Shellfish Allergy Diagnosis: Findings from a service evaluation to assess pathways and identify unmet needs
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Authors
Cahill O.
MadrigalBurgaleta R.
Foster C.
Fernandes B.N.
Ali, F. R.
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2025
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Objectives: Given the lack of standardised shellfish allergy assessment algorithms, a service evaluation was undertaken to identify areas for improvement in the diagnostic pathway. Method(s): Data were collated for patients referred for shellfish allergy investigation at St Bartholomew's Hospital Allergy Service (Dec 2023-Mar 2025). Only patients with results for SPT, prick-prick testing (PPT), and sIgE testing to one or more shellfish species were included. Result(s): Twenty suitable patients were identified. All underwent sIgE, SPT and PPT to prawn/shrimp: 7/20 had positive SPT, 11/20 positive PPT, 8/20 positive SpIgE and 2/20 positive tropomyosin. There was full agreement across all three tests in only 8/20. Thirteen patients in total reported a history of reaction with shellfish: 12/13 to prawn (9/12 positive PPT, 4/12 positive SPT 3/12 positive sIgE), 2/12 also reported a reaction to crab; and 981 1/13 to crab only. Seven had HDM allergy; none had positive tropomyosin. Three patients with reported history of reaction to prawn/ shrimp underwent prawn challenges (2/3 had positive SPT, average wait time for challenge was 8.6 months); all were negative. Three more await challenge. 5/20 patients had PPT to three prawn species. Two had a positive result for all three. A further three had one negative (North Atlantic prawn) and two positives; two of these subsequently passed North Atlantic prawn challenges. Two patients were sensitised to molluscs (squid); one of these had a subsequent negative squid challenge, the second is awaiting challenge. No patients reported a history of reaction to molluscs. Conclusion(s): Several research needs were identified. SPT extract variation requires study to assess false positives. Internal validation is needed to establish SPT and PPT cut-offs. Selective prawn/shrimp eating is helpful in suitable patients. Molluscs are likely to be tolerated by most patients. Challenge waiting lists affect care. The relevance of tropomyosin in unclear in this UK population.
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Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology