Transcript Food Allergy Update

Food Allergy Update
Thomas Flaim, M.D.
Prevalence of Food Allergy
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Prevalence rate is 6% in children < 3
years of age; 4% in adults
Atopic children have higher prevalence
Most common are milk (infants), egg
(toddler), and peanut (school age)
35% of children with moderate to
severe atopic dermatitis have food
allergy
Epidemiology of Food Allergy
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30,000 food-induced anaphylactic
reactions/year in U.S.
2000 hospitalizations/year in U.S.
200 deaths/year in U.S.
Effects of Early Nutritional
Interventions on the Development
of Atopic Disease
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No protective effect of a maternal exclusion diet
during pregnancy
Modest decrease in risk of atopic dermatitis and
milk allergy with exclusive breastfeeding for 4
months in high risk infants
Insufficient data for preventing and/or delaying
food allergy with exclusive breastfeeding
For infants after 4-6 months of age, there are
insufficient data to support a protective effect of
any dietary intervention for the development of
atopic disease
Pediatrics 2008;121;183-191.
Natural History of Food Allergy
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Outgrown by age:
– Milk – 20% (4 years); 40% (8 years);
60% (12 years); 80% (16 years)
– Egg – 10% (4 years); 40% (8 years);
65% (12 years); 80% (16 years)
– Peanut – 20%
– Tree nuts – 10%
Fatality due to Food Allergy
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Peanut/nut most common cause
Milk responsible for 10%
Risk factors include:
– Delayed use of Epinephrine
– Asthma
– Adolescent/young adult
IgE-Mediated Food
Hypersensitivity
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Type I hypersensitivity reaction
Symptoms within minutes to 2 hours after
ingestion
Skin prick testing
– positive results - 50% tolerate foods
– negative results – negative predictive accuracy
of >95%
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In vitro allergen-specific testing
– similar to skin prick testing
IgE-Mediated Food
Hypersensitivity
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Double-blind placebo-controlled food
challenge (DBPCFC) is “gold standard”
for establishing diagnosis
Conducted in clinic or hospital setting
May perform every 1-2 days
Peanut Allergy
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Prevalence of 1%
Rate has doubled in past decade
Severity of clinical reactions does not
correlate with serum peanut-specific
IgE results
Coallergy with legumes is 5% and tree
nuts 25-50%
Peanut Allergy
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Labeling laws now require declaration
of peanut proteins
“may contain peanut” and “made in a
factory that processes peanut”
Casual contact through touch or
inhalation generally not a problem
Peanut Allergy
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20% will outgrow, must be confirmed
with oral challenge
8% have recurrence but these patients
did not incorporate peanut into diet
7% of younger siblings will have
peanut allergy
Peanut Allergy Treatment
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Avoidance
Emergency epinephrine available
Anti-IgE therapy (1/2 to 9 peanuts
tolerated)
Sublingual or oral immunotherapy
Chinese herbal medicine
Immunotherapy (plasmid, peptide etc)
Milk Allergy
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2.5% of newborn infants experience
hypersensitivity reactions <1 year of
age
60% are IgE-mediated; 50% then
develop other food allergies
Most with non-IgE-mediated reactions
‘outgrow’ by 3 years of life
Coallergy – beef in 10% of patients
Egg Allergy
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70% tolerate extensively heated egg
in baked goods
20% will develop peanut allergy
Tree Nut Allergy
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Most common:
– Walnuts – 34%
– Cashews – 20%
– Almonds – 15%
– Pecans – 9%
– Pistachio – 7%
Fish Allergy
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Allergen more susceptible to
manipulation eg. Canned tuna, salmon
Allergens can become aerosolized
allergy to multiple fishes is common
Shellfish Allergy
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Mollusks – snails, clams, oysters,
scallops, squids, octopus, mussels
Crustacea – shrimp, lobsters, crabs,
prawns, crawfish
Allergens can become aerosolized
Considerable cross-reactivity among
crustacea
Treatment
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Injectable epinephrine available
– <50 lbs- Epipen Jr. (.15 mg) SQ
– >50 lbs – Epipen (.30 mg) SQ
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Avoidance
Immunotherapy (SQ, sublingual and
oral) under investigation
Omalizumab (anti-IgE)
Chinese herbal remedies
Non-IgE-Mediated Food
Hypersensitivity
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Type IV – cell-mediated
– Eosinophilic esophagitis and
gastroenteritis
– Atopic dermatitis
– Celiac disease
Non-IgE-Mediated Food
Hypersensitivity
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Food protein-induced enterocolitis
syndrome
Food protein-induced colitis
Dietary protein-induced enteropathy
Symptoms include vomiting, diarrhea
Non-IgE-Mediated Food
Hypersensitivity
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Potential complications include bloody
diarrhea, FTT, malabsorption, dehydration
Etiologic agents – milk and/or soy based
formula, breast milk
Treatment is avoidance and use of
elemental formula
Resolution in majority of infants by 2 years
of age
Class 2 Allergenic
Proteins
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Consequence of an allergic
sensitization to inhalant allergens
“Latex-fruit” allergy (banana, avocado,
chestnut, kiwi, fig)
Oral Allergy Syndrome
Oral Allergy Syndrome
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Symptoms confined to oropharynx and
rarely involve other target organs
Cooked foods tolerated
Birch pollen
– Apple, pear, peach, cherry, apricot, plum,
carrot, celery, potato, hazelnut
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Ragweed
– melons
Conclusions
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Make a correct diagnosis (food allergy
cripples)!
Treatment is avoidance and availability
of injectable epinephrine although we
should have therapy in next 10-20
years