Food Allergy Update

1. Food Allergy Update Thomas Flaim, M.D.

2. Prevalence of Food Allergy • 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

3. Epidemiology of Food Allergy • 30,000 food-induced anaphylactic reactions/year in U.S. • 2000 hospitalizations/year in U.S. • 200 deaths/year in U.S.

4. Effects of Early Nutritional Interventions on the Development of Atopic Disease • 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.

5. Natural History of Food Allergy • 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%

6. Fatality due to Food Allergy • Peanut/nut most common cause • Milk responsible for 10% • Risk factors include: • Delayed use of Epinephrine • Asthma • Adolescent/young adult

7. IgE-Mediated Food Hypersensitivity • 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% • In vitro allergen-specific testing • similar to skin prick testing

8. IgE-Mediated Food Hypersensitivity • 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

9. Peanut Allergy • 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%

10. Peanut Allergy • 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

11. Peanut Allergy • 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

12. Peanut Allergy Treatment • Avoidance • Emergency epinephrine available • Anti-IgE therapy (1/2 to 9 peanuts tolerated) • Sublingual or oral immunotherapy • Chinese herbal medicine • Immunotherapy (plasmid, peptide etc)

13. Milk Allergy • 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

14. Egg Allergy • 70% tolerate extensively heated egg in baked goods • 20% will develop peanut allergy

15. Tree Nut Allergy • Most common: • Walnuts – 34% • Cashews – 20% • Almonds – 15% • Pecans – 9% • Pistachio – 7%

16. Fish Allergy • Allergen more susceptible to manipulation eg. Canned tuna, salmon • Allergens can become aerosolized • allergy to multiple fishes is common

17. Shellfish Allergy • Mollusks – snails, clams, oysters, scallops, squids, octopus, mussels • Crustacea – shrimp, lobsters, crabs, prawns, crawfish • Allergens can become aerosolized • Considerable cross-reactivity among crustacea

18. Treatment • Injectable epinephrine available • <50 lbs- Epipen Jr. (.15 mg) SQ • >50 lbs – Epipen (.30 mg) SQ • Avoidance • Immunotherapy (SQ, sublingual and oral) under investigation • Omalizumab (anti-IgE) • Chinese herbal remedies

19. Non-IgE-Mediated Food Hypersensitivity • Type IV – cell-mediated • Eosinophilic esophagitis and gastroenteritis • Atopic dermatitis • Celiac disease

20. Non-IgE-Mediated Food Hypersensitivity • Food protein-induced enterocolitis syndrome • Food protein-induced colitis • Dietary protein-induced enteropathy • Symptoms include vomiting, diarrhea

21. Non-IgE-Mediated Food Hypersensitivity • 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

22. Class 2 Allergenic Proteins • Consequence of an allergic sensitization to inhalant allergens • “Latex-fruit” allergy (banana, avocado, chestnut, kiwi, fig) • Oral Allergy Syndrome

23. Oral Allergy Syndrome • 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 • Ragweed • melons

24. Conclusions • 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