Alpha-gal Syndrome (AGS) is a serious, potentially life-threatening food allergy that has become an increasing concern in the United States. Unlike many food allergies that develop early in life, AGS is most often linked to the bite of the lone star tick. The condition can cause mild to severe allergic reactions to red meat and other products containing alpha-gal, a molecule found in most mammals.
Alpha-gal is naturally present in mammals such as cows, pigs and deer. It is also found in the saliva of some tick species. When a tick bites a person, it can transfer alpha-gal from its saliva into the bloodstream. In some individuals, the immune system recognizes alpha-gal as a threat and produces antibodies against it. These antibodies can trigger an allergic reaction the next time the person is exposed to alpha-gal through food or other products. This immune response is known as Alpha-gal Syndrome.
People with AGS may react to a variety of foods and ingredients derived from mammals. Alpha-gal is found in red meats such as beef, pork, lamb and venison. It may also be present in dairy products, gelatin made from beef or pork, meat broths and mammal-derived fats such as lard, tallow and suet. Because alpha-gal can be found in a range of food products, people diagnosed with AGS often need to carefully review ingredient labels and follow guidance from healthcare providers regarding dietary restrictions.
Not everyone who is bitten by a lone star tick will develop AGS. In addition, symptoms do not always appear immediately after a tick bite. It can take weeks or even months before a person develops symptoms or experiences an allergic reaction linked to alpha-gal. Once a person has AGS, symptoms typically occur two to six hours after exposure to foods or products containing alpha-gal, which differs from many other food allergies that cause reactions almost immediately.
Symptoms of AGS can range from mild discomfort to severe allergic reactions. Common symptoms include hives or an itchy rash, swelling of the lips, throat, tongue or eyelids, nausea, heartburn or indigestion, shortness of breath, dizziness and a drop in blood pressure after consuming foods containing alpha-gal. In severe cases, AGS can lead to life-threatening reactions that require immediate medical attention.
In the United States, the lone star tick is the species most often associated with AGS. The tick has established populations across the central and eastern regions of the country and can be identified by the distinct white mark on its back. Although much less common, AGS has also been reported following bites from other tick species, including the black-legged tick, also known as the deer tick, and the western blacklegged tick.
Certain groups of people may face a higher risk of developing AGS because of their increased exposure to tick habitats. Cattle farmers and ranchers who spend significant time outdoors have a heightened risk as activities such as walking through tall grass, working around livestock and spending time in heavily wooded areas can increase the likelihood of tick bites.
The best way to protect yourself and your family from AGS is to prevent tick bites. Before spending time outdoors, treat clothing and gear with products containing 0.5% permethrin and follow all product label instructions. Avoid contact with ticks whenever possible by staying away from wooded and brushy areas with high grass. Using an Environmental Protection Agency-registered insect repellent can provide additional protection when used according to label directions.
After coming indoors, take steps to check for ticks. Carefully examine clothing, gear and pets, and shower as soon as possible. Conduct a thorough tick check and if you find a tick, remove it as soon as possible and thoroughly clean the area with rubbing alcohol or soap and water. Anyone who develops symptoms consistent with AGS should contact a healthcare provider and be sure to mention any recent tick bites. Early recognition and medical evaluation can help identify the condition and reduce the risk of serious allergic reactions. To learn more about Alpha-gal Syndrome prevention and symptoms, visit CDC.gov.
