This tick can give you a life-threatening allergy. It’s spreading across the U.S.

**David Greene** (0:04)
This is In Conversation from Apple News. I'm David Greene in for Shumita Basu. Today, what to know about the tick-borne allergy spreading across the US?
It is peak tick season, the stretch from April to September when tick activity spikes in huge swaths of the United States. Right now, according to the CDC, Americans are visiting emergency rooms for tick bites at the highest rate in nearly a decade, and the most rapidly spreading tick-borne illness in the country is something called Alpha Gal syndrome. This is a condition that causes an often severe allergy to red meat and other animal products, and it's primarily spread by a particularly aggressive species called the Lone Star tick.

**Burkhard Bilger** (0:53)
They will actively hunt people down.

**David Greene** (0:56)
That is New Yorker staff writer Burkhard Bilger. He recently reported on the rise of the Lone Star Tick and Alpha Gal syndrome.

**Burkhard Bilger** (1:04)
There have been reports of them actually crawling down from the dune grasses and crossing the hot sand and getting onto beach blankets and biting people as they're sunbathing.

**David Greene** (1:13)
Lone Star ticks were once found mostly in the southeastern US., but they have been spreading, turning up as far west as Texas and as far north as Maine and Michigan. And wherever they go, they bring Alpha Gal along with them.
This syndrome can trigger a range of reactions after you eat meat or dairy, from hives and indigestion to full-on anaphylaxis. That is a life-threatening allergic response that roughly 60% of Alpha Gal patients report having experienced. At least one death has been directly attributed to this allergy. Official estimates indicate about a half a million people in the US have Alpha Gal syndrome, though some researchers say the true number is a lot higher. So I wanted to talk to Burkhard about what we know and don't know about Alpha Gal, how it's impacting people's lives, and what, if anything, we can do about this.
I feel like so many of us are really familiar with Lyme disease. That's the disease we always associated with ticks. But what is Alpha Gal syndrome? What are the thumbnail basics of what this thing is?

**Burkhard Bilger** (2:21)
I mean, it becomes a syndrome when your immune system has an allergic reaction to the sugar. The name comes from Alpha Galactos. It's a sugar that's present in the bodies and the milk of all mammals except for primates. And so to the human body, it's a foreign sugar.
And every lone star tick has Alpha Gal in its saliva. And so when they bite you, it will always put it in your bloodstream. And then it's a question of how your body reacts to that.
Some bodies react by flooding their system with antibodies to that sugar, that foreign sugar that's now in their blood. And some people get high levels of antibodies and have this terrible allergic reaction. And that allergic reaction in people is characterized by, you know, it's when you eat meat or you drink milk or some kind of dairy product or eat some kind of dairy product that has this Alpha Gal sugar in it. And if your body reacts to it, then you can have stomach knotted, you can have hives, rashes, shortness of breath, your tongue and your throat can swell up. You can have full anaphylactic shock. You know, there have been people who have died from this.
One of the tricky things about this is that because Alpha Gal is kind of often wrapped up in fats or in ligaments and other connective tissue, it takes a while for the body to digest. And so often you'll eat a steak at seven in the evening, eight in the evening, and you won't feel any symptoms of the allergy until three in the morning. So people often don't make the connection. It can be mistaken for lots of things. And the interesting thing is that why are we reacting to it in our blood from when a tick bites us? And that's still somewhat of a mystery. A lot of people think there's a co-factor in the tick saliva that somehow also triggers the immune system to react to the Alpha Gal that's carried in that saliva.

**David Greene** (4:11)
But people say like it can give you a meat allergy. And I know as you're telling us, we know relatively little about this, but we do know that like I'm hiking around, I get bitten by a Lone Star Tick, whatever the sugar is that they put into my blood, my immune system can react in a way that will then, next time I eat meat, a burger, a steak, there's a good chance that I'm gonna have an allergic reaction that I've never had before and potentially get very sick.