Tick-Borne ‘Red Meat’ Allergy is Becoming More Common in U.S., What to Know

A person holds a package of red meat.
Ticks can spread a condition called Alpha-gal syndrome that leads people to become allergic to red meat. Oscar Wong/Getty Images
  • The CDC is warning that more people are being diagnosed with a tick-borne illness that leads to a “red meat allergy”.
  • Alpha-gal syndrome is caused by tick bites and is suspected to have affected up to 450,000 people in the U.S.
  • The CDC is concerned that few health providers know about the disease.

Cases of a rare tick-borne illness are growing rapidly in certain parts of the United States and doctors likely don’t have the proper training to diagnose it.

Alpha-gal syndrome (AGS), often referred to as a “red meat allergy,” is caused by tick bites. It is suspected to have affected up to 450,000 people since 2010, according to a new Morbidity and Mortality Weekly Report, published by the Centers for Disease Control and Prevention (CDC).

The report also shows that it is spreading most rapidly across southern, midwestern, and mid-Atlantic states. Public health officials are concerned that knowledge about the disease, and how to identify it, is limited even among healthcare practitioners. Without additional resources and public awareness, the number of cases of AGS is expected to continue to rise.

What is alpha-gal syndrome?

Alpha-gal syndrome is a tick-borne allergic condition. It is caused by the introduction of a sugar molecule that the tick can transmit via its saliva.

Once the molecule, called monosaccharide galactose-alpha-1,3-galactose, enters into a person’s blood there’s a chance that it can lead to an immune response. As a result, it can lead the person to have a sensitivity or allergy if they encounter that sugar molecule again, which is found in non-primate mammals.

This means a person can start to develop an allergic reaction if they eat items like beef, venison, lamb, and pork because they also contain the same sugar molecule. This is why AGS is often called a “red meat allergy”.

Alpha-gal is not found in fish, reptiles, or birds. But it can show up in other food products from commonly consumed animals, such as milk products.

Few physicians know about alpha-gal syndrome

The first report published by the CDC today examined general knowledge of alpha-gal syndrome among healthcare practitioners. Using a nationwide survey, 1,500 doctors and nurse practitioners responded to a series of questions about AGS. The results were startling.

Among those surveyed, 42% had never heard of AGS, and only 5% of respondents felt “very confident” in their ability to diagnose and treat the disease. Even for the 58% of doctors that were aware of alpha-gal syndrome, few had little actual hands-on experience treating it: 78% had not made a diagnosis in the previous year, and 48% reported that they did not know the correct diagnostic tests to order. 

Respondents were also asked to answer three questions related to alpha-gal syndrome testing, counseling, and etiology — among the 865 doctors that were aware of alpha-gal syndrome, only 42 answered all three questions correctly.

The report concludes that the survey “indicated a low level of knowledge” among healthcare providers in the United States, with “78% of providers having little to no knowledge of AGS.”

In a statement to Healthline, Ann Carpenter, Epidemic Intelligence Service Officer, Centers for Disease Control and Prevention, primary author of the recent CDC report said that it is key for healthcare providers to know the signs of the condition.

“Alpha-gal syndrome is an important emerging public health problem, with potentially severe health impacts that can last a lifetime for some patients,” Carpenter said. “It’s critical for clinicians to be aware of AGS so they can properly evaluate, diagnose, and manage their patients, and educate them on tick-bite prevention to protect patients from developing this potentially long-term allergic condition. “

Dr. Thomas Mather, a professor of public health entomology at the University of Rhode Island and the director of the school’s TickEncounter Resource Center, called the findings, “disappointing.”

While he says he doesn’t expect doctors nor the general public to be experts on ticks and tick-borne illnesses, he does urge people to become more educated by using resources like TickEncounter.

“Most people aren’t entomologists. So we’ve built tools so that people can use themselves. And they can take that information to a practitioner, if the practitioner doesn’t know [about tick-borne illnesses]. I think that the important thing is that we’re working together with medical practitioners and they should know about these tools,” he told Healthline.

Where AGS is spreading most rapidly

The second CDC report put together geographical information for alpha-gal syndrome based on nationwide testing data, and helps to paint a clear picture of which regions are most affected.

During 2017–2021, there was an annual increase in positive test results for alpha-gal syndrome in the United States. More than 90,000 suspected alpha-gal syndrome were identified during the study period, and the number of new suspected cases increased by approximately 15,000 each year during the study.

Between January 2017 and December 2022, 357,119 alpha-gal-specific lgE antibody tests (corresponding with 295,400 unique individuals) were submitted to Eurofins Viracor, a clinical testing laboratory that handles almost all AGS testing in the United States.

About one in three individuals that submitted a test received a positive test result. Positive results were viewed as “suspected” cases of alpha-gal syndrome. A positive test result does not confirm alpha-gal syndrome on its own, as it must also be accompanied by clinical symptoms.

Based on testing data, the CDC report found that the highest number of suspected alpha-gal syndrome cases were identified in New York and Virginia, with 4% of all national cases appearing in Suffolk County, New York. However, when controlling for population density, researchers found that counties in Virginia and Kentucky had the highest number of suspected cases.

“The highest prevalences of suspected cases [per 1 million people]  were found throughout a nearly contiguous region of the southern, midwestern, and mid-Atlantic United States, particularly parts of Oklahoma, Kansas, Arkansas, Missouri, Mississippi, Tennessee, Kentucky, Illinois, Indiana, North Carolina, Virginia, Maryland, and Delaware,” says the report.

Why these areas?

Well, the regions most affected by alpha-gal syndrome are home to the lone-star tick (Amblyomma americanum), which is known to transmit the disease. While other species of ticks are capable of causing alpha-gal syndrome, thus far it has predominantly been associated with the lone-star tick in particular.

What are the signs?

Alpha-gal syndrome typically manifests with delayed allergic reactions after the consumption of red meat or other mammal-derived products. The level of severity varies from person to person. 

The most common symptoms include hives; swelling of the lips, tongue, or throat; and gastrointestinal issues like nausea and diarrhea. In some severe cases, individuals may experience anaphylaxis, a potentially life-threatening allergic reaction, leading to difficulty breathing, a drop in blood pressure, and loss of consciousness. Symptoms of AGS are usually delayed, appearing 2-6 hours after eating meat or dairy products. 

Currently, there is no known cure for AGS. The CDC recommends that it be managed like any other known allergen: working with an allergist and avoiding products known to cause a reaction.

Education and prevention, however, are ultimately the best way to protect yourself from AGS and other tick-borne illnesses.

“We need to close the knowledge gap,” said Mather. 

“I had one person once say to me that they were bitten by a lone star tick. Now they were gonna go take their grill over to their doctor’s office and cook a hamburger to see if they have the red meat allergy. That is kind of extreme.”

The bottom line

Alpha-gal syndrome (AGS) is a tick-borne disease predominantly spread by the lone star tick that causes an allergic reaction to red meat, pork, and dairy.

AGS is spreading most rapidly in geographic areas where the lone star tick is known to reside, predominantly in mid-Atlantic states, the midwest, and the south.

There is no cure for AGS. Knowledge and prevention are the best tools to stay safe. Learn more about AGS and other tick-borne diseases at TickEncounter.

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