Crocodile meat can be a dangerous alternative for people allergic to fish
The first reptile allergen has been discovered, suggesting that crocodile meat, a healthy protein source, can trigger allergic reactions in those allergic to fish.
"Fish allergy, often a life-long condition, affects up to 3 per cent of the general population and frequently results in life-threatening anaphylaxis,” says Dr Thimo Ruethers, Research Fellow in Human Health & Aging at the Tropical Futures Institute (TFI) at James Cook University (JCU) in Singapore. “Over 1,000 different species of fish are consumed worldwide; while fish-allergic individuals may be allergic to a narrow range of fish, they are often recommended to avoid all fish and fish products once diagnosed with an allergy to any fish species, which results in significant dietary restrictions.”
Crocodile meat is a known healthy alternative to fish as well as chicken — especially for people who suffer from fish/chicken allergies. As a matter of fact, crocodilian meat (which includes alligators and crocodiles) is commonly eaten throughout the world and particularly across the tropics, including Singapore and its neighbours, where many crocodile farms are located.
However, recent reports of life-threatening anaphylaxis following the consumption of crocodile meat have been associated to a major fish allergen (a protein triggering a cascade of immunological responses in sensitised consumers which can result in an allergic reaction). Dr Ruethers and Professor Andreas Lopata, Professor in Molecular Allergy at the College of Public Health, Medical & Veterinary Sciences and the TFI at JCU — in collaboration with a number of other researchers — set out to investigate this link.
In the study, one of the globally largest group of fish-allergic patients underwent allergen skin prick testing to crocodile and various types of fish. Skin reactions and comprehensive blood analyses then showed that the vast majority (about 70 per cent) of patients would likely have an allergic reaction when eating crocodile.
Dr Ruethers shares, “In the tropics and many Eastern countries, meat from amphibians and reptiles is common food, while it is often considered ‘exotic’ in Western countries. Crocodilians are the closest living relatives of birds, which can be primary sensitisers of food allergies or, in rare cases, also cause clinical cross-reactivity in fish-allergic individuals (fish-chicken syndrome)”
He adds, “We now coined the ‘fish-crocodile syndrome’: Fish-allergic individuals may be at risk of serious allergic reactions upon consumption of crocodilian meat due to them being highly reactive to crocodile parvalbumin. This generally harmless protein is now the very first reptile allergen registered with the WHO.”
“We propose that fish-allergic individuals should avoid the consumption of crocodilian meat unless tolerance is confirmed or following consultation with their allergist.”
Ruethers T, Nugraha R, Taki AC, O’Malley A, Karnaneedi S, Zhang S, Kapingidza AB, Mehr S, Kamath SD, Chruszcz M, Mackay G, Campbell DE, Lopata AL. The first reptilian allergen and major allergen for fish-allergic patients: Crocodile β-parvalbumin. Pediatr Allergy Immunol. 2022;33:e13781. doi:10.1111/pai.13781
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