Posted on 02/13/2006 8:18:03 AM PST by jbwbubba
Bill Christensen
Technovelgy.com Sat Feb 11, 8:00 AM ET
Half of the world's human population is infected with Toxoplasma, parasites in the body—and the brain. Remember that.
Toxoplasma gondii is a common parasite found in the guts of cats; it sheds eggs that are picked up by rats and other animals that are eaten by cats. Toxoplasma forms cysts in the bodies of the intermediate rat hosts, including in the brain.
Since cats don't want to eat dead, decaying prey, Toxoplasma takes the evolutionarily sound course of being a "good" parasite, leaving the rats perfectly healthy. Or are they?
Oxford scientists discovered that the minds of the infected rats have been subtly altered. In a series of experiments, they demonstrated that healthy rats will prudently avoid areas that have been doused with cat urine. In fact, when scientists test anti-anxiety drugs on rats, they use a whiff of cat urine to induce neurochemical panic.
However, it turns out that Toxoplasma-ridden rats show no such reaction. In fact, some of the infected rats actually seek out the cat urine-marked areas again and again. The parasite alters the mind (and thus the behavior) of the rat for its own benefit.
If the parasite can alter rat behavior, does it have any effect on humans?
Dr. E. Fuller Torrey (Associate Director for Laboratory Research at the Stanley Medical Research Institute) noticed links between Toxoplasma and schizophrenia in human beings, approximately three billion of whom are infected with T. gondii: Toxoplasma infection is associated with damage to astrocytes, glial cells which surround and support neurons. Schizophrenia is also associated with damage to astrocytes. Pregnant women with high levels of antibodies to Toxoplasma are more likely to give birth to children who will develop schizophrenia. Human cells raised in petri dishes, and infected with Toxoplasma, will respond to drugs like haloperidol; the growth of the parasite stops. Haloperidol is an antipsychotic, used to treat schizophrenia. Dr. Torrey got together with the Oxford scientists, to see if anything could be done about those parasite-controlled rats that were driven to hang around cat urine-soaked corners (waiting for cats). According to a recent press release, haloperidol restores the rat's healthy fear of cat urine. In fact, antipsychotic drugs were as effective as pyrimethamine, a drug that specifically eliminates Toxoplasma.
Are parasites like Toxoplasma subtly altering human behavior? As it turns out, science fiction writers have been thinking about whether or not parasites could alter a human being's behavior, or even take control of a person. In his 1951 novel The Puppet Masters, Robert Heinlein wrote about alien parasites the size of dinner plates that took control of the minds of their hosts, flooding their brains with neurochemicals. In this excerpt, a volunteer strapped to a chair allows a parasite to be introduced; the parasite rides him, taking over his mind. Under these conditions, it is possible to interview the parasite; however, it refuses to answer until zapped with a cattle prod. He reached past my shoulders with a rod. I felt a shocking, unbearable pain. The room blacked out as if a switch had been thrown.. I was split apart by it; for the moment I was masterless.
The pain left, leaving only its searing memory behind. Before I could speak, or even think coherently for myself, the splitting away had ended and I was again safe in the arms of my master...
The panic that possessed me washed away; I was again filled with an unworried sense of well being...
"What are you?" "We are the people... We have studied you and we know your ways... We come," I went on, "to bring you peace.. and contentment-and the joy of-of surrender." I hesitated again; "surrender" was not the right word. I struggled with it the way one struggles with a poorly grasped foreign language. "The joy," I repeated, "-the joy of . . .nirvana." That was it; the word fitted. I felt like a dog being patted for fetching a stick; I wriggled with pleasure.
Still not sure that parasites can manipulate the behavior of host organisms? Consider these other cases: The lancet fluke Dicrocoelium dendriticum forces its ant host to attach to the tips of grass blades, the easier to be eaten. The fluke needs to get into the gut of a grazing animal to complete its life cycle. The fluke Euhaplorchis californiensis causes fish to shimmy and jump so wading birds will grab them and eat them, for the same reason. Hairworms, which live inside grasshoppers, sabotage the grasshopper's central nervous system, forcing them to jump into pools of water, drowning themselves. Hairworms then swim away from their hapless hosts to continue their life cycle.
Not all science-fictional parasites are harmful; read about the Crosswell tapeworm from Brian Aldiss' 1969 story Super-Toys Last All Summer Long (the basis for the Kubrick/Spielberg film AI), which keeps people who overeat from becoming obese. Not to mention robots based on parasites. Read press release on evidence for link between Toxoplasma and schizophrenia, Suicidal grasshoppers. Story via blogger Carl Zimmer and his readers.
(This Science Fiction in the News story used with permission from Technovelgy.com - where science meets fiction.) Fine Line Revealed Between Creativity and Insanity Brain Breakthrough: Scientists Know What You'll Do
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An explanation for crazy old cat ladies?
Eureaka. You've solved the riddle.
This from Ohio State University:
"Transmission of toxoplasmosis can occur via oocysts or bradyzoites. Since cat feces are the only source of oocysts, exposure to oocysts can be minimized, but not prevented completely. The oocysts are very resistant to adverse environmental conditions, and oocysts in garden soil, sand boxes, etc., can remain infective for months (perhaps years in warmer climates). Infections via bradyzoites occur when raw or undercooked meat is eaten. House cats can be infected this way when they eat rodents and birds. Humans can be infected when they eat raw or undercooked meat products, and considering the very low host specificity of Toxoplasma, no meat product should be considered absolutely "safe." Heating meat to approximately 160 F or cooling it to 0 F (a hard freeze) should kill most of the zoitocysts."
Must be a connection...
Is that Howard Dean?
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Please add me to the Mind Control Parasites ping list.
Dolt!
They made you ask for this ....
You people know what I'm talking about ..
That was fascinating. Must...go....drink....BEER!
Heinlein's puppet masters came from Titan; your cat is from Uranus.
Interesting. There was a warning many years ago to women who were pregnant. Don't empty the cat box. Have someone else do it, because of possible parasitical infection dangers to your unborn child.
Are there ways to get tested to see if you've been infected?
The standard example of parasites altering behavior to facilitate transmission is rabies, which causes the infected animal to become fearless and aggressive, to transmit the infection to new hosts by bites.
Chekov being relieved of a parasitic eel, Ceti Alpha V's only indigenous lifeform, with a penchant for the human cerebral cortex (Star Trek: The Wrath of Khan").
*Ouch*
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