Fish-allergic patients may be able to eat fish

Abstract

Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be ‘allergy’ but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated.

Keywords:

• anaphylaxis
• Anisakis simplex
• fish allergy
• fish poisoning
• food allergy
• occupational asthma
• occupational dermatitis
• occupational allergy
• scombroid poisoning
• seafood allergy

Acknowledgements

The authors thank C Sheaffer for assisting in grammatical review of this manuscript.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Fish is one of the potent allergenic foods and comprises more than 32,000 species. Its increasing consumption has been associated with increased prevalence of fish allergy worldwide.

• The prevalence of fish allergy is estimated at 0.2% of the general population, but varies widely according to the geographic region, dietary habits, population and study methodology.

• Fish allergy sensitization and provocation can occur by ingestion, skin contact or inhalation.

• The manifestations can affect various body systems, vary in severity, and can be IgE or non-IgE mediated.

• Fish allergy is one of many causes of adverse reactions following eating fish. Differential diagnosis should include allergy to other food ingredients, allergy to the fish parasite Anisakis simplex, scombroid poisoning and intrinsic fish toxins.

• In addition to the major allergen – parvalbumin – several fish allergens have been identified, including enolase, aldolase and vitellogenin.

• Fish allergenicity can be markedly affected by the method of processing and tends to increase by heating and decrease by canning.

• The diagnosis of fish allergy is suspected by the medical history, supported by documenting sensitization (skin prick testing or serum sIgE) and often needs to be confirmed by oral food challenge.

• Management of fish allergy is basically avoidance and providing an action plan for treatment of acute reactions. Good control of associated asthma or eczema would reduce the reaction’s severity.

• Fish allergy usually persists for many years, but rarely for life.

• The general notion of universal avoidance of fish is not valid for all fish-allergic subjects. Some patients may only react to certain species or when the fish is prepared in a certain way or consumed without associated enhancing factors.