What To Know About Tick Bite-Induced Alpha Gal Syndrome

Krista Duval, DO

Alpha Gal Syndrome (AGS), commonly known as the “red meat allergy”, is an acquired allergic reaction to the carbohydrate alpha-galactose 1,3 galactose (alpha-gal for short). Alpha-gal is present in meat from mammals (e.g. beef, pork, lamb, goat, venison, rabbit). The allergy develops in response to tick bites. In Ohio, it is associated with the bite of the Lone Star tick (Amblyomma americanum) and is believed to be induced by their saliva. People who spend more time outdoors or have a history of multiple tick bites are at a higher risk of developing AGS. Avoiding tick bites is critical for preventing AGS.

AGS is a unique food allergy in that it is characterized by a delayed onset of symptoms 2-8 hours after consuming mammalian meat. It is common for symptoms to begin during the night after eating a dinner that contained red meat. About 15% of patients with AGS have reactions not only to red meat but also to other mammalian products such as dairy, lard, gelatin, lanolin, or medications derived from mammalian sources.

There are a wide range of clinical presentations ranging from mild to severe. Symptoms may include one or multiple of the following:

• Hives or itching even without a visible rash
• Abrupt swelling of the eyes, lips, throat, genitals
• Nausea, vomiting, abdominal cramping
• Shortness of breath
• Lightheadedness, dizziness, drop in blood pressure or pulse, loss of consciousness
• Anaphylaxis

The symptoms can vary from person to person as well as from one occasion to another.

Cofactors of alcohol, NSAIDs (ibuprofen, for example), and physical activity can increase the severity of symptoms or lower the threshold for having a reaction. Additionally, people may become more sensitive to alpha-gal with additional tick bites. All of this makes it difficult to know if/when a person with AGS will have a reaction and how it will present. Because of this, many people have symptoms for years before the diagnosis is made.

AGS is different than other tick-borne diseases in that it is not caused by bacteria or viruses. That means it cannot be prevented or treated by taking antibiotics or antiviral medications. Management involves avoiding the foods that trigger a reaction. People with AGS should also talk to their provider about a plan for managing reactions if they were to occur. For some people, symptoms may improve or completely resolve over time (generally years) with the avoidance of additional tick bites.

Some people recognize the Lone Star tick by the small white dot on its back for which it was named. However, it should be noted that only the adult female has that classic finding. Larvae, nymphs and adult males are also capable of inducing the allergy but do not have the white dot