Diagnosis of alpha-gal allergy should be made based on a detailed patient history that includes questions about the following: previous tick bite exposure; engagement in activities that would lead to tick bites, including biking, hunting, hiking, and gardening; foods that were eaten several hours before the onset of symptoms; physical exam; and lab tests, including immunoassays for IgE specific to alpha-gal, beef, and pork. Once the diagnosis has been made, management should include patient education about the avoidance of mammalian meat, treatment for an allergic reaction, and future avoidance of tick bites.
It is important to review all possible sources of red meat. Patients should be educated that all beef, pork, lamb, and wild game are considered red meat. Only meat from fish or fowl should be ingested. Mammalian meat byproducts, including organ meats, gelatins, pork rinds, and jellied candy, need to be avoided as well. Management of anaphylaxis after unintended exposure should include antihistamines, epinephrine, and steroids. Patients should be prescribed an epinephrine pen injector, and the signs and symptoms of anaphylaxis and proper use of the injector should be reviewed. Patients should be advised to try an oral antihistamine such as diphenhydramine first and only to use the epinephrine if the reaction advances beyond pruritis and urticaria.1
Avoidance of future tick bites is important. There is a strong likelihood that the acuity of allergic reactions might increase if patients continue to have additional exposure to tick bites.10 Areas known to be infested by ticks should be avoided during summer months due to peak tick activity occuring during that time.11,12 If patients plan to be in areas with known tick infestations, they should wear long shirts tucked in and long pants with pant legs tucked into socks or boots. Use of clothing treated with permethrin and a chemical repellant containing N,N-Diethyl-meta-toluamide (DEET) is recommended as well. Patients should be sure to check their entire body afterwards and, if necessary, remove any ticks found to be attached. Removal of ticks should be done using fine-tipped tweezers and using a stable pressure while grabbing the tick as close to the mouth as possible.13 If patients are hesitant to remove the tick or if they were unsuccessful in their attempt to remove the tick, they would need to be seen by a provider to ensure complete tick removal.
For many years, patients with peculiar complaints of delayed reactions after eating meat have been disregarded by many providers.8 Now equipped with this new information available about IgE specific to alpha-gal and the reactions it can cause, all providers who see patients with complaints of chronic urticaria or angioedema with an unidentified cause should have alpha-gal allergy included in the differential diagnosis. A detailed history is essential in the diagnosis of alpha-gal allergy and should include questions about possible tick-bite exposure, 24-hour diet recall, and timing related to the onset of symptoms after the last meal. Once the diagnosis has been made, treatment and management of the condition is straightforward. Most patients should be successful in avoiding recurrent episodes once equipped with the knowledge of how to avoid mammalian meat products and future tick bites.
Jennifer Spires, MSN, FNP-BC, is a nurse practitioner, practicing at Allergy and ENT Associates of Middle Tennessee in Hermitage.
- Tripathi A, Commins SP, Heymann PW, Platts-Mills TA. Delayed anaphylaxis to red meat masquerading as idiopathic anaphylaxis. J Allergy Clin Immunol Pract. 2014;2(3):259-265.
- Wolver SE, Sun DR, Commins SP, Schwartz LB. A peculiar cause of anaphylaxis: no more steak? The journey to discovery of a newly recognized allergy to galactose-alpha-1,3-galactose found in mammalian meat. J Gen Intern Med. 2013;28(2):322-325.
- Commins SP, James HR, Kelly LA, et al. The relevance of tick bites to the production of IgE antibodies to the mammalian oligosaccharide galactose-α-1,3-galactose. J Allergy Clin Immunol. 2011;127(5):1286-1293.e6.
- Hamsten C, Starkhammar M, Tran TA, et al. Identification of galactose-α-1,3-galactose in the gastrointestinal tract of the tick Ixodes ricinus; possible relationship with red meat allergy. Allergy. 2013;68(4):549-552.
- Van Nunen SA, O’Connor KS, Clarke LR, Boyle RX, Fernando SL. An association between tick bite reactions and red meat allergy in humans. Med J Aust. 2009;190(9):510-511.
- Barbour AG. Does lyme disease occur in the south?: a survey of emerging tick-borne infections in the region. Am J Med Sci. 1996;311(1):34-40.
- Commins SP, Satinover SM, Hosen J, et al. Delayed anaphylaxis, angioedema, or urticaria after consumption of red meat in patients with IgE antibodies specific for galactose-α-1,3-galactose. J Allergy Clin Immunol. 2009;123(2):426-433.
- Commins SP, Platts-Mills TA. Anaphylaxis syndromes related to a new mammalian cross-reactive carbohydrate determinant. J Allergy Clin Immunol. 2009;124(4):652-657.
- Commins SP, James HR, Stevens W, et al. Delayed clinical and ex vivo response to mammalian meat in patients with IgE to galactose-alpha-1, 3-galactose. J Allergy Clin Immunol. 2014;134(1):108-115.
- Fischer J, Hebsaker J, Caponetto P, Platts-Mills TA, Biedermann T. Galactose-alpha-1,3-galactose sensitization is a prerequisite for pork-kidney allergy and cofactor-related mammalian meat anaphylaxis. J Allergy Clin Immunol. 2014;134(3):755-759.e1.
- Pujalte GG, Chua JV. Tick-borne infections in the United States. Prim Care. 2013;40(3):619-635.
- Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hygiene. 2010;83(1):174-182.
- Due C, Fox W, Medlock JM, Pietzsch M, Logan JG. Tick bite prevention and tick removal. BMJ. 2013;347:f7123.