Alpha-galactose allergy

Alpha-galactose allergy (also known as alpha-gal allergy, alpha-gal syndrome, or mammalian meat allergy (MMA)) is a reaction to the carbohydrate galactose-alpha-1,3-galactose (alpha-gal). In alpha-galactose allergy, the body experiences a sharp increase in immunoglobulin E (IgE) upon contact with the meat-derived carbohydrate.

The alpha-gal molecule is found in all mammals except apes, humans, and Old World monkeys. Since humans do not naturally produce this carbohydrate, humans do not have an pre-existing immune tolerance to the carbohydrate. The allergy most often begins when a Lone Star tick bite transmits alpha-gal into the body. In some people, an immune system reaction may later produce mild to severe allergic reactions when red meat is eaten.

The cancer drug cetuximab (trade name Erbitux) contains the alpha-gal carbohydrate, since it is manufactured from mice. Cetuximab can cause a reaction in people who live in regions with a high population of Lone Star ticks, suggesting a link between Lone Star tick bites and an increased vulnerability to alpha-gal syndrome.

Treatment
There is no treatment, other than not eating red meat.

Symptoms

 * Hives, itching, or itchy, scaly skin (eczema)
 * Swelling of the lips, face, tongue and throat, or other body parts
 * Wheezing or shortness of breath
 * A runny nose
 * Abdominal pain, diarrhea, nausea or vomiting
 * Sneezing
 * Headaches
 * Anaphylaxis, a severe, potentially deadly allergic reaction that restricts breathing

Learn more

 * Meat Allergy by ACAAI.org
 * Jan 18, 2019 Mammalian meat allergy: How tick bites can cause allergic reactions to meat, milk and gelatine ABC AU
 * Feb 24, 2019 Likelihood of tick bite to cause red-meat allergy could be higher than previously thought Science Daily
 * Dec 6, 2019 Lone star tick a growing threat to humans, pets as populations expand in CT WFSB News