Egg allergy: A case of ‘egg-zema’

Editor’s Note: In Healio Allergy/Asthma’s new column, “Food Allergy: Fact vs. Fiction,” Douglas H. Jones, MD, breaks down what’s true and what’s myth for a variety of topics related to food allergies. If you have a question you would like answered in this column, email Jones at rmaaimd@gmail.com or Sasha Todak at stodak@healio.com.

During my first year of medical school, I helped treat my first food allergy patient, an adult who reacted to ham-fried rice at a local Chinese restaurant.

Douglas H. Jones

There were several potential triggers for that reaction including milk, egg, soy, sesame, rice, pork and onion. After proper testing, it turned out that egg was the culprit. It was unusual for an adult to have a new-onset egg allergy, as it is often something that happens in children.

Egg allergy has been shown to be the most common food allergy among children with eczema. It is the second most common food allergy, overall, among infants and young children, second only to cow’s milk in prevalence. It commonly presents in the second half of the first year of life, but it can start anytime, even in adults as noted above.

Here are some key pearls to egg allergy:

• Although approximately 50% of children are likely to outgrow their egg allergy by age 6 years, research suggests that children are outgrowing their egg allergy more slowly than before.
• The majority of egg allergies are due to proteins in the egg whites (ovomucoid and ovalbumin). However, egg yolks cannot be safely separated from residual egg whites even if strained.
• Quail (69%) and duck (66%) are the most commonly cross-reactive eggs and should also be avoided in those with hen’s egg allergy given the high rate of cross-reaction.

Vaccinating patients with egg allergy

When it comes to vaccination, there is only one contraindicated vaccine to those with egg allergy: yellow fever. Contrary to popular belief, influenza vaccine is no longer contraindicated for those patients with egg allergy and the Advisory Committee on Immunization Practices revised their guidelines in 2018.

Many doctors and even health care systems still ask about measles, mumps and rubella (MMR). Even though MMR are grown in chick embryo culture tissue, several studies have demonstrated its safety in children with egg allergy. Patients also can receive the influenza and COVID-19 vaccines if egg-allergic.

Testing for egg allergy

If you suspect a child has egg allergy or is at risk for developing egg allergy, the child should be evaluated by an allergist who is fluent in interpreting food allergy tests.

Testing for egg allergy is traditionally done with skin testing or serum-specific IgE tests. IgG tests have no utility in determining egg allergy, egg intolerance or egg sensitivity. Other non-validated tests for food allergy include saliva and hair analysis, electrodermal tests, kinesiology, and Nambudripad's Allergy Elimination Techniques, or NAET, are not recommended by the American Academy of Allergy, Asthma, and Immunology.

If the patient is allergic, then strict avoidance is necessary until the allergy is either outgrown or successfully treated. The most common treatment method, currently, is oral immunotherapy, or OIT.

OIT is not the same as food ladders. I am not a proponent of “food ladders” for those with egg allergy given the inconsistency of the preparations, cooking techniques and variability of the protein amount.

Preventing egg allergy

Young children should not unnecessarily avoid eggs if they are not allergic.

Notably, early introduction of egg in appropriate children lowered the risk for developing egg allergy in babies sensitized to egg. Early introduction of foods including egg also provided protection against egg allergy in babies with moderate or severe eczema at age 3 months.

Early introduction of egg can provide protection against egg allergy for at least some children at high risk for developing egg allergy. Guidance on early egg introduction is likely to evolve as more evidence becomes available.

Early introduction of egg in children is a vital question and should be discussed with your doctor. Children at risk may need to undergo evaluation to see if early introduction of eggs in the diet is appropriate.

There is much nuance to egg allergy and the early introduction of eggs in children. It is important the child be evaluated by a professional who knows proper testing and interpretation of tests, and who can also discuss the risks and benefits of avoidance, early introduction, or if OIT is indicated.

Reference:

• Du Toit G, et al. N Engl J Med. 2015;doi:10.1056/NEJMoa1414850.

For more information:

Douglas H. Jones, MD, FAAAAI, FACAAI, is cofounder of Global Food Therapy, Food Allergy Support Team and OITConnect, the director at Rocky Mountain Allergy at Tanner Clinic, and a Healio Allergy/Asthma Peer Perspective Board Member. He can be reached at rmaaimd@gmail.com.