(CNN) -- An airborne virus is rapidly turning people into zombies. Two-thirds of humanity has been wiped out. Scientists desperately look for a cure, even as their own brains deteriorate and the disease robs them of what we consider life.
Relax, it's only fiction -- at least, for now. This apocalyptic scenario frames the new novel "The Zombie Autopsies" by Dr. Steven Schlozman, a child psychiatrist who holds positions at Harvard Medical School and the Massachusetts General Hospital/McLean Program in Child Psychiatry.
You might not expect someone with those credentials to take zombies seriously, but it turns out the undead are a great way to explore real-world health issues: why certain nasty diseases can destroy the brain, how global pandemics create chaos and fear, and what should be done about people infected with a highly contagious and incurable lethal illness.
"One of the things zombie novels do is they bring up all these existential concerns that happen in medicine all the time: How do you define what's alive?" says Schlozman, who has been known to bounce between zombie fan conventions and academic meetings.
"When is it appropriate to say someone's 'as-good-as-dead,' which is an awful, difficult decision?"
What a zombie virus would do to the brain
So maybe you've seen "Night of the Living Dead," read "World War Z," or can't wait for the return of the AMC show "The Walking Dead," but you probably don't know what differentiates the brains of humans and zombies.
First things first: How does the zombie disease infect its victims? Many stories in the genre talk about biting, but Schlozman's novel imagines a deliberately engineered virus whose particles can travel in the air and remain potent enough to jump from one person to another in a single sneeze.
Now, then, to the brain-eating. The zombie virus as Schlozman describes it basically gnaws the brain down to the amygdala, an almond-shaped structure responsible for the "fight or flight" response. The zombies always respond by fighting because another critical part of the brain, the ventromedial hypothalamus, which tells you when you've eaten enough, is broken.
The brain's frontal lobes, responsible for problem-solving, are devoured by the virus, so zombies can't make complex decisions. Impairment in the cerebellum means they can't walk well, either. Also, these humanoids have an unexplained predilection for eating human flesh.
"The zombies in this book are stumbling, shambling, hungry as hell," Schlozman said. "Basically they're like drunk crocodiles; they're not smart, they don't know who you are or what you are."
How a zombie virus would be made
So the bloodthirsty undead wander (or crawl) around spreading a lethal illness ominously called ataxic neurodegenerative satiety deficiency syndrome, or ANSD, for short.
"When something really terrifying comes along, especially in medicine or that has a medical feel to it, we always give it initials. That's the way we distance ourselves from it," Schlozman said.
The virus has several brain-destroying components, one of which is a "prion," meaning a protein like the one that causes mad cow disease. In real life, prions twist when they are in an acidic environment and become dangerous, Schlozman said. How our own environment has changed to make prions infectious -- getting from the soil to the cows in mad cow disease, for instance -- is still a mystery.
Now here's something to send chills up your spine: In Schlozman's world, airborne prions can be infectious, meaning mad cow disease and similar nervous-system destroyers could theoretically spread just like the flu. Swiss and German researchers recently found that mice that had only one minute of exposure to aerosols containing prions died of mad cow disease, as reported in the journal PLoS Pathogens. A follow-up described in Journal of the American Medical Association showed the same for a related disease that's only found in animals called scrapie. Of course, these are mice in artificially controlled conditions in a laboratory, and humans do not exhale prions, but it could have implications for safety practices nonetheless.
Like mad cow disease, the zombie disease Schlozman describes also progresses in acidic environments. In the book, a major corporation doles out implantable meters that infuse the body with chemicals to artificially lower acidity when it gets too high. But, sadly, when acidity is too low, that also induces symptoms that mimic the zombie virus, so it's not a longterm solution. Everyone who gets exposed eventually succumbs, Schlozman said.
As for the unknown component of the zombie disease that would help slowly zombifying researchers in their quest for a cure, that's up for the reader to figure out -- and the clues are all in the book, Schlozman said.
How we'd fight back
You can't ethically round up fellow survivors to kick some zombie butt unless the undead have technically died. And in Schlozman's book, a group of religious leaders get together and decide that when people reach stage four of the disease, they are basically dead. That, of course, permits zombie "deanimation," or killing.
And how do you kill a zombie? Much of zombie fiction knocks out zombies through shots to the head. That, Schlozman said, is because the brain stem governs the most basic functioning: breathing and heartbeat.
A zombie-apocalypse disease like the one he describes probably wouldn't evolve on its own in the real world, he said.
But, as we've seen, individual symptoms of zombies do correspond to real ailments. And if they all came together, the disease would be creepily efficient at claiming bodies, Schlozman said.
Bad news, folks: Even if people contracted a zombie virus through bites, the odds of our survival aren't great.
A mathematician at the University of Ottawa named Robert Smith? (who uses the question mark to distinguish himself from other Robert Smiths, of course), has calculated that if one zombie were introduced to a city of 500,000 people, after about seven days, every human would either be dead or a zombie.
"We're in big, big trouble if this ever happens," Smith? said. "We can kill the zombies a bit, but we're not very good at killing zombies fundamentally. What tends to happen is: The zombies just win, and the more they win, the more they keep winning" because the disease spreads so rapidly.
The best solution is a strategic attack, rather than an "every man for himself" defense scenario, he said. It would take knowledge and intelligence, neither of which zombies have, to prevail.
Why study zombies?
In his day job, Smith? models how real infectious diseases spread. But he's already reaped benefits from his work on zombies. For instance, while many mathematical models only deal with one complicated aspect of a situation at a time, he tackled two -- zombie infection and zombie-killing -- when it came to speculating about outbreaks.
When it came time for modeling of real-world human papillomavirus (HPV), then, Smith? felt equipped to handle many facets of it at the same time, such as heterosexual and homosexual transmission of HPV.
"Knowing what we knew from zombies allowed us to actually take on these more complicated models without fear," he said.
Studying zombies is also a great way to get young people excited about science. Smith?, who was on a zombie-science panel with Schlozman through the National Academy of Sciences' Science and Entertainment Exchange in 2009, has also seen math-phobic people get interested in mathematics by reading about his work with zombies.
"There are insights that we gain from the movies, and from fiction, from fun popular culture stuff, that actually can really help us think about the way that science works, and also the way science is communicated," he said.
And as to why people like reading about zombies and watching zombies so much, Schlozman points to the impersonal nature of things in our society, from waiting in line in the DMV to being placed on hold on a call with a health insurance company.
Think about all the situations in daily life where you sense a general lack of respect for humanity, and zombies make a little more sense.
"The zombies themselves represent a kind of commentary on modernity," Schlozman says. "We're increasingly disconnected. That might be the current appeal."