Unfortunately, our knowledge in this area is somewhat limited. We have very little published data upon which to make a conclusion about the possible allergenic cross-reactivity between hen and duck egg. What we do know is that immunologic cross-reactivity has been demonstrated between hen (chicken) egg-white and turkey, duck, goose, and seagull egg-white (1). However, the clinical significance of this allergenic cross-reactivity has not been established.
For example, we do know that patients who have IgE-mediated reactions to duck and goose egg can on occasion eat hen egg without difficulty (2).
These articles, when reviewed by Dr. Wesley Burks and Associates (3), had them come to the conclusion that although antigenic cross-reactivity has been demonstrated, such clinical cross-reactivity is rare (3).
Taking these studies into consideration, I think that the idea of skin testing to duck egg-white and yolk is reasonable, but as you know, the only true valid test to detect clinical sensitivity is an oral challenge. Thus, if the skin tests were negative, I would still suggest an oral challenge, and that could be done to cooked duck egg similar to challenges performed to hen egg (4).
Thank you again for your inquiry and we hope this response is helpful to you.
(1) Langeland T. A clinical and immunological study of allergy to hen's egg white. VI. Occurrence of proteins cross-reacting with allergens in hen's egg white as studied in egg white from turkey, duck, goose, seagull, and in hen egg yolk, and hen and chicken sera and flesh Allergy 1983;38(6):399-412.
(2) Anibarro B, Seoane FJ, Vila C, Lombardero M. Allergy to eggs from duck and goose without sensitization to hen egg proteins. J Allergy Clin Immunol 2000;105(4):834-6.
(3) Food allergens Burks, Wesley; Helm, Ricki; Stanley, Steve; Bannon, Gary A. Current Opinion in Allergy & Clinical Immunology. 1(3):243-248, June 2001
(4) J Allergy Clin Immunol. 2012 Jun;129(6):1682-4.e2. Outcomes of 100 consecutive open, baked-egg oral food challenges in the allergy office. Lieberman JA, Huang FR, Sampson HA, Nowak-Wêgrzyn A.
Phil Lieberman, M.D.