According to a study published in Pediatric allergy and immunology.
As part of their search for alternatives to fish for allergy sufferers, the researchers attributed this risk to the major fish allergen, parvalbumin (PV) found in crocodile meat after observing two cases of anaphylaxis involving children with chicken and fish allergies linked to PV who ate crocodile meat.
“It turned out that in order to promote healthy and safe diets, we also needed to assess vertebrates other than bony fish for their potential to trigger an allergic reaction,” Andreas L. Lopata, PhD, associate professor and head of the Molecular Allergy Research Laboratory at the Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, Queensland, Australia, Healio told Healio.
The study is part of a larger fish allergy project involving more than 100 children at Westmead Children’s Hospital in Sydney, funded by the Australian Research Council and the National Health and Medical Research Council, aimed at improve diagnostics and management, Lopata said.
Andreas L. Lopata
“Crocodile meat is consumed worldwide by children and adults. However, published reports of anaphylaxis were of children who had tried crocodile as an alternative to fish/chicken, which they were to avoid. Interestingly, Australia accounts for 60% of the global trade in crocodile products, including meat,” Lopata said.
Alpha PV, which can be found in cartilaginous fish like shark and ray, is less allergenic than beta PV, which can be found in bony fish like bass and salmon. According to the researchers, up to 95% of people with fish allergy exhibit IgE binding to PV beta in fish bone muscle. Crocodiles, the researchers noted, evolved from the earliest bony fish.
In an effort to characterize IgE-binding proteins in crocodile meat, researchers collected muscle tissue from saltwater crocodile, Asian bass, Atlantic salmon, ghost shark, and blue-spotted ray.
The researchers then recruited 77 children who had a history of IgE-mediated symptoms after eating fish. Skin tests on tuna, salmon and sea bass gave positive results in 97% of these patients.
Second, eight of 12 fish-allergic subjects who underwent crocodile SPT testing demonstrated skin reactivity in vivo. In comparison, four people with shellfish allergy who received Crocodile SPT showed no skin reactivity.
The researchers performed analyzes using commercial and in-house antibodies in addition to serum from individual and pooled patients to identify and quantify IgE binding proteins, finding that 44 patients (57%) had IgE binding to at least one PV isoform .
Specifically, 31 (70%) showed IgE binding to crocodile PV, 13 (30%) showed IgE binding to both alpha and beta PV, 14 (32%) showed IgE binding only to beta PV and four (9%) showed IgE binding. only at alpha PV. Moreover, according to the researchers, the signal to beta PV was up to 500 times stronger than the signal to alpha PV.
Although PV alpha is the most abundant isoform, researchers found that PV beta was more frequently and strongly recognized by IgE antibodies, likely due to its greater similarity, including sequence identity , with beta PV in fish, making it the major IgE-binding allergen in bone. fish and crocodile.
“The main crocodile protein allergen, parvalbumin, has a higher IgE antibody-binding capacity than the parvalbumin of some fish. In general, most cartilaginous fish (sharks and rays) and some bony fish seem much more safer than crocodile for fish allergic patients,” Lopata said.
The researchers assigned Cro p 1 to crocodile beta PV and Crop 2 to crocodile alpha PV as allergen names and registered them with the WHO and the International Union of Immunological Societies.
“Crocodiles are much more dangerous than we thought, even when they’re dead on the plate,” Lopata said.
Lopata warned patients with fish allergies to avoid consuming alligator and crocodile meat unless medical providers confirmed their tolerance.
“Fish allergy is very complex with over a thousand different species consumed worldwide. Due to limited diagnostic capacity, it may be best to recommend avoiding all fish and fish products. However, the allergy is often species-specific and can extend to meat from other vertebrates such as crocodiles,” Lopata said.
Additionally, Lopata said, physicians should be aware of fish-crocodile syndrome, be cautious about recommending fish alternatives for allergy sufferers, and advocate for the development of better diagnostic and management tools.
The researchers also called for additional research to improve the accuracy of determining the clinical relevance of new allergens, including the development of corresponding blood diagnostic and management tools, which may obviate the need for oral dietary challenges. Currently, researchers are also exploring alternative menus for people with food allergies.
For more information:
Andreas L. Lopata, PhD, can be contacted at [email protected]