The Lone Star tick is a pest indigenous to the Midwest and Eastern United States, whose bite also comes with a pretty nasty side effect: turning its victims vegetarian.
According to the science side of the internet, the ticks contain a sugar called Galactose-alpha-1,3-galactose, or alpha-gal, that is also present in red meat and some dairy products. When bitten, the human body's immune response creates antibodies to the sugar, resulting in a mild to severe allergic reaction whenever that person bites into a burger.
At least one doctor in Virginia says he sees "two to three new cases every week," with most instances in people with no previous food allergies, though some patients do show signs of recovery over time.
Somewhere up there, the guys who founded PETA are laughing their vegan little heads off.