Surfing is a risk factor of sensitization to poly(gamma-glutamic acid) in fermented soybean-induced late-onset anaphylaxis

RATIONALE: Poly(g-glutamic acid) (PGA) is the allergen of fermented soybeans, natto, that causes late-onset anaphylaxis. We speculated that jellyfish stings sensitize adults to PGA because a surfer had allergies to both natto and jellyfish, which produce PGA while stinging someone. The aim of the study was to identify demographic and behavior factors, such as marine sports, associated with PGA sensitization.

METHODS: Outpatients diagnosed with food allergies based on relevant clinical history, positive skin test and/or food challenge test were asked to answer a questionnaire during a regular visit in 2016.

RESULTS: Questionnaire data from 140 outpatients were analyzed. These patients were divided into two groups: natto allergy group (13 patients, M:F=10:3, mean age 40.6 yrs) and non-natto allergy group (127 patients, M:F=46:81, mean age 44.5 yrs). All 13 patients with natto allergy had positive results in both skin prick test and basophil activation test with PGA. 92.3% of them had a hobby in marine sports, especially surfing (84.6%). PGA sensitization was independently associated with marine sports (odds ratio, 278.0, 95 percent confidential interval, 36.9-6315.9, p<0.001) adjusted for male sex and bathing, but not with male sex nor bathing. In addition, although there is no significant difference of experience in marine sports between natto and non-natto allergy groups, natto allergy group significantly had participated more frequently in marine sports than non-natto allergy group (p<0.001).

CONCLUSIONS: Surfing is a risk factor of PGA sensitization, resulting in subsequent natto allergy. PGA sensitization may occur via inflamed skin in patients by cnidarian stings while floating in the sea.