In a small fishing town on the Pacific coast, a woman from Ohio told me that after eating shrimp her entire life without any problems, she developed hives twenty minutes after consuming a bowl of cioppino. Back home, she didn’t have a shrimp allergy. Or so she believed. Her story has become strangely prevalent among frequent travelers, and it raises an almost unbelievable question: can merely relocating to a coastal area actually cause a new food allergy?
Many allergists believe that the short answer is more complex than a simple yes or no. Allergies are not created by travel alone. People are exposed to allergens, cooking techniques, and even local fish and shellfish species that they have never seen before. A species of crab found off the coast of Maine is not biologically identical to one found in Southeast Asia. A person with a borderline sensitivity may experience a reaction that never materialized at home due to the slight differences in the proteins.
Additionally, doctors claim that travelers underestimate the risk of cross-contact because they believe they are being cautious. Squid, mussels, and white fish may be fried in the same oil on the same grill with the same tongs in a coastal restaurant’s kitchen. Due to the food coming into contact with a surface that came into contact with something else first, a person with a known fish allergy may order something entirely unrelated and still react.
It’s important to note that, contrary to how it is sometimes presented online, allergists are quick to refute the notion that allergies develop suddenly and permanently overnight. Several researchers have noted that it’s more likely that a person already had a mild or undiagnosed sensitivity that remained dormant until it surfaced in a high-exposure setting, such as a coastal area with a lot of seafood. Although a first reaction overseas can seem abrupt and terrifying, it rarely happens out of the blue.
Many people are surprised to learn that histamine also plays a part. Even those without a true shellfish or fish allergy may experience elevated histamine levels that mimic an allergic reaction when certain fish are not kept at consistently cold temperatures. Symptoms that resemble anaphylaxis but are caused by spoiling rather than an immune reaction include flushing, cramping in the stomach, and a racing heart. It can be stressful to distinguish between the two in a foreign clinic and in a language you don’t speak well.
Travelers who’ve been through it tend to share a similar piece of advice afterward: don’t assume past safety guarantees future safety, especially with seafood. In a Mediterranean port town, a man recovering from a reaction expressed regret for not asking more questions about how the fish was prepared, stored, and caught instead of assuming that “fish is fish.”
Doctors still don’t fully understand why some people react differently in different coastal regions. The advice to bring antihistamines, find the nearest clinic before arriving, and handle unfamiliar seafood with a little more caution than the menu’s allure might suggest is what does appear to be consistent. Everywhere you look, the sea looks the same. It frequently isn’t clear what’s swimming in it or how it gets on your plate.
