The Potentially Fatal Tick-Borne Illness You Haven't Heard of Yet
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You've heard of Lyme disease, but there's a relatively new tick-borne illness in town, and its symptoms have been leaving many doctors and patients perplexed.
It’s called Alpha-gal syndrome (AGS), and it can make people bitten by certain ticks severely allergic to certain animal proteins found in mammals — meaning it is often triggered after a person eats red meat or dairy. It's different from Lyme disease, as it's an allergy, whereas Lyme is a bacterial infection.
There are a few reasons why AGS is so mysterious, the first being that it was only recognized in 2002 and there’s a lot that scientists are still learning about it. A 2023 survey found that 45% of health care providers hadn't heard of AGS, and another 35% weren't confident in their ability to treat it.
The other is the fact that the first sign may be a life-threatening allergic reaction known as anaphylaxis (think: throat-swelling, difficulty breathing) in people who develop the condition, often a long while after being bitten by a tick. More than 110,000 people so far have developed Alpha-gal syndrome in the U.S., according to data from the Centers for Disease Control and Prevention (CDC), but the agency notes that the actual number of cases may be higher.
Here’s what infectious disease doctors want you to know about this mysterious disease.
What is Alpha-gal syndrome?
This potentially fatal condition gets its name from the molecule galactose-α-1,3-galactose (a.k.a. alpha-gal), which is found in most mammals. People with AGS can develop symptoms after they eat red meat, dairy or are exposed to other products made from mammals.
Alpha-gal syndrome is mostly linked with the bite of an infected lone star tick, which is more common in the South, East and Central states in the U.S. Those are the areas in which most AGS cases are found, according to the CDC. But scientists haven’t ruled out that other types of ticks can spread it as well, and other tick species in different countries have also been linked to AGS.
“When you’re bitten, the tick transfers that molecule, galactose-α-1,3-galactose, to the body,” explains William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “The body then develops antibodies to it.”
Because the body of a person with AGS then has antibodies to meat, they can end up getting an allergic reaction when they eat meat or are even around meat products, Dr. Schaffner says. “It’s a very strange illness,” he says.
The symptoms of Alpha-gal syndrome
AGS can cause a range of symptoms: mild ones like a rash or hives, or more severe ones such as difficulty breathing, and even anaphylaxis, says infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security. Some people may also have nausea, vomiting, diarrhea, stomach pain and a drop in blood pressure after having animal products, Dr. Schaffner says.
Symptoms usually show up two to six hours after eating or contact with the animal product, according to the CDC, and they include:
Hives or itchy rash
Nausea or vomiting
Severe stomach pain
Heartburn or indigestion
Diarrhea
Cough, shortness of breath, or difficulty breathing
Drop in blood pressure
Swelling of the lips, throat, tongue or eyelids
Some people with a severe form of alpha-gal syndrome may have trouble being around animals after developing the condition. One case study from Spain, for example, showed how three cattle workers with AGS had allergic reactions after touching or breathing in amniotic fluid from cows who were giving birth.
Making things even trickier is that people may not make the immediate connection to a tick bite, especially given that the allergy may not fully develop until three months after the bite. “It is often difficult to figure out exactly what the symptoms are due to, and to link it to a prior tick bite,” Dr. Adalja says. Given that AGS is a newer condition, some doctors also may not be aware that it exists, Dr. Schaffner says.
How to get diagnosed and treated
If you have any of the symptoms above, get to an emergency department. If you've had them, and they've gone away on their own, don't blow it off: speak to your doctor. There’s a test for the antibodies that the body produces in response to AGS; that’s how the syndrome is usually diagnosed. Skin allergy testing may also help guide a diagnosis, according to the CDC.
“Doctors really have to think about this diagnosis,” Dr. Schaffner says. Because it’s a newer illness, they may not have seen AGS before, he explains. Depending on a patient’s symptoms, it may even be chalked up to a foodborne illness at first.
Once someone is diagnosed with Alpha-gal syndrome, it’s usually recommended that they take antihistamines to reverse the symptoms, Dr. Adalja says. In severe cases, doctors may recommend that the person carry around an epinephrine auto-injector, like an Epi-pen, which is used in cases of anaphylaxis.
Doing one’s best to avoid meat and mammalian products is also recommended, although Dr. Schaffner says that people with alpha-gal syndrome can often eat poultry and seafood. “You don’t have to become a vegetarian,” he says.
New treatments are being explored, too, including exposure treatments to try and desensitize people, Dr. Adalja says.
How to protect yourself from AGS
The best way to decrease the risk of developing alpha-gal syndrome? Avoid being bitten by a tick, Dr. Adalja says. According to the CDC, that includes the following:
Be mindful of grassy, brushy, or wooded areas, where ticks like to live
Treat clothing and gear with products containing 0.5% permethrin when you may be around ticks
Walk in the center of trails
Use insect repellents that contain ingredients registered with the Environmental Protection Agency (EPA) like DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone
Check your body and clothes for ticks when you come indoors after being outside
Examine gear and pets after they come inside
Shower within two hours of coming indoors (this may help wash off unattached ticks)
If you suspect that you have Alpha-gal syndrome, Dr. Schaffner says, talk to your doctor, and don't be shy about bringing it up. They can test you for allergies, and recommend the best treatment program from there.
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