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Adverse food reactions Pauline Powell. Young et al. Lancet 1994;343;1127-1130 7500 households in both High Wycombe and the rest of UK 20,000 individuals.

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Presentation on theme: "Adverse food reactions Pauline Powell. Young et al. Lancet 1994;343;1127-1130 7500 households in both High Wycombe and the rest of UK 20,000 individuals."— Presentation transcript:

1 Adverse food reactions Pauline Powell

2 Young et al. Lancet 1994;343;1127-1130 7500 households in both High Wycombe and the rest of UK 20,000 individuals in each location 19.9% and 20.4% complained of food intolerance Prevalence of positive reactions by DBPCFC to 8 test substances indicated 1.5% for the study population (egg, milk, wheat, soya, orange, prawn, peanuts and tree nuts, and chocolate)

3 Food Hypersensitivity among Finnish university students: association with atopic disease Postal questionnaire sent to all 1st yr university students - 14202 413 students identified, 195 asthma/wheezing and 218 symptom free 296/413 took part in final examination, 152 vs 144 172/286 (60%) reported food hypersensitivity (F>M) 10% kiwi and celery (birch/mugwort) 9% peanut Clin Exp Allergy 2003; 33: 600-606 Clin Exp Allergy 2003;33:600-6

4 Food reactions Food allergy including anaphylaxis Food intolerance -related to amount Food aversion - simple dislikes through to anorexia nervosa and bulimia

5 Prophylaxis - with protection Anaphylaxis - without protection Porter and Richet 1902

6 Clinical features of Anaphylaxis Laryngeal oedema Hypotension/collapse Bronchospasm Feeling of impending doom Onset usually within minutes Almost invariably symptoms begin within 60 mins Generally the later the onset the less severe the symptoms 30% have a biphasic reaction, 1-4 hours later

7 Food Allergy Reactions reported in blinded challenges Anaphylaxis, inc food dependent exercise induced anaphylaxis Urticaria and angioedema Rhinoconjunctivitis, laryngeal oedema, asthma Abdominal pain, nausea, vomiting and diarrhoea

8 Common food allergens Adults Peanut Tree nuts Fish Shellfish Wheat Children Milk (cows, goat etc) Hen’s egg Peanut Tree nuts Soya Wheat Fish

9 Prevalence of anaphylaxis - unknown but increasing Mayo Clinic Emergency Dept - 3.5yrs 179 patients with respiratory and/or CVS symptoms with urticaria 66% female 49% atopic 37% previous immediate reaction to the allergen Mayo Clin Proc 1994:69:16-23

10 Probable cause identified in 142/179 Food 33% Bee sting 14% Medications 13% Exercise 7% Idiopathic 19%

11 Foods implicated Peanut Cereals - wheat Egg Tree nuts Milk

12 5yr survey at Children’s Hospital of Philadelphia 7 cases of fatal anaphylaxis during a 16 month period 6/7 unknowingly ingested a food that provoked a previous allergic reaction JAMA 1988;260:1450-1452 Fatalities due to anaphylaxis

13 R isks factors Asthma - albeit well controlled Unaware of ingesting food allergen All experienced previous allergic reaction to the incriminating food - usually milder All had immediate symptoms Half experienced quiescent period prior to major respiratory collapse NEJM 1992;327:380-384

14 Incidence of food allergy maximal in first 2yrs of life and decreases with age Cow’s milk*-3 years Egg* - 5 years Soy (bean)* Wheat Peanut, tree nut, fish and shellfish allergy often persist into adulthood *usually outgrown

15 Increased exposure may result in increased prevalence Peanut in USA Cod fish in Scandinavia Rice and buckwheat in Japan Sesame in Israel - in tehini and halva second only to milk Allergy 57:362-5;2002

16 Food problems in latex sensitive individuals Banana Kiwi Avocado Sweet chestnuts Melon Peach Papaya Passion Fruit Fig Celery

17 Latex allergy-risk factors Atopic status and hand eczema Health care personnel Patients undergoing multiple operations Rubber industry workers

18 Birch pollen oral food syndrome - usually raw fruit and vegetables Hazel nut Apple Peach Cherry Almond Plum Kiwi Apricot Potato peel Brazil nut Cashew Tomato Celery Fennel Carrot

19 Allergy skin testing in predicting positive challenges 555 challenges in 467 children 339 cows milk, 121 egg, 95 peanut. 55% challenges positive, 37%negative, 18% inconclusive No negative challenges if skin weal diameter > 8mm milk, 7mm egg, 8mm peanut (100% specificity) By utilizing these measurements, the need for formal food challenges can be reduced R. Sporik et al. Clin Exp Allergy 2000; 30:1540-1546

20 Peanut - the most allergenic food Family Leguminosae Ground nut Arachis oil - previously in nipple creams Monkey nuts Can affect all ages; < 20% can outgrow this allergy, particularly if they have early onset (< 1yr) and mild symptoms. Hourihane, BMJ 1998:316:1271-5

21 Seafood Crustaceans Shrimps Prawns Crabs Lobster Crayfish More important Molluscs Clams Scallops Oysters Mussels Snails Squid Octopus

22 Food additives Sulphites and Papain are the only ones for which evidence of ‘anaphylaxis’ exists.

23 Factors that enhance severity of anaphylaxis Exercise Viral infection Asthma Stress

24 Diagnosis Very careful history Inciting food is usually obvious Cooked or uncooked Concealed ingredients Contaminants “Natural flavouring” e.g. casein Exclude scombroid poisoning

25 Laboratory evaluation 1 Identify specific IgE antibody in vivo or in vitro A negative skin prick test is a excellent predictor for a negative IgE mediated food reaction in patients with anaphylaxis

26 Skin prick testing issues Concomitant antihistamines Sub-optimal allergen extracts Carry over Use of natural food - prick to prick testing Use negative and positive controls NEVER do intradermal testing without prior skin prick testing

27 Specific IgE antibodies Skin prick testing (>3mm bigger than neg) ‘RAST’ testing Overall, ‘RAST’ is considered less sensitive and less specific than skin prick testing DBPCFC is contraindicated in patients with an unequivocal history of anaphylaxis following the isolated ingestion of a food to which they have significant IgE antibodies

28 Management of food allergy Prevention is the cornerstone but mistakes do happen! Education - home and schools, emergency treatment plan Self injectable epinephrine (Epipen/Anapen)-for whom? Junior 0.15mg vs Senior 0.3mg - use early in anaphylaxis Antihistamine - tablet or liquid - Zirtec sugar free Hydrocortisone iv/im to prevent late phase reactions MedicAlert scheme Anaphylaxis campaign Food re-introduction for milk and egg only

29 Interactions with adrenaline  Blockers Amitriptyline (tricyclics)

30 The future Improved food labelling regulations Avoidance inadvertent contamination Avoid defensive labelling ?Desensitisation/anti IgE Nutritional genomics

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