(RxWiki News) Researchers recently studied allergy rates by region, age and frequency, and some very interesting patterns emerged.
These researchers saw allergies to the same set of 19 allergy-causing agents — called allergens — across the U.S., and that the number of people with allergies was similar across the U.S.
However, the frequency of allergy to particular allergens differed by region. For example, allergies to the German cockroach were greater in the southeast and southcentral U.S., but allergies to the German cockroach were found in people throughout the U.S.
"Talk to your doctor about allergy testing and treatment."
Darryl C. Zeldin, MD, from the Division of Intramural Research at the National Institute of Environmental Health Sciences in Research Triangle Park, NC, was the lead author of this report.
One way to tell if someone has an allergy is to look for a protein in the blood called IgE. Based on the results of these blood tests, the researchers determined which allergen caused the production of the IgE.
The 2005-2006 National Health and Nutrition Examination Survey (NHANES) tested the blood of 9,440 people aged 1 year and older across the U.S. for IgE antibody to different allergens.
Results of the blood tests showed that people developed an antibody to 19 main allergens that clustered by their source. Allergens from food sources were peanuts, shrimp, milk and eggs. The indoor allergens were from dust mites, pets, cockroaches and rodents. The common outdoor allergens were grasses, ragweed, oak, thistle, birch and fungus.
Children under age 1 could only be tested for nine allergens because of the amount of blood required for testing. They were tested for food and indoor allergens.
The research team examined the allergens by type, by age of person with the allergy and by region where the allergen antibody was found.
IgE antibodies, indicating allergies, were found in 45 percent of the people aged 6 and over. They were found in 36 percent of the children aged 1 to 5 years old.
Allergies to different allergens were seen in people from different regions of the United States. Allergies to outdoor allergens like grasses were more prevalent in the south and west, whereas indoor allergies to dust mites were found throughout the country.
Allergies, determined by IgE in the blood, were higher in younger people, males and non-Hispanic blacks.
Allergies to indoor and outdoor allergens peaked in childhood and early adulthood, but food allergies were most common in children aged 1 to 5.
The authors summarized their report: “A large portion of the U.S. population is sensitized to indoor, outdoor and food allergens. ... Although the overall prevalence of sensitization did not vary across census regions, except in early life, the NHANES 2005-2006 data demonstrated regional differences in the prevalence of sensitization to individual allergens and allergen types.”
The research study was published in the February issue of The Journal of Allergy and Clinical Immunology.
Partial funding for the research was provided by the Intramural Research Program of the National Institutes of Health, National Institute of Environmental Health Sciences.
The main authors of the study declared no conflicts of interest.