and you just respond to another or respond more strongly to one" that already causes problems, he says.
Dust mites are a leading cause of allergies and asthma in the United States. In a recent survey, Zeldin and his colleagues found that 85 percent of American homes had detectable levels of the pests in bedding, while half had levels that topped 2 micrograms per gram of dust -- an amount considered ample to make a person sensitive to the allergen. One in four homes had enough mites in bedding to trigger asthma.
More information
Visit the National
Institute of Environmental Health Sciences or the Asthma and Allergy Foundation of America.
