Summertime means barbecues, beach days, outdoor camps—and, unfortunately, ticks.
Lone star ticks are especially worrisome because their bites can trigger alpha-gal syndrome (AGS), an allergic condition linked to a sugar molecule, alpha-gal, found in mammals. That’s why people with AGS can develop allergic reactions after eating red meat, including beef, pork, and lamb. Sometimes, vaccines or medications that contain mammal products also trigger a reaction.
AGS is especially dangerous because, unlike most food allergies with a rapid onset, symptoms appear unexpectedly hours later. They can range from hives and gastrointestinal distress to anaphylaxis, a life-threatening allergic reaction that can cause trouble breathing and loss of consciousness.
AGS cases are rising across the United States. Beginning in April 2026, Massachusetts doctors are required to report cases to the Department of Public Health to improve tracking and prevention efforts.
Tufts University Ph.D. student Cara Martone, who holds a Master of Public Health from Tufts University School of Medicine and currently studies AGS with Professor Sam Telford III, Sc.D., in the Department of Infectious Disease and Global Health at Cummings School of Veterinary Medicine at Tufts University, explains what to know and how to protect yourself.
Cara Martone: It was first identified in the southeastern United States in 2009. People were suddenly having anaphylactic reactions to an intravenous cancer medication. These cases were happening in areas endemic for other tick-borne diseases. It turned out that the cancer drug contained a sugar molecule, alpha-gal, also found in the saliva of lone star ticks. These people had been exposed to the ticks; later, when they went in for cancer treatment, their reaction set off the discovery.
In the United States, we’re only concerned about the lone star tick.
When the tick feeds on us, alpha-gal is present in its saliva, and our body mounts an antibody response against the tick bite itself. Some people will also mount an antibody response against alpha-gal: Those people will experience an allergic reaction when they consume alpha-gal-containing products.
Different species not endemic in the U.S. are implicated in other parts of the world. Deer ticks, which transmit Lyme disease, have not been linked to alpha-gal.
Technically, yes, but lone star ticks don’t carry the bacteria that cause Lyme disease; deer ticks do.
If you live in an area where both tick species are endemic, it’s possible to get both. There doesn’t appear to be any relationship between the two conditions, though. They would come from two separate tick bite incidents.
No. Only some people who are bitten by lone star ticks develop antibodies against alpha-gal. And, a proportion of those people have detectable antibodies specific for alpha-gal without any symptoms, which is a very interesting piece of the puzzle.
With AGS, you need to have symptoms and a detectable antibody response. There’s a delay in those symptoms, which appear after people consume red meat or other alpha-gal-containing products.
It’s diagnosed with a blood test detecting an antibody titer greater than or equal to .1 kU/L (kilounits per liter), as well as symptoms associated with red meat, with a symptom delay of two to 10 hours.
Think about someone with a peanut allergy. Symptoms appear pretty quickly, usually in less than 20 minutes. For people who have AGS, symptoms take longer to appear, which can make it difficult to connect a reaction to a food.
It’s also an atypical allergy because of the symptom presentation. Some people have a typical allergy presentation: redness, hives, swelling, anaphylaxis. But there’s also a subset who have only gastrointestinal (GI) manifestations, including abdominal cramping, bloating, vomiting, and diarrhea, which can make diagnosis difficult as you may not associate those symptoms with an allergy.
The possibility for GI-only manifestations and the delay in symptoms have led to diagnostic delays for a lot of people. If you suspect that you might have AGS, it’s important to track food intake and symptoms.
Anaphylaxis is a life-threatening condition in which the body mounts a strong immune response. People can lose consciousness and/or have difficulty breathing.
That’s why, in certain areas, many medical providers are prescribing EpiPens for all people with AGS, regardless of symptom presentation. For some people, the disease manifestation can change. Initially, they might just have stomach upset when they eat red meat, but, over time, they might begin to experience more severe symptoms.
We don’t know for sure, but typically it can happen weeks or months after a tick bite. Then, after consuming red meat or other alpha-gal products, you’d have a reaction two to 10 hours later. That’s what’s scary about the anaphylaxis—people might wake up in the middle of the night after having a hamburger for dinner.
We’re not sure, but there’s speculation that certain factors amplify the process. There’s evidence to suggest that exercising after consuming meat, or consuming alcohol, can exacerbate the response. The response might also be stronger with fattier foods.
Another complicating factor is that people have varying sensitivities. Some people can’t eat red meat but are able to tolerate mammal products like dairy, medications, or vaccines. Others can’t tolerate any alpha-gal products. The theory is that these items contain different levels of alpha-gal.
Protect yourself against tick bites. Be aware of the tick burden in your area: this map from the Centers for Disease Control and Prevention (CDC) is a useful resource.
Tick activity also varies throughout the year. For example, the larval stage of the lone star tick occurs in late summer and early fall. That’s when people sometimes encounter what researchers call a “tick bomb.” Basically, you’re outside and stumble upon a clutch of larval lone star ticks that have recently hatched, all in close proximity. You end up completely covered. There’s evidence to suggest that the volume of tick bites can increase your chances of developing AGS.
We’re now at the beginning of tick season. (Learn more about the lifecycle timing from the CDC). Larval ticks that hatched last summer will now emerge as nymphs. Those are especially concerning from a public health standpoint because they’re so small compared with adult ticks — about the size of a poppy seed — which means people may not be aware they have been bitten.
Those nymphs emerge starting in the spring. Pretty much from May into the fall is when people should be most concerned about tick bites.
It’s also important to avoid areas where ticks thrive. Ticks love leaf litter.
But the biggest defense is protecting yourself with treated clothing and tracking your symptoms and food intake if you suspect AGS, because that can help healthcare providers narrow down a diagnosis.
Unfortunately, there’s no treatment other than abstaining from red meat once you have been diagnosed. Some people who abstain for several months and avoid additional tick bites are able to tolerate meat again, but it’s unclear why for those individuals.
There have been studies involving slow reintroduction in controlled healthcare settings, administering very small amounts of alpha-gal-containing products. Some people have been able to tolerate this approach.
What’s so interesting, but also scary from a public health standpoint, is how variable this condition is in terms of symptom presentation, what people are able to tolerate, the timing, and the changes needed afterward to prevent symptoms. It’s very individualized.
(Newswise/HG)
