It’s a story right out of a Stephen King novel: One morning you go out for a nice hike in the hills and the next, you end the day nearly dead from a cheeseburger. With just one bite from a lone star tick, you could develop a life threatening meat allergy.
As if the more common tick-borne illness, Lyme disease, weren’t enough of a worry, the lone star tick, so named for its Texas shaped white smudge, has a horrible and baffling way of triggering the human immune system to react adversely to a sugar molecule that’s found in red meat. Galactose-alspha-1, 3-galactose, shortened to alpha-gal, can make you deathly ill.
An as of yet unidentified substance in the tick’s saliva attaches itself to alpha-gal in the human body, which causes the immune system to produce massive amounts of histamines whenever so much as a morsel of red meat passes through a bitten person’s lips. This is anaphylaxis: symptoms can range from intense itchiness to terrible stomach cramps, low blood pressure, trouble breathing and yes, even death.
For some folks, however, the effects are not immediate, which can make it hard for people to make the connection to their tick bite.
There’s a time delay in the reaction,” says Cosby Stone, an allergy and immunology fellow at Vanderbilt University.“It [the Alpha-Gal] has to first travel through your gastrointestinal tract to be released. Hours later, patients wake up with hives, shortness of breath, vomiting, and diarrhea.”
On rare occasions, patients have been admitted to intensive care. “Some patients have had to be given life support because their blood pressure is so low that they’re in imminent danger of dying,” said Stone.
However, most patients experience several allergic reactions before they make the connection between their diet and the reaction. And the more tick bites from an infected tick, the worse the reactions can be over time.
The way in which researchers discovered the cause of this rare allergy is a testament to scientists’ powers of observation. At the University of Virginia (the state of Virginia is one of the lone star tick’s territories), immunologist Thomas Platts-Mills heads a well-known allergy research department. In his years of studying the power of histamines, he’d heard stories of these alleged meat allergies dating to at least the 1990s. It wasn’t until 2004, however, that another group of patients exhibiting similar symptoms came to his attention. These patients experienced itching, swelling, and dangerously low blood pressure. They were all taking a cancer drug called Cetuximab.
Platts-Mills reached out to Cetuximab’s distributor, biopharmaceutical company Bristol-Myers Squibb, to examine blood samples from patients exhibiting the telltale symptoms. To his surprise, the patients who had developed allergic reactions had pre-existing antibodies to alpha-gal. It turned out that Cetuximab contained alpha-gal derived from genetically modified mice.
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