Understanding Mollusc Allergy

A mollusc allergy is an immune system reaction to proteins found in certain marine animals, specifically molluscs. Molluscs include bivalves (e.g., mussels, oysters, scallops, and clams), gastropods (e.g., snails), and cephalopods (e.g., squid and octopus) (Anaphylaxis UK).

Common Symptoms

Symptoms of a mollusc allergy can range from mild to severe and typically occur within minutes to two hours after ingestion. Common symptoms include:

  • Skin reactions: Hives, itching, or swelling.
  • Respiratory issues: Wheezing, coughing, or difficulty breathing.
  • Gastrointestinal distress: Nausea, vomiting, or diarrhea.
  • Anaphylaxis: A severe, potentially life-threatening reaction characterized by swelling of the throat and tongue, difficulty breathing, and a drop in blood pressure (NHS).

Foods That May Contain Molluscs

Molluscs are often used in various dishes and products, sometimes without clear labeling. Foods that may contain molluscs include:

  • Asian cuisine: Dishes like prawn fried rice or seafood chowder may contain molluscs or fish and shellfish disguised in stocks or sauces.
  • Rice dishes: Paella, fried rice, and sushi rolls may contain molluscs.
  • Battered or crumb-coated foods: Items such as scampi, fish fingers, or seafood sticks.
  • Stews, soups, or casseroles: Examples include seafood chowder or bouillabaisse.
  • Dips or pates: Such as taramasalata, salmon, and caviar or roe.
  • Sauces: Worcestershire, oyster, and fish sauces, which can be added to many different types of dishes, including casseroles and stir-fries.

Diagnosis

To diagnose a mollusc allergy, healthcare providers typically:

  1. Medical history: Review symptoms and potential exposure to molluscs.
  2. Skin prick test: Small amounts of mollusc proteins are pricked into the skin to observe for allergic reactions.
  3. Blood test: Measures the level of specific IgE antibodies to mollusc proteins.

In some cases, a medically supervised food challenge may be conducted to confirm the diagnosis (Mayo Clinic).

Severity and Treatment

Mollusc allergies can be severe and are often lifelong. The primary treatment is strict avoidance of molluscs and foods containing mollusc proteins. For accidental ingestion leading to anaphylaxis, immediate administration of epinephrine (adrenaline) is crucial. Individuals at risk should carry an epinephrine auto-injector and seek emergency medical attention promptly.

High-Risk Groups

While anyone can develop a mollusc allergy, certain groups may be at higher risk:

  • Adults: Mollusc allergies often present in adulthood and are less likely to be outgrown .
  • Individuals with other allergies: Those with existing allergies, such as to crustaceans, may be at increased risk.
  • Occupational exposure: Workers in the seafood industry may develop allergies due to repeated exposure.

Precautions

To manage a mollusc allergy effectively:

  • Avoidance: Steer clear of molluscs and foods containing mollusc proteins.
  • Label reading: Always check food labels for mollusc content.
  • Cross-contamination: Be cautious of cross-contact in food preparation areas.
  • Emergency preparedness: Carry an epinephrine auto-injector if prescribed and ensure those around you know how to use it.

By understanding mollusc allergies and taking appropriate precautions, individuals can reduce the risk of allergic reactions and manage their health effectively.

Resources:

  1. Mayo Clinic: Shellfish allergy
  2. NHS: Factsheet
  3. AllergyUK
Note: This article is intended for informational purposes and should not replace professional medical advice.