Sensitization Profile of Individuals to Shellfish in the Chesapeake Bay Area

Rationale: There is limited information on the demographics of adults at risk for shellfish allergy. Past surveys suggest more women are affected. We examined the frequency of serologic sensitization in adults tested for shellfish allergy at a major clinical reference laboratory.

Methods: Shellfish-specific IgE antibody levels were analyzed by ImmunoCAP in serum from 2538 Chesapeake Bay residents who were evaluated from 2010-2015.  The frequency of positive tests (e.g, >0.1 kUa/L) and IgE antibody ranges were determined across gender and age distributions. 

Results: A total of 2165 tests were ordered for subjects >18 years old (Range 18-88 yo). IgE antibody responses to crustacean allergens  (shrimp, crab, and lobster, n=1341) were tested more often than those to mollusks (clam, oyster, scallop, mussel, n= 824). 33% of all tests were positive. While females were tested more (n=1446 tests vs n= 719 tests males), males had a higher rate of positivity (47.71% vs 27.39% in females x²= p< 0.01). For all shellfish allergens, the range of IgE antibody measured was higher in males. The median IgE  (kUa/L) for males (M) and females (F) were: shrimp (M)1.16, (F)0.41; crab (M)1.44, (F)0.50; lobster (M)1.29, (F)0.48; clam (M)0.50, (F)0.57; oyster (M)0.46, (F)0.33; scallop (M)0.36, (F)0.29; mussel (M)0.23, (F)0.45; with the medians higher in females for clam and mussel.

Conclusions: The results support that adult males have a higher frequency of positive IgE antibody results for all species of shellfish. This supports a difference in exposure or gender bias in the acquisition of sensitization, which contrasts with 2 previous surveys.