CDC says bites from lone star ticks are making people allergic to meat, but Minnesota cases are a mystery

Hundreds of thousands of Americans have developed allergies to red meat because of the bite of a lone star tick, according to a Centers for Disease Control and Prevention report released Thursday. Among those afflicted by this little-known ailment are 238 people across northern Minnesota and Wisconsin, far from the tick's known range in the southern and eastern U.S.

Minnesota officials say they have never found the lone star tick in their own surveys, and the insects are only occasionally spotted and reported to the Health Department.

The group of cases is "kind of eye-opening for us," said Elizabeth Schiffman, an epidemiologist supervisor with the Minnesota Department of Health.

Alpha gal syndrome, named after a sugar found in mammals, can be hard to identify. Unlike other food allergies, symptoms usually don't show up until two to six hours after consuming red meat, dairy, or other animal products like gelatin, according to the CDC. Symptoms range widely, including hives and rash; swelling lips, throat, tongue or eyelids; dizziness; stomach pain and a drop in blood pressure.

Doctors have to test for specific antibodies to confirm the disease. The CDC also released a companion report Thursday that showed knowledge of the syndrome was still scant among many providers.

Researchers at the CDC analyzed tests from 295,400 people across the country, taken from 2017 to 2022. Most of the cases on the CDC's map correlate closely with the lone star's territory, which stretches from the Southeast to mid-Atlantic states, and west to roughly the middle of the country.

Johanna Salzer, an epidemiologist with the CDC and senior author on both studies, said counties in Minnesota that show up aren't comparable to hot spots such as one county on Long Island, N.Y., which accounted for 4% of all the alpha gal allergies in the county.

Jonathan Oliver, an assistant professor and public health entomologist at the University of Minnesota, said he was aware of at least one allergist in Duluth who had been catching alpha gal syndrome in patients — which might help to explain the higher case counts for a disease that's still not widely known.

Because of low knowledge among health care providers, the CDC estimates that 450,000 people across the country have been affected by the meat allergy, which is many more than have had positive tests.

There are other possible explanations for why cases are popping up in Minnesota. Schiffman and Oliver said it's important to rule out whether people in this area were bitten by lone star ticks while traveling.

Schiffman also said it's possible other tick species native to the area can trigger the allergy, but she stressed that "we don't have the right info yet to be able to say that is really a risk."

Oliver was hopeful the CDC's work would lead to more funding for research on the disease. Beyond the mystery of Minnesota's case counts, it's unclear exactly how tick bites cause the novel allergy and who is most vulnerable.