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Environmental factors appear to promote development of allergic diseases

Children born outside of the United States have lower rates of allergic disease, but after prolonged US residence, this reduced prevalence is reversible, according to research presented this week at the 2013 Annual Meeting of the American Academy of Allergy, Asthma & Immunology in San Antonio.

Previous studies have demonstrated that allergic disease appears to be less common in certain racial or ethnic groups. However, Jonathan I. Silverberg, MD, PhD, of St. Luke’s-Roosevelt Hospital Center, and colleagues from the State University of New York Downstate Medical Center and Oregon Health Science Center examined a sample of 91,642 children aged 0 to 17 years during the 2007-2008 National Survey of Children’s Health to investigate whether there was an association between birthplace, length of US residence and rates of asthma, eczema, hay fever and food allergy.

The researchers found that compared with US-born children, the children born outside of the United States had lower rates of allergic disease. This was true even after taking into account age, sex, race or ethnicity, household income, residence in urban areas and history of moving to the United States from another country, according to the researchers.

Silverberg and colleagues also looked at birthplace of the parents and what that would reveal regarding prevalence rates in the children who were born outside of the United States. Their investigation revealed that children with parents who also were born outside of the United States had lower rates for all of the allergic diseases vs. children whose parents were born on US soil.

“Most interestingly, our research with this sample uncovered that children whose birthplace was outside the United States who then lived here for more than 10 years had higher odds of developing eczema (P =.03)and hay fever (P =.006) when compared with those who had lived here for up to 2 years. However, we did not find this was true for asthma or food allergy (P>.06),” Silverberg said in a press release. “What we can take away here is that seeing this loss of childhood protection from eczema and hay fever after extended US residence implies that environmental factors may promote the development of allergic disease.”

For more information:

Silverberg JI. Abstract #512. Presented at: 2013 Annual Meeting of the AAAAI; Feb. 22-26, 2013; San Antonio.