Dr Jinan Harith Darwish explains the triggers for anaphylactic reactions and aspects of avoidance and treatment.
Anaphylaxis has been recently defined as “a serious allergic reaction that is rapid in onset and may cause death in an otherwise healthy individual”. Though avoidance of food allergens is critical, timely administration of epinephrine is also crucial in the management of food-induced anaphylaxis.
Food-induced anaphylaxis is the common variant of the condition treated in emergency departments around the world. Peanuts, tree nuts, fish, and shellfish are, for the most part, commonly implicated. Food-induced anaphylaxis may occur in any age group and with any food. However, fatalities disproportionately affect adolescents and young adults with peanut and tree nut allergy. People who have both a food allergy and asthma are at a higher risk of food-induced anaphylaxis fatality. Delayed administration of epinephrine is also associated with fatal outcomes.
Any food can cause anaphylaxis in a vulnerable individual, although in the USA and Germany, peanuts and tree nuts (walnuts, pecans, pistachios, cashews and others) account for the greatest proportion of severe anaphylactic reactions. Shellfish (crustaceans and molluscs) and fish follow. In other parts of the world, foods that are prominent in the regional diet are chief culprits, including sesame in Israel and seafood in China.
Additional observations include the following:
• Milk, egg and sesame are more frequent culprits in children.
• Fatal food-induced anaphylactic reactions may be induced by peanuts, tree nuts and cow’s milk.
• Wheat sensitivity is one of the most common causes in food-dependent, exercise-induced anaphylaxis (FDEIAn), although shellfish, celery, other cereal grains and a variety of foods have been implicated.
• Certain mammalian meats (particularly beef, lamb and pork) can cause anaphylaxis that is delayed in onset by a number of hours, occasionally waking individuals in the middle of the night. While meat is not a common cause of food-induced anaphylaxis, awareness of its distinctive presentation is critical to identifying the guilty food.
It is essential that people with food-induced anaphylaxis receive an in-depth assessment to identify and confirm the culprit food allergen. Defining the patient’s food allergies with certainty allows for the following:
• Effectual evasion without unwarranted dietary restrictions.
• Enhanced observance with avoidance recommendations.
• Reduction of patient/caregiver apprehension linked with an unidentified trigger.
Definitive diagnosis of food allergy is often not straightforward. It customarily requires skin testing and/or in vitro testing, sometimes followed by supervised food challenges
to make certain that the correct food has been identified.
Effective avoidance requires ongoing education, meticulous attention to food labelling and avoidance of situations where foods are commonly cross-contaminated: eg buffets, areas where negligible allergenic ingredients are often present, such as Asian cuisine restaurants, or where food allergens may become aerosolised, such as in seafood restaurants.
Epinephrine can restrict and reverse the allergic reaction and should be administered immediately, or as quickly as possible, following the correct steps. Delayed administration is believed to be a contributing factor in some deaths. In a study of 13 fatal or near-fatal food-induced anaphylactic reactions in children, six of the seven children who survived received epinephrine within 30 minutes of ingesting the allergen, whereas only two of the six children who died received epinephrine within the first hour. Epinephrine auto-injectors are often prescribed for those with a known allergy and it’s recommended to learn and practise their correct usage and carry two at all times.