Have you ever heard of a tick causing an anaphylactic reaction to red meat?
Me neither. But that is just what happened on Saturday June 4, 2016 in rural North Carolina. A 36 year-old male, who happened to work as an emergency room (ER) nurse, presented symptoms of an anaphylactic reaction. He denied any previous allergic reactions, recent bee stings or medication changes, but his blood pressure was 70/30 mmHg and he was complaining of feeling lightheaded with a slow onset of urticaria. The ER administered IM epinephrine, an anti-histamine, three liters of normal saline and steroids before the patient reported relief.
A week later, the patient followed-up with an allergist who asked about tick bites and red meat consumption. The patient confirmed both. The physician ordered a blood serum test looking for antibodies to galatose-alpha-1, 3-galactose (alpha-gal). The test came back positive.
In the early 2000s, experts determined that alpha-gal, a.k.a. meat allergy, antigens are present in all non-primate mammals. They identified the culprit of the transmission as the Lone Star Tick. This tick feeds on mammals and then introduces the antigen to humans, resulting in an anaphylactic reaction to red meat. The cause often goes unrecognized by emergency physicians because the reaction occurs hours after eating meat. This happens because alpha-gal does not enter the bloodstream for several hours after the tick bite.
So in the future, if you have an anaphylactic patient without an identifiable cause, ask about recent tick bites and consumption of red meat or pork within the last six hours. If patients test positive for alpha-gal, doctors recommend the patient avoids red meat and pork for at least two years and then undergo testing for the IgE antibodies to alpha gal. Can you imagine no bacon or steak for at least two years? The horror!