Given all the nasty science swirling around this parasite, is
it time for cat lovers to switch their allegiance to other
animals?
Even Flegr would advise against that. Indoor cats pose no
threat, he says, because they don’t carry the parasite. As
for outdoor cats, they shed the parasite for only three
weeks of their life, typically when they’re young and have
just begun hunting.
Of course the author says that! He has cats, he must be infected too!
But seriously, the claim wasn't that the parasite immediately kills people but makes them more disposed towards self-destructive behavior. The fact that, 2000 years after people started living with cats, humanity yet survives isn't really absolute proof to the contrary.
Well, article claims that people really have started living with cats (that is, keeping them as pets) since 18th century in France, which is also when schizophrenia started to spread. So yeah, just over a century later and by the looks of it humanity is lucky to still survive!
Imagine how different life would have been now without that crazy infected folk who like dangerous driving and become obsessed with insane ideas. =)
By the way, can anyone clarify—is there a way to detect toxoplasmosis even in latent form? It seems from Wikipedia article that blood tests can't provide reliable results here.
Maybe we have evolved with the influence of cats, who are really in power. They use us to achieve their objectives (mining for gold for some reason maybe?). The toxins keep us under control. It makes so much sense!
Except the supposed behavior alteration in women is increased social activity, attention to appearance, neatness, and aversion to the smell of cat urine.
Given the article's suggestion that some people react differently to infection (as in the schizophrenia/immune-system discussion, and not just by gender), plus the similarity of cat ladies' behavior with infected rats in some dimensions, a link between this parasite and the 'cat lady' archetype is not an outlandish conjecture.
Other links on the 'net that I've found are reporting (without any citations) that the parasite can be detected with a blood test (according to wikipedia, not true) and that it cannot be treated (again, according to wikipedia, also not true).
I've seen articles about this parasite pop up over at least the last 5 years. If it was a truly serious problem I'm sure there'd be more information about it. It smells a bit like FUD though.
WebMd [1] and some other places [2] talk about it like it's a bacteria that your immune system fights off then you are safe from for the rest of your life. They don't seem to talk about any long term effects, and focus on just the risk the acute symptoms can have.
Five years isn't all that much time as far as bio-med research is concerned. I would expect to start seeing definite results in maybe a few years.
As for detection and treatment, the subject being discussed in the Wiki article is the effect of initial infection. The parasite sticks around in a latent form after being "fought off" and is being hypothesized to have additional long-term effects.
A search for Toxoplasmosis on G-scholar reveals that this parasite is in fact a problem for immune compromised patients and infants. Although I do not think WebMD is a reliable source, another comment here cites them to indicate that infections are usually cleared up by our immune system. This appears to be plausible, but because the parasite enters cells, and can hide in a latent phase, your immune system may be unable to clear the infection permanently. Because the parasite can halt the cell cycle, it may be able to hide indefinitely. I would not be concerned about a latent parasite, but its re-emergence may become a problem if your immune system becomes compromised.
A correction to your statement that, according to wikipedia, the disease cannot be tested by blood sample. Wikipedia, in fact, stats that it can be tested by blood or other tissue, but only if the parasite is active (non-latent).
Regarding its effect on behavior, the parasite seems to increase dopamine levels and possibly inhibit fear response. Since the increased dopamine is caused by an enzyme made by the parasite, this probably only occurs during a full scale infection. The inhibition of fear may occur while the parasite is inactive, if the parasite is able to enter cells in your amygdala. I do not see this inhibition of fear as long-lasting, except perhaps in extreme cases.
One disclaimer, I grew up with a few cats, so I may have been, or am currently, infected. I cannot rule out that this parasite is manipulating me to write this comment. Now I'm off to find some cat pee. Can't get enough of that smell, mmmmmmmm.....
For dopamine, which according to the cat article is elevated in Toxo-infected humans, the associated personality type is "risk-taking, curious, creative, impulsive, optimistic and energetic". Plus the associated decrease in fear response in rats: who does that sound like?
i.e. I wonder what percentage of entrepreneurs are Toxo infected?
Here's the question, though: are the risk-taking humans risk-taking because they're infected, or are they infected because they're risk taking. Correlation, unfortunately, doesn't imply causation.
The "fatal attraction to cat urine" studies are somewhat imperfect [1]. I'm friends with a student who's doing similar studies with mice but with better spatial discrimination . The consensus seems to be that while the fear response goes down, the idea that it's attractive to the rodents is more difficult to replicate.
Radiolab delved into this a bit in their show "Parasites" from a while back. You can listen to the relevant segment under "The Scratch", although I recommend the whole thing, of course:
This dude knows nothing about cats and crazy. Cats make you crazy by pawing your face all night for attention and sleeping all day because they're tired from being awake until dawn.
hahaha, word. What makes you crazy is that cat wants attention when you are busy or sleepy and wants you away when you want to pet it, screams and breaks stuff when it's hungry and scratches your furniture.
But you still keep the cat, huh? That must be the parasite at work. Actually, now I have a whole new perspective on cat owners in general, and why they put up with their pets..
"Cats make you crazy by pawing your face all night for attention"
For a while one of our cats was waking me up by climbing to the top of a wardrobe and then launching itself onto my stomach as I slept from this considerable height - which appears to be the cat equivalent of BASE jumping.
The fact that I endured this behaviour a few times with relative good humour probably indicates that I probably have this mind control parasite!
I'm glad he was smart/sane enough to even think about going to the lab. When something is messing with your mind, can you even think of such logical reasonable things?
Seriously, OC probably means this: When you're having seemingly psychological affects/things that are just "part of who you are," it's almost impossible to begin to think that it might be some outside force.
I used to take a medicine which I thought was fine; in the mean time, I developed worse and worse depression, anxiety, and all the time I thought it was a reasonable reaction to stuff in my life. THEN I got paranoid and thought my best friend and boyfriend were out to get me. Finally, something snapped. Finally, I thought, "whoa, this is not me." Turns out it was ALL the medicine. Yes, I had reasons to be depressed, but that's just not my type. Ended the medicine, ended all the side effects.
It only took 3 years and a CRAZY extent of the side effects for me to realize it "wasn't me."
"We evaluated 148 case patients with recent T. gondii infection and 413 control patients. In multivariate analysis, an elevated risk of recent T. gondii infection was associated with the following factors: eating raw ground beef (adjusted odds ratio [aOR], 6.67; 95% confidence limits [CLs], 2.09, 21.24; attributable risk [AR], 7%); eating rare lamb (aOR, 8.39; 95% CLs, 3.68, 19.16; AR, 20%); eating locally produced cured, dried, or smoked meat (aOR, 1.97; 95% CLs, 1.18, 3.28; AR, 22%); working with meat (aOR, 3.15; 95% CLs, 1.09, 9.10; AR, 5%); drinking unpasteurized goat’s milk (aOR, 5.09; 95% CLs, 1.45, 17.80; AR, 4%); and having 3 or more kittens (aOR, 27.89; 95% CLs, 5.72, 135.86; AR, 10%). Eating raw oysters, clams, or mussels (aOR, 2.22; 95% CLs, 1.07, 4.61; AR, 16%) was significant in a separate model among persons asked this question. Subgroup results are also provided for women and for pregnant women.
Conclusions. In the United States, exposure to certain raw or undercooked foods and exposure to kittens are risk factors for T. gondii infection. Knowledge of these risk factors will help to target prevention efforts." http://cid.oxfordjournals.org/content/49/6/878.full
We have six cats at the house here, hence the username 'nekojima', Japanese for 'cat island'.
I have long suspected a parasitic role (either us or them for attention rather than brain damaging) or an element of craziness in our having so many cats. So far our own scientific analysis has been interrupted by near constant feline requests for attention, food or having to clean a little more than 'normal'.
The 'ji' (じ) uses the same kana as 'shi' (し), just with some tick marks. Which sound is used in a compound word depends on the previous syllable. So, by itself, yes, it's "shima", but in a compound it could be either.
> It's actually 'shima' for island. Not sure if 'jima' works too, but shima is definitely more common.
Correct, "island" is shima, but in this case we have a phenomenon in Japanese known as "sequential voicing" (連濁, rendaku) in which the first syllable of the second word of a compound is changed from an unvoiced consonant to a voiced consonant. This is particularly common when dealing with native Japanese compounds; i.e., compounds using words not derived from the imported Chinese pronunciations of characters. So "island" (島) by itself would be shima, but when used as a suffix, the initial consonant sh becomes voiced to j, and thus jima. Another example is "fire" (火), pronounced hi alone, but voiced to bi as the second half of words such as "fireworks" (花火, hanabi).
I can't believe I read through the whole thing - it started off kind of crazy. Still, just as Flegr himself says, the change in behavior is minimal - chances are high that the average individual's life wouldn't be much different whether he/she had the parasite or not.
Still, it's amazing how such a primitive organism can change your brain's function - makes you wonder if there's a parasite that's making people stupid/smart/lazy/etc.
Blackmore in her introductions to consciousness suggests something related: that consciousness is an a concept (or illusion, to her) only widely known because it became a social meme.
It's clearly a commensal symbiote: for cats, it assists them in catching prey.
In rats and humans, its changing prevalance helps adjust the relative expression of different behavioral strategies, faster than inheritance alone could.
For example, the risk-taking and increased libido in rats shifts the infected slightly along the K-strategy/r-strategy reproductive spectrum. In some environments that's a win, others a loss, but the T.gondii increases rat behavior diversity, and thus the species' adaptability.
Similarly, its modulating effects on human suspicion, gregariousness, investment in fitness-signalling (clothing), and obedience/trust sometimes help and sometimes hurt, depending on an ever-changing environment.
What if we 'cured' this and found the resulting human populations were less resilient against war, ecological stresses, and rapid technological/cultural change?
(I'm only half joking. And a meta-parasite is making me write apologetics for other parasites. And this entire comment is just a long way of saying "I, for one, welcome our new Toxoplasmosis gondii overlords" without getting immediately downvoted.)
The T. gondii, as viewed from the cat's perspective might be a symbiote, but from the rat's perspective, is certainly a parasite, isn't it? The T. gondii is benefiting at the expense of the rat. Do biologists classify things as both simbiotes and parasites?
I think some rats also benefit: their adventurousness and increased sexual activity isn't always penalized with death, and even when it is, female rats prefer the infected male rats. So even if they live fast and die young, they may leave more offspring.
Whether this is a net benefit at any one time probably depends on lots of things, and especially relative rat/predator populations. Just as human reproductive preferences seem to change in relation to wealth, population density, and life-expectancy.
Regarding semantics, I do think something can be both a symbiote and parasite. When I first learned of 'symbiosis' it was in the context of mutually-beneficial relationships, but it seems the term can be more general. Wikipedia says scientists sometimes disagree whether 'symbiosis' should only be used to describe 'mutualist' relationships (where both benefit) or also 'parasitic' (one benefits and other is harmed) and 'commensal' (one benefits and other neither harmed nor helped) relationships.
I should have used the word 'mutualist' in my above post, as that's what I was intending to imply. But the conjecture is intentionally fuzzy about whether the benefit is to the individual (it perhaps sometimes is) or the species (it perhaps always is, as long as both infection and non-infection are well-distributed).
When and if this research is sufficiently established, people will most likely have an averse (and perhaps unwarrantedly so) attitude to having cats as pets.
Or maybe we will start vaccinating the kitties when they are young enough to start hunting.
I have four cats and they are all indoors, so I guess I'm safe. But even if they weren't indoors, and I was vulnerable to this parasite, it wouldn't matter. I love them too much. The heart overrules the head in this matter.
After reading this article (which was very enjoyable by the way), I am now curious to find out if I myself may be the puppet of some parasite. Is there any way to find this out easily?
> Compared with uninfected men, males who had the parasite were more introverted, suspicious, oblivious to other people’s opinions of them, and inclined to disregard rules. Infected women, on the other hand, presented in exactly the opposite way: they were more outgoing, trusting, image-conscious, and rule-abiding than uninfected women.
This reminds me of a lot of cat-people I know. But that might just be selective recall.
78 comments
[ 5.8 ms ] story [ 133 ms ] threadNot to mention the fact that people seem to live on fine with domestic cats for the last 2,000 years, with no casualties...
But seriously, the claim wasn't that the parasite immediately kills people but makes them more disposed towards self-destructive behavior. The fact that, 2000 years after people started living with cats, humanity yet survives isn't really absolute proof to the contrary.
Imagine how different life would have been now without that crazy infected folk who like dangerous driving and become obsessed with insane ideas. =)
By the way, can anyone clarify—is there a way to detect toxoplasmosis even in latent form? It seems from Wikipedia article that blood tests can't provide reliable results here.
Given the article's suggestion that some people react differently to infection (as in the schizophrenia/immune-system discussion, and not just by gender), plus the similarity of cat ladies' behavior with infected rats in some dimensions, a link between this parasite and the 'cat lady' archetype is not an outlandish conjecture.
Other links on the 'net that I've found are reporting (without any citations) that the parasite can be detected with a blood test (according to wikipedia, not true) and that it cannot be treated (again, according to wikipedia, also not true).
I've seen articles about this parasite pop up over at least the last 5 years. If it was a truly serious problem I'm sure there'd be more information about it. It smells a bit like FUD though.
Can anyone else elaborate on this further?
That's not really how science/epistemology work.
[1] http://www.webmd.com/food-recipes/food-poisoning/toxoplasmos... [2] http://www.pamf.org/serology/clinicianguide.html
As for detection and treatment, the subject being discussed in the Wiki article is the effect of initial infection. The parasite sticks around in a latent form after being "fought off" and is being hypothesized to have additional long-term effects.
A correction to your statement that, according to wikipedia, the disease cannot be tested by blood sample. Wikipedia, in fact, stats that it can be tested by blood or other tissue, but only if the parasite is active (non-latent).
Regarding its effect on behavior, the parasite seems to increase dopamine levels and possibly inhibit fear response. Since the increased dopamine is caused by an enzyme made by the parasite, this probably only occurs during a full scale infection. The inhibition of fear may occur while the parasite is inactive, if the parasite is able to enter cells in your amygdala. I do not see this inhibition of fear as long-lasting, except perhaps in extreme cases.
One disclaimer, I grew up with a few cats, so I may have been, or am currently, infected. I cannot rule out that this parasite is manipulating me to write this comment. Now I'm off to find some cat pee. Can't get enough of that smell, mmmmmmmm.....
More technical wiki article: https://en.wikipedia.org/wiki/Toxoplasma_gondii
(It was probably posted previously before that)
For dopamine, which according to the cat article is elevated in Toxo-infected humans, the associated personality type is "risk-taking, curious, creative, impulsive, optimistic and energetic". Plus the associated decrease in fear response in rats: who does that sound like?
i.e. I wonder what percentage of entrepreneurs are Toxo infected?
The "fatal attraction to cat urine" studies are somewhat imperfect [1]. I'm friends with a student who's doing similar studies with mice but with better spatial discrimination . The consensus seems to be that while the fear response goes down, the idea that it's attractive to the rodents is more difficult to replicate.
[1] Free at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690701/?tool=pu...
http://www.edge.org/3rd_culture/sapolsky09/sapolsky09_index....
http://www.radiolab.org/2009/sep/07/
and this http://www.doggiestylish.com/store/images/wordpress/uploads/...
Cats are awesome!
For a while one of our cats was waking me up by climbing to the top of a wardrobe and then launching itself onto my stomach as I slept from this considerable height - which appears to be the cat equivalent of BASE jumping.
The fact that I endured this behaviour a few times with relative good humour probably indicates that I probably have this mind control parasite!
But then again, I raised him.
But, WTF, cat stories on Hacker News? I don't know what to say!
http://www.ncbi.nlm.nih.gov/m/pubmed/1885421
Also, Maralone or something similar that uses atovaquone and proguanil.
I'm surprised, it's a total cultural meme.
Probably dates back to Newton and those other alchemists who were really fascinated by the, um, transformative properties of mercury.
I used to take a medicine which I thought was fine; in the mean time, I developed worse and worse depression, anxiety, and all the time I thought it was a reasonable reaction to stuff in my life. THEN I got paranoid and thought my best friend and boyfriend were out to get me. Finally, something snapped. Finally, I thought, "whoa, this is not me." Turns out it was ALL the medicine. Yes, I had reasons to be depressed, but that's just not my type. Ended the medicine, ended all the side effects.
It only took 3 years and a CRAZY extent of the side effects for me to realize it "wasn't me."
Conclusions. In the United States, exposure to certain raw or undercooked foods and exposure to kittens are risk factors for T. gondii infection. Knowledge of these risk factors will help to target prevention efforts." http://cid.oxfordjournals.org/content/49/6/878.full
I have long suspected a parasitic role (either us or them for attention rather than brain damaging) or an element of craziness in our having so many cats. So far our own scientific analysis has been interrupted by near constant feline requests for attention, food or having to clean a little more than 'normal'.
Off topic but interesting. Guess "Iwo Jima" follows suit. I learn something new here every day.
It's actually 'shima' for island. Not sure if 'jima' works too, but shima is definitely more common.
> It's actually 'shima' for island. Not sure if 'jima' works too, but shima is definitely more common.
Correct, "island" is shima, but in this case we have a phenomenon in Japanese known as "sequential voicing" (連濁, rendaku) in which the first syllable of the second word of a compound is changed from an unvoiced consonant to a voiced consonant. This is particularly common when dealing with native Japanese compounds; i.e., compounds using words not derived from the imported Chinese pronunciations of characters. So "island" (島) by itself would be shima, but when used as a suffix, the initial consonant sh becomes voiced to j, and thus jima. Another example is "fire" (火), pronounced hi alone, but voiced to bi as the second half of words such as "fireworks" (花火, hanabi).
Still, it's amazing how such a primitive organism can change your brain's function - makes you wonder if there's a parasite that's making people stupid/smart/lazy/etc.
It's clearly a commensal symbiote: for cats, it assists them in catching prey.
In rats and humans, its changing prevalance helps adjust the relative expression of different behavioral strategies, faster than inheritance alone could.
For example, the risk-taking and increased libido in rats shifts the infected slightly along the K-strategy/r-strategy reproductive spectrum. In some environments that's a win, others a loss, but the T.gondii increases rat behavior diversity, and thus the species' adaptability.
Similarly, its modulating effects on human suspicion, gregariousness, investment in fitness-signalling (clothing), and obedience/trust sometimes help and sometimes hurt, depending on an ever-changing environment.
What if we 'cured' this and found the resulting human populations were less resilient against war, ecological stresses, and rapid technological/cultural change?
(I'm only half joking. And a meta-parasite is making me write apologetics for other parasites. And this entire comment is just a long way of saying "I, for one, welcome our new Toxoplasmosis gondii overlords" without getting immediately downvoted.)
The T. gondii, as viewed from the cat's perspective might be a symbiote, but from the rat's perspective, is certainly a parasite, isn't it? The T. gondii is benefiting at the expense of the rat. Do biologists classify things as both simbiotes and parasites?
Whether this is a net benefit at any one time probably depends on lots of things, and especially relative rat/predator populations. Just as human reproductive preferences seem to change in relation to wealth, population density, and life-expectancy.
Regarding semantics, I do think something can be both a symbiote and parasite. When I first learned of 'symbiosis' it was in the context of mutually-beneficial relationships, but it seems the term can be more general. Wikipedia says scientists sometimes disagree whether 'symbiosis' should only be used to describe 'mutualist' relationships (where both benefit) or also 'parasitic' (one benefits and other is harmed) and 'commensal' (one benefits and other neither harmed nor helped) relationships.
I should have used the word 'mutualist' in my above post, as that's what I was intending to imply. But the conjecture is intentionally fuzzy about whether the benefit is to the individual (it perhaps sometimes is) or the species (it perhaps always is, as long as both infection and non-infection are well-distributed).
I don't know about that, but I know ichneumonid and braconid wasps have built exactly that relation with viruses: http://en.wikipedia.org/wiki/Polydnavirus
Or maybe we will start vaccinating the kitties when they are young enough to start hunting.
Pregnant women already routinely get advice not to clean litter boxes and such, which, anecdotally, sometimes translates into getting rid of the cat.
I guess the parasite is working.
This reminds me of a lot of cat-people I know. But that might just be selective recall.
FUNNY HE SURE LOOKS LIKE ONE