What is alpha-gal syndrome? Tickborne red meat allergy appears to be on the rise.
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Conversations about a “red meat allergy” have regularly popped up on social media or in news articles in Missouri throughout the last few years.
As it turns out, this is a real concern in Missouri that comes from the bite of a lone star tick, one of the most common species of ticks found in the state.
Dr. Molly Baker is the lead zoonotic epidemiologist at the Missouri Department of Health and Human Service’s Bureau of Communicable Disease Control & Prevention. That means she studies
how diseases, viruses, parasites and other pathogens can be transmitted from animals to humans.
“Unfortunately, we have lots of reasons in Missouri to be worried about tick bites,” Baker said. “Zoonotic disease is, you know, a lot of them are new and emerging, and 75% of them are linked to animal or insect vectors.”
She said there are many tickborne illnesses to be aware of in Missouri, such as ehrlichiosis and Rocky Mountain Spotted Fever, but lately attention and conversation has focused on this puzzling “red meat allergy,” which is actually known as
alpha-gal syndrome.
“A lot of the tickborne conditions that we work with commonly are bacterial pathogens or viral pathogens,” Baker said. “So, this is very different in that it's not a pathogen. It's a type of sugar molecule that's transferred through the tick bite process.”
Baker said this sugar — scientific name galactose-α-1,3-galactose, or more simply, “alpha-gal” — is found in the saliva of the lone star tick at all life stages, from larva to adult. As a tick bites a human, this sugar molecule is introduced into the human’s bloodstream — sometimes triggering an allergic reaction.
That’s because, Baker said, this particular sugar is naturally produced in the bodies of most mammals — except humans and other higher primates.
“[It’s] found in nearly all mammalian meat, so that includes beef, pork, venison, rabbit,” said Dr. Johanna Salzer, a veterinarian who leads the Centers for Disease Control & Prevention’s epidemiological team on alpha-gal. “And so what happens is… they'll consume a meat product that they maybe have consumed their whole life, and then all of a sudden, they have an allergic reaction.”
Salzer said alpha-gal syndrome is unique in a lot of ways. It’s an allergy one can catch, the allergic reaction is to a sugar (unlike nearly all other food allergies), and the allergic reactions from ingestion are delayed — between 2 and 10 hours can pass before someone has any reaction at all.
Salzer added that the allergic reactions are also unpredictable: some people have gastrointestinal distress, others get full body hives, some deal with heart symptoms or even full anaphylactic reactions, like those seen in people with, for instance, severe allergies to bee stings.
And allergic reactions may not occur every time — those in the alpha-gal community often refer to the condition as an "any time allergy, not an every time allergy.”
One of the other things that makes the condition difficult to manage, Salzer said, is the fact that there’s no good way, at this time, to predict who’s going to develop the alpha-gal allergy from a tick bite.
“There are a fair number of people, especially in areas like Missouri and Arkansas, where people are bitten by lone star ticks more often, that will have antibodies, but they have no clinical symptoms,” Salzer said. “So they don't have alpha-gal syndrome.”
She said the current scientific evidence seems to suggest that an alpha-gal allergic reaction is more likely if someone is bit by a lot of ticks at one time, such as walking into a “tick bomb.” This is a colloquial term for a group of newly-hatched tick larvae, which are commonly referred to as seed ticks.
But, Salzer admitted, since the condition is relatively new — first being identified and named in scientific literature in 2009 — there are still many unknowns about the mechanisms of the condition and why some people have a reaction and some don’t.
She added that the condition is diagnosed with a combination of a blood test looking for a specific antibody and clinical symptoms, but even the blood tests for antibodies can’t predict severity of reaction.
“It’s not consistent,” Salzer said. “So, someone can have very high antibodies and have more, milder reactions — maybe they only react when they consume meat products, but they can still consume dairy, and then you have other people with lower antibodies that are much more sensitive, even reacting to gelatin, and some of the products that have lower concentration of alpha gal in them.”
The sugar alpha-gal is not only found in mammalian meat.
It can be found in a myriad of products that are derived from mammals, such as such as dairy products, lard, tallow, gelatin and more — which means some people have an allergic reaction only when they eat beef and pork, while others struggle with dairy products and fats, and, anecdotally, others even struggle with airborne alpha-gal particles in fumes.
“It's a really life-changing experience,” Missouri’s Dr. Baker said. “It truly is a life-changing condition to have, to cope with and to live with.”
According to the CDC, at least 450,000 people in the county have alpha-gal syndrome, but Baker said it’s hard to know how prevalent the condition really is, especially in Missouri, because many doctors don’t even know to test for it.
In 2022, the CDC did a survey of healthcare providers across the country and 42% of them had never heard of alpha-gal syndrome.
Both Baker and Salter said they believe that awareness of the condition has grown since then — both among healthcare professionals and the general public, but since the condition isn’t nationally reportable, all estimations of disease burden remain a best guess.
So, for now, Baker said the best thing people can do is avoid tick bites and speak with their medical provider if they’re concerned about this odd emerging tickborne condition.
“So, that means, wearing appropriate clothing — long sleeves and long pants whenever possible, applying insect repellent to any exposed skin that's not covered by clothing, considering
the use of something like permethrin to treat your boots or your socks or your pants or any gear that you might be using just to reduce the likelihood of a tick getting onto you and being able to attach and potentially transfer that alpha-gal molecule or bacteria or virus — whatever it may be carrying,” Baker said.
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