Published Online: May 28, 2015
Galactose-alpha 1, 3 galactose [alpha-gal] allergy is a recently described mammalian meat allergy related to sensitization from Lone Star tick bites and is common to the southeastern United States. Not everyone who is bitten by this tick will develop this allergy, but for those who do, the only treatment is to avoid ingestion of mammalian meat, including beef, pork, lamb, venison, and bison. Alpha-gal allergy can cause anaphylaxis. However, it differs from other food allergies in some aspects, which can delay identification, diagnosis, and appropriate treatment recommendations. Food allergic reactions usually occur within an hour of eating the offending food, but alpha-gal reactions are delayed, occurring 3 to 6 hours later. For unknown reasons, reactions may not occur with every ingestion of red meat. The most common symptom reported is itching.
Knight and colleagues report a novel case of alpha-gal dependent exercise-induced anaphylaxis [AGEIA] in The Journal of Allergy and Clinical Immunology: In Practice. Although exercise-induced anaphylaxis [EIA] is well described and known to be triggered in some cases by ingestion of wheat, shellfish and other foods before exercise, this is the first published case report of AGEIA. The reactions described here differ from other alpha-gal reactions in that they occurred more rapidly, within 1½ hours instead of the typical 3 to 6 hours following ingestion of red meat. The patient was a 21 year-old female runner. Prior to running on the two occasions when she developed anaphylaxis, she had eaten meatballs. On the first occasion she ate thirty minutes before running and developed a nondescript feeling of unease thirty minutes into her run, or one hour after eating. This progressed to hives and lip swelling by the end of the run, which she treated with diphenhydramine. On the second occasion with the same food, eaten one hour before running, she developed symptoms thirty minutes into the run, or 1½ hours after eating. With the second reaction she reported intense itching that progressed to hives and swelling.
Evaluation included lab testing to evaluate for specific causes of anaphylaxis and anaphylaxis-like conditions, as well as skin prick tests (SPT) to a panel of common food allergens. SPT were performed using commercial extracts including beef and pork and all were negative. However, SPT using fresh meat extracts rather than commercial ones, are typically positive in alpha-gal allergy. Serum was tested and the patient’s alpha-gal was elevated at 15.80 kU/L.
This case suggests a different time course of reactivity in AGEIA and supports the inclusion of evaluation for alpha-gal allergy for patients with exercise-induced symptoms of anaphylaxis in association with ingestion of mammalian meat (particularly in regions with ticks).
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.