Bird-Egg Syndrome: A Cross-Reactive Allergy Between Birds and Eggs
Bird-Egg Syndrome is a rare but significant IgE-mediated allergic condition where individuals who are sensitized to bird proteins (feathers, dander, meat) develop cross-reactive allergic reactions to egg yolk. The major allergen responsible is Alpha-Livetin (Gal d 5), a serum albumin protein found in both bird tissues and egg yolks.
How Bird-Egg Syndrome Develops in the Immune System
Initial Sensitization (Bird Exposure)
- Frequent exposure to bird feathers, dander, or poultry meat (e.g., pet birds, bird handlers, poultry farm workers) leads to sensitization to bird serum albumin (Livetin).
- Dendritic cells in the respiratory tract present Livetin to naive T-helper (Th2) cells, which then activate B-cells.
- B-cells produce IgE antibodies specific to bird serum albumin (Livetin), which bind to mast cells and basophils, priming them for future allergic reactions.
Cross-Reactivity with Egg Yolk
- When egg yolk is consumed, Alpha-Livetin (Gal d 5) is recognized as “foreign” by pre-existing IgE antibodies.
- Mast cells degranulate, releasing histamine and inflammatory mediators.
- Symptoms appear rapidly, ranging from mild to severe allergic reactions.
Major Allergen in Bird-Egg Syndrome: Alpha-Livetin (Gal d 5)
| Allergen | Protein Family | Molecular Weight | Source | Immune Reaction | Heat Stability |
| Alpha-Livetin (Gal d 5) | Serum Albumin | ~66 kDa | Egg yolk, bird serum, feathers, meat | Triggers IgE-mediated allergy to both birds and eggs | Heat-labile (denatured by cooking) |
- Gal d 5 (Livetin) is a heat-sensitive allergen, meaning cooked egg yolk may be better tolerated than raw egg yolk in some cases.
- Livetin is present in both egg yolk and bird tissues, leading to cross-reactivity between birds and eggs.
Symptoms of Bird-Egg Syndrome
Mild to Moderate Symptoms
- Skin: Hives, eczema, swelling (angioedema)
- Gastrointestinal (GI): Nausea, vomiting, diarrhea, abdominal pain
- Respiratory: Sneezing, nasal congestion, wheezing, asthma-like symptoms
- Oral Allergy Syndrome (OAS): Itchy mouth/throat after eating egg yolk
Severe Symptoms (Anaphylaxis) Requires immediate administration of epinephrine (EpiPen®).
- Airway restriction: Difficulty breathing, throat swelling
- Drop in blood pressure (anaphylactic shock)
- Dizziness, fainting, confusion
- Swelling of lips, tongue, or face
- Tachycardia (rapid heartbeat)
Cross-Reactivity in Bird-Egg Syndrome
Individuals with Bird-Egg Syndrome often develop cross-reactivity with multiple sources of avian proteins.
| Cross-Reactive Allergen | Common Sources | Cross-Reactive Protein |
| Bird Feathers/Dander | Pet birds (parrots, canaries, pigeons), poultry farms | Alpha-Livetin (Gal d 5) |
| Poultry Meat | Chicken, turkey, duck | Serum Albumins (similar to Livetin) |
| Egg Yolk | Chicken eggs, duck eggs, quail eggs | Alpha-Livetin (Gal d 5) |
Individuals with Bird-Egg Syndrome may experience allergic reactions when handling birds, eating poultry meat, or consuming egg yolk.
Diagnosis of Bird-Egg Syndrome
Skin Prick Test (SPT)
- Detects IgE-mediated allergic response to egg yolk and bird proteins.
Serum IgE Testing
- Measures specific IgE antibodies to Alpha-Livetin (Gal d 5).
Oral Food Challenge
- Gold standard for confirming egg yolk allergy, performed under medical supervision.
Component-Resolved Diagnostics (CRD)
- Identifies specific allergenic proteins (Gal d 5) to assess cross-reactivity risk.
Managing Bird-Egg Syndrome
Avoidance Strategies
| Trigger | Avoidance Measures |
| Egg Yolk | Avoid raw or undercooked egg yolk; cooked eggs may be tolerated in some cases. |
| Bird Exposure | Limit contact with pet birds, bird feathers, and poultry farms. |
| Poultry Meat | Some individuals may need to avoid chicken or turkey meat. |
Alternative Egg-Free Options
| Egg-Free Substitute | Safe Alternative |
| Baking (Egg Replacement) | Flaxseed meal, chia seed gel, apple sauce |
| Egg-Free Protein Sources | Lentils, tofu, soy protein |
| Vegan Egg Substitutes | Commercial egg replacers (e.g., JUST Egg) |
Emergency Treatment
- Epinephrine injection (EpiPen®) for anaphylaxis.
- Antihistamines for mild allergic reactions.
- Corticosteroids for prolonged symptoms.
Conclusion
- Bird-Egg Syndrome is a cross-reactive allergy between bird proteins (feathers, dander, meat) and egg yolk (Gal d 5 – Livetin).
- Symptoms range from mild skin reactions to severe anaphylaxis.
- Cooking may reduce allergenicity, meaning some individuals tolerate well-cooked egg yolks.
- Cross-reactivity exists with pet birds, poultry meat, and other avian proteins.
- Diagnosis requires IgE testing for both bird and egg allergens, and strict avoidance or medical management is recommended.