As of July 2023, the CDC estimated that up to 450,000 people in the United States have alpha-gal syndrome (AGS), a tick bite-associated allergy to red meat and other animal products.
What is Alpha-Gal Syndrome?
Alpha-gal syndrome (AGS) is an emerging food allergy linked to tick bites, notably from the Lone Star tick in the United States.
Alpha-gal syndrome is a type of food allergy where the immune system reacts to galactose-alpha-1,3-galactose (alpha-gal), a sugar molecule found on the cells of most mammals like cows, pigs, lambs, and goats. When a person with AGS consumes red meat, innards, or mammalian-derived products such as dairy, or gelatin, they may experience allergic reactions due to their immune system recognizing alpha-gal as a threat.
Causes of Alpha-Gal Syndrome
AGS is primarily caused by bites from ticks, particularly the Lone Star tick in the U.S., although other tick species worldwide can also trigger the condition. During a bite, ticks inject alpha-gal into the bloodstream, prompting the immune system to produce antibodies against it. Subsequent consumption of red meat or mammalian products can then lead to an allergic reaction.
Symptoms of Alpha-Gal Syndrome
Symptoms of AGS typically manifest 2 to 6 hours! after consuming red meat or mammalian products and can range from mild to severe. Common symptoms include:
• Hives
• Swelling of the lips, tongue, throat, or eyelids
• Coughing and difficulty breathing
• Wheezing
• Heartburn
• Nausea or vomiting
• Abdominal pain and diarrhea
• Decreased blood pressure
In severe cases, individuals may experience anaphylaxis, a potentially life-threatening reaction requiring immediate medical attention.
Prevalence and Affected Populations
As of July 2023, the CDC estimated that up to 450,000 people in the United States have alpha-gal syndrome (AGS), a tick bite-associated allergy to red meat and other animal products. This number is up from an estimated 5,000 cases in 2013. However, the actual number of cases is likely underreported because AGS diagnosis requires a clinical exam and a positive diagnostic test, and some people with AGS may not get tested. Additionally, a lack of awareness about AGS can lead to misdiagnosis and delayed diagnosis.
Both children and adults can be affected by this syndrome.
Diagnosis and Treatment
Diagnosis of AGS involves identifying a delayed allergic reaction to red meat or mammalian products and confirming the presence of antibodies against alpha-gal through blood tests. Mild symptoms are typically managed with antihistamines, while severe reactions require an intramuscular injection of epinephrine and possibly additional treatments in an emergency setting. Patients diagnosed with AGS are usually prescribed an epinephrine auto-injector for emergencies.
An allergy specialist can diagnose alpha-gal syndrome based on the patient's history, physical examination, blood tests for antibodies, and skin testing. Individuals with unexplained anaphylactic reactions who test negative for other food allergies may have alpha-gal syndrome.
The most common test for diagnosing alpha-gal syndrome is a blood test that measures immunoglobulin E (IgE) antibodies specific to alpha-gal. Elevated levels of these antibodies can confirm the diagnosis. There is a high false-positive rate to this test, which means it may come back showing you have alpha-gal syndrome when you actually don’t.
A skin test is another method, involving a skin prick with red meat extract or alpha-gal substances. The presence of red bumps (hives or a rash) indicates alpha-gal syndrome.
Lifestyle Adjustments for AGS
Individuals with AGS should avoid all mammalian meat (such as beef, pork, and lamb) and be cautious about consuming mammalian-based products like cow’s milk, cheese, or gelatin. They should also avoid certain medications and treatments derived from mammals, including specific blood thinners, snake antivenom, cancer medications, and cetuximab (Erbitux)!!!
Preventing Alpha-Gal Syndrome
Prevention of AGS centers on avoiding tick bites. Effective strategies include:
• Steering clear of grassy, brushy, and wooded areas where ticks are prevalent.
• Walking in the center of trails.
• Using EPA-registered insect repellents.
• Wearing clothing that covers exposed skin and treating clothes with permethrin.
• Thoroughly checking skin and clothing for ticks after being outdoors.
If a tick is found, it should be carefully removed with fine-tipped tweezers by grasping the tick close to the skin and pulling upward with steady, even pressure.
Conclusion
Understanding and managing AGS is crucial for those affected, and taking preventive measures can significantly reduce the risk of developing this condition. Always consult with healthcare professionals for personalized advice and treatment options.
Additional Resources
Mollah F, Zacharek MA, Benjamin MR. What Is Alpha-Gal Syndrome? JAMA. Published online December 08, 2023. doi:10.1001/jama.2023.23097.
https://www.cdc.gov/alpha-gal-syndrome/about/index.html, Accessed May 31, 2024