In the past month, three patients visited Covenant’s East Brainerd office with reports of a recent tick or chigger bite along with hives, itching, difficulty breathing and/or symptoms of a severe allergic reaction called anaphylaxis.
“We are seeing symptoms of an allergic reaction to mammalian meat,” said Susan Raschal, DO, a board-certified allergist in Chattanooga. “But the allergic reaction doesn’t happen until a person is first bitten by a tick or chigger and then later ingests the meat that comes from a mammal such as beef, pork, lamb, venison, goat or bison.”
Researchers at the University of Virginia recently discovered that when certain people are bitten by ticks or chiggers, the bite appears to set off a chain of reactions in the body. One of these reactions is the production of an allergic class of antibody that binds to a carbohydrate present on meat called galactose-alpha-1, 3-galactose, also known as alpha-gal. When a person with the alpha-gal antibody eats mammalian meat, the meat triggers the release of histamine. Histamine is a compound found in the body that causes allergic symptoms like hives, itching and, in the worst case, anaphylaxis (a reaction that leads to sudden weakness, swelling of the throat, lips and tongue, difficulty breathing and/or unconsciousness).
“This is the first time we have seen this particular food allergy in our office, and I haven’t heard of any other cases in the area,” Dr. Raschal said. “After patients said their symptoms came several hours after ingesting the mammalian meat, we knew this wasn’t a typical food allergy. Most known food allergy reactions can cause the same symptoms, but are immediate.”
Recently researchers at the University of Virginia first discovered the connection between anaphylaxis and the use of a cancer treatment called cetuximab. Anaphylaxis to this medication was only occurring in regions in the southeastern U.S. that have a specific tick, the lonestar tick. Later, research revealed that these patients had experienced tick or chigger bites and had developed an allergic antibody to alpha-gal. Alpha-gal is present in all lower mammals such as beef, pork and lamb, thus causing a food allergy for patients with the alpha-gal antibody if they consume the meat of these animals.
“We are treating this with epinephrine, which causes the allergic reaction to subside and go away,” Dr. Raschal said. “The only way to prevent this allergic reaction is to avoid mammalian meat. Usually, levels of the alpha-gal decrease over time if the person doesn’t receive any other tick or chigger bites.”
For additional information regarding this topic, please contact Kelly Davis at Covenant Allergy and Asthma Care.