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

Background: Shrimp allergy is considered a lifelong condition. The natural resolution of shrimp allergy is not well studied.

Objective: To investigate the natural resolution of shrimp allergy among a cohort of patients diagnosed with shrimp allergy 10 years earlier by oral shrimp challenge.

Methods: 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.

Results: 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.

Conclusions: At ten years after diagnosis, 46% of patients had RSA. These patients had significantly smaller size of shrimp skin test than PSA patients.