The study, “Diagnosing Meat Allergy After Tick Bite Without Delay,” was published in the Journal of the American Board of Family Medicine.
Food allergies can trigger severe angioedema, causing swelling of body extremities, skin rash (hives), nausea, and difficulty breathing. At times, a second exposure to the allergen — an allergy-causing agent — activates the immune system, resulting in delayed-onset angioedema, which can be dangerous if the allergen remains unidentified.
Previous studies have shown that bites from Lone Star ticks introduce alpha-gal into the bloodstream triggering the production of immunoglobulin E (IgE), the antibody responsible for allergic reactions. The Lone Star species of tick are found across much of the eastern part of the U.S.
Similar reports have been published regarding the use of Erbitux (cetuximab), a cancer immunotherapy, predominantly in patients in the southeastern U.S. Erbitux, marketed by Eli Lilly, also contains alpha-gal.
Consumption of red meat after a Lone Star tick bite could cause delayed-onset angioedema.
In this report, the researchers describe the case of a 43-year-old woman who had been camping in Pennsylvania. She presented with symptoms mimicking angioedema several hours after eating grilled steak at dinner. Symptoms included hives, swelling in the feet, hands and face, severe itching, diarrhea, and vomiting. Diphenhydramine, an anti-allergy medication, eased her symptoms.
She visited an allergist three days after the episode. During the consultation, she reported that a week before her camping trip, she was on a hiking trip in Monmouth County, New Jersey. She had multiple tick bites during that trip but did not show any symptoms. A physical examination during her visit did not reveal any symptoms of illness and swelling.
Further discussions revealed that the night of the allergic episode was the first time she had consumed red meat since her trip to Monmouth County.
A blood test showed abnormally high levels of beef-specific IgE, pork IgE, lamb IgE, and alpha-gal-specific IgE, confirming the diagnosis of alpha-gal allergy syndrome.
The patient was prescribed an epinephrine pen for use in emergency and was asked to avoid foods containing alpha-gal, specifically red meat.
Despite following the red meat restriction, she reported a recurrence of hives, swelling, and diarrhea. After 10 months of close monitoring and a mammalian-free diet, including avoiding gelatin and dairy, the severity and frequency of these symptoms was reduced.
“Educating physicians and patients about the distribution of the Lone Star tick, the delayed allergy response, the constellation of symptoms (gastrointestinal symptoms, hives, angioedema, and anaphylaxis), and how to protect oneself with repellents, clothing, and skin checks is of the utmost importance,” the investigators concluded.