Allergy

Alpha Gal Reaction

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Alpha Gal Reaction, Alpha-Gal Reaction, Alpha-Gal Allergy, Alpha-Gal Syndrome, Red Meat Allergy

  • Mechanism
  1. Occurs after Lone Star Tick Bite (Amblyomma Americanum), found in the eastern and southeastern United States
  2. Sensitization to Galactose-alpha-1,3-galactose (alpha-gal) due to IgE cross reactivity
  3. Alpha-gal is present in both tick Saliva and red meat (lamb, pork, beef, venison, rabbit)
  • Findings
  1. New severe, sudden, Allergic Reaction (Urticaria, Anaphylaxis) to red meat (beef, lamb, pork, venison, rabbit)
  • Associated Conditions
  • Other Lone Star Tick related illnesses
  1. Tularemia
  2. Ehrlichiosis
  3. Heartland Virus
  4. Bourbon Virus
  5. Southern Tick Associated Rash Illness (STARI)
  • Findings
  1. Allergic Reaction onset 2 to 6 hours after red meat (or derived product) ingestion
  • Differential Diagnosis
  • Red Meat Allergy
  1. Alpha-Gal Syndrome (described on this page)
  2. Primary Beef Allergy
    1. Young children with Atopic Dermatitis (esp. with Cow's Milk Allergy)
  3. Pork-Cat Syndrome
    1. Patients with cat allergy develop pork allergy (and in some cases beef allergy)
    2. Primarily seen in teens and young adults
  • Management
  1. See Allergic Reaction
  2. See Anaphylaxis
  3. Avoid all red meat products
  4. Avoid animal derived products (e.g. cow's milk, gelatin)
  • Prevention
  1. See Prevention of Vector-borne Infection
  • Resources
  • Patients
  1. Alpha-Gal (Mayo Clinic)
    1. https://www.mayoclinic.org/diseases-conditions/alpha-gal-syndrome/symptoms-causes/syc-20428608
  2. Alpha-Gal (CDC)
    1. https://www.cdc.gov/ticks/alpha-gal/index.html
  • References
  1. Commins (2011) J Allergy Clin Immunol 127(5): 1286-93 [PubMed]
  2. Wilson (2019) Curr Opin Allergy Clin Immunol 19(3):229-35 +PMID: 30844847 [PubMed]