Shellfish sensitization associated with socioeconomic disadvantage

ByRichard Gawel

Fact checked byKristen Dowd

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Key takeaways:

Previous research relied on self-reported data, but this study used skin prick testing and serum-specific IgE.
Adjusting for house dust mite sensitization revealed economic associations.

SAN DIEGO — Shellfish sensitization in adults was linked to younger age, male sex and area-based socioeconomic disadvantage, according to a poster presented here.

“A lot of the sensitization studies have been done in children,” Tarandeep Singh, DO, an allergy and immunology fellow at Penn Medicine, told Healio at the 2025 American Academy of Allergy, Asthma & Immunology/World Allergy Organization Joint Congress.

Associations with sensitization to shellfish after adjustments for dust mite sensitization included Black race (OR = 1.41) and an Area Deprivation Index score of 76-100 (OR = 2.15). — Data were derived from Singh T, et al. Poster 161. Presented at: 2025 AAAAI/WAO Joint Congress; Feb. 23-March 3, 2025; San Diego.

Also, Singh said a lot of previous data also has come from self-reported studies.

“Previously, based off self-reported data, it was suggested that allergy to shrimp was associated with older age, male gender and Black adults,” she continued. “We wanted to look at actual sensitization data based off of skin testing and serum-specific IgE levels.”

The study examined the electronic health records of 1,040 adults with an outpatient allergy visit to a tertiary medical center between Jan. 1, 2015, and Oct. 1, 2023.

These patients had a shellfish allergy label, diagnosis code for shellfish allergy or an adverse food reaction. Also, they were tested for allergies to shrimp, lobster, crab, oyster, clam and scallop.

Analysis found that 361 (34.7%) were sensitized to any shellfish. Associations were negative for age 55 years and older compared with age 18 to 34 years (OR = 0.59; P = .015) and female sex (OR = 0.52; P < .0005). They were positive for Black vs. white race (OR = 1.81; P = .002).

“But there’s also a shared major allergen called tropomyosin that’s found in shellfish and in house dust mite,” Singh said. “It’s believed to cause the oral allergy syndrome shared between house dust mite and shellfish.”

Among the 464 patients in the cohort who also were tested for dust mite, 182 (39.2%) were sensitized to any shellfish as well.

“When we adjusted for house dust mite sensitization, what we found was shellfish sensitization is actually associated with areas of high deprivation index — socioeconomic disadvantage — and not exactly Black race,” Singh said.

After this adjustment, the odds ratio for sensitization to any shellfish with Black race fell to 1.41 (P = .028). The odds ratio for sensitization to any shellfish with an Area Deprivation Index score between 76 and 100, compared with a score between 1 and 25, was 2.15 (P = .046).

“That was a very interesting finding,” Singh said.

The researchers plan on exploring whether these figures reflect shellfish sensitization or allergy.

Singh cautioned that this next step could be difficult since allergy testing requires oral food challenges beyond skin prick testing and serum-specific IgE.

“Not everybody undergoes a challenge. Shellfish challenges are not as frequently offered because of fears of adverse or severe reactions for the adult population,” she said. “It’s not easy to gather as many numbers.”