May 31, 2022

Tick bite can cause red meat allergy

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After a lone star tick bite, reactions can range from itching to anaphylactic shock.

Lone star tick bites are likely the cause of thousands of cases of severe red meat allergies. This condition, known as alpha-gal syndrome, is plaguing patients in Southeastern states including Tennessee, North Carolina and Virginia, spreading up the Eastern Seaboard along with the deer population.

Vanderbilt’s Asthma, Sinus and Allergy Program has seen many people in recent years who are allergic to alpha-gal, a type of sugar present in red meat.

The lone star tick has alpha-gal sugar in its gut, and introduces it to a person’s system when it bites. The human immune system produces an antibody that reacts if the person eats meat.

Symptoms of a red meat allergy

The allergy can cause hives, swelling and broader symptoms of anaphylaxis (hypersensitivity), including vomiting, diarrhea, trouble breathing and a drop in blood pressure.

People who develop an allergy to the alpha-gal sugar can safely eat poultry such as chicken or turkey, but red meats such as beef and pork, and even game, including venison, will cause a reaction. Some patients react to milk.

Delayed reactions

Unlike other allergies which cause a reaction within minutes, the allergic reaction can happen four to six hours after eating red meat and the delay makes diagnosis tricky.

“The allergic reaction can take hours to present, and it doesn’t present in the same way for everyone. Patients don’t always remember being bit by a tick so that can be another factor,” said Basil Kahwash, M.D., of the Vanderbilt Asthma, Sinus and Allergy Program.

Kahwash suggests that people be tested for the allergy if they begin to have unexplained allergic reactions, particularly for those who eat red meat and spend a lot of time outdoors.

How is a red meat allergy diagnosed?

The diagnosis is done with a blood test. But there is no good way to desensitize people once they develop this allergy, so the only way to prevent reaction is to avoid red meat, and for some people, depending on the severity of the allergy, milk.

Getting repeated tick bites causes the level of allergy antibodies to rise. Allergists recommend that people with this allergy take careful steps to avoid ticks and carry an EpiPen in case they unintentionally consume red meat.

Can a red meat allergy go away?

The allergy can go away over time, often within five to seven years, if there is no further tick exposure. Doctors can monitor the levels indicating the allergy. When levels are within a certain range, the doctor may advise the patient that it is safe to try eating red meat again.

Allergies, asthma and sinus problems can produce similar symptoms, ranging from annoying to life-threatening. At five locations in Middle Tennessee, Vanderbilt Asthma, Sinus and Allergy experts give you an accurate diagnosis and treatment tailored to you, your symptoms and your life.

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