Dust Mites

Mrs. A developed this issue, though only with raw or undercooked shrimp.

“If you put a shrimp and a dust mite like face to face, they look pretty darn similar,” Warren said. Their muscles are made of the same proteins, and once your immune system starts reacting to the mites, it might detect in shrimp the same, presumably dangerous, compound.

Dust mites (and their poop) may be unusually likely to trigger allergic reactions, and they bombard us constantly — far more frequently than our guts probably get treated to Maine lobster or jumbo prawns — giving our bodies plenty of chances to consider arthropods a threat. Research in adult-onset allergies remains scarce — they’re rare enough that you’d have to follow tens of thousands of healthy adults to get a big enough subgroup that would develop any given allergy — but it seems reasonable to assume that adult exposure to dust mites may trick your body into thinking shellfish are dangerous.