Clemson Extension Forestry and Wildlife


Anybody who has spent time in the woods or other wild surroundings is familiar with ticks, those blood-sucking arachnids that seek out creatures, including we humans, on which to feed. Most of us also know that ticks are carriers of numerous diseases, the most known being Lyme disease and Rocky Mountain spotted fever. However, many people are unaware of a recently recognized syndrome related to tick bites that can cause serious health conditions, including anaphylaxis and death. This condition is called alpha-gal syndrome (AGS), also known as red-meat allergy or tick bite meat allergy. People who develop this condition show symptoms typically 3-4 hours after eating meat from mammals (beef, pork, venison, mutton, etc.). According to the Centers for Disease Control and Prevention (CDC), symptoms can include:

  • Hives or itchy rash
  • Nausea or vomiting
  • Heartburn or indigestion
  • Diarrhea
  • Cough, shortness of breath, or difficulty breathing
  • Drop in blood pressure
  • Swelling of the lips, throat, tongue, or eyelids
  • Dizziness or faintness
  • Severe stomach pain
round brown tick with spot on its back
Lone star tick (Susan Ellis, USDA APHIS PPQ,

Some people with higher sensitivity may also have a reaction after eating milk and milk products or products containing gelatin. Most people who develop AGS had no previous allergic reactions to these products, and the development of the syndrome is sudden. Development of AGS occurs after being bitten by one or more lone star ticks, although other tick species may be involved as well. The exact mechanism by which tick bites cause this syndrome to develop in the human body is not completely understood and is still being studied.

In addition to North America, AGS has been identified in parts of Europe, Australia, Asia, South Africa, and South and Central America. Based on studies of antibody tests, cases in the United States are found predominantly in counties within the southern, midwestern, and mid-Atlantic U.S.

Not only is AGS not well known by the public, but it appears that it is still poorly known among health care providers (HCPs). A recent survey revealed that 42% of HCPs surveyed had never heard of AGS, and among those who had, fewer than one-third knew how to diagnose the condition (Carpenter et al., 2023). Thompson et al. (2023) reported that between 2010 and 2022, there were more than 110,000 suspected cases of alpha-gal syndrome identified. However, because of the lack of awareness and testing, it is estimated that as many as 450,000 people might have been affected by AGS in the United States since 2010.

map of the United States showing gray and blue areas that indicate cases of alpha-gal syndrome.
Geographic distribution of suspected alpha-gal syndrome cases per 1 million population per year- United States, 2017-2022 (Thompson et al., 2023).

You may ask why I, a forestry and wildlife Extension Agent, am writing an article about tick disease. In 1996, I suddenly developed an allergic reaction after eating red meat, and to this day, I am still unable to eat the meat of mammals. I was doing a lot more work in the field at the time, and I typically had to pick ticks off myself on a daily basis. However, it wouldn’t be until another ten years or so had passed before I started seeing information about a possible link between acquired allergies to red meat and tick bites. That link was confirmed by research in Australia in 2007, but it was not until 2010 that a lab test was developed to make positive diagnoses. Fortunately, I have not developed sensitivity to milk and dairy products, at least not yet. It is still somewhat uncomfortable to explain why I can’t eat a red meat product when offered to me at a meeting or a host’s home, and I have to be vigilant when eating out and reading food labels.

To find out more about alpha-gal syndrome and other tick-borne conditions, as well as how to protect yourself against tick bites, go to the Centers for Disease Control and Prevention website at


Ann Carpenter, DVM; Naomi A. Drexler, DrPH; David W. McCormick, MD; Julie M. Thompson, DVM, Ph.D.; Gilbert Kersh, Ph.D.; Scott P. Commins, MD; Johanna S. Salzer, DVM, Ph.D. (2023). Health Care Provider Knowledge Regarding Alpha-gal Syndrome — United States, March–May 2022 (Morbidity and Mortality Weekly Report / July 28, 2023 / 72(30);809–814. U.S. Department of Health & Human Services, Centers for Disease Control and Prevention.

Julie M. Thompson, DVM, PhD; Ann Carpenter, DVM; Gilbert J. Kersh, PhD; Tyler Wachs; Scott P. Commins, MD; Johanna S. Salzer, DVM, PhD (2023). Geographic Distribution of Suspected Alpha-gal Syndrome Cases — United States, January 2017–December 2022 (Morbidity and Mortality Weekly Report / July 28, 2023 / 72(30);815-820. U.S. Department of Health & Human Services, Centers for Disease Control and Prevention.


TJ Savereno, Cooperative Extension, Forestry and Wildlife Agent

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