REPORT OF A CASE
A 20-year-old woman presented to an emergency department of a Mayo Clinic-affiliated hospital with sudden onset of lip angioedema, throat swelling, diffuse flushing, urticaria, abdominal cramps, nausea, wheezing, severe dyspnea, and hypotension (noninvasive blood pressure level of 80/50 mm Hg) that developed immediately after kissing her boyfriend. Intramuscular diphenhydramine and methylprednisolone, nebulized albuterol, intravenous saline, humidified oxygen by face mask, and intravenous epinephrine were administered, and the patient improved rapidly. She had been aware of an allergy to crustaceans (shrimp and lobster) for several years but despite this history had taken a job as a waitress at a seafood restaurant. Although the patient sometimes wore protective gloves while serving food, she reported that her supervisors frowned on this practice because of concerns about customer perceptions and frequently asked her to remove them. As a result, she often developed urticaria on her arms during her work shifts, but she had never had angioedema or anaphylaxis.
The patient established a romantic relationship with a male coworker at the restaurant. On the night of the reaction described earlier, her boyfriend, who had eaten some shrimp less than 1 hour earlier, gave the patient a passionate good-night kiss at her home. The patient’s symptoms began less than 1 minute after the kiss. She had been asymptomatic at the time she left the restaurant earlier in the evening.
After treatment and a period of observation in the emergency department, the patient was dismissed home. She was given a prescription for an epinephrine injection kit, counseled to scrupulously avoid shellfish exposure, and instructed to follow up with her primary care physician. She pledged to seek new employment.
True anaphylactic reactions are defined as systemic, inflammatory, immediate hypersensitivity reactions mediated by antigen-IgE binding, with subsequent mast cell and basophil degranulation and release of histamine and other vasoactive substances. Food exposures, insect envenomation, and drugs or other therapeutic biological agents are among the most common causes of these reactions.8 The typical responsible food allergens differ according to regional eating habits; peanuts, tree nuts, and crustaceans are among the most common causes of severe allergic reactions in the United States, whereas buckwheat reactions often are seen in the Far East.9
Kissing, an ancient technique for expressing simple affection or erotic desire,10 has been recognized only recently as a vector for transmitting food allergens.4, 5, 6, 7 In a recent review of 379 cases of apparent IgE-mediated food-induced allergic reactions seen at the University of California at Davis, 20 patients (5.3%)—mostly young adults—reported kissing-related reactions, primarily to peanuts and tree nuts.4 Only one of these reactions was considered life-threatening. The only patient in this series who was allergic to fish was intolerant to sea bass and catfish, not to crustaceans (S. Teuber, written communication, June 12, 2002).
Our patient had been exposed repeatedly to a variety of crustacean dishes cutaneously through her employment and as a consequence had experienced a series of mild allergic reactions. These minor reactions may have served to “prime” her immune system to produce more IgE antibodies directed at crustacean proteins, a phenomenon that is well described with respect to seasonal allergens such as ragweed and other noxious pollens.11 A much more severe reaction was then induced by intraoral mucosal allergen contact to shrimp peptides from her boyfriend’s tongue, saliva, and mouth. It is possible that she also had some degree of inhalational exposure to the offending substance, but the relative contribution of the 2 routes of exposure remains uncertain. Detailed immunologic testing such as the radioallergosorbent test or skin prick test was not performed in this patient.
To my knowledge, this is the first report of a life-threatening reaction to shellfish transmitted by passionate kissing. Although most people are aware that passionate kissing can result in a variety of physical and emotional effects, patients with food allergies should be made aware that such intimate physical contact may present extreme dangers that are peculiar to their situation.
This case report underscores the importance of carefully counseling all patients who are allergic to food that they must avoid exposure to offending proteins via all potential routes of contact, including kissing and touching. Carrying an injectable epinephrine kit (and having been instructed in its use) and wearing or bearing emergency medical information (eg, a Medic-Alert bracelet) may also be helpful for patients susceptible to severe allergic reactions.