Fishing for allergy

Who doesn’t like to fish during this time of the year? Doesn’t matter if it’s catfish on the local pond, or trout at Roaring River, there’s nothing like feeling the tug on your line before you set the hook. And I have relatives that are experts at catching any type of fish you want. Fish allergy can be divided into 2 groups: the white fish and shellfish. You are usually not allergic to both groups and testing for sensitivity can be very helpful to avoid anaphylaxis and give you the tools to avoid the wrong kind of fish. Shellfish allergy to shrimp, crab, and lobster isn’t the focus of this writing, so we’ll discuss only allergy to “white fish” today. At times, I enjoy searching the medical literature for other allergist’s opinions on food allergy and this is no exception. What is most important for the white fish allergy, is can you outgrow this condition?

The data of whether someone can outgrow fish allergy is scarce. Fish allergy is one of the most common causes of food allergy, especially in children and young adults, with rates from 0.1 to 0.5%. The major fish allergen identified is beta-parvalbumin, it is resistant to heat and digestion. Many patients with an allergic reaction to one fish will also react upon ingestion of other fish. Sharks and rays mainly contain alpha-parvalbumin which has been shown to be less allergic.

Journal of Allergy and Clinical Immunology: In Practice.

Previous studies have shown that 15% of children can outgrow fish allergy within a period of 2-5 years, whereas telephone studies have shown it to be 3.5% in the United States.

A recent study called “Natural History of IgE-Mediated Fish Allergy in Children” published in The Journal of Allergy and Clinical Immmunology: In Practice, aimed to describe the natural history of fish allergy.

Children in the study ranged from 4 to 18 years who were previously diagnosed with fish allergy. The results showed:

  • 22% of children tolerated all fish tested, the average timeframe was 8 years after their first reaction.
  • Complete tolerance to fish increased with age, from 3.4% in preschool children to over 45% in adolescents.
  • Most children were able to tolerate swordfish (94%) and tuna (95%).
  • The best predictor of fish allergy was the IgE test to cod greater than 4.87 kUA/L.

The study has shown that fish allergy in children starts early, mostly during the first 2 years of life and a considerable proportion of children will outgrow fish allergy.  Particularly those with less sever reactions and a lower level of sensitization (skin prick and IgE testing). Those who continue being allergic may still tolerate several fish species, such as tuna and swordfish. This probably is a reflection of their parvalbumin content and/or composition.

Tolerance to at least 1 fish can be important for allergic children because fish has beneficial effects on health owing to the high omega-3 content and it is associated with a lower risk of coronary heart disease.

  • So what’s the take away from fish allergy, so you can fantasize what the “big fish” is doing underwater before you set the hook?
  • Most children will outgrow fish allergy and this applies particularly to swordfish and tuna. A definite must is to have testing performed to determine the level of IgE (or skin testing) to white fish that will prevent an allergic reaction that can spoil your next great fishing trip.
  • Tolerating fish to include at least one species can have clinical benefit due to omega-3 content to reduce heart disease and stroke.

#allergy, #fish-allergy, #food-allergy