Toxo, the cysts in our brains from cats, can improve self-control (2013) | Hacker News Reader

Toxo, the cysts in our brains from cats, can improve self-control (2013)

theatlantic.com

103 pointsDLay62 comments

There's a fascinating RadioLab episode which focuses on various parasites, including Toxo (Season 6, Episode 3: http://www.radiolab.org/story/91689-parasites/).

One of the key mechanisms of Toxo's behavior is that it can penetrate the brain of rodents and make them sexually attracted to feline urine -- the point is to facilitate the reproduction of the parasite which can occur only on feline intestines.

Some additional examples: http://www.businessinsider.com/scariest-parasites-in-the-wor...

The Sacculina genus of parasitic barnacles--which has dozens of species--is spectacularly creepy: http://en.wikipedia.org/wiki/Sacculina

They infect both female and male crabs and completely subvert their biochemistry, to the extent of feminizing the males. They then lay their own eggs in the crab's carapace, the way the crab normally would, and the crab--male or female--behaves as if it was carrying its own eggs.

wow I've never heard podcasts like these. I already like the story-telling.

Two theories I've thought about.

I have a theory that those infected with cats promote their cats on the internet via photos, videos and social networks. More so than dogs, or other pets, for example. In terms of stories, anecdotes or praise about the animals, a cat would have less said about them, but more and more images and publicity about them. Why? Possibly because the parasite requires animals to have more contact with the cat?

The second to last paragraph in this article is fascinating to me also. Those with flu are more socially outgoing, and I have read that they are more flirtatious, wearing less etc. It leads to a theory that these viruses could actually be sexually transmitted and actually encourage more sexual activity. Slightly related perhaps: the stereotypes of "cat ladies" being single is not because they are single, but because they have cats!

I'm slowly collecting these theories - and the wilder the notions the better when it comes to brain controlling parasites. Of course in terms of behaviour, the range of human behaviour is so wide it almost encompasses the slight influences of parasites. Makes you think what else is in us that could be contributing to our behaviour.

Here's a good take on why we share cats on the internet, including brain-control, by pbs' idea channel: https://www.youtube.com/watch?v=NJ_6aRjYR0w

If the parasite does promote internet-sharing behavior, I can't see it being anything but coincidence. The internet hasn't been around nearly long enough for toxo to evolve around it.

>> Up to a third of the world's human population is estimated to carry a Toxoplasma infection [http://en.m.wikipedia.org/wiki/Toxoplasmosis]

That's almost inconceivable. The other studies around this bounce from 10-25% too. I assumed toxoplasmosis was rare - but that kinda scares me.

How do I get a test for me and the family?

Hmm... The wiki page says that about the antibodies, i.e., that many people have at some point been infected... but my understanding may be off

https://news.ycombinator.com/item?id=8443427

It shouldn't really. Your immune system evolved in an environment where it expected to be under constant barrage from foreign organisms, in the absence of those many modern people suffer from diseases of the immune system where it misbehaves because it doesn't have enough to do.

"Most infected cats will shed oocysts only once in their lifetimes, for a period of about one to two weeks."

Your question is best addressed to your physician. If you spend too much time reading about diseases, you'll spend all of your time needlessly worrying about them.

Yeah, I look forward to perfect medical-introspection technology, but I don't think we're ready for what we'll find. I suspect we'll find that we're positively riddled with parasites, subclinical tumours, and all kinds of squick.

A new business idea (inspired by colechristensen's comment: "Most infected cats will shed oocysts only once in their lifetimes, for a period of about one to two weeks.") - How about selling infected cats who's already shed their oocysts, i.e. "safe cats"? Don't downvote, I'm joking.

What about bio-engineering cats that fluoresce when they're infected?

GMOphobes will close you down before opening!

Is the article sensational when it says that about cysts in the brain? Cause I've had a cat for over 4.5 years now.!?

The wikepedia article says that Toxo is linked to ADHD and OCD, both of which I have, OCD since last year.

While lots of people mention the connection between cats and toxoplasmosis, it's actually more likely for you to get it from eating undercooked meat than from your cats. It comes out in their feces, and you would need to eat the feces to get infected; so while it can happen if you clean the litter box and don't wash your hands afterwards, it's not all that likely.

It is also carried by chickens and pigs, so if you eat undercooked pork or chicken, that could be a risk factor.

Cats use the litterbox and then lick their paws, as well as the rest of their body. If you pet your cat and then absent-mindedly eat something (like I've done all too often, unfortunately), you may become infected.

Throwaway for obvious reasons, but this would actually explain a lot. Oh god...

Hmm, might be a decent reason to train your cat how to use a toilet.

Infection control doesn't work like that.

Anything that touches the cat's litter or butt might be infected. I.e. you'd have to keep the cat off your furniture, especially eating or food preparation areas -- every time. You'd have to not ever put your face on something that the cat might have snuggled against, or walked on. It's just not feasible.

Cat's get far more blame than is really warranted. In order to get it from a cat, you need to first have the cat get infected by eating an infected mouse, then during a roughly two week period where it is shedding the parasite in its feces, you need to eat the cat's feces. If either your cat does not have access to mice to eat, or you don't eat your cat's feces, then you are fine.

To be clear, you don't need to "eat" the cat's feces. Tons of human infections spread by the same route (feco-oral), almost none of which are caused by humans literally eating other humans' feces.

For example, have you ever seen a cat lick its paws? And then lick it's fur (that you pet)? Well, those same paws have been in the cat's litter box (as pointed out by another comment).

Also, if you empty out the litter box and the feces are dried, they can create dust which a human might breath in (and swallow).

So just as with humans, infections spread from cat to human by feco-oral route are not literally from "eating feces".

You let the cat outside, and changed its litter-box.

No I don't let it outside, that's the point. And I don't eat anything I find in the litter box while changing it.

do you really think that the people who get the parasite are knowingly eating pieces of cat feces?

No, I think they are eating undercooked meat. Remember, a cat can only spread it for about two weeks. The people who do get it from cats are most likely not washing their hands after cleaning the litter box. That is eating feces, just indirectly. I do not do that, I wash my hands.

Or petting a cat. Or allowing a cat into their bed. Or sleeping on a couch that an infections cat has climbed onto. Or the cat walks across the dinner table or kitchen counter.

You seem to have a really wrong mental model of how fecal-oral transmission happens.

If I have Norwalk (Norovirus) someone else doesn't need to literally lick my butt or eat my feces to get it. If I wandered around their apartment naked (interesting image) and sat on or walked across random pieces of furniture, they'd be very likely to get it.

You are seriously overestimating the likelihood of transfer via those methods. The odds are actually very small. Simply having a cat walking around gives you very poor odds of transmission. It is not a cold.

Do you touch the faucet handle with your hands and then touch it again when you are done washing?

You're missing out, there's some really tasty stuff in there.

"Most infected cats will shed oocysts only once in their lifetimes, for a period of about one to two weeks."

I don't understand why the downvote though.

I don't understand what you are talking about.

I keep getting downvoted for no obvious reason.

Ok, but why are you asking me about it? I don't control everyone on HN. I can't downvote anyone yet, this is a new account.

Not every cat carries it and not everyone having a cat gets it.

Source? Two cats, a wife that gave me two perfect kids and mandatory 'Do you have that condition' tests during both pregnancies.

So .. she didn't get it. I assume I didn't either. And really, don't fall into any kind of panic mode. Consult your doctor if you want/must, but .. don't treat random articles on the net as medical advice (that includes this very post).

From the stuff I've read, it's normal to think about being infected with this. The symptoms are very vague sounding, after all.

In reality, the effects of Toxo are very subtle. A team of 50 research subjects are needed in order to detect a statistical change in behaviour.

More here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3515034/

The link of Toxo with cats will always be there because "Cats are the only place that the parasite can reproduce sexually."

According to a recent microbiology lecture I had, you are not at risk unless your cats go outdoors.

I believe there is a parasite that infects snails that similarly alters their brain chemistry to drive them to reckless behaviour (if that doesn't sound too comic wrt snails) such that they are more likely to be spotted and eaten by birds, thereby enabling the parasite's dispersal. In fact a hell of a lot of biology and evolution can be seen to be driven by parasitism. The book "Parasite Rex" is a good if unsettling source.

I love(d) cats, but after reading this [1] back in 2012 again, in The Atlantic, I stay away.

[1] http://www.theatlantic.com/magazine/archive/2012/03/how-your...

You are perhaps missing the point, then. You are vastly more likely to get toxo from undercooked meat or unwashed vegetables than from cats, especially if you don't clean litterboxes yourself. Recoiling in horror from cats and cat owners is not productive behavior.

Why do you assume I eat undercooked meat or unwashed vegetables? I was talking about myself and my family, not what everybody else should be doing. I'm Bulgarian and the meat we eat is either well-done (roasted or fried) or boiled (healthiest, no doubt) - we don't ever eat rare meat. That's why we don't like beef - it's hard to chew unless it's rare. Regarding the veggies, our culture is to eat veggies in soups or fried (not ideal, I know), and we eat limited veggies raw, but most of them area easy to clean (like tomatoes, sweet peppers, and cukes), but, in general, washing well or cutting outer layers (which usually contain the most nutrients, I know) is done as people are very cautious. I'm always surprised how farmers markets here in the States give samples from unwashed produce - I'm literary getting grossed out! Some of the germs on them are beneficial, I know, but the risks outweigh the benefits.

You've missed the point entirely. You're looking at toxo infection rates and saying "My God, cats are riddled with disease, shun them!" But most of those infections are not caused by human contact with cats. There's no need to "stay away" from felines as long as you wash your hands after petting them or cleaning the litterbox.

No, I'm not missing the point - I have kids and although they have good hygiene, they don't always wash their hands. In the States though, people are crazy - I've see tons of videos of cat licking people's mouth (right after they wiped their ass clean), sleeping in their beds, and same applies to dogs. Caution is good. In fact, if you read The Longevity Project book, the conclusions are clear - overoptimistic and non-cautious people live less. Also, the myth that living with pets increases lifespan is also busted.

I've always been suspicious of cats.

"it seems to make men more introverted, suspicious, unattractive to women, and oblivious to the way others see them"

So basically, cats created 4chan and its userbase. Well played!

But seriously, none of these articles ever seem to mention that a cure is being worked on. Also, is there an easy way to test for this parasite?

> introverted, suspicious, unattractive to women

I suspect I may be infected.

I think we all are and that's the reason why we're here...

You can detect the infection with an antibody test [1] and treat it with antibiotics [2].

[1] http://en.wikipedia.org/wiki/Toxoplasmosis#Diagnosis

[2] http://en.wikipedia.org/wiki/Toxoplasmosis#Treatment

Ok, so there is a parasite that happens to alter human behavior, and a significant percentage of the human population is infected.

Why is it that I

- have never heard of large-scale testing for infection

- have never heard of an effort to contain or eradicate this parasite (compared to e.g. rabies)

I don't know, it kind of seems like a big deal, or am I completely mistaken?

Because pet enthusiasts are generally highly irrational when it comes to the harm pets can cause? Or more generally, we're acculturated to think of certain things as normal due to widespread exposure or lack of alternatives.

If I punch you in the face, causing you to stay home from work for a few days, but no other lasting damage, I'm a violent criminal. If I go to work while exhibiting flu symptoms because "I just can't afford to stay home", then I'm just a normal human being.

If you're raised in a culture where pet ownership is normal, then the unhygienic aspects of pets are just cleanliness-minded-people-freaking-out. If you're raised in a culture where pets are considered "unclean", then you have a different perspective on people's right to inflict their pets on others.

Because the modifications are slight and still within the normal range of variation in the uninfected population.

Yes, but it seems like it has effects simular to a slight depression on men. So it impacts quality of life, at least thats the impression I got. So even if it does not cause huge costs for the health care system or unability to function in life or work, it still seems strange to just ignore it. At least pregnant women are tested it seems.

Toxo causes the brain to produce more dopamine. Dopamine is released in novel situations (i.e. Stumbling on scattered cash). Seritonin is released during consummatory behaviors (i.e. Eating, sex, etc). While most of the released dopamine and seritonin released is part of private conversations between neurons some of the molecules leak out and diffuse through the brain. These background levels of dopamine influence the brain more globally and the brain uses the ratio of dopamine to seritonin as a measure of 'status' meaning 'of how much there is to get (dopamine), how much am I getting (seritonin)'

Lots of dopamine and little seritonin influence behavior in a lot of subtle ways. It puts reaction times on a hair trigger which makes movements quick but spastic (improves video games, destroys handwriting). Increases the likelihood to escalate quickly when threatened (get away from my stuff!). Increases libido. Mild OCD type behaviors. Etc, etc, etc.

Women seem wired to pick up these clues and avoid low status men. On the flip side. Makes great programmers.

That was quite interesting. The only thing that doesn't fit well with my life experience is the "high libido" part. The high dopamine crowd seems to be less interested in sex than the average male, in my impression.

Look at some of the side effects of dopamine agonists used to treat Parkinson's disease. Hyper sexuality and gambling addictions are common. But I'm not going to argue with your life experience. However there is a difference between desire and expression of that desire which many learn to supress.

Dopamine also increases exploratory behaviors; suppresses oxytocin release (cuddle hormone) and reduces social bonding; increases the ability to form memories; reduces the ability to forget. Think the BBS version of Sherlock Holmes.

> - have never heard of large-scale testing for infection

Every pregnant woman gets tested, isn't that large-scale enough?

Didn't catch that one - thx!

Rabies is horrible and obvious. This is mild and subtle. It is not more extreme then most of the random things in your environment that modify your behaviour.

Rabies leads to an excruciating death...

Because they don't want you to know, clearly.

I realized it sounded a little paranoid after posting it - didn't mean it that way.

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