An allergic reaction to meat-based meals had researchers stumped — until they connected the condition to bites from certain ticks.
Alpha-gal syndrome is a recently identified type of food allergy to red meat and other products made from mammals. In the United States, the condition is most often caused by a Lone Star tick bite. The bite transmits a sugar molecule called alpha-gal into the person's body. In some people, this triggers an immune system reaction that later produces mild to severe allergic reactions to red meat, such as beef, pork or lamb, or other mammal products.
The Lone Star tick is found predominantly in the southeastern United States, and 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.
Researchers now believe that some people who have frequent, unexplained anaphylactic reactions — and who test negative for other food allergies — may be affected by alpha-gal syndrome. There's no treatment other than avoiding red meat and other products made from mammals.
Avoiding tick bites is the key to prevention. Protect against tick bites by wearing long pants and long-sleeved shirts and using insect repellents when you're in wooded, grassy areas. Do a thorough, full-body tick check after spending time outside.
Signs and symptoms of an alpha-gal allergic reaction are often delayed compared with other food allergies. Most reactions to common food allergens — peanuts or shellfish, for example — happen within minutes of exposure. In alpha-gal syndrome, reactions usually appear about three to six hours after exposure. Red meat, such as beef, pork or lamb; organ meats; and products made from mammals, such as gelatins or dairy products, can cause a reaction.
Signs and symptoms of alpha-gal syndrome may include:
Doctors think the time delay between eating red meat and developing an allergic reaction is one reason the condition was overlooked until recently. A possible connection between a T-bone steak with dinner and hives at midnight was far from obvious.
See your primary care doctor or a doctor who specializes in the diagnosis and treatment of allergies (allergist) if you experience food allergy symptoms after eating — even several hours after eating. Don't rule out red meat as a possible cause of your reaction, especially if you live or spend time outdoors 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:
A Lone Star tick bite most commonly causes the condition in the U.S. Bites from other types of ticks can lead to the condition in the U.S., Europe, Australia and Asia.
Ticks that cause alpha-gal syndrome are believed to carry alpha-gal molecules from the blood of the animals they commonly bite, such as cows and sheep. When a carrier tick bites a human, the tick injects alpha-gal into the person's body.
For unknown reasons, some people have such a strong immune response to these molecules that they can no longer eat red meat or products made from mammals without a mild to severe allergic reaction. People who are exposed to many tick bites over time may develop more-severe symptoms.
People with antibodies related to alpha-gal syndrome can have allergic reactions to the cancer drug cetuximab (Erbitux). Cetuximab-induced cases of this condition are most common in regions with a high population of Lone Star ticks, suggesting a possible link between Lone Star tick bites and an increased vulnerability to alpha-gal syndrome. More research is needed to understand the connection between ticks that carry alpha-gal in certain regions and cases of alpha-gal syndrome that don't seem directly linked to tick bites.
Researchers think the hallmark time-delayed reaction of alpha-gal syndrome is due to the alpha-gal molecules taking longer than other allergens to be digested and enter your circulatory system.
Doctors don't yet know why some people develop alpha-gal syndrome after exposure and others don't. The condition mostly occurs in the southeastern United States and parts of New York, New Jersey and New England. You're at increased risk if you live or spend time in these regions and:
In the past 20 to 30 years, the Lone Star tick has been found in large numbers as far north as Maine and as far west as central Texas and Oklahoma in the United States.
Alpha-gal syndrome can also occur in other parts of the world such as Europe, Australia and parts of Asia, where bites from certain types of ticks also appear to increase your risk of the condition.
Alpha-gal syndrome can cause food-induced anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) injector (EpiPen, Auvi-Q, others) and a visit to the emergency room.
Anaphylaxis signs and symptoms can include:
Based on recent research, doctors now believe that some people with unexplained, frequent anaphylaxis may be living with undiagnosed alpha-gal syndrome.
The best way to prevent alpha-gal syndrome is to avoid areas where ticks live, especially wooded, bushy areas with long grass. You can decrease your risk of getting alpha-gal syndrome with some simple precautions:
Doctors can diagnose alpha-gal syndrome using a combination of your personal history and certain medical tests.
Your doctor will likely start by asking about your exposure to ticks, your signs and symptoms, and how long it took for symptoms to develop after you ate red meat or other mammal products. He or she might also perform a physical exam.
Additional tests used in the evaluation of alpha-gal syndrome may include:
As with any food allergy, alpha-gal syndrome treatment involves avoiding the foods that cause your reaction. Always check the ingredient labels on store-bought foods to make sure they don't contain red meat or meat-based ingredients, such as beef, pork, lamb, organ meats or gelatins. Check soup stock cubes, gravy packages and flavor ingredients in prepackaged products. Ask your doctor or allergist for a list of foods to avoid, including meat extracts used in flavoring. The names of some ingredients make them difficult to recognize as meat based.
Use extra caution when you eat at restaurants and social gatherings. Many people don't understand the seriousness of an allergic food reaction, and few realize meat allergies even exist. Even a small amount of red meat can cause a severe reaction.
If you are at all worried that a food may contain something you're allergic to, don't try it. Come prepared to social events to avoid risk of exposure. For example, if you're attending a party where guests prepare food on a shared cooking surface, bring your own precooked food.
For a severe allergic reaction, you may need an emergency injection of epinephrine and a visit to the emergency room. Many people with allergies carry an epinephrine autoinjector (EpiPen, Auvi-Q, others). This device is a syringe and concealed needle that injects a single dose of medication when pressed against the thigh. Once you've been diagnosed with alpha-gal syndrome, your doctor or allergist likely will prescribe an epinephrine autoinjector.
Symptoms of alpha-gal syndrome may lessen or even disappear over time if you don't get any more bites from ticks that carry alpha-gal. Some people with this condition have been able to eat red meat and other mammal products again after one to two years without additional bites.
To get the most from your appointment, it's a good idea to be well prepared. Here's some information to help you get ready for your appointment and to know what to expect from your doctor.
Some basic questions to ask your doctor include:
Your doctor is likely to ask you a number of questions, including:
If you suspect you have alpha-gal syndrome, avoid eating red meat until your doctor's appointment. If you have a severe reaction, seek emergency help.
October 8th, 2021