August 31, 2017

In May, Jessica Sanford of Jefferson City woke up in the middle of the night covered in hives and struggling to breathe. She didn’t know why. It wasn’t until she experienced the same symptoms three more times the next week that she was able to trace them to the pork she had eaten.

“For several days afterward I stayed away from pork and everything seemed to be OK,” Sanford said. “Then I had a burger at a baseball game and hours later experienced the same allergic reaction.”

Even avoiding meat completely didn’t prevent the allergy.

“The most severe reaction occurred as a result of just cleaning our barbeque grill,” Sanford said. “I guess I breathed in some small particles of dust from the grate. Hours later I experienced the same kind of allergic reaction. However, this time it was so severe that I ended up in the emergency room in anaphylactic shock. Now I have to carry an EpiPen. I was beyond scared and felt very anxious every night knowing that I might wake up covered in hives, or worse.”

Sanford saw Christine Franzese, MD, an allergist with University of Missouri Health Care and a professor of otolaryngology at the MU School of Medicine, who pinpointed the cause: a tick bite Sanford had gotten two weeks earlier.

Christine Franzese, MD
Christine Franzese, MD

“Mammalian meat allergy is caused by exposure to the sugar galactose-alpha-1, 3-galactose, also known as alpha gal,” Franzese said. “Alpha gal is present in the blood of most mammals. However, it is not present in human blood. The allergy to meat that Jessica and others are experiencing is caused by the transfer of the alpha gal sugar molecule to humans through the bite of a Lone Star tick.”

Lone Star ticks are found throughout the eastern and southeastern half of the United States. People exposed to the sugar through a Lone Star tick bite develop antibodies against alpha gal. In some cases, this results in an allergy to mammalian meat.

“The human body does not recognize alpha gal and will mount an immune response against it,” Franzese said. “This response includes the development of allergy antibodies to alpha gal. If a person develops enough of these antibodies, they will experience an allergic reaction when meat with alpha gal in it, such as beef and pork, is ingested. The meat allergy is diagnosed by a blood test that looks for the presence of the alpha gal antibodies.”

“Nationally, there are no exact numbers on confirmed cases of alpha gal,” Franzese said. “However, I know that I have seen an increase in the number of patients that I have diagnosed. Over the last four years I have treated approximately 30 patients with this allergy. This year alone I have confirmed the allergy in 16 of my patients.”

Although the symptoms of mammalian meat allergy are similar to other food allergies, they are unique because of their delayed response.

“With most food allergies, people experience hives, itching and throat swelling that also can be life-threatening,” Franzese said. “However, these reactions occur quickly, usually within the first five minutes of exposure. With mammalian meat allergy, the symptoms do not usually appear until four to six hours after exposure.”

This delayed reaction also makes diagnosing the allergy difficult.

“Not everyone puts the pieces together as quickly as Jessica did, because most of us equate allergic reactions to more immediate exposures,” Franzese said.

Treatment for mammalian meat allergy is similar to other allergies. Avoidance is the No. 1 strategy, and antihistamines can help. However, for severe cases like Sanford’s, carrying an EpiPen may be necessary.

“There is no known cure for alpha gal,” Franzese said. “Previous cases lead us to believe that over time, the allergy can slowly go away ― although it may take several years. However, if a person is re-exposed through another Lone Star tick bite, the clock may start back over again, meaning the allergy may last for a longer period of time. Avoidance of tick bites is a key preventive measure.”

To help protect yourself and your family against tick bites when outdoors:

  • Use a chemical repellent with DEET.
  • Wear light-colored clothing, preferably long pants and a shirt with long sleeves.
  • Tuck your pant legs into your socks.
  • Avoid tick-infested areas, such as tall grass and vegetation.
  • Check yourself, your children and your pets for ticks when coming in from outdoors.

“I am much more aware of ticks now than I was before,” Sanford said. “I pre-treat my family’s clothing when I know we will spend time outdoors. We also check for ticks and then make sure to shower when we come in. I don’t want my family or anyone else to have to go through this.”

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