Mind control by parasites bill christensen (Technovelgy.com ) Updated: 2006-02-13 11:52
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.
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