7.Food Allergy

May 21, 2007 smt vi lecture, foodallergy 1

Food allergy

Dewi KumaraChild Health Dept


Definition a group of disorders distinguished by the

way the body's immune system responds to specific food proteins.

Most by type I hypersensitivity reaction


Adverse reaction to food General terminology toward unwanted

reaction to food. Maybe secondary to food allergy or intolerance to food


Food intolerance Is a non immunological reaction The most common cause of adverse reaction to

food. Maybe caused by toxic contaminant ( histamine in

scromboid fish, toxin secreted by salmonella, shigella, camphylobacter)

Pharmacologic (cafein in coffee, tyramine in cheese)

Genetic: metabolism disorder( lactase/maltase deficiency)


Adverse reaction to food

Immunologic Non immunologic

Toxic

pharmacologic

metabolism

Type IHypersensitivity

Other typehypersensitivity


Some children may also be intolerant of food colorings, additives, and preservatives. Among these are yellow dye number 5, which can cause hives; and monosodium glutamate, which produces flushing, headaches, and chest pain. Sulfites, another additive, have been found to cause asthmatic reactions and even anaphylactoid reactions. Sulfites are preservatives used in wines, maraschino cherries, seafood, and soft drinks. They are sometimes put on fresh fruits and lettuce to maintain their fresh appearance, on red meats to prevent brown discoloration, and even in prepared deli foods like crab salad. Sulfites appear on food labels as sodium sulfite, sodium bisulfite, potassium bisulfite, sulfur dioxide, and potassium metabisulfite. The U.S. Food and Drug Administration (FDA) has banned the use of sulfites as a preservative for fruits and vegetables, but they are still in use in some foods.

http://www.healthline.com/adamcontent/hives

http://www.healthline.com/adamcontent/pubic-lice


Statistics:

Eight percent of children < 6 years experience food intolerances. Of this group, 2 to 4%: allergic reactions to food.

Peanut and/or tree nut (e.g. walnut, almond and cashew) allergy affects about three million Americans, or 1.1% of the population.

In US, 150 die / year from food-related anaphylaxis. .


Etiology of food allergyChildren Adultmilk peanutsegg tree nutspeanuts fishwheat shellfishsoy

tree nuts (walnuts and pecans

Children will often outgrow their allergy to these food protein

The majority cause


Phatophysiology Allergen in food:

is a protein, glicoprotein or polypeptides Molecular weight > 18 000 Dalton Resistant to heat Resistant to proteolytic enzymes Fish: allergen M, egg: ovomucoid (major), cows

milk:lactoglobulin (BLG), lactalbumin (ALA), bovine serum albumin (BSA), bovine globuline (BGG)


Fish: allergen M egg: ovomucoid (major), cows milk:lactoglobulin (BLG), lactalbumin

(ALA), bovine serum albumin (BSA), bovine globuline (BGG)

Peanut: arachin, conarachin Shrimp: allergen-1, allergen 2 Wheat: albumin, pesudoglobuline, euglobuline


PathogenesisVasoctive amine: histamine,serotonin, protease

lipid mediators: prostaglandin, Leukotriene

allergenTH2 activation by Allergen

IgE class switching in B cell

IgE secreting plasma cell

Binding of IgE to FcέRI on mast cells

Degranulation of mast cell: release mediators

GIT, RT,CV

Cytokine:

Late phase reaction: 2-4 hrs


Predisposing factors associated with Food allergy Genetic : risk of allergy from parent GI immaturity: GI mucosal integrity,

peristaltic , enzymes, acidity, sIgA Allergen exposure : in utero – milk,

breastmilk, norm & tradition in certain area.

Triggering factors are not the cause. Without exposure, triggering factors are not matters. Could be cold, heat, rain, psychological stress, excercise


Clinical manifestation


Clinical manifestation GIT: tingling, itchy mouth, edema

mouth, tongue, palatum, pharyngeal, nausea/vomitting, abdominal cramp, distention, diarrhea, bleeding, protein losing enteropathy

Respiratory tract: Rhinitis, asthma, recurrent chronic cough, difficult breathing

Skin: hives, angioedema, atopic dermatitis

Cardiovascular: drop in blood pressure anaphylaxis shock death

eyes ache,

Food induced anaphylaxis: peanut, sea fish, shrimp, cow’s milk, egg, soy


Symptoms of food allergies

Symptoms typically appear within minutes to two hours after the person has eaten the food to which he or she is allergic.

Individuals with food allergy and asthma appear to be at an increased risk for severe or fatal allergic reactions.


Laboratory investigation Skin test CBC CXR IgE total & Specific


Information obtainable from history Description of symptom & sign Timing from ingestion to onset of symptoms Frequency with which reactions have occurred Time of most recent occurrence Quantity of food required to evoke reaction Associated factors (activity) Medication Reproducibility, esp for subjective symptoms (behaviour,

headache) Potential cross-contact (contamination of other foods, dust

mites)


Diagnosis (Elimination and ) Provocation test

Not done if clinical manifestation is anaphylactic and laryngeal edema


Management Based on symptoms Pharmacotherapy Avoidance


Prognosis Can not be cured Control symptom, reduce intensity Reduce frequency Reduce medication use Reduce absence day Dermatitis reduce after 12 year


•Breast feed at least 4 months (preferably at least 6 months) •Avoid exposure to tobacco smoke and don't smoke during pregnancy •Delay the introduction of solids until age 4-6 months •Introduce new foods one at a time so that allergic reactions can be more readily identified •Introduce rice, vegetables, meat and fruits first •Delay the introduction of egg until at least 12 months •Delay the introduction of nuts and seafood until at least 24 months

Can food allergies be prevented?


There is little or no evidence at this time that severely restricting a mother's diet during pregnancy will prevent food allergy. Indeed, severe restrictions may affect the nutrition of the developing baby.

There is some evidence that certain dietary restrictions during breast feeding may be of some benefit. Any food avoidance should be done with medical or dietetic advice so that maternal nutrition is not compromised.


Case A girl, 5 years old, complaining of red wheal all over the body,

started a day before admission. This is the second episode after the same complaint 4 month ago. Her mother did not notice any possible cause, but, history taking showed that patient is an-egg lover, who has been consumed 4-5 egg everyday since she was 3 years-old. Father has asthma, but mother is generally well. In this case:1. What is the mechanism that underlying the clinical manifestation, if egg

is really a cause of the red wheal?2. Food allergy mediated by immunoglobulin (Ig). Which class of Ig it is ?3. What is the role of loving egg for the development of the disorder?4. What is the importance of parental history?5. Do you have any other question to ask to parents. Name them.6. What test(s) that you plan for the patient?7. What is your suggestion for the management of the case?


Learning task In true food allergy, what mechanism that related

to the clinical manifestation Why food allergy manifests in various organ

systems? What test are needed to support diagnosis of food

allergy? What tests are needed to confirm food allergy ? What are the basic principles of management of

food allergy

7.Food Allergy

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