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Tick Bite-Induced Meat Allergy: Alpha-Gal Syndrome

Link to this Practical Nutrition podcast episode:


Understanding Alpha-Gal Syndrome (AGS)

In the world of (what seems like) a zillion different kinds of allergies, there’s a curious and relatively new addition that has caught everyone slightly off guard (and it’s caused by a tick bite). The attention of researchers and healthcare professionals have been drawn to learn about a new allergy: Alpha-Gal Syndrome (AGS). This unusual allergic reaction to red meat has left many confused as to how it came about and its mechanisms are still being studied and understood. Today’s episode is to inform and provide awareness to the newest allergy, Alpha-Gal Syndrome.   

 What specifically is Alpha-Gal?

  • Alpha-Gal Syndrome got its name from the sugar molecule—alpha gal. 
  • Alpha-gal (galactose-α-1,3-galactose) is a sugar molecule found in most mammals.
  • It is NOT found in fish, reptiles, birds, or humans. It IS found in meat of pork, beef, rabbit, lamb, venison, etc. and products made from mammals including gelatin, cow’s milk, and milk products. 


What is Alpha-Gal Syndrome (AGS)? 

  • AGS is a type of food allergy. It makes some allergic to red meat and other products made from mammals. The condition usually begins with the bite from a Lone Star tick (tick has a reddish-brown oval body. Females have a single whitish spot on their backs). 
  • The Lone Star tick is found mainly in the SE United States. Most cases are reported in the south, east and central US, but the condition appears to be spreading farther north and west (thanks in large part to our deer friends). 
  • AGS first discovered at UVA in 2007 by Platts-Mills 
  • The bite transfers a sugar molecule called alpha-gal into the body. In some people, this triggers a reaction from your immune system. It causes mild to severe allergic reactions to red meat and sometimes other foods that come from mammals such as dairy products, gelatins, meat broth, bouillon, stock, and gravy.


Do people know about it?

 A recent press release from the CDC summarizes this question (July 27th, 2023):  

  • “The CDC reports that between 2010 and 2022, there were more than 110,000 suspected cases of AGS diagnosed. However, because the diagnosis requires a positive diagnostic test and a clinical exam, and some individuals with AGS may not get tested, it is estimated that as many as 450,000 people might have been affected by AGS in the US.” 
  • Knowledge among practitioners may still be lacking. In one study, 1,500 family/general practitioners, pediatricians, NPs, and PAs across the country were surveyed, and results showed that nearly 50% of respondents had not heard of AGS, approximately 1/3rd reported that they were ‘not too confident’ in their ability to diagnose or manage patients with AGS, and only 5% felt ‘very confident’ in treating. 
  • In another study, CDC researchers examined lab test results from 2017 to 2022 from a lab that, until August 2021, was the primary commercial lab offering testing in the US. More than 300,000 specimens were submitted by healthcare providers on behalf of patients with presumed AGS, and more than 30% were positive. 

Diagnosis: Health care providers can diagnose AGS based on your history and additional tests including:  

  1. A blood test. A blood test can confirm and measure the amount of alpha-gal antibodies in your bloodstream. 
  2. Oral Food Challenge (OFC): For the diagnosis of a food allergy, OFC is a technique offering further information regarding food tolerability. 
  3. A skin prick test. A health care provider pricks your skin and exposes it to small amounts of substances taken from commercial or fresh red meat. If you’re allergic, you get a raised bump (hive) at the test site on your skin. Your provider or allergist also may test your skin for an allergic reaction to certain types of red meat.   


  • AGS reactions can include:
    • Hives, itchy rash, N/V, heartburn, indigestion, diarrhea, cough, shortness of breath, difficulty breathing, drop in BP, swelling of the lips, throat, tongue, or eyelids, dizzy/faint AND/OR severe stomach pain
  • Symptoms commonly appear 2-6 hours after eating meat or dairy products


Treatment (this is where we as dietitians can help!):

  • Nutrition counseling: YAY for dietitian help! A game plan to meet needs, receive ideas, label reading education, etc. (checking for B12, iron status, etc. with doctor)
  • Tick bite avoidance/environment education: those who successfully avoid tick bites  long term (1–2 years), have a higher chance of recovering tolerance to meat products, allowing the reintroduction of red meat
  • Prompt removal: prompt embedded tick removal should be performed in order to reduce the amount of secreted salivary allergens 
  • Medical: Due to AGS delay and unexpected symptoms, treatment is necessary to correctly manage allergic reactions and potentially life-threatening anaphylaxis (aka an epi-pen may be prescribed)–yikes.
    • Eventual creation of a tick-antigen-based vaccine—time will tell on this one and much more research is needed


Can you grow out of it?

In most cases, alpha-gal syndrome is a lifelong condition (boo). However, it does go away from some patients, sometimes after a few years—especially if not getting a tick bite again. Allergists can do an annual blood test to look at antibody levels. 


 Ongoing Research and Future Directions

ASG remains an area of active research, with scientists working to better understand its underlying mechanisms and factors contributing to its development. The link between tick bites and AGS is still being explored to determine why some tick bites lead to AGS while others do not. Furthermore, researchers are investigating potential treatments, including desensitization strategies and allergy medications that may help alleviate symptoms.


-CDC, Mayo and Cleveland Clinic