African American Children More Likely Than Whites To Be Allergic To Shellfish, Finfish

African American children are more likely than white children to develop allergies to shellfish and finfish, and also to develop asthma, a multicenter study suggests.

The analysis of data from more than 650 children found that compared to white children, African American children were more than twice as likely to be allergic to finfish and more than three times as likely to be allergic to shellfish. Black children were also more than twice as likely to have asthma, researchers report in the Journal of Allergy and Clinical Immunology in Practice.

In addition, asthma was independently associated with shellfish allergy after controlling for race, the researchers found.

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"At this point the really big problem is asthma in African American children," said the study's lead author, Dr. Mahboobeh Mahdavinia, chief of the division of allergy and immunology at Rush University Medical Center in Chicago. "One thing that is very concerning to us is that children with both asthma and food allergy are at more risk for a severe reaction."

It's not yet known why the African American children are at greater risk than white children for fish allergies. Right now, the researchers aren't ruling out the possibility of a biological explanation, Dr. Mahdavinia said. "It's possible that there is a genetic predisposition to allergies," she added. "We are collecting samples from children to look for genetic markers and we are also looking at the microbiome."

Environmental factors may be the more likely explanation, however. Dr. Mahdavinia and her colleagues note that an allergy to cockroaches may make children more prone to react to shellfish and finfish. The theory is that children might become sensitized to shellfish when they inhale a cockroach version of the tropomyosin protein that is similar in structure to the version of the protein found in shellfish.

Dr. Mahdavinia and her team are currently testing the children who are allergic to shellfish to see if they are also allergic to cockroaches.

To explore whether there is racial disparity in shellfish and finfish allergies, the researchers recruited 239 African American children and 425 white children aged 0 to 12 years with an allergist-confirmed diagnosis of IgE-mediated food allergy.

White children had a median age of 5.7, while the median age of the African American kids was 8. Among white families, 80% had annual incomes of $100,000 or more, as compared to 21.8% of the African American families.

After accounting for factors such as gender, age, yearly household income and recruitment site, the study team found that African American children had significantly higher odds of comorbid asthma compared to white children (odds ratio 2.70). Overall, children with a shellfish allergy also had significantly higher odds of asthma (OR 1.94).

The researchers noted some limitations to the study, including self-reported race, the recruitment locations being only in the midwestern and eastern U.S., and the higher number of white children than Black children in the cohort.

The potential of cross-reactivity between cockroach and fish allergies was intriguing to Dr. Desha Jordan, an assistant professor of pediatrics in the division of allergy and immunology at the University of Pittsburgh School of Medicine and the UPMC Children's Hospital of Pittsburgh.

"I have heard a lot about dust mite allergies and shellfish allergies," Dr. Jordan said. "It looks like cross reactivity between cockroach allergies and shellfish allergies could be key."

And while introducing shellfish and finfish to African American children at an early age might help, ultimately, "having people in better housing would be a great thing to help with asthma," Dr. Jordan said.

One thing that may be difficult to tease out is the role of low socioeconomic status in the development of these allergies and asthma, Dr. Jordan said. That generally translates into a lack of resources and a lack of access to healthcare, she added.

—Linda Carroll

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