Egg White Allergy Test
Latin name: Gallus spp.
Source material: Freeze-dried hen’s egg-white
Egg white is a food which may result in allergy symptoms in sensitised individuals.
Egg White 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 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 white is also sometimes used for producing foam in root beer, and in some coffee and wines for clarification.
Egg White 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.
Ovomucoid, ovalbumin, ovotransferrin (also called conalbumin) and lysozyme are the most important allergens in egg white.
Egg White 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 White Allergy Test: Clinical Experience
Hen’s egg is one of the most frequent causes of immediate 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.
Egg white is often responsible for the early development of urticaria and eczema during infancy. Pruritus and exacerbation of atopic dermatitis were the symptoms most often recorded in a study of 84 egg-allergic children.
In one study of 75 children in Singapore, aged below 3 years, with symptoms of asthma, rhinitis, eczema, or food allergy, the prevalence of IgE sensitisation was highest for cow’s milk (45.9%) followed by egg white (38.7%).
In a study of 674 patients referred to an allergy unit in Spain, the prevalence of food allergy was found to be 9.1%. The foods most frequently involved in allergic reactions were fruits (56.6%) and tree nuts (22.6%). However, egg white was implicated in about 10% of the food allergy group.
An Australian study of 59 predominantly breast-fed young infants found that 80% were positive to egg white, which was by far the most common positive test.
Egg white has also been implicated in adult patients with eosinophilic esophagitis.