Dishing out danger
Vienna, June 14, 2006. Anaphylaxis, the specialist term for a serious life-threatening generalized hypersensitivity reaction, was one of the main issues presented at the 25th Congress of the European Academy of Allergology and Clinical Immunology (EAACI) in Vienna. "Characteristic signs are the sudden occurrence of severe physical symptoms within minutes to a few hours after eating. Anaphylactic shock is fatal in approximately five percent of cases,"(1) revealed Dr. Karin Hoffmann-Sommergruber, a lecturer at the Physiology Department of the Medical University of Vienna.
Small amounts of an allergy-causing substance (allergen) are enough to trigger anaphylaxis in some people with allergies. Food allergies head the culprit list in most of the anaphylaxis studies performed to date. The allergens responsible for triggering anaphylaxis vary widely depending on regional eating habits. Peanuts, hazelnuts and walnuts are among the most common causes of fatal reactions in the USA and UK, (2, 3) whereas chicken eggs, shellfish and fish are the main allergy-causing foods in countries like France and Australia. Celery is a leading cause of anaphylactic reactions in Switzerland.4 The range of foods most likely to cause allergies also differs between children and adults. The main causers of allergies in children - very young children in particular - are milk, eggs and nuts (peanuts, hazelnuts and walnuts) followed by soybean and wheat. Most children grow out of these allergies and no longer suffer from them during adulthood. The foods most likely to trigger allergic symptoms in adults are shellfish, fish, nuts and celery.
People with allergies who eat foods containing relevant allergens may start by developing mild allergic symptoms such as hives and allergic rhinitis. In severe cases, exposure to these allergens may cause a narrowing of the respiratory tract accompanied by shortness of breath, gastrointestinal symptoms like diarrhea and vomiting, and whole-body reactions such as low blood pressure and shock.
Children are at greater risk of anaphylactic reactions. (3) Most of the patients who develop fatal anaphylactic shock from a food allergy die not because they don't know they're allergic to a particular food, but because they eat a particular foodstuff without knowing it contains "their" allergen. (3)
A new EU food labeling directive that came into effect as long ago as November 2003 is intended to help protect food allergy suffers from these risks. "Unfortunately, some countries - including Austria - have been very slow to transpose the directive into national law. I would also be in favor of a system that allows people with allergies to see exactly what's in the meals they might order in a restaurant," the microbiologist Hoffmann-Sommergruber said at this year's EAACI Congress in Vienna.
She advises people with a food allergy to make sure to study the lists of ingredients labeled on foodstuffs and to tell restaurant staff that they're allergic to a particular food. People with food allergies also need to be well informed about ways they can prevent and treat allergic symptoms. An extensive program of information significantly reduces the risk of anaphylactic reactions, as studies show. (5) Since ingestion of allergenic foods is usually accidental, people with food allergies need to be able to administer self-treatment in an emergency. Therefore, food allergy sufferers should always carry an emergency kit containing an antihistamine, epinephrine and a cortisone product.
(1) Burks WA, Sampson HA, Anaphylaxis and Food Allergy, in "Food Allergy and Adverse Reactions to Food and Food Additives" 3rd edition 2003, Blackwell publishing, D. Metcalfe, H Sampson, R Simon eds: 192- 205.
(2) Bock SA, Munoz-Furlong A, Sampson HA. Fatalities due to anaphylactic reactions to foods. J Allergy Clin Immunol 2001; 107: 191-193.
(3) Pumphrey RS, Stanworth SJ. The clinical spectrum of anaphylaxis in northwest England. Clin Exp Allergy 1996; 26: 1364-1370.
(4) Rohrer CL, Pichler WJ, Helbling A. Anaphylaxie: Klinik, Aethiologie und Verlauf bei 118 Patienten. Schweiz Med Wochenschr 1998; 128: 53-63.
(5) Ewan PW, Clark AT. Long-term prospective observational study of patients with peanut and nut allergy after participation in a management plan. Lancet 2001; 357: 111-115.
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