One bite from the Lone Star tick can forever alter a person’s life and diet. The tick’s bite triggers a unique food allergy to red meat and other products from mammals.
The mechanism behind the allergy called Alpha-Gal Syndrome (AGS) is most unusual. The saliva in the Lone Star’s bite transmits a sugar molecule, known as alpha-gal, which is found in mammals, but not humans or primates.
In some people, when alpha-gal enters the bloodstream, it triggers the immune system to begin producing IgE allergy antibodies to this sugar. That primes the system to begin having allergic reactions when the person with AGS eats meat, such as beef, lamb, venison and pork.
Many people alpha-gal syndrome also can’t consume dairy (a mammalian product) or take certain medications.
As the Lone Star tick spreads to more regions, the number of AGS patients is also quickly growing. The Centers for Disease Control and Prevention (CDC) released data in 2023 that revealed about 110,000 cases of AGS in the United States over a decade. But CDC researchers estimate the true number of Americans with the alpha-gal allergy is closer to 450,000.
The syndrome can be difficult to diagnose. An alpha-gal reaction often occurs several hours after consuming meat, dairy or other mammal byproducts, and the food connection can be missed. Healthcare providers may mistake gastrointestinal symptoms for other conditions. Or, they may not think to ask a patient about whether they recall a tick bite.
Dr. Scott Commins on AGS Patient Issues
One of the best-known alpha-gal syndrome researchers is Dr. Scott Commins, the associate chief for allergy and immunology at the University of North Carolina’s School of Medicine.
He was among the researchers who first confirmed the AGS’s association with tick bites.
Allergic Living recently caught up with Commins to discuss the latest on alpha-gal syndrome.
What’s the most reliable way to test for alpha-gal allergy?
A blood test is the best method, Commins says. A skin-prick test, typically used to test for other food allergens, is not an accurate way to diagnose AGS.
However, patients who suspect an alpha-gal allergy should not just be requesting a blood test, he stresses. It is important to discuss symptoms with a physician, as well.
“The diagnosis is made after development of clinical symptoms, confirmed by a blood test,” says Commins, who sees patients at UNC’s Allergy & Immunology Clinic at Eastowne, where he is the medical director.
Blood test results are now quicker to get than a decade ago. This is because national blood testing labs now all run the alpha-gal test. A 2015 study showed the average diagnosis took up to seven years. But with growing awareness, Commins says researchers now think that timeframe is being significantly reduced.
What symptoms should make you suspect AGS?
One common scenario is patients who wake up in the middle of the night, hours after eating something like beef or ice cream, Commins says. They awaken with hives, itching or swelling.
“There’s not much else that will cause that new onset swelling in an adult at midnight,” he says.
Yet, some patients only have gastrointestinal symptoms. They don’t experience the other symptoms of an allergic reaction, such as hives or shortness of breath, Commins says.
New or chronic abdominal symptoms, such as nausea, diarrhea, or terrible belly pain will usually send patients to a gastrointestinal specialist. But a patient who suddenly experiences episodes of abdominal cramping and pain, particularly in the evening, might need an AGS allergy test, he says.
Once diagnosed, allergists recommend AGS patients carry epinephrine, in case of anaphylaxis.
When do AGS patients have issues with dairy, gelatin or fumes?
It is quite common for patients, about 30 percent of those with AGS in Commins’ clinic, to experience issues with dairy. Gelatin is also a fairly common trigger, he says.
About 3 to 5 percent of his AGS patients have reacted to cooking fumes. The issue here is inhaling meat fat droplets. For example, Commins will hear of reactions from being in proximity of meat grilling. “That can be really hard on folks.”
Should all patients with alpha-gal syndrome avoid dairy and gelatin?
“I do not ask people to avoid dairy right away, unless they came in with symptoms specifically tied to dairy,” Commins says. Some people will only react to meat and meat derivatives.
He talks to patients about their experiences to decipher which foods trigger their symptoms. For example, if an alpha-gal patient experiences symptoms after eating a cheese pizza, then it may be time to try limiting dairy.
With AGS, which medications are ones to watch out for?
Patients should be aware of the blood thinner heparin, which can be derived from pig intestines, Commins says.
But he encourages AGS patients not to refuse a heparin injection in an emergency where they need the drug. Communicate about the alpha-gal allergy with emergency healthcare workers, so they are ready to respond if there is a reaction, he says.
Cetuximab, a chemotherapy drug, contains alpha-gal. The CDC warns alpha-gal patients to be careful as well about heart valves (from pigs or cows) and magnesium stearate used in medical tablets and cosmetics. Many other health products are also animal-derived.
To find out if the gelatin in capsules for any medication is of animal origin, Commins recommends checking the website VeganMed.org. “It’s a trusted source, run by pharmacists. They’ve been a real help to patients with AGS,” he says.
Can alpha-gal syndrome go away?
Yes. If a patient has a tick bite that leads to AGS, it can resolve in about three to five years, Commins says.
However, especially in the Southeast, patients often get another tick bite in that timeframe. The additional bite acts like a booster to the allergy, extending the longevity of AGS in the patient.
“It’s not uncommon for people to get more bites. So it doesn’t go away as frequently as you would anticipate,” he says. Commins encourages patients to get retested for the alpha-gal allergy every year.
Is there allergy therapy available to AGS patients?
While there is not a known and trusted desensitization method for alpha-gal, patients have had success with the injectable drug Xolair (omalizumab), Commins says.
Xolair was approved in February 2024 to help patients with IgE-based food allergies to avoid severe allergic reactions. This includes alpha-gal and Commins says the anti-IgE biologic drug is proving helpful to AGS patients.
It is not intended to re-introduce steak to your diet, but “Xolair is a huge win for people who react to fumes,” he says.
Is alpha-gal awareness improving among healthcare workers?
While he is seeing more awareness, Commins points to the 2023 CDC survey results as evidence that more education is needed. The survey showed 42 percent of healthcare providers surveyed had not heard of AGS.
Despite public awareness about the allergy seemingly increasing, “provider awareness seems to be lacking,” he says.
As the tick spreads to more regions, it is hard to keep up with educating health professionals. “These ticks enter new geographic locations and completely take providers off-guard,” Commins says.
The CDC data reported prevalence of alpha-gal cases in the southern, midwestern, and mid-Atlantic regions of the U.S. But Commins notes that the ticks seem to be moving into the central U.S. and north into the Great Lakes area. He is now hearing of alpha-gal cases in Minnesota, Michigan and Wisconsin that would have not been the case even five years ago.
Related Reading:
Two Alpha Gals: Change Agents for a Seriously Underserved Allergy
How to Avoid Lone Star (and Other) Ticks
