Peanut Traces in House Dust May Double Allergy Risk

Marcia Frellick

November 21, 2014

Infant exposure to peanut traces in house dust may double the risk for peanut allergy, researchers have found.

In a new study, published online November 18 in the Journal of Allergy and Clinical Immunology, environmental peanut exposure increased likely peanut allergy 2.10-fold (95% confidence interval [CI], 1.20-fold to 3.67-fold; P < .01). It also increased the odds of peanut skin prick test (SPT) sensitization (1.71-fold; 95% CI, 1.13-fold to 2.59-fold; P = .01).

In children who have a history of eczema or atopic dermatitis, the effect of exposure on risk for peanut allergy was even higher (odds ratio [OR], 2.34; 95% CI, 1.34 - 4.18; P < .01). The risk for SPT sensitization was also higher in children with any history of eczema and environmental peanut exposure (OR, 1.97; 95% CI, 1.26 - 3.09; P < .01) or severe eczema (OR, 2.41; 95% CI, 1.30 - 4.47; P < .01).

Lead author Helen Brough, MSc, FRCPCH, from the Department of Pediatric Allergy, King's College London, United Kingdom, and colleagues note that eczema "is often cited as the first step in the allergic march."

They conclude that exposure to peanut proteins in dust through an impaired skin barrier in eczema-inflamed skin can trigger SPT sensitization and peanut allergy. The authors found the effects on SPT sensitization and peanut allergies were specific to peanut exposure because environmental peanut exposure did not increase the risk for egg or cow's milk SPT sensitization.

"I find it very interesting that the patients who were exposed to more peanut protein in the environment had enough response to classify them as having a likely peanut allergy," Carla M. Davis, MD, a specialist in pediatric immunology, allergy, and rheumatology at Texas Children's Hospital in Houston, told Medscape Medical News. "This has not been demonstrated previously."

She said physicians should be aware of the findings of this study and could make parents of infants with eczema aware of possible consequences of peanut exposure. However, she said about the possibility of eliminating peanuts, "I don't think it should be a given that [parents] should avoid it, but they should know that there may be a risk of developing a peanut allergy if infants with atopic dermatitis are around a lot of peanuts."

How the peanut allergies develop is not yet clear, according to Dr Davis. There is still plenty of controversy in the field, she said. For instance, she noted, some researchers are testing a "patch" for people who already have the allergy that would introduce the allergen through the skin to build tolerance, which is a seemingly contradictory approach, given the findings of the current study.

The researchers looked at the amount of peanut protein to which infants aged 3 to 15 months were exposed by measuring dust vacuumed from the patients' living rooms, the rooms with the most traffic from various family members. Researchers studied 359 children in the National Institutes of Health Consortium for Food Allergy Research study who had a high risk of developing a peanut allergy because they were already allergic to cow's milk or eggs or had moderate or severe levels of eczema and had tested positive for allergies to those foods. Then the researchers checked the exposure–response relationship.

Dr Brough said in a university news release: "This study adds to the growing body of evidence that exposure to peanut via a damaged skin barrier may increase the risk of peanut allergy. Previous studies have shown, for example, that infants with eczema treated with creams containing peanut oil in the first six months of life had a higher risk of developing peanut allergy later in life."

Several coauthors report receiving support from the Immune Tolerance Network, the Wellcome Trust Intermediate Clinical Fellowship, DBV Technologies, Dyax, and Hycor Biomedical. One coauthor is a minority stockholder in Allertein and Mastcell Pharmaceuticals. Another has stock options with DBV Technologies. Several coauthors report receiving royalties from UptoDate. One coauthor is a member of the Scientific Advisory Board for DBV Technologies. Several coauthors report consultancy arrangements or having received payments for lectures from one or more of the following companies or groups: Novartis, Abbott Laboratories, Dow AgroSciences, McNeill Nutritionals, Merck, Schering Plough, GLC Research, ExploraMed Development, Regeneron Pharmaceuticals; Unilever; Allertein Therapeutics; Danone Research Institute; Anaphalaxis Campaign; and the National Peanut Board. ThermoFisher Scientific, UCB, Pfizer, Sodilac, Nestle Nutrition, and GlaxoSmithKline. Several coauthors and Dr Davis have disclosed no relevant financial relationships.

J Allergy Clin Immunol. Published online November 18, 2014. Abstract


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