The Vande Berg family doesn't go out for ice cream. When Andrew, Caroline and Gracie dress up for Halloween, it's not to trick-or-treat in the regular sense-they wouldn't be able to bring the candy back to the house. The children know to decline the birthday cake and Rice Krispie treats in their classroom celebrations. And Chinese food? Forget about it.
Six-year-old Caroline is severely allergic to peanuts, and these measures are precautions the Vande Berg family takes to avoid exposure.
"It only takes a really small amount-enough that it would look like a dusting on a teaspoon-to cause a severe reaction," says Dr. Wesley Burks, chief of the Division of Allergy and Immunology in the Department of Pediatrics at Duke University Medical Center.
If Caroline or children who share her allergy are exposed to peanuts, their reactions range from hives and swelling to anaphylaxis, a multi-system allergic response that can be fatal.
Burks is working to change that, through two concurrent studies-one examines how food allergy develops, and another is testing a new therapy for food allergy.
Participants in the latter study, which is split into two separate groups according to age, ingest increasing amounts of a liquid peanut concentrate (for older children) or a peanut protein powder (younger) over a several-month period.
"At the end of the study we've done challenges to see how much peanut you'll tolerate," Burks says. "The kids that are in it so far, eight of them tolerated the equivalent of about 15 peanuts and never had a reaction. And at the start of the study they reacted to about a 300th of a peanut."
The principle behind the study is similar to the use of antivenin to desensitize an allergic subject to bee stings. Burks hopes that by giving the allergic children increasing amounts of peanut proteins, he can reduce their sensitivity to peanuts forever.
Doctors attempted a similar study before, with injections; it became too unsafe to continue after some of the patients experienced severe life-threatening reactions.
"We really did have to think about whether we wanted to do it, because if you think about it, we were taking a child that was so allergic she couldn't be in the same room as peanut butter, and we were going to start feeding her peanut protein," says Janet Vande Berg, Caroline's mother. "It was nerve-wracking."
Ultimately, Caroline's all-but-inevitable exposure to peanuts upon entering kindergarten the next year gave the Vande Bergs the final push to sign their daughter up for the study.
Peanut allergy is the dominant food allergy in the United States, and is on the rise-a 2003 study in the Journal of Allergy and Clinical Immunology reported that the incidence of peanut allergies in children doubled between 1997 and 2002. And of all the food allergies, peanuts cause about 80 percent of all severe reactions to food, Burks says.
Burks began studying the peanut and its allergic properties 25 years ago. His fellowship supervisor was researching food allergy in children, and the two recognized that peanut allergy caused a significant number of life-threatening reactions. He spent the next ten years researching peanut proteins at the molecular level, seeking to understand the property of peanut proteins that cause a reaction.
Since the foods to which children become allergic depend on the foods to which they're exposed, different societies have different food sensitivities. Scandinavian countries have a higher fish allergy rate; in the Middle East, mangoes provoke strong reactions in some children.
"You inherit the allergy genes from your family, and then you're exposed to the food sometime early in life," Burks says. "The more food you're exposed to, the more likely you'll develop an allergy to that food."
But some children who have never eaten peanuts experience a severe allergic reaction on their first exposure-a phenomenon Burks says he and other researchers don't fully understand.
Vande Berg noticed something was different when she was still breast-feeding Caroline. "Any time I ate peanut butter and nursed her, she would cry hysterically and burst out in a rash head-to-toe," she says. Doctors officially diagnosed Caroline with peanut allergy when she was 15 months old.
After the initial diagnosis, every ordinary-seeming activity took on greater significance. A trip to the grocery store was fraught with questions. What has traces of peanuts? What doesn't have traces of peanuts? What does being manufactured in a plant that uses or processes peanuts mean-can she eat that?
"Knowing that your child is going to be different for their entire life, and that they're going to be set apart, and that you're always going to have to say, 'No, I'm sorry, you can't have something'. those are kind of the big difficulties in the beginning," Vande Berg says.
These days, shopping is a lot easier, thanks to a combination of experience and a 2006 law that requires food manufacturers to publish an allergy warning on every package. Caroline understands that she can't eat what the other kids eat, and for the most part, Janet says her daughter doesn't mind.
"The things that she likes are different than the things you or I would like," Janet says, "For instance, she doesn't like chocolate, because most chocolate has nuts in it, so she doesn't get to eat a lot of it."
One thing Caroline dislikes is the smell of peanut butter. As Janet opens the cabinet and takes down the peanut protein powder-a chalky mixture that looks like the dried-out innards of a Snickers bar-Caroline approaches and crinkles her nose.
"It smells funny," she says.
"It smells like peanut butter," her mother answers.
Janet disguises Caroline's daily dose of peanut protein by mixing it with yogurt, ice cream or applesauce.
Other than the peanut powder, the house is peanut-free. So are the school cafeteria, the entire pre-kindergarten, kindergarten and first-grade classrooms at school. Eventually, as the children move up through the grades, the entire school will be peanut-free.
It's a trend many organizations have become aware of, most notably evident in major airlines' switch from peanuts to pretzels for the in-flight snack.
"Before she was in the study, I never ate [peanuts] when I was out," Janet says. "Now that she's in the study, and we know her allergy is so low, I am more likely to eat it when I'm out, by myself, but I come home, and I wash up, I take my clothes off, I put them in the garage."
So let's say a visitor ate Reese's Pieces a few hours before coming to the house-would she ask her to wash her hands?
"Three years ago, I would have said, 'Yes, please do,'" Janet says. "Now we don't have to worry about it so much.
"The biggest thing is that I know I'm never going to get a call from the school saying, 'She's stopped breathing. We're taking her by ambulance to the hospital.' It's a huge relief."
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