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Question: Why are severe food allergies on the rise in children?
Answer: There is no clear answer as to why food allergies seem
to be on the rise in children. We know that allergies as a whole
are rising in our population and therefore one would expect food
allergies to rise as well. The current prevalence of food allergies
is approximately 8% of children and 2% of adults.
Question: What is protracted anaphylaxis?
Answer: Anaphylaxis may present in a variety of ways. The most
common is the immediate form where one has symptoms within
5 to 30 minutes of exposure to the offending substance. One may
also
experience a bi-phasic response
whereby one develops symptoms of anaphylaxis
approximately 6 to 12 hours after the initial episode. Symptoms
may mimic or be worse than the initial reaction. Protracted anaphylaxis
is a term that describes a persistent episode, which may last
hours
to days. There may be asymptomatic periods during a period
of protracted anaphylaxis. Given that anaphylaxis is unpredictable
it is essential
that all patients be treated promptly and observed in an emergency
room where they can be monitored for the development of biphasic
or protracted symptoms.
Question: Why are some food allergies in children often
outgrown but not peanut?
Answer: This is a good question
and one that is not easily answered. It is not well understood
why children and adults for that
matter often outgrow sensitivity to foods such as milk, wheat,
and soy
but retain reactivity to peanuts and tree nuts. There are
now reports that as many as 20% of children may “outgrow” peanut
allergy. Most of these children had very mild reactions at a
very early age and then successfully avoided peanuts for a prolonged
period of time. Children should periodically be reevaluated to
determine if they have lost their sensitivity. If appropriate,
an oral challenge could be performed in the office under physician
supervision. Patients who have “outgrown” their peanut
allergy must be monitored carefully for the redevelopment of
sensitivity and must continue to carry their injectable epinephrine.
There are reports in the literature of patients who have “outgrown” their
peanut allergy becoming sensitive to peanut once again.
Question: Why does having the combination of asthma and food allergies
put someone at a greater risk of having anaphylaxis?
Answer: Several factors are associated with an increased risk
for anaphylaxis. Patients with asthma are at higher risk because
they
can develop significant acute spasm of the airways along with the
other symptoms of anaphylaxis. This was obvious in the articles
published on fatal/near-fatal food anaphylaxis. Patients taking
beta-blockers for other medical conditions such as high blood pressure
and migraine headaches may be resistant to standard therapeutic
agents used to treat anaphylaxis and may be at increased risk for
severe protracted anaphylaxis. These risk factors have also been
demonstrated in studies pertaining to insect sting allergy and
patients experiencing anaphylaxis while receiving allergy immunotherapy.
Question: What is a late phase or bi-phasic anaphylactic
reaction?
Answer: A late phase reaction is a second reaction
that occurs between approximately 4 to 8 hours after the initial
reaction.
Late phase reactions can be in the form of rhinitis, asthma, hives,
and even anaphylaxis. Generally, one must have an immediate reaction
to set up a late phase reaction but this is not always the case.
The immediate reaction releases chemical mediators in the body
that then recruit more cells that release more chemicals that causes
a continuation of the reaction. In patients who have anaphylaxis,
there is about a 60% chance of a late phase reaction, which is
why observation in an emergency room is essential. A late phase
reaction may even be more severe than the immediate response.
These questions were answered by:
Marc S. McMorris MD
Clinical Assistant Professor
University of Michigan
Division of Allergy & Clinical Immunology
Director, University of Michigan Food Allergy Service
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