Tracking Peanut Allergy Onset in Children
About 20 percent of babies with eczema or milk and egg allergies will develop an allergy to peanuts by age five, studies show. Duke University Medical Center researchers are now enrolling infants into a trial to study how and when peanut allergies arise in children.
Most children sensitive to peanuts experience their first allergic reaction between 14 and 24 months of age, often at the time of first exposure. These allergic reactions are potentially life-threatening, even the first time. Some children react to as little as 1/1000th of a peanut. The number of children with peanut allergy has doubled in the U.S. between 1998 and 2003. If signs of allergy, such as eczema, appear before six months of age, there is a one in five chance a child will develop peanut allergy by age five.
"Parents are increasingly concerned as they hear more about peanut allergies. They want to know what they can do to prevent their children from developing a peanut allergy," said Wesley Burks, M.D., chief of the division of pediatric allergy and immunology at Duke.
Burks and his colleagues will track 400 children for five years to better understand the development of peanut allergies. In partnership with the child's family physician, the researchers will watch for signs of peanut allergy, periodically collect blood samples and search for genes that influence peanut allergy. The team will also examine potential environmental factors affecting allergy.
"We hope that by better understanding when peanut allergies develop, we can offer improved treatment and prevention strategies for children," Burks said. The study may also help physicians predict which patients with peanut allergy are most at risk for a recurrence of severe allergic reactions after first exposure to peanuts.
Despite their best efforts, many people with peanut allergy will accidentally ingest peanut products. Signs of an allergic reaction to peanuts in young children include skin, respiratory and gastrointestinal symptoms: hives, an itchy rash, wheezing, throat tightening, vomiting or diarrhea. Peanuts are the leading cause of food-induced anaphylaxis, a life-threatening reaction that constricts the airway and lungs, severely lowers blood pressure and causes swelling of the tongue and throat. Nearly 100 adults and children die from allergic reaction to peanuts each year, and the allergy causes as estimated 15,000 emergency room visits yearly. The only treatment once symptoms appear is taking an antihistamine, and then epinephrine, to relieve shortness of breath.
The trial is funded by the National Institute of Allergy and Infectious Diseases, through a grant to the Consortium of Food Allergy Research (CoFar). Other CoFar institutions enrolling children in the trial include Mount Sinai Medical Center, Johns Hopkins University, National Jewish Medical and Research Center, University of Arkansas for Medical Sciences and Yale School of Medicine.
Burks is also studying a possible new method for fighting peanut allergy in children. "What we're doing is to take small amounts of peanut protein and gradually giving increasing amounts over an initial day and then over a period of three-and-a-half to four months. Every other week, we give them a larger dose," explains Burks. "At the end of that period, they're getting about 300 milligrams of peanut protein, which is the equivalent of one peanut."
"What we're finding is that they're less sensitive when they eat a peanut accidentally, so that they're not having the same reaction they did before," Burks said. "We hope by the end of this study they've actually 'outgrown' their peanut allergy."