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Food Allergy Review

Food Allergy Review. November 6, 2013 Seattle School Nurse Practitioner Thao N. Tran, MD Northwest Asthma & Allergy Clinic Univ WA, Dept Allergy & Infectious Diseases. Objectives. Review food allergies Discuss other mechanisms of adverse reaction to foods

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Food Allergy Review

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  1. Food Allergy Review • November 6, 2013 • Seattle School Nurse Practitioner • Thao N. Tran, MD • Northwest Asthma & Allergy Clinic • Univ WA, Dept Allergy & Infectious Diseases

  2. Objectives • Review food allergies • Discuss other mechanisms of adverse reaction to foods • Review other complicating medical conditions in the care of allergic students

  3. Epidemiology • Food allergy: abnormal immune response to foods in susceptible hosts • 20-25% of adults & children in US alter their diet due to perceived adverse reaction to foods • Actual prevalence: 2-8% children, <2-4% in adults • 12 million Americans have food allergies

  4. Food allergy • 25% of first-time anaphylactic reaction occurs in the school setting

  5. Food allergy • Involves immunological mechanisms • IgE-mediated • Cell-mediated • Mixed (IgE & cell-mediated) • Associated with eosinophilic inflammation

  6. Food allergy • Reproducible each time food is ingested • Often not dose-dependent • >170 different foods have been reported to cause food allergies

  7. IgE mediated • Cross linking of food allergen to IgE antibody on mast cells & basophils leading to release of allergic mediators (histamine, tryptase, platelet activating factors) • Acute (<2hrs) urticaria/angioedema, anaphylaxis, asthma, rhinitis symptoms • Children > adults

  8. Common food allergies • US: milk, egg, peanut, soy, wheat, tree nuts, fish, shellfish • Japan: milk, egg, wheat, peanut, soy, sesame, buckwheat • E Europe: citrus, chocolate, apple, hazelnut, strawberry, fish, tomato, egg, milk • Sweden: tree nuts, apple, pear, kiwi, stone fruits, carrot

  9. Prevalence

  10. Food cross reactivity Sicherer, Sampson JACI 2010

  11. Resolution of food allergies * Recurrence of peanut allergy described in patient who successfully completed oral food challenges, but did not continue to consume

  12. Oral allergy syndrome • Sensitization of pollens through respiratory route. IgE then binds to homologous antigens on fruits/vegetables • Affects 40% of patient with pollinosis • Pruritis & mild swelling of oral cavity; vary with the season; 7% extend beyond • 1-2% result in anaphylaxis

  13. Oral allergy syndrome

  14. Food-associated exercise induced anaphylaxis • Ingestion of food allergen followed temporally by exercise; usually <2hrs • Common triggers: wheat, shellfish, celery • Late childhood > adult

  15. Testing: IgE sensitizations • Skin prick testing to commercial whole allergen or fresh allergens • Serum IgE antibodies to specific whole allergens • Specific IgE to recombinant allergenic proteins. FDA approved for peanut. • Ara h 1, 2, 3, (9)- anaphylaxis; Ara h 8- low clinical relevance

  16. IgE mediated • 50% will experience accidental ingestion within 5 yrs; 75% within 10 yrs • Food is the most common cause for anaphylaxis treatment in the ED • 30000 anaphylactic reaction, 2000 hospitalizations, & 150-200 deaths/yr • Food allergy rxn is common at school; 18% chance of 1 reaction per 2 yrs

  17. Fatalities • Rare; primarily reported to peanut & tree nuts • Associated with delayed treatments with epinphrine • Risk group: teenagers/young adults with asthma • 1/3 of children with food allergies have asthma

  18. Prevention? • “We do not yet have enough evidence to make firm recommendations about the timing of dietary allergen exposure.” Jones & Burkes, et al. JACI 2013. • Consortium of Food Allergy Research (CoFAR) & Learning Early About Peanut study (LEAP): longitudinal studies on genetic & dietary factors.

  19. Advocacy • Food Allergy Research & Education (FARE; www.foodallergy.org). Merger between Food Allergy & Anaphylaxis Network and Food Allergy Initiatives • Center for Food Safety & Applied Nutrition (CFSAN) of the FDA • AAAAI, ACAAI

  20. Labeling laws • US Food Allergen Labeling and Consumer Protection Act of 2004 (www.fda.gov/Food/FoodSafety/FoodAllergens): requires labeling for major allergens with common names listed. • Egg, milk, wheat, soy, fish, crustacean/shellfish, peanut, & tree nuts.

  21. Food label law • Exempts highly refined oils derived from food allergens. • Does not regulate advisory labeling (e.g., “may contain...,” “manufactured on equipment with...”). • CFSAN has not set thresholds for the major allergens.

  22. Other laws • Food Safety Modernization Act & Food Allergy & Anaphylaxis Management Act of 2011 • Voluntary policy to manage the risk of food allergy & anaphylaxis among students & provide for incentive grants to support implementation of food allergy management guidelines

  23. Pending Federal law • School Access to Emergency Epinephrine Act- introduced in 2011 (Senate bill 1503; House bill 2094) • Incentive to states to enact laws allowing stock epinephrine (non-student specific) in schools & allowances for personnel to administer if student experiences anaphylaxis.

  24. WA State: ESB 5104 • Signed into law May 16, 2013 • Licensed professional may prescribe epinephrine autoinjectors in the name of school district or school w/ standing order for administration • May be used on school property, playground, school bus, sanctioned field trips

  25. ESB 5104 • Contains language used to protect prescribing licensed professionals, school nurses, school employees in case of adverse reaction • School employees may file with school district a written letter of refusal to use epinephrine autoinjectors

  26. Epinephrine use in school • Up to 24% of all epinephrine administration in school provided to students and personnel whose allergy was unknown at time of adminstration. McIntyre, et al. Pediatric 2005.

  27. Cell-mediated • Food protein-induced enterocolitis (FPIES) • Food protein-induced enteropathy • Food protein-induced protocolitis • Celiac disease/dermatitis herpetiformis • Heiner syndrome

  28. FPIES • Protracted emesis, diarrhea, abdominal distention, FTT, dehydration • Sxs present 1-3 hrs after feeding • Infancy; usually outgrows by 2 yo • Cow’s milk, soy, rice, oat, meat • Elimination of food leads to resolution within 24-72 hrs

  29. FPIES • Rechallenge induces vomiting within 1-2 hrs; 15% of patient will have hypotension • Tx: aggressive fluid/hydration.

  30. FPI enteropathy • Diarrhea, steatorhea, abdominal distention, weight loss, nausea, vomiting, oral ulcers, anemia • Infancy to 2-3 years (spontaneous remissions) • Milk & soy • Elimination of food leads to resolution within 72 hrs

  31. FPI enteropathy • Rechallenge induces GI bleeding • Bx: intraepithelial lymphocytes & eosinophils, atrophy of villuses

  32. FPI protocolitis • Mucus-laden, bloody stools (gross, occult) • Infancy (first few months of life); resolves by 2 yo • Milk (often through breast milk) • Elimination of foods leads to resolution within 72 hrs; rechallenge induces bleeding with 72 hrs

  33. Celiac disease • Chronic inflammatory disorder of the small intestine due to immune response to & malabsorption of gluten (wheat) secalins (rye), & hordeins (barley) • Incidence is 1:3000 in W Eur & N Amer • Sxs: wt loss, diarrhea, steatorhea, iron/folate def anemia, osteoporosis • Vit K & D deficiency found in 50% of pt

  34. Celiac disease • Immune response is T-cell mediated leading to production of autoreactive B-cell producing Ab to gliadin, endomysium, or tissue transglutaminase • Bx: intraepithelial lymphocytes, flat mucosa, loss of villi • Genetic susceptibility: HLA-DQ2, -DQ8

  35. Celiac: serologic tests • Elisa IgA to tTG Ab: good sensitivity & specificity; must check IgA level • IgA endomysial Ab, gliadin Ab • Lack of HLA DQ2 (90-95% of pt with celiac) & DQ8 (5-10% of pt with celiac) virtually rules out celiac disease

  36. Dermatitis herpetiformis

  37. Heiner syndrome • Rare infantile disorder • Pulmonary hemosiderosis triggered by milk; FTT, iron def anemia • Circulating immune complexes & alveolar deposition of IgA, IgG, & C3 • Resolves with cow’s milk protein elimination diet

  38. Atopic dermatitis • Mixed IgE & cell-mediated disease • 35% of children with moderate to severe AD develop IgE mediated food allergies • Compared to children who develop eczema >6 mo, those with eczema at <6 month has 2-fold increase risk of developing milk, egg & peanut allergies

  39. Atopic dermatitis • Homing of food responsive T-cell to skin • Infant > child > adult • Egg & milk are common allergens • Usually the child will outgrow allergies

  40. Eosinophilic esophagitis • Sxs: heartburn, dysphagia, odynophagia, regurgitation, “spitting up,” abdominal pain, failure to respond to GERD therapy • Milk, egg, wheat, rye, beef • Endoscopy/bx: at least 15 eosinophils/HPF • 50% of pt with EE have other atopy

  41. Eosinophilic gastroenteritis • Sxs: recurrent abdominal pain, early satiety, intermittent vomiting, failure to thrive, ascites, bowel obstruction, edema • 50% have peripheral eosinophilia • Diagnosed by biopsy

  42. Adverse reactions to foods • May not be reproducible • Often is dose-dependent • Multiple mechanisms

  43. Pharmacologically active • Caffeine • Tyramine in aged-cheese • Histaminergic chemicals in spoiled fish, alcohol, mushroom

  44. Metabolic disorders • Host-specific metabolic disorders • Lactose intolerance • Galactosemia • Fructase deficiency • Fructose malabsorption • Aldehyde dehydrogenase deficiency

  45. Lactose Intolerance • Lactase deficiency • Bloating, cramping, gas, diarrhea • 30 million ppl/yr diagnosed in the US • Lactase enzyme supplements or removal of lactose from diet

  46. Galactosemia • Galactase deficiency; AR; newborn screening; 1:30000-60000 • Lethargy, FTT, jaundice, liver damage & abnormal bleeding, sepsis, shock • Remove galactose from diet

  47. Fructose malabsorption • Lack of fructose carrier on enterocytes • 30-40% of central European • Bloating, diarrhea/constipation, flatulence, reflux, abdominal pain • Associated with celiac disease • Low fructose diet

  48. Other adverse rxn • Psychologic • Food aversions • Anorexia nervosa • Neurologic • Auriculotemporal syndrome • Vasomotor/ gustatory rhinitis

  49. Frey’s/auriculotemporal syndrome. Hussain N. Postgrad Med J 2010

  50. Urticaria Kanani, et al. AACI 2011

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