Lab Notes
The Worms Are in Their Brains!

You know that feeling you get when people start acting strangely? When they abandon old habits, abuse friends, break promises, even break the law? Drugs are often to blame, from mood-altering steroids to highly addictive stimulants and opiates. Certain types of physical or emotional trauma can alter the normal functioning of the brain as well, producing behavior even the victim's own mother wouldn't recognize. But sometimes there's no reason at all; people just seem to flip. In the past this kind of thing could be dismissed as demonic possession, but through the miracle of science fiction we now understand a new possibility: MIND CONTROL PARASITES.

In Universal Pictures' newest horror flick, Slither, we're treated to sluglike creatures that enter a human host through the mouth or skin and are capable of tapping into the nervous system to alter—and eventually control—the host's behavior. This is, of course, hardly a new idea in science fiction; Robert Heinlein first broached something similar in The Puppet Masters (1951), and since then it's appeared in everything from Star Trek to Red Dwarf to Futurama, where the "brain slugs" even have their own political party.

With normal parasites, the usual medical response is to shoot the body up with some chemical that's harmless—or nearly harmless—to the host but highly toxic to the parasite. For protozoa we use antibiotics like metronidazole, atovaquone and clindamycin. For parasitic worms we use drugs like thiabendazole and praziquantel, and sometimes even heavy metals like antimony. Unfortunately, since the Slither slugs are of extraterrestrial origin, we have no way of knowing whether these substances will have any effect on them. For all we know the right medication may be Pepsi, or chili powder, or even hyperbaric oxygen, but without a double-blind scientific study it would be hard to say for sure. In the absence of hard data, I think the best defense is to, you know, keep your mouth shut. Luckily for us, the slugs are big enough to succumb to external therapies like bullets, pointy objects and heat, so in my professional opinion as a science-fiction writer, every household should stock these along with the duct tape and bottled water. It's a crazy world, and you just never know what's going to happen next.

They crawl in, they crawl out—of you!

The symptoms of Slither-slug infection include malaise, confusion, movement disorders and an insatiable hunger for protein. Victims gradually turn into flesh-eating zombies of an unusually smartass nature, before finally succumbing to the hive mind of the parasites. Can parasites really affect our brains? You bet: Last month we took a look at the mind control features of toxoplasmosis (see "It's Cooler at Night," March 2006), a disease caused by microscopic parasites. But parasitic worms can get into your head as well; just over a year ago a Phoenix politician's graphic suicide was blamed on personality changes and "frontal lobe disinhibition" from cystercosis, a disease caused by tapeworms burrowing into the muscles, eyes and brain. Other parasites are known, for example, to drive their victims toward water or predators, or toward other conditions that aid the parasite's life cycle. Real brain parasites can also cause seizures—in fact, they're the leading cause of seizure disorders worldwide—but in the movie these quickly subside, which suggests we're dealing with a parasite of unusual sophistication.

But we already knew that, because the Slither slugs are able to control people's behavior with uncanny precision. That's not impossible, either; recent experiments have shown that electrodes carefully placed in the brain can control the movement of rats and sharks and even, to a limited extent, decode what they're thinking and feeling. By placing more complex circuitry in the brain—computer chips, for example—we can even stimulate one brain region in response to the activity of another. We can not only read the mind, but rewrite what it's thinking. This has all kinds of creepy Orwellian implications, but the technology also has huge medical potential. One of the great tragedies of neuroscience is that we're getting better and better at diagnosing specific problems, but our progress in actually curing people has lagged far behind. Neural implants have the potential to turn psychology into a hard science, combining elements of neuromedicine and pharmacology with hardware and software engineering, fixing all sorts of problems we presently consider incurable. And why stop there? With the right implants, we could have Wikipedia running full-time in our heads, or acquire new abilities at the flick of a switch, without the years of learning and practice.

Big and gross and (unfortunately) possible

The slugs, unfortunately, don't have our best interests at heart. They're not going to cure our diseases or solve our mental problems. Like electric eels, they seem to have the ability to sense and generate electric fields, although they must be doing it with millimeter precision or better. Like the pigments of an octopus, the fields on the skin of a Slither slug must be shifting constantly in response to the neural activity of the host. What's more, the slugs can obviously talk to each other across a few meters of distance, probably via radio. That sounds a bit crazy, I realize—there are no animals on Earth that communicate this way—but if they have the ability to create shifting electric fields, radio waves are going to be produced anyway as a natural side effect. The result is a kind of hive mind—the whole is greater than the sum of its parts—although the individual slugs don't seem to have any independent awareness of their own. Hive creatures on Earth—from ants and hornets to mammals like the naked mole rat—have never developed hive minds in the science-fiction sense, but there's no law of nature to prevent it.

Anyway, in no way is an infection of Slither slugs good for your health. The movie actually features a woman whose body has swollen into an eight-foot sphere filled with wriggling slugs. This is so horrific that I'm tempted to say it couldn't really happen, but frankly I'm not so sure. A disease called echinococcosis—closely related to cystercosis—creates numerous worm-filled cysts in the liver, lungs, kidneys and spleen, and (I warn you, this is gross) in severe cases these cysts can grow larger than basketballs. Surgical removal is tricky, because if the cysts rupture the release of thousands of worms into the body causes shock and rapid death. The only thing I actually find hard to believe is that the victim of really huge worm infection would be rigid enough to retain a spherical shape. In fact, we can learn a lot from the example of Patrick Deuel, the "Half-Ton Man," who briefly weighed in at 1,072 pounds. There was enough mass in Deuel's body to form a sphere, but instead he looked a lot like a flattened water balloon. Worse, he was unable to sit up or roll over, and nearly suffocated under the weight of his own back before gastric bypass surgery saved his life. However, Deuel's weight was mainly in the form of adipose tissue, aka "fat," which has a notably flabby consistency. Cysts and worm bodies are a lot stiffer, so it's possible—disgusting, but possible—that in the final stages of the infection the victim's body really could be spherical.

In another well-worn science-fiction cliché, the victims spit a corrosive venom that's yellow-green in color, although for some reason they're not affected by the venom themselves. This is possible, I guess, if it's really a slug doing the spitting, and if it secretes a mucous layer to protect the throat and mouth of the human host. The animal kingdom is full of weird defense mechanisms; the bombardier beetle, for example, stores two different chemicals in its body which, when combined, form a stream of boiling acid. Even our own stomachs contain a potent hydrochloric acid that will, for example, strip the paint off your car. Not so different from slug vomit.

Could the events of Slither actually happen? Unfortunately, yes. My advice is to keep Wil's Horror Movie Litany in mind: "Shotgun, chainsaw and sweet cleansing fire." If these three items don't solve your problem, I'm guessing you were doomed anyway. Cheerio!

Sources:
www.slithermovie.com

The Encyclopedia Britannica, 2004 Edition: ("bombardier beetle")

Wikipedia, en.wikipedia.org ("flagyl,""toxoplasmosis," "schistosomiasis," "echinococcosis")

Manzo, Andrea: "Brain Worms and Brain Amoebas: They Do Exist," Engineering & Science Magazine, California Institute of Technology, 2002

"Rare parasite may have caused Phoenix official to fall or jump from car," The Arizona Daily Star, 10 December 2004

"Half ton man loses 573 pounds in one year," www.msnbc.msn.com/id/8357654/

Brown, Susan: "Stealth Sharks to Patrol the High Seas," New Scientist, March 2006.