A puzzle: an Orthodox Jewish patient with an allergy to shellfish. How is that possible?

Jewish cuisine is a collection of cookery traditions linked by Jewish dietary laws and holiday traditions. Certain foods, notably pork and shellfish, are forbidden.

A question from Twitter:

@kidneynotes A puzzle: an Orthodox Jewish patient with an allergy to shellfish.


Patients with seafood allergy are frequently reported to also have allergic reactions to mites and insects. This cross-reactivity is probably due to the high amino acid homology of these invertebrate tropomyosins and may have significant clinical implications.

A recent study demonstrated sensitization to shrimp tropomyosin in orthodox Jews who are prohibited by religious dietary laws from eating shellfish; however, as they were never exposed to crustacean allergens, this sensitization to tropomyosin is probably due to a noncrustacean source, such as house dust mites (HDM), cockroaches or both, via inhalation.

Seafood hypersensitivity in mite sensitized individuals: is tropomyosin the only responsible allergen?

Tropomyosin does not seem to be the main allergen involved in mite-seafood sensitization in mite sensitized individuals. However, high levels of sIgE to tropomyosin seem to be related to severity of symptoms. http://goo.gl/Wj9xW

A 20-year-old man with a known dust mite-related allergic rhinitis develops rash, dyspnea, bradycardia, dizziness 30 minuts after eating oysters. What is the cause?

(A) Shigella
(B) Cholera
(C) Scrombroid
(D) Tropomyosin
(E) Parvalbumin

Answer: Tropomyosin. Shrimp Allergy in Italian Adults: Skin reactivity to house dust mite (HDM) was found 70% (Int Arch Allergy Immunol. 2011),

Immunoglobulin E antibody reactivity to the major shrimp allergen, tropomyosin, in unexposed Orthodox Jews. Fernandes J, Reshef A, Patton L, Ayuso R, Reese G, Lehrer SB. Clin Exp Allergy. 2003 Jul;33(7):956-61.
New Insights Into Seafood Allergy. Andreas L. Lopata; Samuel B. Lehrer. From Current Opinion in Allergy and Clinical Immunology.
Exposure to cockroach is linked to high shrimp IgE with questionable clinical reactivity - food challenge is needed for diagnosis (JACI, 2011).
Shellfish allergy is a frequent, long-lasting, life-threatening disorder. As shellfish consumption increases, the number of allergic reactions to shellfish is expected to continue to rise too http://goo.gl/D2PRx


  1. How "pure" are the shrimp tropomyosin extracts? The reason I ask is that much has been written about chitinases and asthma. I think chitinases also might play a role in allergic rhinitis. Could the chitin in arthropod exoskeletons (HDM, crabs, shrimp, etc) also be a common denominator in these findings?

  2. Fasinating. Thanks -- I'd always wondered how I ended up with a shellfish allergy (according to skin testing) when I'd never eaten them. (I'm also Jewish, although not kosher, but grew up not eating pork or shellfish in a somewhat kosher-style home.) I'm totally allergic to dust mites, too.

  3. Anonymous9/21/2015

    There is a reason for the kosher laws and I have been Vegetarian for 26 years knowing of my food allergies.The other day I accidentally ate crab in my pasta unknown and swelled,got spots,purged,almost died!It wasn't known or psychological.Shellfish is not for me.I'm Jewish.


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