First came Miami: the case of a naked man eating most of another man's face. Then Texas: a mother accused of killing her newborn, eating part of his brain and biting off three of his toes. Then Maryland, a college student telling police he killed a man, then ate his heart and part of his brain.

It was different in New Jersey, where a man stabbed himself 50 times and threw bits of his own intestines at police. They pepper-sprayed him, but he was not easily subdued.

He was, people started saying, acting like a zombie. And the whole discussion just kept growing, becoming a topic that the Internet couldn't seem to stop talking about.

The actual incidents are horrifying — and, if how people are talking about them is any indication, fascinating. In an America where zombie imagery is used to peddle everything from tools and weapons to garden gnomes, they all but beg the comparison.

Violence, we're used to. Cannibalism and people who should fall down but don't? That feels like something else entirely.

So many strange things have made headlines in recent days that The Daily Beast assembled a Google Map tracking "instances that may be the precursor to a zombie apocalypse." And the federal agency that tracks diseases weighed in as well, insisting it had no evidence that any zombie-linked health crisis was unfolding.

The cases themselves are anything but funny. Each involved real people either suspected of committing unspeakable acts or having those acts visited upon them for reasons that have yet to be figured out. Maybe it's nothing new, either; people do horrible things to each other on a daily basis.

But what, then, made search terms like "zombie apocalypse" trend day after day last week in multiple corners of the Internet, fueled by discussions and postings that were often framed as humor?

"They've heard of these zombie movies, and they make a joke about it," says Lou Manza, a psychology professor at Lebanon Valley College in Pennsylvania, who learned about the whole thing at the breakfast table Friday morning when his 18-year-old son quipped that a "zombie apocalypse" was imminent.

Symbolic of both infection and evil, zombies are terrifying in a way that other horror-movie iconography isn't, says Elizabeth Bird, an anthropologist at the University of South Florida.

Zombies, after all, look like us. But they aren't. They are some baser form of us — slowly rotting and shambling along, intent on "surviving" and creating more of their kind, but with no emotional core, no conscience, no limits.

"Vampires have kind of a romantic appeal, but zombies are doomed," Bird says. "Zombies can never really become human again. There's no going back.

"That resonates in today's world, with people feeling like we're moving toward an ending," she says. "Ultimately they are much more of a depressing figure."

The "moving toward an ending" part is especially potent. For some, the news stories fuel a lurking fear that, ultimately, humanity is doomed.

Speculation varies. It could be a virus that escapes from some secret government lab, or one that mutates on its own. Or maybe it'll be the result of a deliberate combination and weaponization of pathogens, parasites and disease.

It will, many believe, be something we've created — and therefore brought upon ourselves.

Zombies represent America's fears of bioterrorism, a fear that strengthened after the 9/11 attacks, says Patrick Hamilton, an English professor at Misericordia University in Dallas, Pa., who studies how we process comic-book narratives.

Economic anxiety around the planet doesn't help matters, either, with Greece, Italy and Spain edging closer to crisis every day. Consider some of the terms that those fears produce: zombie banks, zombie economies, zombie governments.

When people are unsettled about things beyond their control — be it the loss of a job, the high cost of housing or the depletion of a retirement account — they look to metaphors like the zombie.

"They're mindless drones following basic needs to eat," Hamilton says. "Those economic issues speak to our own lack of control."

They're also effective messengers. The Centers for Disease Control got in on the zombie action last year, using the "apocalypse" as the teaser for its emergency preparedness blog. It worked, attracting younger people who might not otherwise have read the agency's guidance on planning evacuation routes and storing water and food.

On Friday, a different message emerged. Chatter had become so rampant that CDC spokesman David Daigle sent an email to the Huffington Post, answering questions about the possibility of the undead walking among us.

"CDC does not know of a virus or condition that would reanimate the dead," he wrote, adding: "(or one that would present zombie-like symptoms.)"

Zombies have been around in our culture at least since Mary Shelley's "Frankenstein" was published in 1818, though they really took off after George Romero's nightmarish, black-and-white classic "Night of the Living Dead" hit the screen in 1968.

In the past several years, they have become both wildly popular and big business. Last fall, the financial website 24/7 Wall Street estimated that zombies pumped $5 billion into the U.S. economy.

"And if you think the financial tab has been high so far, by the end of 2012 the tab is going to be far larger," the October report read.

It goes far beyond comic books, costumes and conventions.

— An Ace Hardware store in Nebraska features a "Zombie Preparedness Center" that includes bolts and fasteners for broken bones, glue and caulk for peeling skin, and deodorizers to freshen up decaying flesh. "Don't be scared," its website says. "Be prepared."

— On uncrate.com, you can find everything you need to survive the apocalypse — zombie-driven or otherwise — in a single "bug-out bag." The recommended components range from a Mossberg pump-action shotgun and a Cold Kukri machete to a titanium spork for spearing all the canned goods you'll end up eating once all the fresh produce has vanished.

— For $175 on Amazon, you can purchase a Gnombie, a gored-out zombie garden gnome.

Maybe it's that we joke about the things we fear. Laughter makes them manageable.

That's why a comedy like "Zombieland," with Woody Harrelson blasting away the undead on a roller coaster and Jesse Eisenberg stressing the importance of seatbelts is easier to watch than, say, the painful desperation and palpable apocalyptic fear of "28 Days Later" and "28 Weeks Later."

The most compelling zombie stories, after all, are not about the undead. They're about the living.

The popular AMC series "The Walking Dead" features zombies in all manner of settings. But the show is less about them and more about how far the small, battered band of humans will go to survive — whether they'll retain the better part of themselves or become hardened and heartless.

It's a familiar theme to George Romero, who told The Associated Press in 2008 that all of his zombie films have been about just that.

"The zombies, they could be anything," he said. "They could be an avalanche, they could be a hurricane. It's a disaster out there. The stories are about how people fail to respond in the proper way."

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Follow Tamara Lush on Twitter at http://twitter.com/tamaralush and follow Vicki Smith on Twitter at http://twitter.com/wvapgal