D2.219 - An “egg-bird syndrome” in a 12-year-old male child

Introduction

Bird-egg syndrome is a rare form of food allergy, characterized by sensitization to egg proteins followed by allergic reactions to eggs and poultry meat. The primary allergen is usually alpha-livetin (Gal d 5), a chicken serum albumin present in egg yolk and poultry meat, causing a cross-reactivity syndrome. 

We present a case of secondary poultry meat allergy in a 12-year-old male child, showcasing a complex sensitization profile. Mother consent was obtained.

Case report

The patient's allergic journey began at age two with cutaneous reactions to hen's egg. By age three he had a cutaneous syndrome upon dog exposure. At age six he experienced cutaneous/gastrointestinal symptoms when exposed to cashew. At age eight he developed pharyngeal itching when consuming poultry meat. By age nine he began to have rhinitis and asthma upon direct/indirect contact with dogs. 

ImmunoCAP testing showed positivity to Ana o 3, Cor a 9, Gal d 5, Gal d 3, and polysensitization to various dog and cat molecular allergens. 

To differentiate between secondary poultry meat allergy due to hen's egg sensitization and potential cross-reactivity with dog serum albumin, SDS-PAGE immunoblotting was performed, which failed to demonstrate cross-reactivity between poultry and dog proteins (in line with the literature, according to which cross-reactivity between mammal and avian serum albumins is uncommon, as sequence identities is low). The diagnosis of secondary poultry meat allergy in the context of bird-egg syndrome was made, as initial sensitization to egg alpha-livetin led to cross-reactivity with avian serum albumins in muscle tissue. 

The patient was placed on a restrictive diet, excluding pistachio, cashew, poultry meat, and undercooked hen's egg. By age 10, due to the restrictive diet and a poorly controlled asthma from dog epithelium exposure, omalizumab has been initiated. After one year of treatment the child experienced a significant reduction in asthmatic crises and improved tolerance to poultry meat.

This case illustrates a rare/complex food allergy profile. It highlights how sensitization to egg can evolve into a broader spectrum of allergies, including poultry meat allergy. The case underscores the importance of comprehensive allergen testing and long-term follow-up, while demonstrating the potential of omalizumab in managing severe/multi-faceted allergic conditions.