"While parasites are known to manipulate the behaviour of ants, as well as various other creatures, to the human race, the idea of ‘zombies’ has been delegated entirely to the realm of science fiction.
That is until now. As parasitologist Jaroslav Flegr reveals that beneath the aberrant behaviour of a driver, or the vicious attack of a placid politician, lies an insidious microbe that appears bent on world domination.
Taxoplasma gondii is the culprit, a microorganism with a favourite haunt – the inside of a rat. In fact, the only time it doesn’t like dwelling inside a rat, is during reproduction, when it prefers to live in a cat. How about that!
However, far from just hanging with the rats and the cats, T. gondii, is also known to inhabit roughly 40% of the human population, although ostensibly without the same behavioural effect.
Recently, Dr Flegr tested the blood of drivers known to cause accidents, and found it was two and a half times more likely that hoons were inhabited by T. gondii than otherwise. According to Dr Flegr, zombies are indeed on our roads, and microorganisms are making a ruckus on our highways.
Although it is currently not known to what extent the parasite can control human behaviour, T. gondii has been positively implicated in the development of schizophrenia."
|EXTRACTS From "HOW YOUR CAT IS MAKING YOU CRAZY" (Check the link below for the full story)|
No one would accuse Jaroslav Flegr of being a conformist. A self-described “sloppy dresser,” the 53-year-old Czech scientist has the contemplative air of someone habitually lost in thought, and his still-youthful, square-jawed face is framed by frizzy red hair that encircles his head like a ring of fire.
Certainly Flegr’s thinking is jarringly unconventional. Starting in the early 1990s, he began to suspect that a single-celled parasite in the protozoan family was subtly manipulating his personality, causing him to behave in strange, often self-destructive ways. And if it was messing with his mind, he reasoned, it was probably doing the same to others.
The parasite, which is excreted by cats in their feces, is called Toxoplasma gondii (T. gondii or Toxo for short) and is the microbe that causes toxoplasmosis—the reason pregnant women are told to avoid cats’ litter boxes. Since the 1920s, doctors have recognized that a woman who becomes infected during pregnancy can transmit the disease to the fetus, in some cases resulting in severe brain damage or death. T. gondii is also a major threat to people with weakened immunity: in the early days of the AIDS epidemic, before good antiretroviral drugs were developed, it was to blame for the dementia that afflicted many patients at the disease’s end stage. Healthy children and adults, however, usually experience nothing worse than brief flu-like symptoms before quickly fighting off the protozoan, which thereafter lies dormant inside brain cells—or at least that’s the standard medical wisdom.
But if Flegr is right, the “latent” parasite may be quietly tweaking the connections between our neurons, changing our response to frightening situations, our trust in others, how outgoing we are, and even our preference for certain scents. And that’s not all. He also believes that the organism contributes to car crashes, suicides, and mental disorders such as schizophrenia. When you add up all the different ways it can harm us, says Flegr, “Toxoplasma might even kill as many people as malaria, or at least a million people a year.”
An evolutionary biologist at Charles University in Prague, Flegr has pursued this theory for decades in relative obscurity. Because he struggles with English and is not much of a conversationalist even in his native tongue, he rarely travels to scientific conferences. That “may be one of the reasons my theory is not better known,” he says. And, he believes, his views may invite deep-seated opposition. “There is strong psychological resistance to the possibility that human behavior can be influenced by some stupid parasite,” he says. “Nobody likes to feel like a puppet. Reviewers [of my scientific papers] may have been offended.” Another more obvious reason for resistance, of course, is that Flegr’s notions sound an awful lot like fringe science, right up there with UFO sightings and claims of dolphins telepathically communicating with humans.
But after years of being ignored or discounted, Flegr is starting to gain respectability. Psychedelic as his claims may sound, many researchers, including such big names in neuroscience as Stanford’s Robert Sapolsky, think he could well be onto something. Flegr’s “studies are well conducted, and I can see no reason to doubt them,” Sapolsky tells me. Indeed, recent findings from Sapolsky’s lab and British groups suggest that the parasite is capable of extraordinary shenanigans. T. gondii, reports Sapolsky, can turn a rat’s strong innate aversion to cats into an attraction, luring it into the jaws of its No. 1 predator. Even more amazing is how it does this: the organism rewires circuits in parts of the brain that deal with such primal emotions as fear, anxiety, and sexual arousal. “Overall,” says Sapolsky, “this is wild, bizarre neurobiology.” Another academic heavyweight who takes Flegr seriously is the schizophrenia expert E. Fuller Torrey, director of the Stanley Medical Research Institute, in Maryland. “I admire Jaroslav for doing [this research],” he says. “It’s obviously not politically correct, in the sense that not many labs are doing it. He’s done it mostly on his own, with very little support. I think it bears looking at. I find it completely credible.”
What’s more, many experts think T. gondii may be far from the only microscopic puppeteer capable of pulling our strings. “My guess is that there are scads more examples of this going on in mammals, with parasites we’ve never even heard of,” says Sapolsky.
Familiar to most of us, of course, is the rabies virus. On the verge of killing a dog, bat, or other warm-blooded host, it stirs the animal into a rage while simultaneously migrating from the nervous system to the creature’s saliva, ensuring that when the host bites, the virus will live on in a new carrier. But aside from rabies, stories of parasites commandeering the behavior of large-brained mammals are rare. The far more common victims of parasitic mind control—at least the ones we know about—are fish, crustaceans, and legions of insects, according to Janice Moore, a behavioral biologist at Colorado State University. “Flies, ants, caterpillars, wasps, you name it—there are truckloads of them behaving weirdly as a result of parasites,” she says.
Consider Polysphincta gutfreundi, a parasitic wasp that grabs hold of an orb spider and attaches a tiny egg to its belly. A wormlike larva emerges from the egg, and then releases chemicals that prompt the spider to abandon weaving its familiar spiral web and instead spin its silk thread into a special pattern that will hold the cocoon in which the larva matures. The “possessed” spider even crochets a specific geometric design in the net, camouflaging the cocoon from the wasp’s predators.
Flegr himself traces his life’s work to another master of mind control. Almost 30 years ago, as he was reading a book by the British evolutionary biologist Richard Dawkins, Flegr was captivated by a passage describing how a flatworm turns an ant into its slave by invading the ant’s nervous system. A drop in temperature normally causes ants to head underground, but the infected insect instead climbs to the top of a blade of grass and clamps down on it, becoming easy prey for a grazing sheep. “Its mandibles actually become locked in that position, so there’s nothing the ant can do except hang there in the air,” says Flegr. The sheep grazes on the grass and eats the ant; the worm gains entrance into the ungulate’s gut, which is exactly where it needs to be in order to complete—as the Lion King song goes—the circle of life. “It was the first I learned about this kind of manipulation, so it made a big impression on me,” Flegr says.
After he read the book, Flegr began to make a connection that, he readily admits, others might find crazy: his behavior, he noticed, shared similarities with that of the reckless ant. For example, he says, he thought nothing of crossing the street in the middle of dense traffic, “and if cars honked at me, I didn’t jump out of the way.” He also made no effort to hide his scorn for the Communists who ruled Czechoslovakia for most of his early adulthood. “It was very risky to openly speak your mind at that time,” he says. “I was lucky I wasn’t imprisoned.” And during a research stint in eastern Turkey, when the strife-torn region frequently erupted in gunfire, he recalls being “very calm.” In contrast, he says, “my colleagues were terrified. I wondered what was wrong with myself.”
His bewilderment continued until 1990, when he joined the biology faculty of Charles University. As it happened, the 650-year-old institution had long been a world leader in documenting the health effects of T. gondii, as well as developing methods for detecting the parasite. In fact, just as Flegr was arriving, his colleagues were searching for infected individuals on whom to test their improved diagnostic kits, which is how he came to be asked one day to roll up his sleeve and donate blood. He discovered that he had the parasite—and just possibly, he thought, the key to his baffling self-destructive streak.
He delved into T. gondii’s life cycle. After an infected cat defecates, Flegr learned, the parasite is typically picked up from the soil by scavenging or grazing animals—notably rodents, pigs, and cattle—all of which then harbor it in their brain and other body tissues. Humans, on the other hand, are exposed not only by coming into contact with litter boxes, but also, he found, by drinking water contaminated with cat feces, eating unwashed vegetables, or, especially in Europe, by consuming raw or undercooked meat. Hence the French, according to Flegr, with their love of steak prepared saignant—literally, “bleeding”—can have infection rates as high as 55 percent. (Americans will be happy to hear that the parasite resides in far fewer of them, though a still substantial portion: 10 to 20 percent.) Once inside an animal or human host, the parasite then needs to get back into the cat, the only place where it can sexually reproduce—and this is when, Flegr believed, behavioral manipulation might come into play.
|The parasite T. gondii, seen here, may be changing connections between our neurones, altering how we act and feel. (Dennis Kunkel Microscropy, Inc./Visuals Unlimited/Corbis Images)|
"Still, he (Dr Flegr) concedes, the parasite could be very bad news for a small percentage of people—and not just those who might be at greater risk for car accidents. Many schizophrenia patients show shrinkage in parts of their cerebral cortex, and Flegr thinks the protozoan may be to blame for that. He hands me a recently published paper on the topic that he co-authored with colleagues at Charles University, including a psychiatrist named Jiri Horacek. Twelve of 44 schizophrenia patients who underwent MRI scans, the team found, had reduced gray matter in the brain—and the decrease occurred almost exclusively in those who tested positive for T. gondii.
But T. gondii is just one of an untold number of infectious agents that prey on us. And if the rest of the animal kingdom is anything to go by, says Colorado State University’s Janice Moore, plenty of them may be capable of tinkering with our minds. For example, she and Chris Reiber, a biomedical anthropologist at Binghamton University, in New York, strongly suspected that the flu virus might boost our desire to socialize. Why? Because it spreads through close physical contact, often before symptoms emerge—meaning that it must find a new host quickly. To explore this hunch, Moore and Reiber tracked 36 subjects who received a flu vaccine, reasoning that it contains many of the same chemical components as the live virus and would thus cause the subjects’ immune systems to react as if they’d encountered the real pathogen.
The difference in the subjects’ behavior before and after vaccination was pronounced: the flu shot had the effect of nearly doubling the number of people with whom the participants came in close contact during the brief window when the live virus was maximally contagious. “People who had very limited or simple social lives were suddenly deciding that they needed to go out to bars or parties, or invite a bunch of people over,” says Reiber. “This happened with lots of our subjects. It wasn’t just one or two outliers.”
I may have dodged T. gondii, but given our knack for fooling ourselves—plus all those parasites out there that may also be playing tricks on our minds—can anyone really know who’s running the show?
"Exactly how gut bacteria influence gene expression in the brain is unclear, but one possible line of communication is the autonomic branch of the peripheral nervous system, which controls functions such as digestion, breathing and heart rate. A better understanding of cross-talk within this so-called 'brain-gut axis' could lead to new approaches for dealing with the psychiatric symptoms that sometimes accompany gastrointestinal disorders such as IBS, and may also show that gut bacteria affect function of the mature brain."
THE CASE OF FLESH EATING BACTERIA
CANCER CAUSED BY BACTERIA
T. GONDII CONTROLS THE IMMUNE SYSTEM OF INFECTED PEOPLE