Alpha-gal Syndrome (AGS)

Fact sheet on Alpha-gal Syndrome (AGS)

What is alpha-gal syndrome (AGS)?

AGS (also known as alpha-gal allergy, red meat allergy, mammalian meat allergy, and tick bite meat allergy) is an allergic reaction to the alpha-gal sugar molecule found in most mammalian meat and some other products made from mammals. AGS can develop after the bite of certain types of ticks and the symptoms can be serious, and sometimes even life-threatening.

What products contain alpha-gal?

High amounts of alpha-gal may be found in mammalian meat such as beef, pork, lamb, deer (venison), goat, rabbit, or other meat from mammals. Other foods and food products that may contain alpha-gal include dairy products such as milk, cheese, yogurt, and ice cream; gelatin made from beef or pork; foods made or cooked with mammal fat such as lard, tallow, or suet; and meat-based broths, bouillon, and gravy.

Ingredients in some medications and vaccines may contain alpha-gal, such as gelatin/gel caps, glycerin, magnesium stearate which is added to some food products, drugs and cosmetics, and bovine extract which may be included in some supplements. In addition, some animal-derived medical products, such as heart valves from pigs or cows, monoclonal antibodies, heparin, and certain antivenoms may contain alpha-gal.

Foods that do not contain alpha-gal include chicken, turkey, duck, pheasant, quail, fish, shellfish, seafood, eggs, fruits, and vegetables.

How is AGS spread?

In the United States, AGS is primarily associated with the bite of a lone star tick. Although it is less common, AGS can occur after a bite from other tick species, including the blacklegged (deer) tick and the western blacklegged tick. In other countries, bites from the Asian longhorned tick have been reported to cause AGS.

The alpha-gal sugar is found in the saliva of a tick and is transferred into a person’s bloodstream through a tick bite. In some people, the immune system responds to the alpha-gal sugar and produces antibodies to alpha-gal. These antibodies can cause an allergic reaction the next time the person is exposed to alpha-gal by eating red meat, dairy or other alpha-gal containing product.

Where do cases of AGS occur?

In the United States, AGS most commonly occurs in the Southern, South-Central, and Eastern states. These are areas with higher populations of the lone star tick. In Massachusetts, AGS is most common in places where populations of lone star tick have become established, including Cape Cod, Martha’s Vineyard and Nantucket.

When can I get exposed to the ticks that can cause AGS?

Exposure to the lone star tick in Massachusetts can occur during any time of the year. Ticks are most active from spring through fall but may also be out searching for a host any time that temperatures are above freezing.

How soon do symptoms of AGS appear after a tick bite?

It can take weeks to months after being bitten by a tick for a person’s immune system to produce antibodies to alpha-gal and cause AGS. Once a person has AGS, allergic reactions usually occur 2-10 hours after eating or drinking a product containing alpha-gal. However, allergic reactions to injected medications containing alpha-gal can occur immediately.

What are the symptoms of AGS?

Symptoms of AGS differ from person-to-person and can be mild or severe and may even be life-threatening. A person’s allergic reaction after consuming a product containing alpha-gal can be different each time.

AGS allergic reactions can include hives or an itchy rash, heartburn, indigestion, severe stomach pain, nausea, vomiting, diarrhea, swelling of the lips, throat, tongue, or eyelids, drop in blood pressure, dizziness, faintness, cough, wheezing, shortness of breath, difficulty breathing and anaphylaxis (a life-threatening allergic reaction). 

How is AGS diagnosed?

If you have symptoms of AGS after eating red meat, dairy products or another product with alpha-gal, talk to your healthcare provider. Allergy skin tests and a certain kind of blood test may be useful to diagnose AGS.

Is there a treatment for AGS?

Severe AGS allergic reactions (such as low blood pressure, shortness of breath, and anaphylaxis) should be treated immediately in an emergency medical setting. People who are diagnosed with AGS should talk to their healthcare provider about how to manage non-life-threatening allergic reactions with over-the counter medications, such as antihistamines.

There is no cure for AGS. However, this allergy can be managed by avoiding foods and products that contain alpha-gal. AGS should be managed under the care of an allergist or other healthcare provider.

New tick bites may make AGS allergic reactions worse and everyone, including people with AGS, should take steps to avoid tick bites. In some people, AGS allergic reactions to alpha-gal products may decrease over time. 

Does the lone star tick spread other diseases?

Yes. The lone star tick can spread several infectious diseases, most of which are very rare in Massachusetts. These diseases include ehrlichiosis caused by two different kinds of bacteria and Heartland virus. The tick can also spread tularemia, a bacterial disease that occurs on both Martha’s Vineyard and Nantucket islands.

What can I do to lower my chances of getting AGS, or any other disease, from ticks?

Prevention begins with you! Take steps to reduce your chances of being bitten by any tick. Ticks are most active during warm weather, late spring through fall. However, ticks can be out any time that temperatures are above freezing. Ticks cling to vegetation and are most numerous in brushy, wooded, or grassy habitats. When you are outside in an area likely to have ticks (e.g., brushy, wooded, or grassy places), follow these simple steps to protect yourself and your loved ones:

• Use tick repellents.
• Products with DEET (the chemical N-N-diethyl-meta-toluamide) may be used on skin. Repellents containing DEET should not be used on children less than 2 months of age and should be used in concentrations no higher than 30% on older children.
• Use permethrin products on items such as clothing, shoes, bed nets and camping gear. Permethrin should not be applied to skin.
• Other repellents, such as picaridin, oil of lemon eucalyptus and IR 3535, have also been found to provide protection against ticks. More information on choosing a repellent and how to use repellents safely is included on the DPH Public Health Fact Sheet on Tick Repellents at mass.gov/DPH/Ticks.
• Wear long, light-colored pants tucked into socks or boots, and a long-sleeved shirt. This may be tough to do when the weather is hot, but it will help keep ticks away from your skin and help you spot a tick on your clothing faster.
• Stay on trails when walking or hiking, avoiding the edge habitat where ticks are likely to be.
• Talk to your veterinarian about tick control options (tick collars, repellents) for your pets.

After spending time in an area likely to have ticks, check yourself, your children, and pets for ticks. Young ticks, called nymphs, are the size of a poppy seed. Adult ticks are the size of a sesame seed. Both nymph and adult ticks can cause AGS; however, nymphs are more of a concern. They are aggressive feeders and so tiny that it can be difficult to see them on the body unless you look carefully. When doing a tick check, remember that ticks like places that are warm and moist. Always check the back of the knees, armpits, groin, scalp, back of the neck and behind the ears. If you find a tick attached to your body, remove it as soon as possible using fine-point tweezers. Do not squeeze or twist the tick’s body, instead grasp it close to your skin and pull straight out with steady pressure.

Know the symptoms of alpha-gal syndrome as described in this fact sheet. If you have been someplace likely to have ticks and develop symptoms of any disease carried by ticks, see your health care provider right away.

Where can I get more information on AGS?

• For questions about your own health, contact your doctor, nurse, or clinic.
• For questions about diseases spread by ticks, contact DPH at [phone] or online at mass.gov/DPH/Ticks. You may also contact your local Board of Health.
• Health effects of pesticides, DPH, Bureau of Climate and Environmental Health at [phone].