Egg Allergy Test
Latin name: Gallus spp.
Source material: Freeze-dried content of whole hen’s egg
Egg is a food which may result in allergy symptoms in sensitised individuals.
Egg Allergy Test: Allergen Exposure
Birds’ eggs are a common food source. Those most commonly used by humans include chicken, duck and goose eggs, however other species’ eggs are used occasionally, often as a delicacy, for example ostrich or quail eggs.
Foods that may contain egg include salad dressings, breads, breaded foods, muffins, pancakes, waffles, meringues, marshmallows, prepared soups and beverages, frostings, ice cream and sherbets, pie fillings, sausages, prepared meats, mayonnaise, coatings and breading for fried foods, tartar and hollandaise and other sauces.
Egg yolks, separated from the egg white, are an important ingredient in many European dishes due to the emulsifying action of lecithin which makes them an ideal binding agent. This is vital for the proper preparation and desired consistency and texture of mayonnaise and sauces such as Béarnaise, and hollandaise; custards such as crème anglaise, crème brûlée, crème caramel, lemon custard and key lime pie; and meat dishes such as pâté and meatloaf.
Egg white, or albumen, contains little to no fat but does contain protein. When separated from the yolk, it can be used in a number of dishes, often whipped into a fluffy consistency and used to make desserts such as meringues and mousse.
Egg Allergy Test: Allergen Description
The total number of egg proteins is not known, but more than 40 have been suggested for egg-white alone, and up to 24 different antigenic protein fractions have been isolated.
Although the main allergens in egg are found in the egg white, egg yolk also contains a large number of specific IgE-binding allergens.
Egg Allergy Test: Potential Cross-Reactivity
Although cross-reactivity between egg white and egg yolk is not common (unless there is contamination of either by the other), some degree of cross-allergenicity has been demonstrated between hen’s egg white and egg yolk proteins, signifying that there are a number of common allergenic determinants on these egg proteins.
Cross-reactivity between chicken egg white and turkey, duck, goose and seagull egg whites has been demonstrated.
Egg Allergy Test: Clinical Experience
Allergy to egg is generally agreed to be one of the most common causes of food allergy in infants and young children. Egg white is generally more allergenic than egg yolk. Clinical reactions to egg are predominantly characterised by atopic dermatitis, urticaria, angioedema, vomiting, diarrhoea, rhinoconjunctivitis and asthma.
Clinical reactions to egg are predominantly characterised by atopic dermatitis, urticaria, angioedema, vomiting, diarrhoea, rhinoconjunctivitis and asthma.
Isolated respiratory symptoms are infrequent and almost always associated with cutaneous or digestive symptoms. Respiratory symptoms after egg ingestion are more frequent in patients sensitised to bird proteins (bird-egg syndrome). The onset of symptoms may be rapid, developing a few minutes after ingestion of the causative allergen.
Eosinophilic esophagitis as a result of allergy to egg has been described. Egg has also frequently been associated with childhood asthma.
Egg-allergic children may occasionally develop contact urticaria to hen’s egg and yet have no overt symptoms on ingestion.