Pangasius hypophthalmus hypersensitivity
Introduction: Fish is a relatively common source of food allergens and its ingestion may cause fatal anaphylactic reactions. Fish allergic subjects usually present IgE antibody to several fish species, although clinical cross reactivity may be more limited. We report a patient allergic to Pangasius hypophthalmus (Panga fish) but no to other fish. This exclusive sensitivity was confirmed by in vivo and in vitro tests, and a unique Pangasius hypophthalmus allergen was detected. Panga is a fish from Vietnam rivers which is being exported to many countries (included Spain) in the last years.
Clinical case: A 18-year-old man reported five reactions a few minutes after eating panga fish; he had upper and lower respiratory tract dyspnea, laryngeal oppression, wheezing and heartburn. He declared that he did not suffer allergic symptoms with the ingestion of any other kind of fish or seafood.
Results: Prick-test with Anisakis simplex, seafood, panga fish and thirteen different commercial fish extracts (hake, cod, salmon, sole, trout, tuna, bream, bass fish, sardine, herring, South African Anchovy, anglerfish and bonito) was positive only to octopus, panga and bass fish. Prick-prick with panga fish was positive (cooked: 10x7; raw: 12x9) and negative with sardine, cod, hake, salmon, South African Anchovy, swordfish, sole, guilthead bream, squid, cuttlefish, octopus and shrimp. The open oral challenge test was negative with salmon, sole, trout, bass fish, guilthead bream, squid, cuttlefish, octopus and shrimp.
Specific IgE against extracts from panga (cooked: 4.3 kU/L ; raw: 3.1 kU/L), sardine (2.1 kU/L), hake (0.7 kU/L), cod (0.6 kU/L) and shrimp (0,9 kU/L) was detected by means of EAST method (Enzyme AllergoSorbent test). IgE-Immunoblotting with panga extracts (cooked and raw) revealed IgE-binding bands of 14 kDa and 12 kDa, the same molecular mass as the ones appeared after incubation with a rabbit serum anti-sardine parvalbumin.
Conclusion: We report a patient who is allergic exclusively to panga fish. Probably the allergen involved is parvalbumin.