From the Guidelines
Alpha-gal syndrome is an allergic reaction to alpha-gal, a sugar molecule found in most mammalian meat and products, which can be managed by eliminating alpha-gal from the diet and avoiding products made from mammals, such as lard, butter, milk, and gelatin-containing foods. This condition typically develops after a bite from a Lone Star tick, which transmits the alpha-gal molecule into the human body, triggering an immune response 1. Symptoms include hives, itching, swelling, stomach pain, diarrhea, nausea, vomiting, headaches, and in severe cases, anaphylaxis. These reactions usually occur 3-6 hours after consuming mammalian meat products, making diagnosis challenging.
Key Points to Consider
- The diagnosis of alpha-gal syndrome can be made among patients with GI distress and increased serum alpha-gal IgE antibodies whose symptoms are relieved adequately on an alpha-gal–avoidance diet that eliminates pork, beef, and mammalian-derived products 1.
- Patients with suspected alpha-gal allergy should be counseled on an alpha-gal–avoidance diet because that is the primary management, and counseling also should include measures to avoid tick bites because further bites can drive alpha-gal IgE titers higher and worsen the allergy 1.
- Management primarily involves avoiding all mammalian meat (beef, pork, lamb, venison) and products containing mammalian ingredients like gelatin, dairy, and certain medications.
- Patients should carry an epinephrine auto-injector (EpiPen) for emergency treatment of severe reactions, typically prescribed as 0.3mg for adults or 0.15mg for children, to be injected into the outer thigh at the first sign of a severe reaction.
- Antihistamines like diphenhydramine (Benadryl) can help manage mild symptoms.
- The condition may resolve over time if further tick bites are avoided, but this varies by individual.
- Patients should wear protective clothing, use tick repellents, and check for ticks after outdoor activities to prevent additional sensitization.
From the Research
Definition and Causes of Alpha-Gal Syndrome
- Alpha-Gal Syndrome (AGS) is a unique allergy to non-primate mammalian meat and derived products, associated with tick bites and caused by a specific IgE antibody to the oligosaccharide galactose-α-1,3-galactose (alpha-gal) 2, 3, 4, 5, 6.
- The syndrome is characterized by delayed reactions to mammalian meats, typically occurring 2-6 hours after ingestion 2, 3, 5.
Symptoms and Diagnosis
- Symptoms of AGS may include urticaria, abdominal pain, nausea, and occasionally anaphylaxis, with wide inter- and intra-personal variability 3, 4, 5.
- Diagnosis relies on a combination of clinical history, positive alpha-gal IgE blood testing, and improvement on a mammalian-restricted diet 3, 5.
- Percutaneous testing with commercial meat skin-prick testing extracts is not a reliable tool for diagnosis, while prick-prick skin testing to fresh cooked meat may be considered 5.
Management and Treatment
- Management of AGS centers primarily on avoidance of mammalian meats and medications that express the same carbohydrate antigen 2, 3, 5.
- Counseling about tick avoidance measures is also important, as AGS will wane over time in many patients 3.
- Prolonged avoidance of mammalian meat and avoidance of further tick bites can decrease alpha-Gal sIgE over time, and some patients are able to reintroduce mammalian meat into their diet 5.
Awareness and Knowledge among Healthcare Providers
- Despite the potential life-threatening reactions associated with AGS, many healthcare providers have limited knowledge of the condition 6.
- A survey of healthcare providers revealed that 42% had never heard of AGS, and among those who had, fewer than one third knew how to diagnose the condition 6.
- Limited awareness and knowledge of AGS among healthcare providers likely contributes to underdiagnosis and inadequate patient management 6.