Alpha-gal syndrome is a recently identified type of food allergy to red meat and other products made from mammals. The condition often begins when a person is bit by a Lone Star tick. The bite transmits a molecule called alpha-gal into the person's body. In some people, this triggers an immune system response that can cause the person to develop mild to severe allergic reactions to all red meats, including beef, pork or lamb, milk, cheese, and ice cream, or other mammal products.
The Lone Star tick is found predominantly in the southeastern United States so most cases of alpha-gal syndrome occur in this region. The tick can also be found in the eastern and south-central United States. The condition appears to be spreading farther north and west, however, as deer carry the Lone Star tick to new parts of the United States. Alpha-gal syndrome also has been diagnosed in Europe, Australia, and Asia, where other types of ticks carry alpha-gal molecules.
Some people who have frequent, unexplained anaphylactic reactions — and who test negative for other food allergies — may be affected by alpha-gal syndrome. There is currently no treatment other than avoiding red meat and other products made from mammals, such as dairy and gelatin.
How to avoid alpha-gal?
The best way to prevent alpha-gal syndrome is to avoid tick bites as much as possible. You can decrease your risk of tick bites with some simple precautions:
- Cover up. When in wooded or grassy areas, wear shoes, long pants tucked into socks, and a long-sleeved shirt. A hat and gloves can provide even further protection. Try to stick to trails and avoid walking through low bushes and long grass. Keep your dog on a leash.
- Use insect repellents. Apply insect repellent with a 20% or higher concentration of DEET to your skin. If parents choose to apply repellent to their children, they should avoid the child’s hands, eyes, and mouth. Keep in mind that chemical repellents can be toxic, so follow directions carefully. Products with permethrin can be applied to clothing or pre-treated clothing can be purchased.
- Do your best to tick-proof your yard. Clear brush and leaves where ticks live. Keep woodpiles in sunny areas.
- Do a thorough, full-body check for ticks on yourself, your children, and your pets after spending time outside. Be especially vigilant after spending time in wooded or grassy areas.
- It's helpful to shower as soon as you come indoors. Ticks often remain on your skin for hours before attaching themselves. Showering and using a washcloth might remove unattached ticks.
- Remove a tick as soon as possible with tweezers. Gently grasp the tick near its head or mouth. Don't squeeze or crush the tick, but pull carefully and steadily. Once you've removed the entire tick, dispose of it and apply antiseptic to the bite area.
Symptoms of alpha-gal
As with other food allergies, signs or symptoms of an allergy to alpha-gal may include:
- Hives and itching (most common symptom)
- Swelling of your lips, face or eyelids
- Shortness of breath, cough or wheezing
- Abdominal pain, nausea, diarrhea or vomiting
- The most severe reaction, anaphylaxis, can present as a combination of several of these symptoms, may include low blood pressure, and is potentially fatal.
Symptoms of alpha-gal reactions are often delayed, usually (but not always) appearing three to six hours after exposure. Because of this delay, a person may find symptoms occur most often in the late afternoon, evening or in the middle of the night.
A person may not have symptoms after every alpha-gal exposure. This inconsistency, in addition to the delay in alpha-gal reactions, can make it challenging for a person to pinpoint the specific trigger or cause of their symptoms.
How it’s diagnosed.
An alpha-gal allergy is diagnosed much like other allergies. An allergist will perform a blood test and possibly a skin reaction test to determine if your body views alpha-gal as a threat. If exposure to alpha-gal causes a histamine reaction in your blood, your allergy test to alpha-gal will show as positive. Gathering a detailed history of symptoms is also a key part in the diagnosis of alpha-gal syndrome.
See your primary care doctor or a board-certified allergist if you experience food allergy symptoms after eating — even several hours after eating. Don't rule out alpha-gal syndrome as a possible cause of your reaction, especially if you have a history of tick bites or live in the southeastern United States or in other parts of the world where alpha-gal syndrome is known to occur.
Seek emergency medical treatment if you develop signs or symptoms of anaphylaxis, such as:
- Difficulty breathing
- Rapid, weak pulse
- Dizziness or lightheadedness
- Drooling and inability to swallow
- Full-body rash (hives) or redness and warmth (flushing)