The Internet has been on high alert for zombies since last Saturday, when a 31-year-old homeless man from Miami named Rudy Eugene was discovered chomping on another homeless man's face and neck before he was shot and killed by police.

The cannibal attack has raised the general zombie awareness level, but in an email to the Huffington Post, the Centers for Disease Control and Prevention (CDC) officially announced on Thursday that zombies don't exist.

CDC does not know of a virus or condition that would reanimate the dead (or one that would present zombie-like symptoms), said David Daigle, a representative of the CDC.

For those still in doubt, however, the CDC has a tongue-in-cheek page dedicated to Zombie Preparedness, including a blog, some downloadable posters, and a readable novella.

The blog, authored by Dr. Ali S. Khan, the director of the CDC's Office of Public Health Preparedness and Response, includes a brief history of zombies, an emergency kit, and an emergency plan. The CDC even sells Zombie Task Force T-shirts.

If you are generally well-equipped to deal with a zombie apocalypse, you will be prepared for a hurricane, pandemic, earthquake, or terrorist attack, said Khan, who is also the U.S. assistant surgeon general.

The zombie apocalypse reportedly began on May 17, but it officially took off on May 26, when 31-year-old Rudy Eugene, who was completely nude and likely on drugs at the time, was caught in a zombie-like state of bliss as he gnawed away at his victim, another homeless man named Ronald Poppo.

He was ripping into his face with his teeth, said Larry Vega, a Miami resident who happened to spot the attack on Saturday, in an interview with Miami's WSVN TV. He was ripping his skin, his neck. He had him held down. The guy couldn't move really, and he was just tearing into his flesh.

Vega was riding his bicycle off the MacArthur Causeway between Miami and Miami Beach when he saw the attack occurring on the bridge's off-ramp. When Vega spotted a police cruiser driving along, he flagged it down and brought the cops' attention to the attack. The police officers approached the bloody scene and repeatedly told Eugene to stop and back away from the man.

Vega described Eugene's reaction to the police officers: The guy just stood his head up like that, with a piece of flesh in his mouth, and growled, Vega said.

After Eugene failed to step away from his victim, the officers opened fire. Eugene was killed after several shots.

It was one of the most gruesome things I've ever seen in my life in person, Vega said. You see these things in the movies, but when you see it up front and up close, it's pretty traumatic. It really is.

But before the world learned about the horrific scene in Miami, there were several other instances of zombie-type behavior, especially in Florida. On May 19, the Fort Lauderdale-Hollywood International Airport had an unknown chemical released into the air. Two passengers and three Transportation Security Administration agents were hospitalized with respiratory issues.

Five days later, nearby Lauderdale Lakes Middle School was put on lockdown when two students and a science teacher discovered a series of mysterious red rashes. Hazardous Materials, or HazMat, personnel were called in to investigate the scene.

One day later, another school in Minneola, Fla., called HazMat personnel when 27 children and faculty members complained about not feeling well. That same day, an anesthesiologist was driving erratically down the Central Florida Greenway, and when he was pulled over by police, he suddenly became enraged, banged his head repeatedly against the inside of the car until he bled, and then spat a big mouthful of blood into the face of the arresting officer.

The next day, Poppo's face was largely eaten off by a crazed, naked man. He is still in critical condition at Jackson Memorial Hospital in Miami.

But the zombie apocalypse has just begun. On May 30, a 29-year-old Canadian man named Luka Magnotta reportedly stabbed, decapitated, and performed sexual acts on the dismembered body parts of his lover, recording and then posting the film online for people to see.

Then, on May 31, an engineering student from Maryland killed and dismembered his 37-year-old roommate, ate his heart and parts of his brain, and hid other body parts in his family's house and in the dumpsters behind a nearby church.

The CDC may deny the existence of a zombie apocalypse, but the number of related cases is only increasing, and their details are becoming more grisly. The CDC may not know of any virus or condition that could lead to zombies, but please advise: Take caution, and be prepared for anything. They live among us.