Alpha-gal syndrome is a food allergy to red meat, likely caused by an infected tick bite. Alpha-gal syndrome has been reported in 17 countries worldwide, found in Australia, Asia, and Europe as well as the United States. The allergy was first formally linked to an infected tick bite in 2002 in the United States, and in 2007 in Australia. 

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Signs and Symptoms 

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Unlike other common food allergies, the signs of alpha-gal don’t show up until about six hours after eating red meat. Symptoms usually include hives and itching, swelling of the face, wheezing, runny nose, sneezing, headaches, and in some serious cases, anaphylaxis (an allergic reaction which constricts breathing). 

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Since the allergic reactions are delayed, it’s only in recent years that doctors have been able to diagnose the disorder accurately. Furthermore, symptoms are not standard across all patients. While some may have classic signs of allergy like hives, others may go into anaphylactic shock. Others might experience gastrointestinal problems like heartburn or cramping. 

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Alpha-gal is not known to cause fatigue, but it’s always recommended to see your doctor if you start feeling sick after getting a tick bite. For more info about alpha-gal allergy, see the CDC’s resources here:  https://www.cdc.gov/ticks/alpha-gal/ 

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What Bacterium Causes Alpha-gal Syndrome? 

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Alpha-gal is not a bacterium, but a carbohydrate. It’s short for galactose-alpha-1,3-galactose and it’s found in all mammals’ blood and meat – except for in humans, apes, and Old World monkeys. Alpha-gal can be transferred from a mammal, such as a deer, to a tick that’s feeding on it. When a tick bites a human, the carbohydrate can be transmitted. 

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Some people’s immune systems respond to the alpha-gal in their body by producing antibodies to fight off alpha-gal, which leads to allergic reactions to red meat as they build over time. Alpha-gal syndrome can also trigger reactions from dairy products or medicines containing gelatin. In addition, alpha-gal syndrome is the first known food allergy that can cause a delayed anaphylaxis response. It’s also the first food allergy caused by a carbohydrate rather than a protein. 

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Which Tick Carries Alpha-gal Syndrome? 

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The lone star tick has been associated with alpha-gal in the United States. In Europe, Australia, and other parts of the world where the disorder is prevalent, it’s caused by other tick species. The alpha-gal is passed through the tick’s saliva, so when it bites you, the carbohydrate passes into your bloodstream, causing a reaction from your immune system. 

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Typical allergy tests usually won’t identify alpha-gal. A blood test can be done to diagnose alpha-gal syndrome, although the US Food and Drug Administration hasn’t approved a blood test for this. Tests can be purchased commercially by individuals, though. 

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Alpha-gal is associated with the lone star tick bite, but the carbohydrate is also present in the cancer drug cetuximab and in the pig’s tissue used for xenografts in organ transplants. Only one case of alpha-gal syndrome following an organ transplant has been reported, however. 

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Cures and Treatments 

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There is no cure for alpha-gal syndrome. The best treatment is to avoid foods that trigger allergic reactions. This includes red meat, but not poultry or fish. Consequently, an alpha-gal diet plan doesn’t have to be exclusively vegetarian. Most people do have to be careful about how their food is prepared though, to make sure it didn’t come into contact with red meat or red meat products. Some patients with alpha-gal syndrome also have to avoid dairy products and items containing gelatin. 

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With proper diet management, you can avoid symptoms of alpha-gal syndrome. In some people, the allergy might go away eventually if they’re not bitten by another tick. There have been reports of anywhere from 8 months to 5 years for the allergy to resolve itself. 

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It’s believed that alpha-gal goes underreported since many people don’t draw the connection between the red meat they eat and an allergic reaction several hours later. 

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Areas in Danger of Being Bitten 

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While most cases of alpha-gal syndrome are reported in the Southeast of the United States, populations of the lone star tick have been expanding beyond the Southeast in the last 20 years. Lone star ticks were reported in Connecticut recently as well. Lone star ticks like shaded, wooded areas and are known to aggressively attack humans, dogs, and cats. 

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Lone star ticks are vectors for other tick-borne diseases like tularemia and ehrlichiosis, so their bite can be dangerous. Prevention is the best defense again diseases and disorders like alpha-gal syndrome. When heading out to woodlands, always cover yourself with long sleeves and pants, as well as socks and closed-toe shoes. Keep ticks away with a DEET repellent and always check yourself and your pets for ticks before you go back inside. 

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Awareness and prevention are the best ways to ward off tick-borne diseases. For more info from the CDC on tick bite prevention, see here:   https://www.cdc.gov/ticks/avoid/on_people.html