Can cat parasites alter human personalities?

[emad]

January 17, 2006
The Return of the Puppet Masters
Posted by Carl Zimmer

Are brain parasites altering the personalities of three billion people? The question emerged a few years ago, and it shows no signs of going away.

I first encountered this idea while working on my book Parasite Rex. I was investigating the remarkable ability parasites have to manipulate the behavior of their hosts. The lancet fluke Dicrocoelium dendriticum, for example, forces its ant host to clamp itself to the tip of grass blades, where a grazing mammal might eat it. It's in the fluke's interest to get eaten, because only by getting into the gut of a sheep or some other grazer can it complete its life cycle. Another fluke, Euhaplorchis californiensis, causes infected fish to shimmy and jump, greatly increasing the chance that wading birds will grab them.

Those parasites were weird enough, but then I got to know Toxoplasma gondii. This single-celled parasite lives in the guts of cats, sheddding eggs that can be picked up by rats and other animals that can just so happen be eaten by cats. Toxoplasma forms cysts throughout its intermediate host's body, including the brain. And yet a Toxoplasma-ridden rat is perfectly healthy. That makes good sense for the parasite, since a cat would not be particularly interested in eating a dead rat. But scientists at Oxford discovered that the parasite changes the rats in one subtle but vital way.

The scientists studied the rats in a six-foot by six-foot outdoor enclosure. They used bricks to turn it into a maze of paths and cells. In each corner of the enclosure they put a nest box along with a bowl of food and water. On each the nests they added a few drops of a particular odor. On one they added the scent of fresh straw bedding, on another the bedding from a rat's nests, on another the scent of rabbit urine, on another, the urine of a cat. When they set healthy rats loose in the enclosure, the animals rooted around curiously and investigated the nests. But when they came across the cat odor, they shied away and never returned to that corner. This was no surprise: the odor of a cat triggers a sudden shift in the chemistry of rat brains that brings on intense anxiety. (When researchers test anti-anxiety drugs on rats, they use a whiff of cat urine to make them panic.) The anxiety attack made the healthy rats shy away from the odor and in general makes them leery of investigating new things. Better to lie low and stay alive.

http://www.corante.com/loom/archives/2006/01/17/the_return_of_the_puppet_masters.php

[Wickerman]

1. wow!

the ultimate kitty thread!

You know, I have felt more suspicious since the Kitty entered our household, but I attributed it to Bush entering office about the same time. :tinfoilhat:

[Orrex]

2. A wild and interesting theory!

Of course, I'd say with confidence that my parasitic cats clearly alter my behavior, causing me to venture into the kitchen to feed them when I'd rather stay in bed. But I hadn't even considered the possibility that they were vectors for parasites, too...

[emad]

3. Another theory I read about recently said cat flu was transmittable

to humans and had been linked to lower cortex inflammations found in some cases associated with sudden onset psychosis.

[Richard D]

4. parasites are scary things . . .

... but cats . . .

[soothsayer]

5. Interesting! My GF has bizarre brain lesions that are tox-related

(well, are thought to be. no one really seems to know)

She is sooo cat crazy, I wonder if, like the infected rats, the toxo is making her even MORE attracted to those wonderful hosts.

[moggie]

6. Be sure to read the comments to that article

Two, in particular, stand out:

With all this said and done. I think the real issue to debate would be the cover up of the zombie outbreak in Cambodia last year. Where it was reported on the BBC alittle over 1 year ago that a mutated form of a Malaria causing Protazoa was killing a large nuber of people within 24 hours of infection. They clamed that the mortality rate was 100%. Within 12 hours after death, the protazoa was clamed to reanimate the heart and brain of the dead. Resulting in dead people flailing around with limited nerve function long after post-mortem The next day it was said that the outbreak had been controled and U.S. forces where stepping in to clean up the situation.(The same artical now severly reduced. After all this there was not one trace of information to be found that even mentioned a Malaria quarentine in Cambodia in 2005. What are peoples feelings after reading about Toxoplasma virus altering the brain? How does the consept of a single celled protazoa mutating to alter the nerve center of a mammal host(on a very simple level), creating a "zombie like " stasis sit? Does it not seeem a little more plausable? Is there anyone out there who can confirm the existance of this this international clam that was made in spring of 2005 on the BBC?

http://www.corante.com/loom/archives/2006/01/17/the_return_of_the_puppet_masters.php#58891

Clue: for "spring of 2005" read "1 April 2005", but some people still take this seriously.

And then there's the inevitable wingnut:

This must explain why, despite all evidence of its disastrous effects on humankind, collectivism in various forms (communism, socialism, naziism, fascism, tribalism, jihadism) continues to thrive, especially amongst the very uneducated and the over-educated.

Hmmm? Maybe the parasite wants to kill off the truly intelligent amongst us (conservatives, libertarians), so that it can propagate freely within the brainless masses of Dimocrats, socialists, university professors, et nauseum...?

http://www.corante.com/loom/archives/2006/01/17/the_return_of_the_puppet_masters.php#59003

Real classy...

[NNadir]

7. That is one of the more intriguing reports I've read.

I definite clue on the chemistry of the mind.

Thanks. That was an excellent find.

[trotsky]

8. Fascinating!

3 billion infected humans, eh? I've been around cats my whole life, and have changed litter for years. I'm sure I have it.