the prevalence of allergies is relatively the same for every part of the US
March 5, 2014

Allergy Prevalence Is The Same Across The US

Brett Smith for - Your Universe Online

From the temperate climes of northern states to the sub-tropical environs of the southern states, Americans live in a wide range of ecosystems – all of which contain their own unique allergens.

Despite this range of potential exposure, a new study from the National Institutes of Health has found that the prevalence of allergies is relatively the same for every part of the US – except for children younger than 5 years old.

“Before this study, if you would have asked 10 allergy specialists if allergy prevalence varied depending on where people live, all 10 of them would have said yes, because allergen exposures tend to be more common in certain regions of the US,” said Dr. Darryl Zeldin, scientific director of the National Institute of Environmental Health Sciences (NIEHS), part of NIH. “This study suggests that people prone to developing allergies are going to develop an allergy to whatever is in their environment. It’s what people become allergic to that differs.”

Published on Friday in the Journal of Allergy and Clinical Immunology, the NIH study is based on blood serum data culled from about 10,000 Americans in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2006.

While the prevalence of allergies among adults was fairly uniform, young children between 1 and 5 years old living in southern states from Texas to Florida showed a higher prevalence for allergies compared to children living elsewhere around the country.

“The higher allergy prevalence among the youngest children in southern states seemed to be attributable to dust mites and cockroaches,” said study author Paivi Salo, an epidemiologist in Zeldin’s research group at NIEHS. “As children get older, both indoor and outdoor allergies become more common, and the difference in the overall prevalence of allergies fades away.”

Study researchers also tested blood serum samples for sensitivity to particular allergens – nine different allergens in children between ages 1 to 5, and 19 allergens in samples from older individuals. The scientists were able to find certain factors that made a person more likely to be allergic.

According to the study, those in the 6 years and older group, males, non-Hispanic blacks, and those who did not live with pets had an elevated chance of having allergen-specific IgE antibodies, the primary biomarker for allergy development. The researchers also found that people with a relatively high socioeconomic status had been more sensitive to cats and dogs, while individuals with comparatively lower status were commonly hypersensitive to shrimp and cockroaches. Sensitivity to indoor allergens was more widespread in the South, while susceptibility to outdoor allergens was more typical in the western US. Food allergies for those 6 years and older were found to be highest in the South.

The scientists said they would use more NHANES 2005-2006 information to look at other allergy-related questions or misconceptions. For instance, using dust samples extracted from subjects’ homes, the team plans to look at the link in between allergen exposure and outcomes in the greater US population.