More than 100,000 people in the U.S. have become allergic to red meat since 2010 because of a weird syndrome triggered by tick bites, according to a government report released Thursday. But health officials believe many more have the problem and don’t know it.
A second report estimated that as many as 450,000 Americans have developed the allergy. That would make it the 10th most common food allergy in the U.S., said Dr. Scott Commins, a University of North Carolina researcher who co-authored both papers published by the Centers for Disease Control and Prevention.
Health officials said they are not aware of any confirmed deaths, but people with the allergy have described it as bewildering and terrifying.
The reaction, called alpha-gal syndrome, occurs when an infected person eats beef, pork, venison or other meat from mammals — or ingests milk, gelatin or other mammal products.
It’s not caused by a germ but by a sugar, alpha-gal, that is in meat from mammals — and in tick spit. When the sugar enters the body through the skin, it triggers an immune response and can lead to a severe allergic reaction.
Scientists had seen reactions in patients taking a cancer drug that was made in mouse cells containing the alpha-gal sugar. But in 2011 researchers first reported that it could spread through tick bites, too.
They tied it to the lone star tick, which despite its Texas-themed name is most common in the eastern and southern U.S. (About 4% of all U.S. cases have been in the eastern end of New York’s Long Island.)
Experts say cases may be up for a variety of reasons, including lone star ticks’ expanding range, more people coming into contact with the ticks or more doctors learning about it and ordering tests for it.
People with the syndrome can experience symptoms including hives, nausea, vomiting, diarrhea, severe stomach pain, difficulty breathing, dizziness and swelling of the lips, throat, tongue or eye lids. Unlike some other food allergies, which occur soon after eating, these reactions hit hours later.
Some patients have only stomach symptoms, and the American Gastroenterological Association says people with unexplained diarrhea, nausea and abdominal pain should be tested for the syndrome.
Doctors counsel people with the allergy to change their diet, carry epinephrine and avoid tick bites.