Meat allergy from tick bites is on the rise—and US doctors are in the dark
Enlarge / A vector ecologist displays a vial of live lone star ticks. (credit: Getty | Ben McCanna)
A little over a decade ago, researchers discovered that bites from lone star ticks could cause some people to develop a food allergy to meat and meat products-an allergic condition called alpha-gal syndrome (AGS), which can vary from mild to life-threatening.
The condition is named after a carbohydrate called galactose--1,3-galactose (aka alpha-gal), which is commonly found on proteins in most mammals-with the important exception of primates, like humans. Alpha-gal shows up on all sorts of non-primate mammalian tissue, which means it's also in meat-such as pork, beef, rabbit, and lamb-and animal products, like milk and gelatin. Its presence on animal tissue is one of the big, long-recognized barriers to xenotransplantation-that is, transplanting pig hearts into people, for example. Human immune systems will, in part, reject the organ because of the presence of the foreign alpha-gal.
But, in recent years, researchers have also discovered that alpha-gal is in tick saliva. And, for reasons researchers still haven't worked out, some people bitten by ticks develop a type of antibody called anti-alpha-gal IgE. This antibody may help protect people from tick bites, but it also renders them allergic to anything with alpha-gal-i.e., mammalian meat and animal products. It's a double-edged sword that has been hypothesized to be an "allergic klendusity."