From the Guidelines
Individuals with shellfish allergies, specifically crustacean allergies, do not necessarily have mollusk allergies, as the two groups contain different allergenic proteins. The allergenic proteins in crustaceans, such as tropomyosin, are distinct from those in mollusks, which may involve different allergens 1. According to the guidelines for the diagnosis and management of food allergy in the United States, research suggests that about 14-20% of people allergic to crustaceans can safely consume mollusks, although cross-reactivity between these groups does occur in some individuals 1. Key points to consider include:
- Crustacean allergies are typically triggered by a protein called tropomyosin, while mollusk allergies may involve different allergens 1
- Cross-reactivity between crustaceans and mollusks occurs in some individuals, with approximately 47% of individuals with crustacean allergy also reacting to mollusks 1
- If you have a diagnosed crustacean allergy but want to try mollusks, you should first consult with an allergist who may recommend skin testing or supervised food challenges to determine if mollusks are safe for you 1 It is essential to note that shellfish allergies can cause severe, potentially life-threatening reactions, and individuals with confirmed shellfish allergy should always carry prescribed emergency medication like epinephrine auto-injectors 1.
From the Research
Allergies to Crustaceans and Mollusks
- Individuals with crustacean allergies do not necessarily have mollusk allergies, as the two are distinct groups of shellfish 2, 3.
- However, cross-reactivity between crustaceans and mollusks can occur, and some individuals may react to both 2, 4.
- The degree and pattern of cross-reactivity between different shellfish species is still unclear, and more research is needed to fully understand the relationship between crustacean and mollusk allergies 3, 4.
Diagnosis and Detection of Shellfish Allergies
- Current diagnostic methods, including skin tests and IgE reactivity measurements, are inadequate to predict cross-reactivity between crustaceans and mollusks 3.
- Skin tests with fresh material may be more effective in detecting mollusk hypersensitivity, but a combination of clinical history, diagnostic instruments, and tolerance tests is recommended to make an informed decision about avoiding mollusks 3.
- Various analytical methodologies, including ELISA and real-time PCR, are employed in crustacean shellfish allergen detection, but the choice of method depends on the specific application and matrix 5, 6.
Clinical Characteristics of Shellfish Allergic Patients
- Shellfish allergic patients often exhibit a high degree of skin test cross-reactivity between different species of shellfish, including both crustaceans and mollusks 4.
- A history of severe anaphylaxis is common among shellfish allergic patients, and strict dietary avoidance of shellfish is often necessary to prevent adverse reactions 4, 6.
- Food processing techniques can alter the allergenic properties of crustacean shellfish, but no available methods can completely eliminate the risk of allergy, and sensitive detection techniques are necessary to ensure consumer safety 6.