Listen up, steak lovers: New research has found being bitten by a tick can cause some people to develop an allergy to red meat.
Researchers from Virginia Commonwealth University have identified a new condition known as “delayed anaphylaxis” – a severe, life-threatening allergic reaction – to meat that has emerged in the southeastern United States. Patients typically wake up in the middle of the night, with hives or other allergic reactions usually three to six hours after having eaten red meat for dinner.
Drs. Susan Wolver and Diane Sun who studied patients with the condition found it is caused by antibodies to a carbohydrate (alpha-gal) produced in a patient's blood in response to a tick bite, specifically the Lone Star tick. This carbohydrate is also present in meat. When people who have been bitten by a tick eat meat, their immune systems activate the release of histamine in response to the alpha-gal, which can cause hives and anaphylaxis.

"Where ticks are endemic, for example in the southeastern United States, clinicians should be aware of this new syndrome when presented with a case of anaphylaxis,” the researchers said. “Current guidance is to counsel patients to avoid all mammalian meat – beef, pork, lamb and venison."
The study, reported in the Journal of General Internal Medicine, indicates meat-induced anaphylaxis is the first food-induced allergic reaction due to a carbohydrate rather than a protein. It is also the first time anaphylaxis has been noted to be delayed rather than occurring immediately after exposure.