Toxoplasma & Other Parasites Affecting Human Behavior

McAvennie

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No good pesky felines!


16:24 22Sep2003 RTRS-Wife reckless? Hubby morose? Blame the cat.

PRAGUE, Sept 22 (Reuters) - Kicking the cat may be a metaphor about venting frustrations on the innocent family feline, but could it be that Snowball really is to blame?
Czech scientist Jaroslav Flegr of Charles University in Prague told Reuters his research showed a parasite called toxoplasma gondii in cats, rabbits or raw meat, may make women reckless and friendly while making men jealous and morose.
Just contracting the bug might not be life-threatening but infected women behind the wheel can be fatal, and those out for a stroll in busy traffic may be a hazard, he said.
"It is not much fun. Our research has shown that toxoplasmosis raises 2.6 times the risk of a traffic accident by prolonging the reaction time of infected people," he said.
"It is not only about driving accidents but also about the probability of being run over by a car."
Flegr said his research shows men infected by the bug tend to be quiet, withdrawn, suspicious, jealous and dogmatic. He said he could not find a reason for the different reactions.
The illness could be responsible for up to one million of deaths on the roads worldwide, making it the one of the deadliest parasitic diseases, second only to malaria, he said.
 

OneWingedBird

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http://www.avma.org/careforanimals/animatedjourneys/pethealth/pethealth.asp#6

Toxoplasmosis is only particularly dangerous to children, pregnant women (as it infects the foetus) and immunodecifient individuals.

It can be passed via the stools of any warm blooded animal, including humans, so singling out cats seems rather unfair.

It's also relatively difficult to contract from stools unless standards of hygeine are poor.

It was used as a premise in the film Trainspotting, where a HIV+ IV heroin user dies after contracting it from a pet kitten.

No mention of psycho/affective symptoms in this above link, though such things do tend to be underreported.

IMO perhaps not impossible but I do think the account given is seriesly overplaying its hand.
 
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Anonymous

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Cats are vile, disease riddled little bundles of poo. Yuck, yuck and yuck again.
 

GodzillaGirl

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Ah, but cats are handy when there is an unwanted chipmunk running around the house!:p
 
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Anonymous

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I saw that report too, it said it makes women more kittenish and sexy but i haven't got a cat. ;) .

It also said that infection rates were 22% in the uk but as high as 90% in france and Germany. I'm not being flippant here but I really wonder if that might account for the more healthy relaxed attitude to realtionships, the way flirtation is a past-time, more passionate natures in regards to all things-family, food, country? I apologise in advance if I have perpetuated any racial stereotypes here but it's an interesting thought.....it's also probably complete nonsense.
 
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Anonymous

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Interesting how the British papers concentrated on the 'Cats make women sexier' element

Further down the story was, 'And they can kill you too'

Tonight hundreds of tabloid readers are wondering if they should rub the cat against their loved ones or throw the cat out of the window??
 

Beakmoo

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Sounds like utter bollox to me. I've been snogging the cat for years and I'm not sexy.
:p
 

Imperial_Call

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My cat sleeps on my bed during the day, and I sleep in it (alone) at night, draw your own conclusions people ...
 

Pete Younger

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beakboo said:
Sounds like utter bollox to me. I've been snogging the cat for years and I'm not sexy.
:p

We're not in a position to put that to the test beak, but I suspect your fibbing.;)
 

Mighty_Emperor

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There is a piece in today's Guardian on this:

http://www.guardian.co.uk/life/thisweek/story/0,12977,1048642,00.html

It appears that some of the things people are concentraing on is old research:

Jaroslav Flegr, the professor of parasitology behind the research at Charles University in Prague, says he is baffled how these 1996 results made their way into the British press this week.

The story is pretty similar though.

Emps
 

James_H

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Cat's bug changes our personalities!

beat that

http://www.timesonline.co.uk/article/0,,8122-826557,00.html
September 21, 2003

The Sunday Times

Dangerrrr: cats could alter your personality
Jonathan Leake, Science Editor



THEY may look like lovable pets but Britain’s estimated 9m domestic cats are being blamed by scientists for infecting up to half the population with a parasite that can alter people’s personalities.

The startling figures emerge from studies into toxoplasma gondii, a parasite carried by almost all the country’s feline population. They show that half of Britain’s human population carry the parasite in their brains, and that infected people may undergo slow but crucial changes in their behaviour.

Infected men, suggests one new study, tend to become more aggressive, scruffy, antisocial and are less attractive. Women, on the other hand, appear to exhibit the “sex kitten” effect, becoming less trustworthy, more desirable, fun- loving and possibly more promiscuous.

Interestingly, for those who draw glib conclusions about national stereotypes, the number of people infected in France is much higher than in the UK.

The findings will not please cat lovers. The research — conducted at universities in Britain, the Czech Republic and America — was sponsored by the Stanley Research Medical Institute of Maryland, a leading centre for the study of mental illness. The institute has already published research showing that people infected with the toxoplasma parasite are at greater risk of developing schizophrenia and manic depression.

The study into more subtle changes in human personality is being carried out by Professor Jaroslav Flegr of Charles University in Prague. In one study he subjected more than 300 volunteers to personality profiling while also testing them for toxoplasma.

He found the women infected with toxoplasma spent more money on clothes and were consistently rated as more attractive. “We found they were more easy-going, more warm-hearted, had more friends and cared more about how they looked,” he said. “However, they were also less trustworthy and had more relationships with men.”

By contrast, the infected men appeared to suffer from the “alley cat” effect: becoming less well groomed undesirable loners who were more willing to fight. They were more likely to be suspicious and jealous. “They tended to dislike following rules,” Flegr said.

He also discovered that people infected with toxoplasma had delayed reaction times — and are at greater risk of being involved in car accidents. “Toxoplasma infection, could represent a serious and highly underestimated economic and public health problem,” he said.”

In Britain, concern over toxoplasma is growing among health experts — especially as the number of pet cats has grown to about 9m. Roland Salmon, an epidemiologist with the National Public Health Service for Wales, said: “The evidence is that cats are the main cause of infection.”

Toxoplasma moves in a natural cycle between rats and cats. Rats acquire it from contact with cat faeces and cats reacquire it from hunting infected rats. It has long been known that humans can become infected with the parasite through close contact with cats.

Pregnant women are advised to keep clear of the animals because the parasite can damage unborn babies. People with damaged immune systems, such as Aids victims, are also vulnerable.

Until now, however, the parasite has always been thought harmless to healthy people because their immune systems could suppress the infection. But this view seems certain to change, especially in the light of research at Oxford University.

Scientists there have found that when the parasite invades rats it somehow reprograms their brains, reversing their natural fear of cats. It is this same ability to destroy natural inhibitions that is thought to be at work in humans.

Doctors Manuel Berdoy and Joanne Webster at Oxford University are studying how toxoplasma alters rat behaviour and the chemical weapons it uses to subvert the brain.

Berdoy said: “The fact that a single-celled parasite can have such an effect on the mammalian or even human brain is amazing.”

One startling fact to emerge from research is the great differences in levels of infection. In France and Germany, for example, about 80%-90% of people are infected — nearly twice that in Britain or America.

“I am French and I have even wondered if there is an effect on national character,” Berdoy said.

Dr Dominique Soldati, a researcher at Imperial College in London, is studying ways of blocking toxoplasma from getting into cells. “Once you are infected you cannot get rid of this parasite and the numbers of them slowly grow over the years,” she said. “It’s not a nice thought.”
 
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Anonymous

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Re: Cat's bug changes our personalities!

Faggus said:
He found the women infected with toxoplasma spent more money on clothes and were consistently rated as more attractive. “We found they were more easy-going, more warm-hearted, had more friends and cared more about how they looked,” he said. “...and had more relationships with men.”

Hmmm. Perhaps I've been infected.

“However, they were also less trustworthy ..."


Or not. ;)

:laughing:
 

littleblackduck

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Other Mind-altering Parasites

Mother Nature is a wicked old gal.

I've read of a number of parasites that do pretty nasty things in order to ensure that their host gets eaten by the next host in their life cycle.

Most famously, perhaps, is the parasite which makes its way to the brain of an ant, causing it to climb to the top of of a blade of grass and waive its legs, no doubt shouting "Eat me! Eat me!" at passing birds.

Then there is the recently discovered parasite that causes frogs to grow extra legs. I saw it on a nature programme: a tiny worm that commutes from herons to frogs: as a young worm, it invades the limb buds of the frog, disrupting them, which causes the frog to grow multiple hind legs, making it easy for herons to catch them. Bird - poo - tadpole - frog - bird.

I expect that the only reason humans don't have a lot of similar parasites is that not many predators eat us on a regular basis.

I expect the military will be exploiting this information by and by. Imagine a parasite that destroys the fear centres in the Amygdala.

It might also have other applications: a parasite which infects sharks and humans might make for some Olympic-class swimmers.

The motion picture spin-off will be called "Fearless in Seattle", starring Sigourney Weaver as the soldier who is infected by her Government with an alien parasite that causes people to walk up to giant aliens with hand grenades strapped all over their person and say "Eat this, you M*****-****er!"

Don't eat the popcorn. It will be laced with a parasite that makes you willing to pay the price of dinner for two to buy a bathtub full of cardboard slathered in polyunsaturated tropical oils. Adam Sandler movies will seem funnier. In fact, you'll be willing to sit through FREDDY GOT FINGERED over and over again.

Better you should get eaten by an alien.
 

amester

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This study was apparently conducted by cat-haters

Of course many of the tips given here are common sense as far as cat box hygiene. But this research seems to be motivated by hatred of cats on some level :evil:
(As you might have guessed, I love cats)

http://www.schizophrenia.com/prevention/cats.html


Avoiding Childhood Exposure to Cats with the the T. Gondi virus may reduce schizophrenia risk

Recent epidemiologic studies indicate that infectious agents may contribute to some cases of schizophrenia. In animals, infections with Toxoplasma gondii can alter behavior and neurotransmitter function. In humans, acute infection with the cat virus "T. gondii" can produce psychotic symptoms similar to those displayed by persons with schizophrenia. Two other studies found that exposure to cats in childhood was a risk factor for the development of schizophrenia.

Since 1953, a total of 19 studies of T. gondii antibodies in persons with schizophrenia and other severe psychiatric disorders and in controls have been reported; 18 reported a higher percentage of antibodies in the affected persons; in 11 studies the difference was statistically significant.

Whether any geographic association exists between the prevalence of toxoplasmosis and the prevalence of schizophrenia is unknown. France, which has a high prevalence of Toxoplasma-infected persons, was reported to have first-admission rates for schizophrenia approximately 50% higher than those in England (41). Ireland also has a high rate of Toxoplasma-infected persons in rural areas (42)

Action: Minimize exposure of young children to cats, and or observe the following prevention tips below (source: http://www.fabcats.org/toxo.html): Minimize exposure of children to un-cooked or rare meat (which can also be a means of transmission of the virus). Dr. Torrey (the leading researcher on this topic) advises parents not to buy pet cats for young children, and to cover their sandboxes to prevent cats from using them as litter boxes.

How can the risk of transmission of toxoplasma from a cat to its owner be reduced?

Although the risk of transmission of infection from a cat to its owner is very low, this can be reduced further and/or its consequences minimised by adopting the following recommendations:

People in 'high risk' groups should not have contact with the cat's litter tray. Where possible, only non-pregnant and immunocompetent people (i.e. not those people with diseases or drug therapy suppressing their immune system) should handle cat litter trays (following all of the guidelines below).
Empty litter trays daily so that oocysts do not have sufficient time to sporulate (become infective) whilst in the litter tray.
Wear gloves when handling cat litter and wash hands thoroughly after cleaning the litter tray.
Use litter tray liners if possible and periodically clean the litter tray with detergent and scalding water (which kills oocysts) eg fill the litter tray with boiling water and leave for 5 - 10 minutes before emptying.
Dispose of cat litter safely. For example, seal it in a plastic bag before putting it with other household waste.
Cover children's sandpits when not in use to prevent cats using them as litter trays.
Feed only properly cooked food or commercial cat food to your cat to avoid infection.
Washing hands after contact with a cat (especially before eating) is a sensible hygiene precaution.
If very concerned, ask your vet to check your cat's Toxoplasma titre (antibody test for exposure to T gondii):
a. Cats with a positive titre have been infected in the past and will not be a source of infection in the future as they have completed their period of oocyst shedding.
b. Cats with a negative titre have not been infected with T gondii in the past and are likely to shed oocysts in their faeces for a short time if they become infected in the future. The risk of acquiring infection can be minimised by:
Avoiding feeding raw meat to the cat to reduce the risk of T gondii infection (see point 7 above).
Keeping the cat indoors to prevent hunting and access to intermediate hosts such as voles and mice
How can the risk of transmission of toxoplasma from other sources be reduced?

These measures are essential in all 'high risk' groups of people (see above) and are also sensible routine hygiene precautions:

Gloves should be worn when gardening and hands thoroughly washed after contact with soil which may contain sporulated (infectious) oocysts.
Gloves should be worn when handling food to prevent exposure to oocysts and tissue cysts. Hands should always be washed thoroughly afterwards.
Fruit and vegetables should be thoroughly washed before eating to remove any oocysts present on their surface.
All food preparation surfaces and utensils should be cleaned with detergent in warm water before and after use to inactivate any tissue cysts.
Meat should be cooked to a minimum of 58oC for 10 minutes or 61oC for 4 minutes to kill the tissue cysts (Dubey et al 1990). Microwaving is not a safe way to kill tissue cysts as the heating is uneven. T gondii oocysts can remain infectious when stored in a refrigerator (4oC) for up to 54 months (Dubey 1998).
Freezing meat at -12oC to -20oC for three days kills tissue cysts as does curing or smoking (Dubey 1988, Lunden and Uggla 1992).
Gamma irradiated food is free from any risk of infection.
If drinking a non-mains water supply, boil or filter before drinking to remove oocysts.
Supporting Research (a sample):
 

Graylien

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Infected rats make easy cat snacks

By BBC News Online's Matt McGrath

A parasitic infection in some rats alters their natural behaviour and makes them easy prey for cats, research shows.

It ensures its return to its favourite host by affecting the brains of the normally cautious rats, making them outgoing and active and an easy meal for a hungry cat.

Dr Manuel Berdoy, and colleagues, report their work in the Proceedings of the Royal Society.

One of the team, Dr Joanne Webster, a lecturer in infectious disease at Oxford, told BBC News Online: "The infection makes the rats less fearful of novelty.

"Rats can usually detect subtle changes in their environment. It makes them very hard to trap or poison but this parasite overrides the innate response - they almost taunt the cats in a sense."

In rats, the infection is usually contracted from eating cat faeces. The parasite then works itself into every organ in the rat's body especially the brain where it forms dormant cysts.

There it remains viable for the lifetime of the rat, waiting for a cat to come along and eat the rodent so that it can spring to life again.

Impact on children

Dr Webster has been studying the effects of this parasite for years.


This parasite overrides the innate response - they almost taunt the cats in a sense.

"None of the other parasites I've ever looked at have had any of these effects upon behaviour," she said.

The parasite is also widespread in human brains, but does not cause a problem unless the immune system is compromised.

"If we become immuno-suppressed with Aids or chemotherapy, the parasites reactivate in us. Basically, this is what causes the madness at the terminal stage of Aids," Dr Webster said.

"It's actually the Toxoplasma making great big holes in your brain."

She also says we are likely to find more evidence of the parasite's impact on children.

"There is some initial research that has found hyperactivity and low IQ in children with high Toxoplasma levels.

"I don't think we can be that dismissive of such a prevalent parasite in our brains - its effects are probably very subtle but I would be quite confident that we will find evidence of its impact in most species".

source

The Return of the Puppet Masters


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.

Then the researchers put Toxoplasma-carrying rats in the enclosure. Rats carrying the parasite are for the most part indistinguishable from healthy ones. They can compete for mates just as well and have no trouble feeding themselves. The only difference, the researchers found, is that they are more likely to get themselves killed. The scent of a cat in the enclosure didn't make them anxious, and they went about their business as if nothing was bothering them. They would explore around the odor at least as often as they did anywhere else in the enclosure. In some cases, they even took a special interest in the spot and came back to it over and over again.


The scientists speculated that Toxoplasma was secreted some substance that was altering the patterns of brain activity in the rats. This manipulation likely evolved through natural selection, since parasites that were more likely to end up in cats would leave more offpsring.

The Oxford scientists knew that humans can be hosts to Toxoplasma, too. People can become infected by its eggs by handling soil or kitty litter. For most people, the infection causes no harm. Only if a person's immune system is weak does Toxoplasma grow uncontrollably. That's why pregnant women are advised not to handle kitty litter, and why toxoplasmosis is a serious risk for people with AIDS. Otherwise, the parasite lives quietly in people's bodies (and brains). It's estimated that about half of all people on Earth are infected with Toxoplasma.

Given that human and rat brains have a lot of similarities (they share the same basic anatomy and use the same neurotransmitters), a question naturally arose: if Toxoplasma can alter the behavior of a rat, could it alter a human? Obviously, this manipulation would not do the parasite any good as an adaptation, since it's pretty rare for a human to be devoured by a cat. But it could still have an effect.

Some scientists believe that Toxoplasma changes the personality of its human hosts, bringing different shifts to men and women. Parasitologist Jaroslav Flegr of Charles University in Prague administered psychological questionnaires to people infected with Toxoplasma and controls. Those infected, he found, show a small, but statistically significant, tendency to be more self-reproaching and insecure. Paradoxically, infected women, on average, tend to be more outgoing and warmhearted than controls, while infected men tend to be more jealous and suspicious.

It's controversial work, disputed by many. But it attracted the attention of E. Fuller Torrey of the Stanley Medical Research Institute in Bethesda, Maryland. Torrey and his colleagues had noticed some intriguing links between Toxoplasma and schizophrenia. Infection with the parasite has been associated with damage to a certain class of neurons (astrocytes). So has schizophrenia. Pregnant women with high levels of Toxoplasma antibodies in their blood were more likely to give birth to children who would later develop schizophrenia. Torrey lays out more links in this 2003 paper. While none is a smoking gun, they are certainly food for thought. It's conceivable that exposure to Toxoplasma causes subtle changes in most people's personality, but in a small minority, it has more devastating effects.

A year later, Torrey and his colleagues discovered one more fascinating link. They raised human cells in Petri dishes and infected them with Toxoplasma. Then they dosed the cells with a variety of drugs used to treat schizophrenia. Several of the drugs--most notably haloperidol--blocked the growth of the parasite.

So Fuller and the Oxford scientists joined forces to find an answer to the next logical question: can drugs used to treat schizophrenia help a parasite-crazed rat? They now report their results in the Proceedings of the Royal Society of London (press release). They ran the original tests on 49 more rats. Once again, parasitized rats lost their healthy fear of cats. Then the researchers treated the rats with haloperidol and several other anti-psychotic drugs. They found that the drugs made the rats more scared. They also found that the antipsychotics were as effective as pyrimethamine, a drug that is specifically used to eliminate Toxoplasma.

There's plenty left to do to turn these results into a full-blown explanation of parasites and personalities. For example, what is Toxoplasma releasing into brains to manipulate its hosts? And how does that substance give rise to schizophrenia in some humans? And even if the hypothesis does hold up, it would only account for some cases of schizophrenia, while the cause of others would remain undiscovered. But still...the idea that parasites are tinkering with humanity's personality--perhaps even giving rise to cultural diversity--is taking over my head like a bad case of Toxoplasma.

source
 

littleblackduck

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There are new developments on the toxoplasmosis/human behaviour front in the science news.

A new study speculates that toxoplasmosis might affect human culture. Researchers compared various studies of human personality traits by region with toxoplasmosis antibody rates in humans and found that the later correlate with neurotic guilt.

http://www.sciencedaily.com/releases/20 ... 085444.htm

I looked around for distribution maps of toxoplasmosis, unsuccessfully, but found that France, Central America and Central Africa have particularly high human infection rates--over 80% have antibodies.

The "catty" personalities are certainly congruent with negative stereotypes of the French.

However, this could be nothing more than coincidence. Corrolation does not imply causation, as the scientists say.

A cat loving skeptic suggests an alternative theory: cats teach catty behaviour to cat lovers by example:

Clea Simon, author of "The Feline Mystique," said cats do have an effect on people's personalities, but this probably has nothing to do with any parasite.

"In some ways cats can and do teach women to be more independent and more desirable," she said. "And maybe cats’ independence also teaches men to think for themselves, to become more free-spirited."


It wouldn't be surprising to find a correlation between cat-keeping and toxoplasmosis, and hence, catty personalities.

Either way, there are cat-people and non-cat people and that is all we know for sure.

One thing I would like to see studied, however, is do cat people (people with catty personalities) like cats more or less than cat-lovers. I suspect that cat people often don't like cats because they are too much alike.

You know how it goes sometimes--people loathe each other as much for what they have in common as their differences.

This is suggested to me by the fact that many people who do not like cats attract them by their very reserve. To the cat, human friendliness can appear aggressive, while aloofness is, well, a cat trait. We must never forget that animals don't necessarily think like humans. A smile is friendly to a human, the barring of teeth is aggressive to a dog and still more so, a wild animal.

I wonder how many cats the Konigsberg family had when "Woody Allen", aka Allen Stewart Konigsberg, was a child in a damp, low-lying region of the New York City metropolitan area? (Vide Radio Days) He doesn't seem like a cat lover, though. Too neurotic and paranoid, perhaps. Seems like the type who wouldn't care for cats because they would make him constantly wonder what they were disapproving of, now.

And what of the traditional association of bookstores and literature with cast? This goes back to the days of the Egyptian goddess of liteature, Bast.

Of course, keeping books means rats and mice and other pests, so the cats are a practical necessity, but bookworm stereotypes (at least for men but then, aren't chatty, catty, socialable book clubs more a woman thing?) also fit the catty personality stereotype. Unkempt, aggressive, suspicious loners--Byronesque to Existentialist. Philip K. Dick to Samuel Johnson. Again, the corrolation could be coincidental--books and cats may simply inspire similar personality traits by emphasizing underlying sex differences.

It would be interesting, however, if parasites do alter human cultures and personalities. You might be able to use pets as antidotes to mental illness or bat habits, for example. Finish that novel you've been working on for years--buy a cat. Get a cat and cure your insomnia by acquiring the ability to cat nap. Baudelaire got by on very little sleep.
 

ramonmercado

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Literally mind-boggling.

Common Parasite May Trigger Suicide Attempts: Inflammation from T. Gondii Produces Brain-Damaging Metabolites
http://www.sciencedaily.com/releases/20 ... 170400.htm

The Toxoplasma gondii parasite has been linked to inflammation in the brain, damaging cells. (Credit: Image courtesy of Michigan State University)

ScienceDaily (Aug. 16, 2012) — A parasite thought to be harmless and found in many people may actually be causing subtle changes in the brain, leading to suicide attempts.

New research appearing in the August issue of The Journal of Clinical Psychiatry adds to the growing work linking an infection caused by the Toxoplasma gondii parasite to suicide attempts. Michigan State University's Lena Brundin was one of the lead researchers on the team.

About 10-20 percent of people in the United States have Toxoplasma gondii, or T. gondii, in their bodies, but in most it was thought to lie dormant, said Brundin, an associate professor of experimental psychiatry in MSU's College of Human Medicine. In fact, it appears the parasite can cause inflammation over time, which produces harmful metabolites that can damage brain cells.

"Previous research has found signs of inflammation in the brains of suicide victims and people battling depression, and there also are previous reports linking Toxoplasma gondii to suicide attempts," she said. "In our study we found that if you are positive for the parasite, you are seven times more likely to attempt suicide."

The work by Brundin and colleagues is the first to measure scores on a suicide assessment scale from people infected with the parasite, some of whom had attempted suicide.

The results found those infected with T. gondii scored significantly higher on the scale, indicative of a more severe disease and greater risk for future suicide attempts. However, Brundin stresses the majority of those infected with the parasite will not attempt suicide: "Some individuals may for some reason be more susceptible to develop symptoms," she said.

"Suicide is major health problem," said Brundin, noting the 36,909 deaths in 2009 in America, or one every 14 minutes. "It is estimated 90 percent of people who attempt suicide have a diagnosed psychiatric disorder. If we could identify those people infected with this parasite, it could help us predict who is at a higher risk."

T. gondii is a parasite found in cells that reproduces in its primary host, any member of the cat family. It is transmitted to humans primarily through ingesting water and food contaminated with the eggs of the parasite, or, since the parasite can be present in other mammals as well, through consuming undercooked raw meat or food.

Brundin has been looking at the link between depression and inflammation in the brain for a decade, beginning with work she did on Parkinson's disease. Typically, a class of antidepressants called selective serotonin re-uptake inhibitors, or SSRIs, have been the preferred treatment for depression. SSRIs are believed to increase the level of a neurotransmitter called serotonin but are effective in only about half of depressed patients.

Brundin's research indicates a reduction in the brain's serotonin might be a symptom rather than the root cause of depression. Inflammation, possibly from an infection or a parasite, likely causes changes in the brain's chemistry, leading to depression and, in some cases, thoughts of suicide, she said.

"I think it's very positive that we are finding biological changes in suicidal patients," she said. "It means we can develop new treatments to prevent suicides, and patients can feel hope that maybe we can help them.

"It's a great opportunity to develop new treatments tailored at specific biological mechanisms."

Brundin and co-senior investigator Teodor Postolache of the University of Maryland led the research team. Funding for the project came from several sources, most notably the Swedish Research Council and American Foundation for Suicide Prevention.

Story Source:

The above story is reprinted from materials provided by Michigan State University.

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Journal Reference:

Yuanfen Zhang, Lil Träskman-Bendz, Shorena Janelidze, Patricia Langenberg, Ahmed Saleh, Niel Constantine, Olaoluwa Okusaga, Cecilie Bay-Richter, Lena Brundin, Teodor T. Postolache. Toxoplasma gondiiImmunoglobulin G Antibodies and Nonfatal Suicidal Self-Directed Violence. The Journal of Clinical Psychiatry, 2012; DOI: 10.4088/JCP.11m07532
 

EnolaGaia

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The T. gondii parasite has now made it to Hawaii ...
'Mind-control' cat parasite has now reached Hawaii

Toxoplasma gondii, a "mind-controlling" parasite that causes the disease toxoplasmosis, has been found in public lands in Oahu, Hawaii for the first time, researchers have discovered.

This parasite was previously unknown across Hawaii's island landscapes, so how did it get to Oahu? It hitchhiked there in free-ranging cats, which are a non-native species and are known hosts of the parasite. ...

Toxoplasma gondii is transmitted from cats to other animals — including humans — when cats expel the parasite in feces, in a capsulelike eggs, or oocysts. Once T. gondii oocysts enter a new host they transform to an actively multiplying form called tachyzoites, which can replicate so quickly that they overwhelm the host's immune system and lead to serious health problems.

One of the ways that Toxoplasma gondii affects mice and rats is by tweaking their brain chemistry to change their behavior. Rodents typically avoid cats, but under T. gondii's "mind control" they seek out felines. And that's exactly what T. gondii wants, because the infected rats need to be ingested by cats in order for T. gondii to complete its life cycle. ...
FULL STORY: https://www.livescience.com/mind-control-parasite-oahu-cats.html

See Also:
Parasites & Odd Effects Caused By Parasites
https://forums.forteana.org/index.php?threads/parasites-odd-effects-caused-by-parasites.37455/
 

EnolaGaia

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This Live Science article provides an updated summary on what we know about Toxoplasma gondii, its nature and its effects on humans.
Can a cat parasite control your mind?

There's a single-celled parasite called Toxoplasma gondii, and it can turn a normally risk-averse mouse into a bold, cat-seeking rodent. Cats that devour such mice can then pass the parasite onto humans.

But once humans are infected, what happens to them? Do they become Toxoplasma gondii zombies, acting however the parasite deems fit?

The answer is complex; studies show that people who test positive for this condition are more likely to take certain kinds of risks than those who don't have toxoplasmosis, but it's not yet clear how this happens. ...

... Humans are not immune to Toxoplasma gondii — in fact, at least a third of the world's population is thought to have toxoplasmosis, the infection this parasite causes. Some humans get infected when they clean out their pet cat's litter box, but many of us simply eat undercooked meats or unwashed vegetables. So, what does this mean for the one in three of us who end up playing host to the parasite? ...


... just like an infected mouse is more adventurous, an infected human is also more prone to take risks — sometimes with pretty devastating consequences. At least two studies — one analyzing 370 people in Turkey and another looking at nearly 600 people in the Czech Republic — have shown that people who test positive for Toxoplasma gondii antibodies are more likely to have a car crash. There isn’t a lot of evidence to explain why and how latent infections of toxoplasmosis might affect people’s personalities, such as making them less afraid of risk. The researchers behind the car crash studies, however, wrote that the parasite leaves behind life-long cysts in the brain, which is thought to increase the production of dopamine (a chemical messenger in the brain that is known to affect people's risk and reward calculations), and that may have a role to play. ...

Toxoplasmosis is also linked to rage problems. People with the psychiatric disorder known as Intermittent Explosive Disorder, or IED, were twice as likely to have a toxoplasmosis diagnosis than healthy individuals with no psychiatric diagnosis, Live Science previously reported. ...

... scientists have yet to pin down a direct way that Toxoplasma gondii might control human minds, Live Science previously reported. In rodents, it's possible that the parasite secretes molecules that somehow rewire the brain; others think it may be due to brain cysts interfering with dopamine production; and another idea is that Toxoplasma gondii triggers inflammation in rodent brains, which may, in turn, change brain behavior and function, a 2019 study in the journal mBio found. ...

FULL STORY: https://www.livescience.com/can-cat-parasites-control-human-brains.html
 

EnolaGaia

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Newly published research results suggest discrepancies among past T. gondii epidemiological studies can be resolved by focusing on rodent-eating (i.e., free-ranging) cats owned in childhood. The study also seems to indicate males are more likely to develop psychotic symptoms than females.
Annoying Cat Parasite Has Again Been Linked to Psychotic Episodes, But Only in Men
PETER DOCKRILL 24 APRIL 2022

A ubiquitous parasite estimated to infect millions of people around the world has been linked with schizophrenia and a host of neurological disorders, but the evidence hasn't always been clear.

While there are a number of studies linking the 'mind-altering' parasite Toxoplasma gondii with altered behavior or weird patterns in human activity, there are also data debunking the association.

Now, a new study led by first author and psychiatry resident Vincent Paquin from McGill University in Canada could help to explain this parasitic paradox – while going some way to identifying where the apparent dangers of T. gondii may actually lie. ...

"Domestic cats generally become infected with the parasite by feeding on rodents, and will only be contagious during the days or weeks that follow," Paquin and his co-authors write in their new paper.

"Hence, specifying whether the cat was known to hunt rodents might provide a better proxy for probable exposure to T. gondii compared to cat ownership alone." ...

Hypothetically speaking, they might then transmit the infection to children, who could go on to develop psychological issues in adulthood, as identified in some studies, potentially through effects on the immune system. ...

In analyzing the responses, the team observed that male participants who had owned a rodent-hunting cat during childhood showed an increased risk of having psychotic experiences in their adulthood; female respondents did not have the same link.

People who owned indoor-only cats during childhood (or no cat at all) did not show the same increased risk, which the team said was "consistent with our hypothesis based on the life cycle of T. gondii as the putative mechanism of this association". ...

While the study has a number of limitations ... the team says their findings illustrate the importance of examining interactions among different kinds of environmental exposures, which may in the future help us to identify with greater accuracy where problems from T. gondii exposure are more likely to arise. ...
FULL STORY: https://www.sciencealert.com/myster...ed-to-psychotic-episodes-but-it-s-complicated
 

EnolaGaia

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Here are the bibliographic details and abstract from the published research report.


Vincent Paquin, Guillaume Elgbeili, Julia Munden, Norbert Schmitz, Ridha Joober, Antonio Ciampi, Suzanne King,
Conditional associations between childhood cat ownership and psychotic experiences in adulthood: A retrospective study,
Journal of Psychiatric Research, Volume 148, 2022, Pages 197-203, ISSN 0022-3956
https://doi.org/10.1016/j.jpsychires.2022.01.058.

Abstract
Ownership of cats in childhood has been inconsistently associated with psychosis in adulthood. Parasitic exposure, the putative mechanism of this association, may be more common with rodent-hunting cats, and its association with psychosis may depend on other environmental exposures. We examined the conditional associations between childhood cat ownership and the frequency of psychotic experiences in adulthood. Adults (n = 2206) were recruited in downtown Montreal to complete a survey about childhood cat ownership (non-hunting or rodent-hunting), winter birth, residential moves in childhood, head trauma history, and tobacco smoking. The frequency of psychotic experiences (PE) was measured with the 15-item positive subscale of the Community Assessment of Psychic Experiences. Associations between exposures and PE were examined in linear regressions adjusted for age and sex. Interactions among variables were explored using a conditional inference tree. Rodent-hunting cat ownership was associated with higher PE scores in male participants (vs. non-hunting or no cat ownership: SMD = 0.57; 95% CI: 0.27, 0.86), but not in female participants (SMD = 0.10; 95% CI: −0.18, 0.38). In the conditional inference tree, the highest mean PE score was in the class comprised of non-smokers with >1 residential move, head trauma history, and rodent-hunting cat ownership (n = 22; mean standard score = 0.96). The interaction between rodent-hunting cat ownership and head trauma history was supported by a post-hoc linear regression model. Our findings suggest childhood cat ownership has conditional associations with psychotic experiences in adulthood.

SOURCE: https://www.sciencedirect.com/science/article/abs/pii/S0022395622000681?via=ihub
 

James_H

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Are Toxoplasma-infected subjects more attractive, symmetrical, or healthier than non-infected ones? Evidence from subjective and objective measurements

First, we found that infected men had lower facial fluctuating asymmetry whereas infected women had lower body mass, lower body mass index, a tendency for lower facial fluctuating asymmetry, higher self-perceived attractiveness, and a higher number of sexual partners than non-infected ones. Then, we found that infected men and women were rated as more attractive and healthier than non-infected ones. Conclusions Our results suggest that some sexually transmitted parasites, such as T. gondii , may produce changes in the appearance and behavior of the human host, either as a by-product of the infection or as the result of the manipulation of the parasite to increase its spread to new hosts. Taken together, these results lay the foundation for future research on the manipulation of the human host by sexually transmitted pathogens and parasites.
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Images A are composites of 10 men and women with toxoplasmosis, b are 10 without.
 

Mythopoeika

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I can imagine the next craze among the wealthy glitterati, wishing to enhance their looks... deliberately getting infected with toxoplasmosis to look more attractive!
 

James_H

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It's somewhat reminiscent of the Futurama episode 'Parasites Lost' in which
an infestation of parasitic worms make the central character Fry much more intelligent, thoughtful and charming, to the point where his long-term love interest finally falls in love with him.
 
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