The US Food and Drug Administration (FDA) has given clearance to an allergy blood test developed by Thermo Fisher Scientific to detect allergy to red meat. The company’s ImmunoCAP Specific IgE alpha-Gal Allergen Component test has been cleared for in vitro diagnostic use by the federal regulatory agency.
The red meat food allergy, known as ‘alpha-gal syndrome’ or ‘alpha-gal allergy,’ was only identified fairly recently. The allergy can cause a severe and potentially life-threatening reaction to the galactose-alpha-1, 3-galactose (alpha-Gal) carbohydrate that is commonly found in mammalian meat.
The allergy test can help diagnose a person’s sensitivity to the alpha-Gal carbohydrate found in mammal-based meats and meat products, and assess risk for an anaphylactic reaction. The meat allergy results in mild to severe allergic reactions to red meat such as beef, pork, lamb or other mammal products.
Signs and symptoms of the alpha-gal allergy can include hives and itching, swelling of the face, lips, tongue and throat or other parts of the body, wheezing or shortness of breath, runny nose, sneezing, headaches, abdominal pain, nausea and vomiting. A severe reaction can lead to anaphylaxis, which has the potential to be fatal.
Unlike other food allergies, reactions from eating red meat may be delayed, occurring three to eight hours after eating, according to the American Academy of Asthma, Allergy and Immunology (AAAAI). Most food allergies are responses to a protein molecule, but alpha-gal is unusual because it is a carbohydrate, and a delay in its absorption may explain the delay in symptoms, the AAAI noted.
Doctors believe the time lag 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, said the Mayo Clinic.
The condition can appear in people who have tolerated meat for years.
“Alpha-gal is dramatically different from other forms of food allergy,” said Thomas Platts-Mills, Professor of Medicine and Microbiology at the University of Virginia School of Medicine and a leading researcher on the topic. “Previously healthy adults can suddenly develop potentially life-threatening reactions to red meats such as beef, pork and lamb. The delayed nature of the reactions adds to the difficulty that clinicians and patients have in identifying the cause of the symptoms. This unique set of circumstances makes an accurate diagnosis critical for managing this disease.”
Thermo Fisher Scientific’s ImmunoCAP Specific IgE blood testing is the most widely used blood test for the specific detection of IgE antibodies, elevated levels of which indicate the presence of an active allergic process in the body. The tests can help identify allergic sensitivities to common environmental allergens (both indoor and outdoor, and seasonal or perennial), as well as food allergens such as peanut, egg and milk. The ImmunoCAP Specific IgE Stinging Insect Allergen Component tests were recently cleared by the FDA to help improve the diagnosis of bee and wasp allergies, according to a press release from Thermo Fisher Scientific.
“Sensitization to the alpha-Gal carbohydrate has been notoriously difficult to measure in patients,” said Lakiea Wright, Medical Director, US ImmunoDiagnostics at Thermo Fisher Scientific. “Skin prick testing to red meats such as beef, pork or lamb often gives weak or negative results, which is why, based on clinical studies, quantification of IgE antibodies to alpha-Gal in the blood is the preferred diagnostic method. Information from these tests can help providers be more precise in their diagnosis and management recommendations.”
Allergy Triggered by Lone Star Tick Bites
In the US, researchers believe that sensitization to alpha-gal may result from a bite from the Lone Star tick (Amblyomma americanum). Through the bite, the tick transfers the alpha-gal sugar molecule into a person’s body, which in some people, can trigger an immune reaction.
The Lone Star tick is mostly found in southeastern US, with most cases of the alpha-gal syndrome found to occur in this area. However, the condition appears to be spreading further north and west, as deer can carry the Lone Star tick to different parts of the country. Alpha-gal syndrome has also 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,” said the Mayo Clinic.
Currently, there is no treatment for alpha-gal syndrome apart from avoiding red meat and products made from mammals, as well as avoiding tick bites. Therefore, long-sleeved shirts, long pants and insect repellant are recommended when in wooded, grassy areas.