Hours after savoring that perfectly grilled steak on a beautiful summer evening, your body turns traitor, declaring war on the very meal you just enjoyed. You begin to feel excruciating itchiness, pain, or even swelling that can escalate to a point requiring emergency care.
The culprit isn’t food poisoning—it’s the fallout from a tick bite you may have gotten months earlier and didn’t even notice.
This delayed allergic reaction is called alpha-gal syndrome. While it’s commonly referred to as the “red meat allergy,” that nickname is misleading, as alpha-gal syndrome can also cause strong reactions to various products beyond just red meat.
The syndrome is rapidly spreading in the US and around the globe. The Centers for Disease Control and Prevention estimates as many as 450,000 people in the US may have it, and it’s carried by many more tick species than most people realize.
CDC
What is alpha-gal syndrome?
Alpha-gal syndrome is an allergy to a sugar molecule with a tongue-twisting name: galactose-alpha-1,3-galactose, or alpha-gal for short.
The alpha-gal sugar molecule exists in the tissues of most mammals, including cows, pigs, deer, and rabbits, but is absent in humans. When a significant dose of alpha-gal enters your bloodstream through a tick bite, it can trigger your immune system to generate antibodies against alpha-gal. During subsequent exposure to foods containing alpha-gal, your immune system may initiate an inappropriate allergic response.
Judy Gallagher via Wikimedia, CC BY
Triggers and Management of Alpha-Gal Syndrome
Often triggered by consuming red meat, this allergy can also respond to a variety of animal-based products, including dairy, gelatin (think Jell-O or gummy bears), medications, and personal care items. For instance, the blood-thinning drug heparin, derived from pig intestines, has elicited severe reactions in some individuals with alpha-gal syndrome.
It is possible to overcome the allergy by significantly modifying your diet, avoiding triggering reactions for a few years, and avoiding more tick bites. However, this requires time and careful vigilance regarding less obvious sources of exposure.
Why the Rise in Alpha-Gal Syndrome Diagnoses?
As an entomologist studying insects and the diseases they transmit, I am concerned about the rapid increase of this allergy globally.
Initially, experts believed that alpha-gal syndrome was primarily confined to the southeastern U.S. due to the geographical range of the lone star tick. However, shifting reports now identify numerous tick species across six continents capable of causing this syndrome, including the black-legged tick, which transmits Lyme disease.
Understanding the Mechanisms
When a tick bites, it looks for a warm, dark area to attach itself, using a serrated mouthpart to penetrate the skin. As it feeds, it releases saliva containing anesthetics and blood thinners, along with alpha-gal sugars.
One theory suggests that the large amount of tick saliva or skin damage during feeding activates a strong immune response, while others propose a combination of these and other factors might be involved.
Symptoms of Alpha-Gal Syndrome
Reactions to alpha-gal syndrome typically occur one to three months post-tick bite. Symptoms can include hives, swelling, severe abdominal pain, nausea, or even anaphylactic shock. Symptoms usually appear 2 to 6 hours after consuming meat products containing alpha-gal.
Unfortunately, many healthcare providers may not recognize alpha-gal syndrome. A 2022 study found that 42% of U.S. health care practitioners had never heard of it, which can delay diagnosis.
If You Suspect Alpha-Gal Syndrome
If you think you might have alpha-gal syndrome, discuss your concerns with your doctor and request a blood test to check for an immune reaction to alpha-gal.
Upon confirmation, the primary strategy for managing the allergy is to avoid consuming any mammal-derived food products, including milk and cheese, along with avoiding further exposure.
In severe cases, individuals may need to carry an EpiPen to combat anaphylactic shock. Reputable sources like the CDC and alphagalinformation.org provide further guidance.
Mysteries of Alpha-Gal Syndrome
Although progress has been made in understanding alpha-gal syndrome since it was first documented in the early 2000s, many mysteries remain. Researchers are still working to determine how exactly the tick bite manipulates the immune system and why some individuals develop the allergy while others do not.
As public interest in alpha-gal syndrome grows, the next decade may yield advancements in prevention, diagnosis, and treatment.
For now, if you’re out in the woods or long grasses, ensure you check for ticks on your body, wear long sleeves, long pants, and apply tick repellent to protect yourself from these bloodthirsty hitchhikers. And be alert for unusual allergic symptoms after your next steak or handful of gummy bears.
Lee Rafuse Haines, Associate Research Professor of Molecular Parasitology and Medical Entomology, University of Notre Dame
