More and more, I hear of folks coming down with “alpha-gal syndrome.” While it sounds like a playful nickname for a fierce female or a dominant she-wolf, in fact, it is nothing so charming. In short, alpha-gal syndrome is a condition which causes an allergic reaction to eating mammalian products such as beef, pork, venison, and in some cases dairy and gelatin.
My latest friend to develop this condition is Tipi Joe. “I almost died,” he greeted me recently. I assumed it was a bear attack, but he went on to tell me about a mysterious and life-threatening bout of anaphylaxis. Upon ceasing consumption of mammals, he feels better, better in fact than he has in years. Allergan tests show he does indeed have alpha-gal syndrome, putting a disheartening end to his enjoying some of his favorite foods. No more bacon-jalapeno poppers. No more slow-cooked raccoon stew.
Everything about this syndrome, from the name to the nemesis, seems strange. How on earth could we develop an allergy to such a specific category of food? Why mammals?
Most mammalian cell membranes contain the carbohydrate galactose-a-1,3-galactose (alpha-gal), which functions as a signal to the immune system that the cells are part of the whole. There is one group of mammals whose cell membranes do not contain alpha-gal: the catarrhine primates – the monkeys of Africa and Asia, the apes, and the humans.
It’s a good thing it’s raining, and I have a full pot of coffee, because I’ve spent the morning in this evolutionary conundrum. The likely explanation is that a pathogen which either contained or mimicked alpha-gal sneakily entered select primates without alerting their immune systems and wiped them out, mostly.
Perhaps a handful of the catarrhine primates with random mutations silencing the gene responsible for signaling the production of alpha-gal survived. Their immune systems, alerted to the presence of foreigners, attacked, and these primates without alpha-gal but with an awakened immunity to it survived.
Natural selection, then, did its thing, and the catarrhine primates now live with a defunct and dormant alpha-gal gene.
So here we humans are, living in the world with no alpha-gal in our cell membranes, likely not thinking about it much, if at all, unless trying to survive a valve transplant from a pig. Our immune systems detect porcine alpha-gal, kicking our rejection mechanisms into full gear.
And then we humans take to the woods and get bitten by ticks.
One tick in particular, the Lone Star Tick, which happens to be the most human-biting tick in the United States, carries alpha-gal in its saliva, or, as the article, “Tick Saliva and the Alpha-Gal Syndrome: Finding a Needle in a Haystack,” published in “Frontiers in Cellular and Infection Microbiology” so eloquently states, they have “saliva proteins decorated with a sugar molecule,” alpha-gal. There is not enough coffee in the universe to get me through the literature on tick saliva and alpha-gal, so I’ll leave it to the immunologists and parasitologists to explain to you why ticks carry alpha-gal as well as a host of other disease-causing molecules in their saliva.
Anyway, along comes this tick with alpha-gal decorated saliva. It bites Tipi Joe, mixing its saliva all into his blood, and Tipi Joe’s immune system comes alive, swords drawn, to fight this invader. As is the case with allergic reactions, it overdoes its job, causing a cascade of signals to tumble into action, leaving a person with conditions ranging from itching, swelling, and hives to a fatal inability to breathe.
Unlike most allergic reactions, the reaction to alpha-gal is delayed, sometimes up to several hours, thus making the allergen difficult to pinpoint. Additionally, the severity of the syndrome can increase with repeated infected tick bites, and wane in time with less exposure. Still, the consensus is that alpha-gal syndrome is a lifelong condition.
Alpha-gal syndrome is on the rise. It’s vector, the lone star tick (Amblyomma americanum), also the carrier of Rocky Mountain spotted fever, is thriving in our warming climate. Rising temperatures contribute to increasing its geographical range and its active season. The Centers for Disease Control estimates that over 500,000 Americans currently have alpha-gal syndrome, with the assumption that it remains undetected in untold others.
Symptoms of alpha-gal syndrome may begin as mysterious itching, hives, or unexplained gastrointestinal pains. Symptoms may disappear and reappear, and also include shortness of breath, heartburn, a drop in blood pressure, or coughing. Sneaky symptoms like depression, fatigue, insomnia, and irritability make it even more difficult to detect. Alpha-gal syndrome can only be definitively diagnosed with a specific allergen test, and it is often overlooked in favor of testing for more common ailments.
As for Tipi Joe, he’ll be feasting on duck, alligator, and fish from now on. And he’ll do well to limit future tick bites.
Great article, Mary!
This is truly an overlooked reason for allergic reactions and, as of a year or two ago, the test is not always definitive. A friend’s adult son was bitten by a tick and soon started reacting to red meat. His doctor sent blood for the alpha-gal allergy test and it came back negative. Believing the test accuracy, he again ate some meat and again reacted. (I don’t think he has been tested again.) No more red meat for him! Strangely enough, his mother also has it but not as severe a reaction. She just aches all over if she eats meat. That’s not to say it can’t progress to the other signs of allergy. She also has fibromyalgia and thinks the symptoms may be related to it because the symptoms she has are exactly the symptoms she has with a fibromyalgia flare. I think I’d believe the symptoms and not necessarily the test.
As an aside, one of the main researchers for alpha-gal was at the Auburn University Veterinary College so if you want to do a deep research dive, you may find some info in veterinary journals; his name is Byron Blagburn. (I just learned he passed away in May)
Holy smoke. i have a friend with this. She can only eat chicken. I’ll have to tell her about alligator… does it come in bacon flavor?