The warning from my friend’s bug guy in Wellfleet sounded outlandish. A new tick — the Lone Star — is invading the Cape, and a single bite can render you allergic to red meat. Apparently a roast beef sandwich can now send you into anaphylactic shock.

Really?

Well, let’s just say that over the course of a week I went from blasé — I don’t even eat red meat — to a woman lusting after the full-body, hooded, anti-tick jumpsuit that costs $140.

In between those two mood states, I spent time with my junior high school friend Laura. She lives in North Carolina, where the Lone Star tick, and the allergy it can trigger, “Alpha-gal Syndrome,’’ is as infamous as the Lyme-carrying deer tick is here.

I hadn’t seen Laura in years, but she came to Plymouth last weekend for a small reunion, and because the tick is moving up the East Coast, I would soon come to think of her as a visitor from a frightening future.

As the conversation among seven middle-aged friends moved from eighth grade to our lives now, our joys, our fears, Laura told a terrifying tale: First came a tick bite. Then, a few weeks later, a Sunday football game, a bowl of beef chili, and soon, hives, a swelling throat, the feeling she couldn’t breathe, a rush to the emergency room, a collapse on the floor. “I think I was panicking,’’ she said.

The diagnosis came the next day, from an allergist who, as good fortune would have it, happened to have learned about Alpha-gal Syndrome at a conference. “Have you been bitten by a tick recently?’’ he asked.

(A study just published by the Centers for Disease Control and Prevention reported that 42 percent of health care providers were not aware of Alpha-gal Syndrome, and another 35 percent were not confident in their ability to diagnose or manage such patients.)

Alpha-gal is a sugar molecule found in most mammals (but not humans) — and also in products made from and by mammals, including gelatin, cow’s milk, and milk products. My friend Laura soon learned this the hard way, after having intense allergic reactions to Tylenol gel caps and candy corn, both of which she had no idea would be hazardous for her in her new state.

According to the CDC, short of showing up in the ER gasping for breath, Alpha-gal symptoms can include: hive or an itchy rash, nausea or vomiting, heartburn or indigestion, diarrhea, a drop in blood pressure, swelling of the lips, tongue or eyelids, dizziness or faintness, or severe stomach pain.

The Lone Star tick, which is known to be particularly aggressive, is named for the white dot on the female’s hard-shell back, not for any resemblance to the Texas state flag. A second study published Thursday by the CDC found that suspected Alpha-gal Syndrome cases in the United States have increased substantially since 2010, and that more than 100,000 people have become allergic to red meat since then.

Suspected cases predominantly occurred in counties within the Southern, Midwestern, and Mid-Atlantic US Census Bureau regions, the CDC reported, but suspected Alpha-gal cases were also identified in areas outside of the Lone Star tick’s range

In Massachusetts, the highest number of suspected cases per capita was in Dukes, Nantucket, Barnstable, and Berkshire counties, according to the study. The larger counties of Worcester, Plymouth, and Middlesex had the highest absolute counts of suspected cases.

The growing threat can also be seen in data from the University of Rhode Island’s TickEncounter Resource Center, which allows people to upload photos of ticks. In the past few years, there has been an enormous growth in local Lone Star sightings, said the center’s director, entomologist and professor Thomas Mather.

“We’ve had TickSpotters submissions of Lone Stars from southern and mid-Atlantic states’’ since 2006, he said in an email, “but in Rhode Island and probably the Cape and Islands, we saw a 300% increase between 2019-2022 when compared to 2014-2018.’’

Scientists say likely drivers of the tick explosion include the warming climate and the exceptional growth in the numbers of white-tailed deer, especially in populated areas.

The good news, such as it is, is that not every one of the “millions and millions’’ of people who have been bitten by Lone Stars develop the meat allergy — far from it, said Mather.

“I am not trying to diminish it,’’ he said, but he’s concerned the fear may be out of proportion to the threat. “I’ve had people say, ‘I was bitten by one of those things, I’m going to cook a hamburger and eat it in my doctor’s parking lot in case anything happens.’ ’’

Just how big a risk are we facing? Without data on the number of bites and the number of allergies, doctors just don’t know the odds, said Scott Commins, an allergist and associate professor of medicine at the University of North Carolina School of Medicine.

Some people who are diagnosed with the condition go into a “clear period of denial,’’ he added. “They really enjoy red meat.’’

If you do not get subsequent Lone Star bites, the allergy generally resolves in three to five years, Commins said. But so many people are bitten repeatedly over the years, he added, that it only goes away in about 15 to 20 percent of people.

As for treatment, there is none, he said. “We manage with an appropriate avoidance diet and access to emergency medications [epinephrine] when needed.’’

The emotional side effects can be seen on Facebook, where the pain pours out in support and educational groups, some with thousands of members.

There are groups for diabetics with Alpha-gal Syndrome, singles who suffer from it, family members of its victims, kids, people on budgets, artists looking for Alpha-gal-safe art supplies, women in need of Alpha-gal-safe beauty products, people searching for Alpha-gal recipes.

“A lot of people have talked about being depressed — you have to be so careful,’’ said Laura, who’s in two groups. “They feel like it limits social activities. You don’t want to eat anyone else’s food and you don’t know what’s in something when you go to a restaurant.’’

Larry Dapsis, an entomologist with the Cape Cod Cooperative Extension — and the producer, director, and star of the 10-part “Tickology’’series on YouTube — said that by this point, the Lone Star tick is “pretty much all over’’ Cape Cod.

“This red meat allergy is the real game changer,’’ said Dapsis, who told a reporter he’s been called a “rock star’’ of the tick world. “When I get to this part of the presentation I do get people’s full attention. Their eyes are wide open like they are in a Stephen King film festival.’’

The person publicly credited with the first Lone Star sighting on the Cape is Eugene McNeill, a crew chief with the Cape Cod Mosquito Control Project.

McNeill spends his days hunting mosquito outbreaks, and on a recent afternoon he took a break to recall the day about a decade ago when he returned to his truck on the Sandwich/ Barnstable town line along Route 6A to record his observations and felt something on his left thumb.

“I looked down and it was a tick,’’ he said, “but I had never seen anything like it.’’

“But it was hard to control.,’’ he said. “It was so fast.’’

When I asked which he feared more, sharks or Lone Stars, it was kind of a toss-up.

“The Lone Star, I guess,’’ he said. Pause. “But that’s because I don’t go in the ocean any more because of the sharks.’’

Beth Teitell can be reached at beth.teitell@globe.com. Follow her on Twitter @bethteitell.