II. Epidemiology
- Prevalence U.S.: 450,000 estimated cases in U.S.
- Lone Star Tick is active in eastern, southeastern and south central U.S. states
III. Mechanism
- Occurs after Lone Star Tick Bite (Amblyomma Americanum), found in the eastern and southeastern United States
- Sensitization and Antibody formation to Galactose-alpha-1,3-galactose (alpha-gal) due to IgE cross reactivity
- Alpha-gal are Carbohydrates present in both tick Saliva and red meat (lamb, pork, beef, venison, rabbit)
- In contrast, alpha-gal is not present in the Muscle of primates including humans (hence the potential for sensitization)
- Syndrome was first described in 2007 by Dr. Thomas Platts-Mills
IV. Findings
- New sudden, Allergic Reaction (Urticaria, Anaphylaxis) to red meat (beef, lamb, pork, venison, rabbit)
- Initial reaction is a delayed, IgE mediated Allergic Reaction
- Symptom onset 2-6 hours after ingestion after red meat (or derived product) ingestion
- Common symptoms
- Gastrointestinal (Abdominal Pain, Nausea or Vomiting, Diarrhea)
- Urticaria (or other pruritic rash)
- Severe reactions
- Angioedema (facial swelling)
- Dyspnea
- Anaphylaxis
V. Associated Conditions: Other Lone Star Tick related illnesses
- Tularemia
- Ehrlichiosis
- Heartland Virus
- Bourbon Virus
- Southern Tick Associated Rash Illness (STARI)
VI. Differential Diagnosis: Red Meat Allergy
- Alpha-Gal Syndrome (described on this page)
- Primary Beef Allergy
- Young children with Atopic Dermatitis (esp. with Cow's Milk Allergy)
- Pork-Cat Syndrome
- Patients with cat allergy develop pork allergy (and in some cases beef allergy)
- Primarily seen in teens and young adults
VII. Labs
- Alpha-Gal IgE
- Consider testing in idiopathic gastrointestinal symptoms after red meat ingestion
VIII. Management
- See Allergic Reaction
- See Anaphylaxis
- Allergist referral for severe reactions
- Reaction Treatment
- Epinephrine Home Injectable Devices (e.g. Epi-Pen)
- Antihistamines (e.g. Cetirizine, Diphenhydramine)
- Prevent exposure
- Avoid all red meat products
- Additional measures in more severe reactions (or if symptomatic with these additional exposures)
- Avoid animal derived products (e.g. cow's milk, gelatin)
- Medications, Vaccines or supplements that are mammal derived (e.g. lactose, lanolin)
IX. Course
- Alpha-Gal antibodies wane over-time (without re-exposure from Lone Star Tick Bite)
- Patients may once again tolerate some red meat products with time
X. Prevention
XI. Resources: Patients
- Alpha-Gal (Mayo Clinic)
- Alpha-Gal (CDC)