Alpha-gal Syndrome (AGS)

(Images courtesy of CDC)

What is alpha-gal and alpha-gal syndrome (AGS)?

  • Alpha-gal is a sugar molecule found naturally in some types of food, animal products, and tick saliva.
  • Alpha-gal syndrome (AGS) is an allergy to foods containing alpha-gal. This occurs after people are bitten by ticks, especially the lone star tick.
  • Other names for AGS include mammalian meat allergy, alpha-gal allergy, red meat allergy, and tick bite meat allergy.
  • AGS is not caused by a virus, parasite, or bacteria.
  • AGS is a serious and potentially lifelong condition that can occur after a tick bite, even if the tick is removed promptly. Therefore, prevention is extremely important.

Where does AGS occur?

  • In the United States (U.S.), many people who have AGS live in Southern, Eastern, and Central states.
  • New York State residents are diagnosed with AGS every year, particularly on Long Island where lone star ticks are common.
  • Rates of people with positive alpha-gal laboratory test results in the U.S., by county, can be viewed on this CDC map, but viewers should keep in mind that a positive test result doesn't necessarily mean a person has AGS.

How would I get AGS?

  • Alpha-gal molecules are a normal part of tick saliva of some tick species, but some people can become sensitive to alpha-gal following tick bites.
  • In New York State, AGS is mostly associated with lone star tick bites, but other kinds of ticks have the potential to trigger the allergy.
  1. When a tick bites, it can pass a sugar molecule called alpha-gal into your body through its saliva.
  2. Your immune system may see the sugar molecule as harmful and start reacting to it by producing antibodies.
  3. Alpha-gal is found naturally in non-primate mammals (such as cows, pigs, lambs, and goats), and some mammalian products (like milk or gelatin). When some people eat foods or food products that contain alpha-gal, their body can have an allergic reaction, usually 2–6 hours later.

Lone star ticks

(Images courtesy of JL Occi)

  • Lone star ticks do not always have a white dot.
  • Lone star ticks look different when they reach different stages in their life.
  • Bites from larval lone star ticks, the youngest and smallest life stage, are also associated with AGS.
  • Not everyone bitten by a lone star tick will develop AGS.

Who is at risk for AGS?

  • Anyone can be at risk for AGS, but especially those who spend time outdoors. This includes:
    • People who frequently spend time outside (such as hikers, gardeners, and hunters).
    • People who work outdoors (such as farmers, construction workers, and landscapers).
  • People of all ages can develop AGS, but most cases have been reported in adults.

What does AGS look like?

  • AGS symptoms can differ from person-to-person ranging from mild to severe.
  • Unlike conditions where symptoms occur without a specific trigger, AGS symptoms are directly related with the consumption of foods or food products that contain alpha-gal.
  • AGS symptoms are usually delayed. They appear 2-6 hours after consuming products that contain alpha-gal.
  • Anyone who has a severe allergic reaction should seek emergency medical care right away.
  • Some people may not be allergic at all.

(Timeline concept credit to the Arkansas Department of Health)

  1. 1. Lone star tick bite(s) occur.
  2. 2. Then, weeks to months later…
  3. 3. Foods or products that contain alpha-gal are consumed.
  4. 4. Two to six hours pass. AGS symptoms develop.
  5. 5-7. Symptoms can include:
    • Rash or hives
    • Gastrointestinal symptoms (such as stomach pain, nausea, vomiting, diarrhea, heartburn, and indigestion)
    • Swelling of the lips, throat, tongue, or eyelids
    • Cough, shortness of breath, wheezing, and difficulty breathing
    • Severe symptoms can include:
      • a drop in blood pressure,
      • dizziness,
      • feeling faint/fainting,
      • severe stomach pain, and/or
      • anaphylaxis

Prevention & tick removal

AGS is a serious and potentially lifelong condition that can occur after a tick bite, even if the tick is removed promptly. Therefore, prevention is extremely important.
To help prevent AGS, practice techniques to reduce your chances of a tick bite:

  • Consider using EPA-registered repellents. Check the label to make sure the repellent works against ticks and follow the instructions.
  • Consider treating clothing and gear with products containing permethrin. Permethrin is an EPA-registered insecticide that kills ticks on contact.
  • Wear light-colored clothes so you can easily spot and remove ticks.
  • Tuck the ends of your pants into socks or boots and shirts into pants.
  • Walk in the center of hiking trails.
  • Avoid tick-heavy outdoor places including fallen leaves and wooded, bushy, and grassy areas.
  • Regularly check for ticks when outdoors and at home.
  • Put clothes on high heat in dryer for 10 minutes to kill ticks.
  • Shower after spending time outdoors.
  • Remove attached ticks (youtube) right away. Don't wait.
  • Make sure to include any outdoor pets in a tick check. Ticks can catch a ride into your home on your outdoor animals, which increases the chances of a tick bite at home.

To help prevent the symptoms of AGS if you already have it:

  • Avoid foods with alpha-gal, like meat from mammals (such as beef, pork, rabbit, lamb, and venison) and some mammalian products (including gelatin and milk products). A comprehensive list can be found within CDC’s Fast Facts: Products That May Contain Alpha-gal.
  • A person with AGS can still eat meat that does not contain alpha-gal, like poultry (such as chicken and turkey) and fish.

For more information about tick removal and prevention, visit: Lyme Disease and Other Diseases Carried by Ticks.

How is AGS diagnosed?

Diagnosis of AGS involves a combination of symptoms, medical examination, and testing.

To diagnose AGS, an allergy specialist or health care provider needs:

  • A detailed patient history,
  • A medical examination, and
  • A blood test that looks for alpha-gal-specific IgE antibodies.

AGS testing

  • Alpha-gal-specific IgE antibody testing is the main type of AGS testing.
  • A positive alpha-gal-specific IgE test alone does not necessarily mean someone has AGS. Some people have a positive alpha-gal specific IgE test without an AGS reaction. Therefore, in addition to testing, AGS is diagnosed using a detailed patient history and medical examination.

How is AGS treated?

  • AGS should be managed under the care of an allergist or health care provider familiar with AGS.
  • People with AGS should practice tick bite prevention techniques because new tick bites may reactivate allergic reactions to alpha-gal. A provider will likely recommend that a patient with AGS avoid food and food products that contain alpha-gal.
  • A person with AGS can still eat meat that does not contain alpha-gal, like poultry (such as chicken and turkey) and fish.

Frequently asked questions for patients

  • If you think you might have AGS, talk to an allergy specialist or health care provider familiar with AGS about avoiding foods with alpha-gal, like meat from mammals (such as beef, pork, rabbit, lamb, and venison) and some mammalian products (including gelatin and milk products). A comprehensive list can be found within CDC’s Fast Facts: Products That May Contain Alpha-gal.
  • Immediately seek emergency medical care if you are having a severe allergic reaction.
  • A person with AGS can still eat meat that does not contain alpha-gal, like poultry (such as chicken and turkey) and fish.
  • If you do not have symptoms of AGS, screening is not recommended because some people may have a positive alpha-gal specific IgE antibody test without truly having AGS.
  • A positive alpha-gal-specific IgE antibody test doesn't necessarily mean you have AGS. It is important that you speak with an allergy specialist or health care provider familiar with AGS to discuss your medical history and symptoms.
  • Work with an allergy specialist or your health care provider familiar with AGS to determine what dietary restrictions are recommended and how long those restrictions should stay in place.
  • Use tick bite prevention techniques to avoid additional tick bites.
  • Not necessarily. It's possible for sensitivity to alpha-gal to decrease over time in some patients if additional tick bites and foods or food products that contain alpha-gal are avoided.
  • You should seek emergency care if you have any severe AGS symptoms, including:
    • a drop in blood pressure,
    • dizziness,
    • feeling faint/fainting,
    • severe stomach pain, and/or
    • anaphylaxis.
  • Symptoms usually occur 2-6 hours after eating foods with alpha-gal.
  • Remove the tick (youtube) right away. Don't wait.
  • Watch for symptoms. If you develop a rash or flu-like symptoms, contact your health care provider right away.
  • Tick testing is not recommended for AGS.
  • Tick testing for alpha-gal is not useful because alpha-gal is a normal part of tick saliva. The body's reaction to tick bites is what results in AGS, not a germ the tick could be carrying.
  • Non-primate mammals (such as dogs, cats, rodents, horses, and other livestock) cannot get AGS because they already have the alpha-gal molecule in their body.

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