By A.J. Hostetler 

A once-rare allergy that can cause severe reactions hours after eating red meat is dramatically rising across the United States, according to preliminary findings by researchers at VCU Health and Virginia Commonwealth University. 

The condition, known as alpha-gal syndrome (AGS), is typically linked to bites from the lone star tick and is increasingly recognized as a growing health concern in many regions of the country. Different types of ticks cause the syndrome in other parts of the world. 

The findings, presented this week at the American College of Gastroenterology’s 2025 annual scientific meeting in Phoenix, Arizona, show a 100-fold increase in positive test results for alpha-gal antibodies between 2013 and 2024. While these results are preliminary, the study represents one of the largest real-world analyses of AGS to date. 

“Alpha-gal syndrome is unlike any other food allergy we treat,” said Vinay Jahagirdar, M.D., the study’s co-author and gastroenterology fellow with VCU Gastroenterology Fellowship Training Program and Stravitz-Sanyal Institute for Liver Disease and Metabolic Health. “Symptoms often appear several hours after a person eats red meat, making it difficult to connect a meal with an allergic reaction. Many patients are misdiagnosed or go years without answers.” 

AGS is triggered when a tick bite causes a person’s immune system to develop antibodies to a sugar molecule (galactose-alpha-1,3-galactose) found in the meat of mammals such as beef, pork or lamb. Reactions can include hives, swelling, nausea, vomiting, abdominal pain, diarrhea and even life-threatening anaphylaxis. Researchers believe the allergic response to alpha-gal triggers inflammation in the gut, leading to discomfort and other digestive problems that can significantly affect quality of life. 

“Alpha-gal syndrome has gone from a medical curiosity to a major public health issue in just a decade,” Jahagirdar said. “Our study shows this is not a localized problem anymore. We’re seeing cases far beyond the Southeast, including in the Northeast and Midwest.” 

Using information from the extensive TriNetX U.S. Collaborative Network, the research team reviewed data between 2010 and 2025 of more than 3,800 adults tested for the antibodies produced in the immune system to fight AGS. The study showed a sharp rise in positive test results for the condition with nearly a quarter, or 749 patients, diagnosed with it. 

Across 69 U.S. health systems, the incidence proportion climbed markedly, from about 1.8% in 2013–2014 to 38.5% in 2021–2022. Researchers say this increase likely reflects better awareness among doctors as well as more tick bites across the country.  

Other key findings from this study include: 

• Patients with AGS were generally older, white and female.  
• Lyme disease appeared in 17% of cases, suggesting an overlapping risk from tick exposure. 
• Other common conditions AGS patients have include joint disorders, high cholesterol, food allergies, vitamin D deficiency and asthma. 
• Most cases were reported from the Northeast (69%) and the South (23%). 

Once largely confined to southeastern states, lone star ticks have expanded their range north and west in recent years, aided by warmer winters and rising deer populations. The study’s geographic data align with those ecological changes, showing a strong clustering of cases where ticks are most prevalent. 

Researchers hope study helps doctors better diagnose alpha-gal syndrome 

Gastrointestinal (GI) symptoms are among the most common and confusing signs of AGS. Many patients experience abdominal pain, cramping, bloating, nausea, vomiting, or diarrhea several hours after eating red meat or foods made from mammalian products.  

Because these reactions are delayed, often appearing three to six hours after a meal, they are frequently mistaken for food poisoning, irritable bowel syndrome or other digestive disorders. Some individuals with AGS report only stomach-related symptoms and never develop hives or swelling, making the condition even harder to recognize.  

Since many people with AGS experience GI symptoms, the VCU Health researchers emphasized the need for greater awareness among gastroenterologists, who are often the first specialists these patients see. 

 “The spread of ticks is bringing new allergic diseases to areas where doctors and patients may not expect them. Recognizing this connection is key to protecting public health,” said Ravi Vachhani, M.D., study co-author, VCU Health gastroenterologist and director of the VCU Gastroenterology Fellowship Training Program. 

Those diagnosed with AGS must avoid red meat and, in some cases, dairy products or gelatin. While no cure exists, avoiding further tick bites may help antibody levels decline over time. 

Other co-authors of the abstract are from VCU. They include Kaanthi Rama, M.D., Prabhat Kumar, M.D., Raseen Tariq, M.D., and Stephen J. Bickston, M.D. 

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