Natural resolution of non-anaphylactic shrimp allergy in patients diagnosed 10 years earlier by oral food challenge.

Abstract

Shrimp allergy is considered a lifelong condition. The natural resolution of shrimp allergy is not well studied. To investigate the natural resolution of shrimp allergy among a cohort of patients diagnosed with shrimp allergy 10 years earlier by oral shrimp challenge. A prospective study recruited patients diagnosed with shrimp allergy to Penaeus monodon (Pm), Macrobrachium rosenbergii (Mr), or both from a study conducted during 2005-2006. The current oral shrimp challenges were conducted during 2015-2016. The negative oral shrimp challenge was designated 'resolved shrimp allergy' (RSA), with a positive challenge designated 'persistent shrimp allergy' (PSA). Skin prick and prick-to-prick testing to shrimp were used to determine sensitization. Sixty patients who had positive shrimp challenge from the previous cohort were contacted. Patients who had previous anaphylactic reaction (8 subjects) or allergic reaction after shrimp ingestion within 6 months (6 subjects), were not included. Nine patients refused to participate and 20 patients could not be contacted. Seventeen patients were included. Three were previously diagnosed with allergy to Pm, 3 to Mr, and 11 to both species. RSA was observed in 1 patient with isolated Pm allergy, and in 3 patients with isolated Mr allergy. Three of 9 patients with dual allergy had RSA to both species. RSA patients had significantly smaller size of shrimp skin test than PSA patients at both diagnosis and follow-up. At ten years after diagnosis, 46% of patients had RSA. These patients had significantly smaller size of shrimp skin test than PSA patients.