Fish & Shellfish Allergies

Seafood, primarily shellfish, is the No. 1 food that causes allergic reactions in people. Shrimp, crab and lobster are the most common culprits. Approximately 60 percent of people first experience an allergic reaction as adults, which will then become a lifelong allergy. Seafood can be one of the easiest foods to avoid, but these allergies cause the most serious reactions.

Prevalence

• Seafood allergies affect 3 percent of the population, or 7 million Americans, according to the Asthma and Allergy Foundation of America. They are the leading cause of anaphylactic shock in emergency rooms (about 30,000 per year), and 200 deaths per year. According to the Auckland Allergy Clinic, it has been estimated that if someone is allergic to a type of fish, they have a 50 percent chance of being allergic to at least one other type of fish, and if they are allergic to a shellfish, they have a 75 percent chance of being allergic to another shellfish.

Causes

• Caesar salad dressing is a hidden source of seafood (anchovies).

  The major allergen in fish responsible for hypersensitivity are called para-albumins. Cod, haddock, trout and salmon are the fish people are most commonly allergic to. The major shellfish allergen producer is called tropomyosin. Shellfish is divided into two types: mollusks (oysters, mussels and squid) and crustaceans (shrimp, lobster, and crabs). Hidden sources of seafood products include: anchovies in worsesterchire sauce pizzas, caesar salad and dressing; gelatin derived from fish or shellfish bones; and fish oil supplements contaminated with fish proteins.

Symptoms

• Symptoms of an allergy to seafood usually begin within minutes to a few hours after eating. Minor symptoms include itching and hives. A more serious reaction begins with tingling or swelling of the tongue and throat, wheezing, difficulty breathing and dizziness. If this progresses, it can lead to anaphylaxis, a sudden, severe and potentially fatal reaction affecting multiple areas of the body.

Treatment

• The treatment of a seafood allergic reaction varies depending on the severity of symptoms. Medical attention should be sought immediately, especially with trouble breathing or swallowing. Emergency rooms are prepared with several medications to prevent anaphylaxis, including epinephrine, intravenous steroid medication and antihistamines. Take over-the-counter antihistamines for mild reactions. People with severe, known allergies are advised to wear medical alert bracelets and to carry a special kit containing an epinephrine injection for emergencies.

Prevention/Solution

• Avoidance of seafood or seafood products is key to prevention of an allergic reaction. Read all labels for foods, medications, cosmetics and lotions. Assume cross-contamination is possible in any restaurant. Asian restaurants often serve dishes with fish sauce as a flavor base. Cooking shellfish causes the protein allergen to become airborne with the steam. Food labels must clearly list "shellfish" in the actual ingredient list or "contains shellfish" after the list.