Did you vomit like an oyster? You may not be able to eat it anymore – Sciences et Avenir

“Once you rip out an oyster, it’s gone, you can never eat it again.” Many people have heard this popular adage, between a diagnosis and a curse. This oyster allergy, which is considered rare, but which can manifest itself at any point in adolescence and adulthood, is by no means just an accepted idea, and has a name: SEIPA.

“SEIPA is a syndrome of enterocolitis (inflammation of the intestines, editor’s note) induced by dietary proteins,” translated for Sciences et Avenir by Dr. Madeleine Epstein, an allergist. SEIPA has been more widely described in infants, in which it is the cause of a minority of known allergies to cow’s milk proteins, as well as to eggs, fish, or any other food. “The most common SEIPA in adults is caused by oysters, to the point that allergists are wondering to what extent all the toxic infections attributed to oysters are actually SEIPA,” says Madeleine Epstein.

rare data

Internationally, seafood in general is also isolated to the adult SEIPA, the incidence of which remains unclear. One study estimated only 0.22% of the proportion of adults affected by SEIPA (all animal proteins combined), compared to 0.55% among infants in the United States. In France, a survey of allergists in Île-de-France co-signed by Dr. Epstein found only 38 cases of SEIPA oysters in 2019. the proportion of real cases that are often discussed during the consultation on a different issue. The patients were mostly women, with an average age of 40 years. The numbers, which replicate the 2020 Canadian study, report 68% of women in the SEIPA adult program.

But the data are rare, because while the parents of infants with allergies to milk proteins, to which they are exposed every day, worry and consult, adults, on the contrary, are rarely observed by specialists. “Oysters are a rare dish, so allergies are quickly detected, and after the second attack, most adults simply stop eating them without consulting,” explains Madeleine Epstein.

Recognize SEIPA

The recurrence of allergic episodes is just one of the criteria for identifying SEIPA. “Many people who get sick for the first time think that they just encountered an infected oyster and therefore can eat it again. But every time they get sick,” describes Madeleine Epstein. The symptoms of SEIPA are purely digestive, with severe vomiting and possibly diarrhea occurring an average of two hours after ingestion. “Statistically, there is very little chance that you will encounter an infected oyster twice in a row,” adds the allergist. Thus, the problem arises because of the internal reaction of the body.

Sometimes, after many years of eating oysters without problems, the occurrence of an allergy raises the question of its provoking factor. “We don’t know,” admits Madeleine Epstein. “Gastroenteritis can, for example, change the lining of the digestive tract and reveal hidden intolerances. It’s always a combination of factors, but we don’t know them all and therefore we don’t know how to regulate them.”

unknown mechanism

The physiological mechanism itself remains unknown. During a classic allergy, food triggers the production of specific antibodies called IgE. It is the detection of these IgE that allows you to confirm the allergy. But nothing like that in SEIPA. A “real” allergy to oysters with IgE is “very rare,” confirms Madeleine Epstein. If researchers suspect an imbalance in the gut microbiota, then the role of the immune system is beyond doubt. It is this immune response to an external protein that determines the allergic status of SEIPA.

It remains to be clarified which subjects of immunity we are talking about, since we are not talking about antibodies.”this is a reaction cell mediated via T-lymphocytes (as opposed to an IgE reaction, which is thought to be humoral rather than cellular, editor’s note), but the exact mechanism is unknown“, – sums up the allergist. Thus, in the absence of any marker that allows to objectify its presence, the diagnosis of SEIPA remains the so-called “exception” diagnosis, i.e. it is made in the presence of clinical signs and in the absence of IgE.

unspecified medicine

Can SEIPA be cured? In infants, the syndrome usually resolves within two years. But in adults, recovery is not guaranteed even after several years of avoiding oysters. The only way to know if you have SEIPA is to expose yourself to food. “But I can’t advise you,” says Madeleine Epstein. “The only recommendation is to avoid food.” A discouraging piece of advice for former oyster lovers, but one that will probably keep the magic of next New Year’s Eve more effective.

COOKED OYSTER. Some people who are allergic to raw oysters will be able to eat them cooked again. But this will depend on the antigenic determinant, which is the protein that causes the allergy, explains Dr. Epstein. If it denatures when cooking, this may be the solution. However, it is impossible to know without exposing yourself.

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