Allergic klendusity —

Meat allergy from tick bites is on the rise—and US doctors are in the dark

The allergy, called alpha-gal syndrome, came to light a little over a decade ago.

A vector ecologist displays a vial of live lone star ticks.
Enlarge / A vector ecologist displays a vial of live lone star ticks.

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-α-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."

If this is all news to you, you're far from alone. Although tens of thousands of people in the US have been diagnosed with AGS in recent years, awareness of the condition has remained low—and this is leading to a critical public health problem, researchers say in a pair of complementary studies published Thursday.

The studies indicate that while the actual number of Americans with AGS may be as high as 450,000, few primary health care providers know the condition. In a survey of 1,500 primary care doctors, pediatricians, physician assistants, and nurse practitioners, a concerning 78 percent (1,165) had little to no knowledge of AGS.

Specifically, 635 (42 percent) of the survey takers said they had not heard of AGS at all. Another 530 said they were "not too confident" in their ability to diagnose it. Of the 865 medical professionals who had at least heard of the condition, only 42 of them were able to correctly answer three basic questions related to the condition's cause, diagnosis, and counseling.

"Alpha-gal syndrome is an important emerging public health problem, with potentially severe health impacts that can last a lifetime for some patients," Dr. Ann Carpenter, an epidemiologist at the Centers for Disease Control and Prevention and the lead author of the newly published survey study, said in a statement. "It’s critical for clinicians to be aware of AGS so they can properly evaluate, diagnose, and manage their patients and also educate them on tick-bite prevention to protect patients from developing this allergic condition."

Channel Ars Technica