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Food Allergy
Prof. Dr. Saad S Al AniSenior Pediatric ConsultantHead of Pediatric DepartmentKhorfakkan Hospital Sharjah ,[email protected]
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Epidemiology
1. 5% - 8% in pediatric population2. Most common allergens in children: □ Milk □ Eggs □ Peanuts □ Tree nuts □ Soy □ Wheat
Jason W.C. the Harriet lane Handbook.8th ed.p:388.Mosby.2009
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Nature of symptoms with immune (allergy) and non-immune
hypersensitivity reactions (intolerance)
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ManifestationsOften a combination of several syndromes
1.Anaphylaxis
2.Skin syndromes
3.Gastroentistinal syndromes
4.Respiratory syndromes
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1.Anaphylaxis
Risk factors for fatal outcome:
1.History of asthma
2.Peanut or tree nut allergy
3.Delayed administration of epinephrine
Uniphasic , Biphasic, or Protracted patterns
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2.Skin SyndromesA. Urticaria / Angioedema:
1.Chronic Urticaria rarely related to food allergy
2.Acute urticaria predicts risk for future anaphylaxis
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Cont.B. Atopic Dermatitis / eczema
1. Food allergy more common in patients with atopic dermatitis
2. Acute and chronic skin changes often coexist
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3.Gastrointestinal SyndromesA. Oral allergy syndrome
1- Edema of oral mucosa after ingestion of certain fresh fruits and vegetables in patients with pollen allergies
2 - Inciting antigens destroyed by cooking
3 - Caused by cross-reactivity of antibodies to pollens
4 - Rarely progresses beyond the mouth
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Cont.
B. Allergic Eosinophilic Gastroenteritis , Esophagitis
1- Reflux ,abdominal pain ,diarrhea ,early satiety
2 – characterized by eosinophilic infiltration of digestive tract
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Cont. C. Food –induced Enterocolitis
1- Presents in infancy
2 – vomiting and diarrhea (may contain blood ) when severe may lead to : Lethargy ,Dehydration ,Hypotension ,Acidosis
3 – Most commonly associated with milk ,soy
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Cont.D. Infantile Proctocolitis
1- Confined to distal colon and presents with only diarrhea
2 – Symptoms of short duration ,rarely leads to anemia
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4.Respiratory syndromes
C. Heiner syndrome
A. Rhinitis
B. Asthma
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Heiner syndrome
Features: - Pulmonary infiltrate - Hemosiderosis - Anemia - Recurrent pneumonia - Failure to thrive
Precipitating IgG antibody to cow’s milk
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Diagnosis
Food allergy is suspected when typical symptoms occur with the introduction of specific foods.
2.Pharmacologic activity of foods
Other non-allergic mechanisms of food intoleranceshould be ruled out:
1.Compromised digestive or absorptive processes
3.Contamination with microbes or toxins
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Cont.
• Lactose intolerance should be considered when cow's milk allergy is suspected.
• Elimination diet and subsequent double-blind, placebo-controlled food challenge (DBPCFC) are the gold standard for diagnosis of food allergy.
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Cont.
• In DBPCFC, suspected foods are administered in capsules in progressively increasing amounts, alternating with placebo, and reactions are evaluated in a blinded fashion.
• Open food challenges, although commonly performed, are less reliable (except in young infants).
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Cont.
• When anaphylaxis has followed ingestion of a food, challenge should not be performed, and an allergist should evaluate the child.
• Symptoms can be reproduced by DBPCFC in only 40% of children with suspected food allergy
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Cont.• The judicious use of a skin prick test or radioallergosorbent test (RAST) can be very useful in determining whether an IgE allergic reaction is the cause of a food allergy.
• Children can be tested for IgE reactions to foods at any age because IgE is made by 24 wk gestation.
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Cont.• A negative IgE test, especially if the patient is older than 1 yr of age, is very accurate in predicting that the reaction is not IgE mediated.
•The significance of a positive IgE test has to be determined by the history and the age of the patient.
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Cont.
Total-serum IgE is unreliable in diagnosing food allergy.
• A positive skin test is found in nearly 100% of children 3yr of age or older who have a positive DBPCFC.
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Cont.• In infancy, hypersensitivity is
most often associated with ingestion of cow's milk or soy protein.
Among infants and children with food allergy, 90% of reactions are to egg, milk, peanuts, soy, and wheat
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Cont.
Seventy-five per cent of children with food allergy react only to a single food.
•Children with allergic eosinophilic gastroenteritis
are the exception, often
reacting to multiple foods
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Treatment and Prognosis. The only therapy proved effective for food allergy is an elimination diet.
Most gastrointestinal manifestations resolve within several days, although some may take weeks (food-induced enteropathy).
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Cont. A child at risk for a severe and life-
threatening IgE-mediated reaction should have access to injectable epinephrine and an antihistamine.
At least 30% of infants with cow's milk allergy also demonstrate sensitivity to soy protein.
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Cont.• These infants improve with protein hydrolysate formula; • less than 5% have persistent symptoms and these cases resolve with the use of amino acid- based formulas.
•Re-lactation is an alternative when cow's milk allergy presents early.
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Cont.
About 50% of infants who experience proctocolitis while nursing improve with removal of cow's milk from the mother's diet.
If the symptoms are severe enough (anemia and hypoproteinemia) decide to change in the infant's diet to a protein hydrolysate formula.
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Cont.
Eighty-five per cent of infants with non-IgE-mediated food hypersensitivity to milk proteins no longer have symptoms on food challenge by 3 yr of age.
Resolution of symptoms from cow's milk or soy protein hypersensitivity is common by 1 yr of age.
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Cont.
When milk is reintroduced, only a teaspoon or less should be offered at first and then increased progressively over a few days if tolerated
Even older children and adults may lose their sensitivity to an offending food when it is eliminated from the diet for 1 to 2 yr
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Cont.
Symptoms from IgE-mediated allergy to peanut, nuts, fish, or shellfish are the exception and
do not resolve.
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References
• Jeffrey Hyams . Food Allergy (Food Hypersensitivity) .in Nelson textbook of pediatrics(19th ed)chap318
• Kokkonem J, Haapalabit M, Laurila K, et al: Cow's milk protein-sensitive enteropathy at school age. J Pediatr 2001;139:797-803.
• Sampson HA, Anderson JA: Summary and recommendations: Classification of gastrointestinal manifestations due to immunologic reactions to foods in infants and young children. J Pediatr Gastroenterol Nutr 2000;30:S87
• Sicherer SH, Noone SA, Koerner CB, et al: Hypoallergenicity and efficacy of an amino acid-based formula in children with cow's milk and multiple food hypersensitivities. J Pediatr 2001;138:688
• Sicherer SH: Food protein-induced enterocolitis syndrome: Clinical perspective. J Pediatr Gastroenterol Nutr 2000;30:S45.
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