Estimated read time: 1-2 minutes
This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.
More than half of all Americans test positive in response to one or more allergens, double the percentage who did 30 years ago, a new study reports.
Researchers at the National Institutes of Health found that 54% of people tested positive to at least one of 10 allergens. The highest response was to dust mites, 27.5%. The lowest was to peanuts, 8.6%. The findings appear in the August issue of the Journal of Allergy and Clinical Immunology.
Researchers analyzed data from skin-prick allergy tests on 10,500 people by the Centers for Disease Control and Prevention.
The number of positive reactions is much higher than cases of actual allergic disease, notes lead researcher Samuel Arbes of the National Institutes of Health. Though a positive skin test for allergens such as ragweed or cats doesn't necessarily mean a person has or will develop allergies, there is a strong association between the two.
About 20% of U.S. residents have allergies or hay fever; 8% to 10% have asthma.
Though there is evidence asthma rates have peaked, allergy rates appear to still be increasing, Arbes says.
Researchers don't know why positive skin tests, allergy and asthma are increasing. One theory is that people simply don't go outside as often and have higher exposures to indoor allergens. Another theory is that children have less resistance now because they are exposed to fewer bacteria and viruses.
To see more of USAToday.com, or to subscribe, go to http://www.usatoday.com
© Copyright 2004 USA TODAY, a division of Gannett Co. Inc.
