Alpha Gal Syndrome: Understanding the Tick-Borne Allergy

July 01, 2025

Alpha-gal syndrome (AGS) is a serious and potentially life-threatening food allergy that has gained increasing attention in recent years, mostly due to its transmission through tick bites.

Unlike typical food allergies that manifest immediately after consumption, AGS presents a unique challenge with its delayed onset and unusual trigger:  mammalian meat. This condition, which can develop suddenly, is caused by tick bites and represents one of the most intriguing examples of how environmental factors can fundamentally alter our immune system's response to food.

“Alpha-gal syndrome is an allergic reaction to galactose-alpha-1,3-galactose, commonly called ‘alpha-gal,’ a sugar molecule found in most mammalian meat including beef, pork, lamb and venison,” said Alica Albers, MD, hospitalist physician at Fitzgibbon Hospital. “The condition was first identified in the early 2000’s when researchers noticed an unusual pattern of delayed allergic reactions occurring several hours after patients consumed red meat. What makes AGS particularly distinctive is its delayed onset – reactions typically occur three to six hours after eating mammalian meat, rather than the immediate response seen in most food allergies.”

The syndrome develops when certain tick species, primarily the lone star tick in the United States, bite humans and introduce alpha-gal into their bloodstream. The person’s immune system mistakenly identifies this sugar molecule as a threat and produces antibodies against it. Subsequently, when the person consumes meat containing alpha-gal, these antibodies trigger an allergic reaction ranging from mild digestive upset to severe anaphylaxis.

“AGS symptoms vary significantly among individuals and can include hives, swelling, digestive problems such as nausea, vomiting, and diarrhea, difficulty breathing, dizziness, and severe drops in blood pressure,” said Dr. Albers. “The delayed nature of symptoms often makes diagnosis challenging, as patients and healthcare providers may not immediately connect the reaction to meat consumption hours earlier.

Diagnosis typically involves a combination of clinical history, symptom assessment and blood tests that measure antibodies to alpha-gal. Healthcare providers often look for patterns of delayed reactions following red meat consumption, particularly in patients with known tick exposure.

The lone star tick, which carries this illness, is most prevalent in the southeastern, south-central and mid-Atlantic regions, though its range has been expanding northward and westward. There have been several known cases of AGS diagnosed in Saline County, Mo.

Risk factors for developing AGS include living in or visiting tick-infested areas, spending time outdoors in wooded or grassy environments, having occupations that involve outdoor work and having a history of multiple tick bites. The syndrome appears to be more common in adults than children, and some research suggests that individuals with type O blood may be at higher risk.

Since there is no cure for AGS, and the primary treatment involves strict avoidance of mammalian meat, prevention of tick bites is crucial.

“When venturing into tick-prone areas, wear long-sleeved shirts and long pants, preferably light-colored clothing that makes ticks easier to spot,” said Dr. Albers. “Tuck pants into socks and shirts into pants to create barriers. Apply EPA-approved insect repellents containing DEET, picaridin or permethrin to exposed skin and clothing, following label instructions carefully.”

After outdoor activities, conduct thorough tick checks on yourself, family members and pets. Pay close attention to hidden areas such as the scalp, behind ears, underarms, groin area and behind knees. Shower within two hours of coming indoors, as this can help wash away unattached ticks and provides an opportunity for tick detection.

Landscape management around homes can significantly reduce tick populations. Keep grass short, remove leaf litter and brush, create wood chip or gravel barriers between wooded areas and recreational spaces and consider professional tick control treatments in high-risk areas.

For pet owners, regular veterinary care including tick prevention medications is essential, as pets can bring ticks into the home environment. Check pets regularly for ticks, especially after outdoor activities.

For those diagnosed with AGS, management involves complete avoidance of mammalian meat and careful attention to hidden sources of alpha-gal in processed foods, medications and personal care products. Some individuals may also need to avoid dairy products and gelatin. Working with healthcare providers and registered dietitians can help ensure nutritionally adequate diets while avoiding triggers.

The good news is that AGS may not be permanent for everyone. Some individuals experience a gradual decrease in sensitivity over time if they avoid additional tick bites, though this varies considerably among patients.

If you are experiencing the above symptoms and know that you have had contact with a tick, you are encouraged to make an appointment with your primary care provider. If you do not have a primary care provider, staff at Marshall Family Practice, Missouri Valley Physicians and Mid-MO Family health in Marshall are all taking new patients. Call any of these practices to schedule. A complete listing of clinics and providers can be found at www.fitzgibbon.org.