Diagnosing Meat Allergy After Tick Bite Without Delay

Galactose-alpha-1, 3 galactose (alpha-gal) is a carbohydrate found in mammalian meat. In 2007, it was implicated as a cause of severe hypersensitivity reactions when a study found elevated levels of antibodies directed against this oligosaccharide among patients treated with cetuximab, a monoclonal antibody that contained an alpha -gal epitope. The majority of these cases were reported in the Southeast United States in a distribution similar to that of Rocky Mountain spotted fever and ehrlichiosis, and that geographic association led researchers to the conclusion that a bite from the Lone Star tick can induce this antibody. Here, we present a case of delayed urticarial angioedema due to a mammalian meat allergy caused by alpha-gal immunoglobulin E acquired after tick exposures, and the knowledge and patient education required to prevent recurrences. It is estimated that approximately 0.5% to 1.0% of the general population will experience an episode of angioedema in their lifetime, and this case demonstrates why clinicians in areas that are inhabited by ticks, particularly the Lone Star species, should include this cause in their differential.