Children who outgrow peanut allergy have a slight
chance of recurrence, but researchers from the
Johns
Hopkins Children's Center report that the risk is much
lower in children who frequently eat peanuts or peanut
products.
In a study published in the November issue of the
Journal of Allergy and Clinical Immunology, the
Johns Hopkins team recommends that children who outgrow
peanut allergy eat concentrated forms of peanut products,
such as peanut butter, shelled peanuts or peanut candy, at
least once a month in order to maintain tolerance.
"The exact mechanism by which peanut allergy may recur
is not known, but we know that the children in our study
who ate concentrated forms of peanut frequently had a
considerably lower chance of having a recurrence of their
allergy," says Robert Wood, the study's senior author and a
pediatric allergist at the Johns Hopkins Children's
Center.
According to Wood, an estimated 20 percent of children
stop having allergic reactions to peanut as they grow
older. Few studies have been able to clearly assess the
rate of recurrence because many such children,
understandably, tend to avoid eating peanuts.
"It is common because of an ongoing dislike of peanut
or an ongoing fear of a reaction," Wood says. "That is
reasonable because there is a risk of recurrence, and
reactions could be worse."
As a result, Wood says he and his team continue to
recommend that children who eat peanut infrequently or in
limited amounts carry epinephrine injections at all times
and that they continue with annual blood tests to monitor
allergy antibodies and assess the risk of recurrence.
Wood also recommends that those children who do eat
concentrated peanut products frequently carry epinephrine
injections for at least one year after passing an oral food
challenge, a highly accurate allergy test in which the
child eats small amounts of the suspected allergen in a
clinical setting and is watched carefully for symptoms.
In the study, Wood and colleagues at Arkansas
Children's Hospital evaluated 68 children between the ages
of 5 and 21 who outgrew a peanut allergy. Each family
completed a questionnaire to establish a detailed history
of the child's peanut consumption since passing an oral
peanut challenge. Twenty-one children also underwent a
double-blind, placebo-controlled oral peanut challenge.
Overall, the researchers found that 34 children who
consumed concentrated peanut products frequently, and 13
children who ate peanut products in limited amounts but
passed the oral peanut challenge, continued to tolerate
peanut. Three children — all of whom reported eating
peanut products infrequently and in limited amounts —
experienced an allergy recurrence, yielding an 8 percent
recurrence rate. The status of the remaining 18 children
was unclear because they ate peanut infrequently or in
limited amounts and declined to undergo the oral peanut
challenge. Although the findings serve as recommendations
for families and clinicians managing a child who has
outgrown a peanut allergy, Wood hopes future research will
help to better identify patients who are truly at risk for
a peanut allergy recurrence. "Then we can recommend that
these patients continue to avoid peanut for life rather
than risk the chance of having a serious allergic reaction
in the future when their allergy may recur," he says.
In an accompanying study, also in the November issue
of the Journal of Allergy and Clinical Immunology, Wood and
colleagues report that while severe allergic reactions do
occasionally occur with all foods tested during an oral
food challenge, these reactions can be reversed with prompt
treatment of routine medications, such as short-acting
antihistamines. Therefore, researchers say the risk of a
reaction is warranted as long as the challenge is performed
under the supervision of an experienced clinician. They
also report that no foods were more or less likely than
others to cause a severe reaction; for example, severe
reactions to egg were just as common as they were to
peanut.
Without a definitive diagnosis from a food challenge,
children may unnecessarily avoid foods like milk, eggs and
peanuts that have significant nutritional benefits. Wood
says the second study's findings provide reassurance that
food challenges can be safely performed and "we hope this
information helps families make a more informed decision
about whether or not their child should undergo a
challenge," he says.
Experts say peanut allergies, which affect
approximately 1 percent to 2 percent of young children and
1.5 million Americans overall, are on the rise. The allergy
can be triggered by as little as 1/1,000th of a peanut and
is the leading cause of anaphylaxis, the life-threatening
allergic reaction that constricts airways in the lungs,
severely lowers blood pressure, causes swelling of the
tongue or throat and sometimes leads to death.
Co-authors of the study were David Fleischer and Mary
Kay Conover-Walker, of the Johns Hopkins Children's Center
Division of Immunology and Allergy; and Lynn Christie and
A. Wesley Burks, of Arkansas Children's Hospital.
The study was funded by the National Institute of
Allergy and Infectious Diseases, the Eudowood Foundation
for the Consumptives of Maryland, the Myra Reinhard Family
Foundation and two General Clinical Research Center
grants.