A 28-year-old woman presents with recurrent episodes of urticaria and angioedema following ingestion of shellfish. Skin prick testing confirms IgE-mediated sensitization. Which of the following is the most common cause of IgE-mediated food hypersensitivity in adults in India?

Explanation

## Most Common IgE-Mediated Food Allergen in Indian Adults **Key Point:** Shellfish and crustaceans (shrimp, crab, lobster) are the most common cause of IgE-mediated food hypersensitivity in Indian adults, reflecting high seafood consumption in the Indian diet. ### Epidemiology of Food Allergy in India **High-Yield:** The prevalence and pattern of food allergies vary geographically based on dietary habits: - **Shellfish/crustaceans**: Most common in coastal and seafood-consuming populations; accounts for ~40–50% of adult-onset food allergies in India - **Peanuts**: More common in Western populations; accounts for ~25% of food allergies in USA and Europe - **Milk**: More common in children globally; becomes less prevalent in adults due to lactase persistence - **Wheat**: Associated with celiac disease (IgA-mediated) and wheat allergy (IgE-mediated); less common than shellfish allergy ### Mechanism of Shellfish Allergy 1. **Allergen**: Tropomyosin (cross-reactive across crustaceans and molluscs) and other heat-stable proteins 2. **IgE binding**: Sensitization occurs via oral mucosa and GI tract 3. **Symptoms**: Urticaria, angioedema, oral allergy syndrome, anaphylaxis (within minutes to 2 hours) 4. **Diagnosis**: Skin prick test (immediate wheal-and-flare), serum-specific IgE ### Comparison of Common Food Allergens | Allergen | Geographic Prevalence | Age of Onset | Persistence | Clinical Features | |---|---|---|---|---| | **Shellfish** | High in Asia/India | Adults | Lifelong | Urticaria, anaphylaxis | | **Peanuts** | High in Western countries | Childhood | Lifelong | Severe anaphylaxis | | **Milk** | High globally | Infancy/childhood | Often resolves by age 3–5 | GI + cutaneous | | **Wheat** | Moderate | Variable | Variable | Oral allergy, anaphylaxis | **Clinical Pearl:** Shellfish allergy in Indian patients often presents with acute urticaria and angioedema within 30 minutes of ingestion; anaphylaxis risk is significant, warranting epinephrine auto-injector prescription. **Tip:** In NEET PG exams, when asked about "most common food allergen in India" without age specification, default to **shellfish** for adults and **milk** for children.