PhotoFood allergies are becoming a more common occurrence, a result perhaps of new types of processes, substances and additives in the modern diet. But at least one type of increasingly common food allergy appears to have a very natural cause.

There is a growing body of research suggesting that consumers stricken by a sudden allergy to red meat may have developed a sudden sensitivity because of a tick bite. In particular, the lone star tick may be causing thousands of new allergy cases, doctors say.

Food allergies are reactions of the body's immune system to the introduction of a certain food, according to the Mayo Clinic. The immune system detects something in the food that isn't supposed to be there and goes to war. The result can be something as mild as digestive distress to hives, swelling and a life-threatening reaction known as anaphylaxis.

One of the most common food allergies is to peanuts, which can cause immediate severe and sometimes fatal reactions. For the most part, a peanut allergy begins in childhood.

How it's different

What is different about many cases of red meat allergy is that the symptoms occur later in life without warnings. One minute you're eating a hamburger and a couple of hours later you're headed for the emergency room.

A 2012 study led by researchers at Virginia Commonwealth University linked the lone star tick to red meat allergies, causing a severe, life-threatening allergic reaction. The cases were predominantly in the southeastern U.S. The study focused on antibodies in the blood to a substance called an alpha-gal found in the tick bite.

That substance is also found in red meat so, when the body's immune system detects it following a nice steak dinner, it goes to war once again.

"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 authors wrote. “Current guidance is to counsel patients to avoid all mammalian meat -- beef, pork, lamb and venison."

Cases on the rise

At Vanderbilt University’s Asthma, Sinus and Allergy Program (A.S.A.P.) clinic in Nashville, Tenn., doctors are seeing one or more new red meat allergy cases each week.

“It is not completely understood exactly how the allergy starts,” said Dr. Robert Valet said, assistant professor of medicine at Vanderbilt. “The thought is that the tick has the alpha-gal sugar in its gut and introduces it as part of the allergic bite and that causes the production of the allergy antibody that then cross-reacts to the meat.”

Valet said the allergy's symptoms have included hives and swelling, as well as broader symptoms of anaphylaxis, such as vomiting, diarrhea, trouble breathing, and a drop in blood pressure.

Among most important food allergies

“I think it is something that certainly belongs among the most important food allergies, particularly in the Southeast,” he said. “Certainly these patients can present with every bit as severe of an allergy as someone who is allergic to peanuts.”

Adding to the danger is the fact that someone can develop this food allergy literally overnight, with no warning they could have a problem. Valet recounts the case of September Norman, vacationing with her husband in Tennessee’s Fall Creek Falls State Park. After a steak dinner she was awakened in the middle of the night with a severe allergic reaction and had to be driven several miles to find cell coverage to call 911. Treatment included an epinephrine injection, Benadryl, an IV, and steroids.

Developing this allergy is bad news for a carnivore because Valet says there is no good way to desensitize people once they develop this allergy. While chicken can remain in your diet, red meats and, in some cases, milk are off-limits.


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