Egg Yolk Allergy Test
Latin name: Gallus spp.
Source material: Freeze-dried hen’s egg yolk
Egg yolk is a food which may result in allergy symptoms in sensitised individuals.
Egg Yolk 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 yolk is an important emulsifier agent in the food industry for a number of processed foods, and may therefore be considered a hidden allergen.
Egg Yolk Allergy Test: Allergen Description
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 Yolk 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.
Egg Yolk 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. Some researchers have reported that in egg-allergic children, IgE antibodies were found in more than 65% of children with eczema and respiratory tract symptoms. However, few studies have differentiated between allergies to whole egg, egg white and egg yolk.
Egg yolk has been implicated in adult patients with eosinophilic esophagitis.
It has been suggested that egg intolerance in adults is due to sensitisation to egg yolk and can be provoked by inhalation of tame bird dander (bird-egg syndrome), and thus is not the same as egg white allergy in atopic children.
One case report described an elderly woman who became egg allergic as a result of inhalant allergen sensitisation from a parrot. The patient revealed high levels of IgE antibodies to Egg yolk and to various bird sera.
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.