tick
A tick turned Kristie Downen into a vegan.

"It was the last thing on my mind," the Missouri farmer tells Springfield's KSPR TV of her "life-changing experience ... [it's] unbelievable that a tick can make you allergic to food."

Downen was bitten by a common "lone star" tick four years ago — but doctors were unable to diagnose the array of symptoms she developed until this year.

"It got to the point where my stomach would swell up, I was vomiting," Downen says. "The rashes were real bad, it was getting to the point [I told doctors], 'You're missing something, I'm still dying.' "

She was given a test for an alpha-gal allergy and tested positive. Alpha-gal is a sugar molecule found in the majority of mammals, with the exception of humans and monkeys. An allergy to it can, as in Downen's case, cause severe allergic reactions to mammal meat.

"I'm allergic to almost 29 other food items plus chicken, plus all mammal meat, plus dairy," Downen, who now carries an epi-pen with her at all times, tells local station KOLR10.

Diagnosing alpha-gal is difficult, in part due to the wide array of symptoms, including rash, hives and fainting, often appearing three to six hours after meat consumption and varying significantly from person to person, according to the Centers for Disease Control and Prevention.

Because ticks are more common during the summer, medical experts warn the public to beware while outdoors during cookout season.

"Lots of ticks are on cattle," Missouri allergist Dr. Minh-Thu Le tells KSPR. "And so they picked up the alpha-gal from the cattle, transfer it to humans, and then when you eat cow's meat — beef, pork or whatever else — that's when the alpha-gal comes into your system and you react to it."

Downen may not always have such restricted eating, though: It is possible to outgrow the allergy, allergists say.