Swordfish Allergy Test
Latin name: Xiphias gladius
Source material: Fish muscle
Swordfish is a food which may result in allergy symptoms in sensitised individuals.
Swordfish Allergy Test: Allergen Exposure
Swordfish are large marine predatory fish found widely in tropical and temperate parts of the Atlantic, Pacific, and Indian Oceans. They have been caught by humans for food since ancient times in places such as the Strait of Messina, and are now an important commercial food fish around the world.
Swordfish is sold both fresh and frozen, although fresh swordfish is generally agreed to be of a higher quality. As they are large in size and have relatively firm flesh, swordfish is usually sold cut into steaks (loins), which are often grilled or barbecued. Cooked swordfish is described as meaty, and similar in texture to marlin.
Swordfish are classed as an oily fish, and have high levels of omega-3 fatty acids. They are a good source of vitamin B6, and a very good source of protein, niacin, vitamin B12, phosphorus and selenium.
Swordfish Allergy Test: Allergen Description
No specific allergens present in swordfish have been characterised, although a number of proteins have been identified.
Swordfish Allergy Test: Potential Cross-Reactivity
Species within groups of fish, like Gadiformes (examples: codfish and hake) and Scombroid fishes (examples: mackerel and tuna) seem to share allergenic components. The overlap of allergen specificity between the groups seems to be moderate or even small.
Cross-reactivity to swordfish within the order Istiophoriformes can therefore be expected, which includes barracudas, sailfishes and marlin.
Swordfish Allergy Test: Clinical Experience
A patient with clinical sensitivity to swordfish had IgE antibodies to a protein present in the fish but to no other protein from 10 other species of fish which were tested. It is therefore thought that the allergen may be specific for the family Xiphidae.
Sensitisation to fish allergen is common. Fish, including swordfish, is a potential cause of food allergy and atopic dermatitis.
Immediate allergic reactions may follow ingestion of even minute amounts of swordfish.
Symptoms can include oral allergy syndrome, generalised urticaria, facial angioedema and anaphylaxis.
Because patients react to both cooked and raw fish, it is assumed the allergens are heat-resistant. However, more recent studies indicate that patients may react differently to processed food and that allergic reactions may be species-specific.
It has been reported that some fish allergic persons can exhibit allergic symptoms due to the steam (airborne allergens) from cooking fish.
Acute anisakiasis as a result of the larvae of the fish parasite Anisakis simplex may occur following ingestion of undercooked or raw swordfish.
Symptoms can include abdominal pain, nausea, vomiting, abdominal distention, diarrhea, blood and mucus in stool, and mild fever. Allergic reactions with rash and itching, and infrequently, anaphylaxis, can also occur.
Predatory fish which are high in the food chain, such as swordfish, generally contain higher concentrations of mercury than others, and so regular consumption is not advised. The presence of mercury in fish can be a particular health concern for women who are or may become pregnant, nursing mothers, and young children.
Fish allergy is sometimes confused with a reaction to histamine in spoiled fish.