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About a third of the world’s population is chronically infected with the protozoan parasite Toxoplasma gondii. Data from the U.S. Centers for Disease Control and Prevention (CDC) suggest that about 11% of the U.S. population aged 6 years and over is infected with the parasite, while in other countries the infection rate has been shown to be up to 95%. Researchers from 16 institutions across the U.S., Canada, England, Scotland, and Australia have now analyzed genetic, transcriptomic, and proteomic data from infected individuals, and from studies in cell cultures, to link T. gondii infection with a number of brain disorders,...

Toxoplasma is a common 'cat parasite', and has previously been in the spotlight owing to its observed effect on risk-taking and other human behaviours. To some extent, it has also been associated with mental illness. A study led by researchers from Karolinska Institutet in Sweden now demonstrates for the first time how the parasite enters the brain to influence its host. "We believe that this knowledge may be important for the further understanding of complex interactions in some major public health issues, that modern science still hasn't been able to explain fully," says Antonio Barragan, researcher at the Center for...

Jaroslav Flegr is no kook. And yet, for years, he suspected his mind had been taken over by parasites that had invaded his brain. So the prolific biologist took his science-fiction hunch into the lab. What he’s now discovering will startle you. Could tiny organisms carried by house cats be creeping into our brains, causing everything from car wrecks to schizophrenia? → more...

Jaroslav Flegr is no kook. And yet, for years, he suspected his mind had been taken over by parasites that had invaded his brain. So the prolific biologist took his science-fiction hunch into the lab. What he’s now discovering will startle you. Could tiny organisms carried by house cats be creeping into our brains, causing everything from car wrecks to schizophrenia? No one would accuse Jaroslav Flegr of being a conformist. A self-described “sloppy dresser,” the 63-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...

Jaroslav Flegr is no kook. And yet, for years, he suspected his mind had been taken over by parasites that had invaded his brain. So the prolific biologist took his science-fiction hunch into the lab. What he’s now discovering will startle you. Could tiny organisms carried by house cats be creeping into our brains, causing everything from car wrecks to schizophrenia? A biologist’s science- fiction hunch is gaining credence and shaping the emerging science of mind- controlling parasites.

Sometimes it’s hard to tell the difference between danger and sex appeal, at least for rats infected with a parasite that twists ancient rat instincts to its own advantage.The parasite, a common single-celled organism called Toxoplasma gondii, infects all sorts of animals, including rats, in which it causes a strange transformation. For obvious reasons, rats normally avoid cats. In the presence of cat urine they become very timid — unless they’re infected with Toxoplasma. Research over the past 10 years has shown that infected rats drop their normal fearful “freezing” response, and instead go exploring. They even approach the cat...

On paper, Toxoplasma gondii looks as if it ought to be the most famous parasite on earth. This single-celled pathogen infects over half the world's population, including an estimated 50 million Americans. Each of Toxoplasma's victims carries thousands of the parasites, many residing in the brain. As if that were not enough of an accomplishment, Toxoplasma is equally adept at infecting all other warm-blooded animals, as disparate as chickens and kangaroos. Scientists are now discovering some of the secrets of Toxoplasma's success. Researchers in Sweden report that the parasite fans out through the body by manipulating mobile cells that are...

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...