Despite common belief, allergy prevalence is actually about the same in all regions of the United States, according to a new study in the Journal of Allergy and Clinical Immunology.
"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 U.S.," Dr. Darryl Zeldin, M.D., the scientific director of the National Institute of Environmental Health Sciences, said in a statement. "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."
However, there was one age group where there did seem to be differences in allergy prevalence based on location. Among kids ages 1 to 5, allergy prevalence seems to be higher in the southern U.S. states, including Texas, Mississippi, North and South Carolina and Florida. Researchers noted that dust mites and cockroaches seem to be to blame for the higher prevalence.
The findings are based on data from 10,000 Americans who were part of the National Health and Nutrition Examination Survey 2005-2006, which examined number of allergens as well as extent of sensitization to allergens. People in the study between ages 1 and 5 were tested for nine different antibodies, and people in the study ages 6 and older were tested for 19 different antibodies.
While the researchers didn't find that overall allergy prevalence differed between regions, they did find that the prevalence of specific kinds of allergies differed. For instance, residents of Southern states had more sensitization to indoor allergens, as well as more food allergies in people ages 6 and older, while outdoor allergy sensitization was more prevalent in the Western states.
There were also some groups that seemed to be more allergic than others. Among people ages 6 and older, males, people who avoid pets and non-Hispanic blacks were more likely to have a known hallmark of allergies. People in higher socioeconomic groups were more likely to be allergic to pets, while people in lower socioeconomic groups were more likely to be allergic to shrimp and cockroaches.