Can a Tick Bite Make You Vegetarian?

This female Lone Star tick could induce an allergy for meat in humans. Lisa Zins/flickr

Would you like a side of anaphylaxis with your burger? How about nausea, stomach cramps, indigestion, vomiting, diarrhea, congestion, sneezing, headaches or asthma?

Such is the possibility if you have been nibbled upon by a Lone Star tick because a single bite can cause "alpha-gal allergic reaction," according to a 2012 study presented at the Annual Scientific Meeting of the American College of Allergy, Asthma and Immunology (ACAAI).

Alpha-gal is a sugar carbohydrate found in red meats such as beef, pork and lamb.

Following a tick bite, antibodies to alpha-gal in the tick's saliva are produced in the person's blood. Since alpha-gal is also found in meat, once bitten, a person's immune system can trigger the release of histamine in response to the presence of the substance, causing an allergic reaction ranging from mild to severe. Some people also have an allergic response to dairy products.

"Blood levels of antibodies for alpha-gal in the human body can rise after a single bite from the Lone Star tick," said allergist Stanley Fineman, M.D., ACAAI president. "This can result in allergic symptoms which are usually delayed after meat ingestion and may present as mild hives but may also be a severe, potentially deadly reaction known as anaphylaxis."

According to the study, positive alpha-gal rates are 32 percent higher in the central and southern regions of the United States, which is Lone Star tick territory. But researchers also found surprisingly high positive rates in the north-central and west regions of the country, places where the Lone Star tick doesn't reside.

"These findings suggest that other species of ticks, or possibly human factors, may play a role in allergic reactions to alpha-gal," said Fineman. "Patients with delayed allergic reactions after eating meats should see an allergist to determine if it is an alpha-gal allergy. The best treatment is strict avoidance of meat.”

Becoming more common

There were only a few known cases of the allergy about a decade ago when it was first identified, according to Dr. Scott Commins, an allergist and associate professor of medicine at the University of North Carolina, Chapel Hill, who was one of the first physicians to identify the allergy in patients with tick bites.

Numbers have risen sharply since then.

"We're confident the number is over 5,000 [cases], and that's in the U.S. alone," Commins tells NPR. There are even cases in other parts of the world, including Sweden, Germany and Australia, that are likely associated with other species of ticks.

Commins says that as the Lone Star tick has move beyond the Southeast, there have been case of alpha gal meat allergies farther north, including Maine, Minnesota and New York.

"The range of the tick is expanding," says Commins, who mentioned that awareness about the allergy is also spreading. "We have a blood test, and the word is getting out."