Reviewed by: Stephen C. Eppes, MD and Clifton Castleman, WEMT a tick safety expert with TickSafety.com
Indeed, it's true. Alpha-Gal (Galactose-alpha-1,3-galactose) is a delayed severe allergy to red meat affecting a growing number of the population. This allergy is initially caused by the bite of a Lone Star tick (Amblyomma americanum).
What is Alpha-Gal?
The reaction is a systemic release of antibodies that binds to a carbohydrate present in mammalian meat called galactose-alpha-1,3-galactose (alpha-gal). Mammalian meat is any meat that comes from a mammal including beef, pork, lamb, venison, goat and bison. Fish, turkey and chicken are not mammals, so they don’t have alpha-gal. When a person with the alpha-gal antibody eats mammalian meat, the meat triggers the release of histamine, a compound found in the body that causes allergic symptoms like hives, itching and even anaphylaxis.
Since the reaction to eating mammal meat is delayed by several hours, the proper diagnosis is often missed or misdiagnosed. People who are afflicted with the Alpha-Gal allergy have to be constantly vigilant about the ingredients they consume, because an allergic reaction can be severe and life-threatening.
Though it hasn’t been scientifically proven, researchers think the Lone Star tick produces a sugar from its gut called galactose-alpha-1,3-galactose, or “Alpha-Gal.” In some cases, the human immune system develops an allergic response to that sugar. Because Alpha-Gal is also found in red meat, a bite by the Lone Star tick may translate to an allergic reaction to anything from beef hamburgers to bacon. Repeated tick bites can potentially cause the antibody level of Alpha-Gal to rise, worsening reactions. People with the allergy can go into a delayed anaphylactic shock, four to six hours after eating red meat.
Alpha-gal allergy is different from other food allergies like the peanut allergy as the response is delayed. Unlike someone with a peanut allergy who has an immediate allergic response after eating peanuts, people with the alpha-gal allergy do not start having symptoms until several hours after they eat mammalian meat.
People with certain blood types appear to be more at risk. Those with the rarest types -- B and AB -- do not appear vulnerable, because their blood is chemically similar to alpha-gal. According to studies done at the University of Virginia, as well as in North Carolina, Boston, Australia and Scandinavia, those with types O and A are the ones most susceptible to the Alpha-Gal allergy.
When it comes to allergies, the human immune system has a “memory”. Proteins found in peanuts and eggs trigger the immune system much faster than the proteins found in Alpha-Gal sugar, which takes significantly longer for the immune system to recognize. This explains the red meat allergy’s delayed reaction. Doctors hope the allergy will be less durable than others since it’s caused by an enzyme (sugar).
According to research being done at the University of Virginia, more than 2,000 known cases have cropped up in less than 10 years in the U.S. Cases have also been reported in Australia, Germany, and Japan.
While it is not known exactly how long it takes for transmission to occur, it is thought that once any saliva has been transmitted, there is a chance of giving the host (the human) Alpha-Gal.
The Lone Star Tick
The Lone Star (Amblyomma americanum) tick is a medium-sized, reddish-brown tick that’s common in the Southeastern United States. It gets its name from a white dot found on the backs of all female adults. Lone Star ticks "bite" by inserting needle-like mouth parts into the skin, while backward-facing teeth act as hooks, securing them in place. They also secrete a cement-like substance that helps them to stay attached.
Signs and symptoms of a severe allergic reaction and anaphylaxis typically includes truncal hives, but may also include swelling, vomiting, diarrhea, trouble breathing and a rather significant (and quick) drop in blood pressure. Be sure to dial 9-1-1 for anyone who is having trouble breathing -- especially if you suspect anaphylactic shock!