How has toxoplasma turned the world into zombies?


Announcer

Welcome to Stuff You Should Know from howstuffworks.com.

Josh

Hey and welcome to the podcast, I'm Josh Clark. With me is the always lovely and effervescent Charles W. Bryant.

Chuck

I have on shorts today.

Josh

You do. You look like you're ready to go to the beach or play basketball or -

Chuck

In flip flops?

Josh

Or play beach at the basketball. And I meant the opposite of that.

Chuck

Play basketball at the beach.

Josh

Yeah.

Chuck

You can do that in Southern California buddy.

Josh

You can do anything in Southern California Chuck.

Chuck

That's what I hear.

Josh

Yeah.

Chuck

I can do anything because my wife's out of town.

Josh

I know, Chucks a bachelor today.

Chuck

Bachinette, as we say.

Josh

He looks terrible. He's dressed shabbily, he clearly hasn't showered.

Chuck

Bachinette for a few days.

Josh

He's got food stuff stained on the front of his shirt -

Chuck

It's probably steak.

Josh

And his beard, that's a big hunk of steak on your beard.

Chuck

It is.

Josh

So Chuck, how you feeling?

Chuck

I feel a little tired and under the weather because of my bachelor experiences. But I am ready to go.

Josh

Are you?

Chuck

Yeah.

Josh

You bringing it?

Chuck

Yes.

Josh

So Chuck you know how neurotic I am, right? Like right now I'm thinking about what you're really thinking about me.

Chuck

Yeah, you're a little neurotic. I wouldn't say hugely neurotic.

Josh

I'm definitely not Woody Allen neurotic.

Chuck

No, no, no.

Josh

But things like guilt, self doubt -

Chuck

Right.

Josh

What was the third one?

Chuck

Self doubt, you always think you stink on the show which is just ridiculous.

Josh

Well I do.

Chuck

Because you're good.

Josh

Regardless, these things drive me, right?

Chuck

Yes, they do.

Josh

So yeah, I would consider myself fairly neurotic and I recently found out Chuck, actually thanks to a new show that has inspired this podcast and the next one, we're doing a pair of them on parasites, it's an Animal Planet show actually called Monster's Inside of Me.

Chuck

Yes and the staff is parasite crazy right now.

Josh

It's all over the blogs. The blogs are lousy with parasites.

Chuck

Lousy with parasites because it's a really cool show. Have you seen it yet?

Josh

I've seen parts of it, yeah on the DMC.

Chuck

It's wicked cool.

Josh

Yeah, it is wicked cool.

Chuck

And frightening.

Josh

Yeah, I like it. I think it's cool. Mainly though because it relieves me from any responsibility from my own personality, my own horrible, disappointing, obnoxious personality, actually probably is the result of a latent infection by a little thing called Toxoplasma Gondii.

Chuck

Yup.

Josh

T-

gondii

ChuckT-gondii, I'm gonna call it --

Josh

Toxo.

Chuck

I'

m gonna call it Toxo

JoshOr T.

Chuck

You can call it T, I'll call it Toxo.

Josh

Okay. Yeah, just for ease of pronunciation.

Chuck

Yes.

Josh

But yeah, this is a parasite. It's a zoonotic disease which means we catch it from animals.

Chuck

Right, it's a relative of malaria.

Josh

It is but this thing is possibly running the world.

Chuck

Yeah. This is a little disturbing I gotta tell you.

Josh

A tad bit, so let's talk about T.

Chuck

Let's talk about Toxo.

Josh

Yeah.

Chuck

It is a parasite as we said. It has a complex life cycle, like most parasites. And the lifecycle has a purpose to get into its final host. And that word just crept me out, host.

Josh

Or definitive host.

Chuck

Yeah.

Josh

Yeah.

Chuck

And this one is unusual because it completes its lifecycle in one place and once place only and that is inside of a cat.

Josh

A cats guts, actually.

Chuck

A cat's gut.

Josh

Yeah, this is where T wants to be.

Chuck

Yes.

Josh

Because this is where it gets it on and reproduces.

Chuck

Yeah, so weird how it works.

Josh

Everywhere else, it does it goes to incredible lengths to get back into the cat gut.

Chuck

Yeah.

Josh

It's crazy like really honestly, we haven't gotten into this yet but this is like master blaster from Thunderdome. It's like the little guy, like just running things and making whatever it needs to carry it to the cat gut, do whatever it wants.

Chuck

Right.

Josh

To get it into the cat gut, right?

Chuck

Right.

Josh

And toxoplasma is actually really common. Estimates run to as much as 80 percent of the world population -

Chuck

I saw that.

Josh

Is infected, has a latent infection with toxoplasma, right?

Chuck

Yeah, 67 percent of Brazilians alone.

Josh

Yeah, but then on the other side, seven percent of the UK is infected.

Chuck

So yeah.

Josh

It's lopsided. And this may sound familiar already because for many, many years we've known that pregnant women should stay away from cat feces which is where you can pick up a T infection.

Chuck

We should go ahead and say that our guest producer, we have a guest producer this week.

Josh

Oh yeah, hey Lizzy.

Chuck

The lovely and fetching Lizzy. She thought I was kidding with her when I told her that.

Josh

Oh really.

Chuck

That pregnant women can't clean out the cat box. She thought I was pulling her leg and I was gonna like pull on her.

Josh

That was actually like the first public health warning I ever came across. I've known that since I was knee high to a grasshopper.

Chuck

Yeah, God I love that phrase.

Josh

Yeah, I know you do.

Chuck

So yeah, you're not allowed, you're not allowed, you're not supposed, the police - the cat box police will come get you. You're not supposed to clean out the cat box if you're with child because fetus is one of the things that can be harmed, but grown adults supposedly can't be harmed.

Josh

Yeah brain damage, birth defects, like serious birth defects.

Chuck

Yeah.

Josh

So yeah, if your lady is pregnant, you want to go ahead and take care of cleaning out the cat box during that nine months because that's how toxoplasma infections result from handling cat feces or more specifically, and I got the impression that it's much more virulent when cat feces mixes with soil.

Chuck

Right.

Josh

It has much more staying power, that kind of thing. So if you have a cat that likes to poop in your garden and you're a big gardener, you're gonna wanna murder your cat and get rid of all of your top soil and start over again, pretty much.

Chuck

Right. I imagine you could also get it from eating a rat because rats and mice tend to get it as well, but.

Josh

You can also very easily get it from eating undercooked livestock -

Chuck

Yeah, pork especially.

Josh

That has been around cat feces, I mean how many farms have cats on them?

Chuck

Quite a few I would say.

Josh

So let's talk about the lifecycle of this because it's interesting that you mention rats or mice because these things are under arguably the most control of T.

Chuck

Yes.

Josh

You know?

Chuck

That confuses me because I had a car named T.

Josh

So all right, I'll call it Toxo.

Chuck

Well I had a car named Toxo as well.

Josh

Man.

Chuck

It's not true.

Josh

Did you have one named T-gondii?

Chuck

No.

Josh

Okay well I'll go with that one. Thanks Chuck, you know I have this speech impediment.

Chuck

Well go with Toxo.

Josh

Okay, so Toxo gets into the soil, let's say your little kitty goes and poops outside and a mouse passes by the soil, passes over it, eats it, rolls around in it, plays with it, makes a little clay sculpture out of it and it's his friend and the rats infected. So this parasite actually goes through the bloodstream and travels to the brain where all sorts of freaky, freaky stuff starts happening to the rats behavior, rat or mouse.

Chuck

And that's slightly alarming to us because as everyone knows, which is why we use lab rats, we have very similar brains to rats.

Josh

Yeah.

Chuck

Chemically, the way it's put together, the whole deal.

Josh

Right.

Chuck

Which I've always thought was interesting.

Josh

Well let's talk about rats as the intermediate host.

Chuck

Okay.

Josh

So now a rat is infected with toxoplasmosis.

Chuck

Gross.

Josh

Its brain is being taken over. What are some of the weird things that begin happening?

Chuck

Well one thing I thought was most disturbing was they actually become fond of cat urine.

Josh

They do. They're attracted to the scent of cat urine.

Chuck

And they did a test.

Josh

Which is the opposite of what's supposed to happen.

Chuck

Yeah, they did a test did you see the one with the little sleeping, they made the little beds for the rats and one of them was soaked in cat urine and they would actually go for that bed.

Josh

They preferred that bedding over the normal bedding.

Chuck

Yeah.

Josh

Which is really weird.

Chuck

Really weird.

Josh

I read of another study that found that these rats were actually attracted to cat urine, not just the scent of it, they would go in an investigate cat urine and they investigated the brains of these rats, meaning they chopped their heads off and cut them open.

Chuck

They just didn't ask some questions?

Josh

No.

Chuck

Okay.

Josh

Although they did do studies, like they did different trials and what they found essentially was that the rats or rodents lose specifically their fear of cat urine.

Chuck

Okay.

Josh

That's it. Everything else remains intact. All other innate fears that they have that all rats and mice display remain intact. It's just their fear of cat urine.

Chuck

Yeah.

Josh

So they're attracted to cat urine plus also Toxo has an effect on your motor reflexes so you're not quite as fast as you used to be.

Chuck

Right, right.

Josh

So these two things together, an attraction to cat urine, the scent of cat urine and slow reflex time means that you can get eaten by a cat.

Chuck

And that means you get into your final host.

Josh

Right, that means the toxoplasma has made its way back into its definitive host, the guts of the cat by -

Chuck

Controlling the brain -

Josh

By taking over the brain of the rodent. And it's the coolest, most frightening thing I've ever heard of in my entire life.

Chuck

It really is.

Josh

Because like you said Chuck, like rodent brains are very similar to humans in composition, at least chemically right? That's why we're always experimenting on rodents to find out you know, how we can treat schizophrenia, that kind of thing. So which leads us to -

Chuck

Humans.

Josh

Since 80 percent of the human population is infected with a latent toxoplasma infection, is it having an effect on us, it looks like yes.

Chuck

Well yeah, for many, many years they always said, oh so many people have it but it's really not that big of a deal because once it enters the human body it's kind of, we're notgonna get eaten by a cat anymore, like a lion or tiger, so it probably doesn't matter.

Josh

Not only that, once we're infected they go inform a resistant cysts, they basically just hide and that's it. They don't do anything else.

Chuck

They set up camp in your body.

Josh

Right but generally that's it unless you have AIDS or another repressed immune system disease.

Chuck

Sure, that's when it can attack.

Josh

Right but it's gonna just sit there because we have antibodies that can you know, keep them in check.

Chuck

Right.

Josh

But that's what we thought.

Chuck

Exactly.

Josh

But around I think 1992 is when they really started to begin to look to see what kind of behavioral changes toxoplasmosis might cause in humans and we started to find some startling results like that lowered motor reflex time.

Chuck

Right, they did some tests that I know they did a couple. One where they were supposed to stroke a specific key stroke on the key board and in a certain amount of time and another where they showed a white recognition test where they showed like a white square on the screen and you were supposed to react when you saw the white square. And they found that people that had the latent toxoplasmosis, there was a lag, they were definitely behind the rest of the crowd in recognizing these things.

Josh

Right, you know who conducted that study?

Chuck

Your buddy.

Josh

A guy named Dr. Jaroslav Flegr.

Chuck

You just talked to him.

Josh

I just talked to the guy on the phone. This guy is arguable the preeminent expert. He's a parapsychologist out of Charles University in Prague.

Chuck

Did you call Prague just now?

Josh

Uh-huh.

Chuck

No way.

Josh

Way.

Chuck

Wow.

Josh

And I need to expense that because I did it on my cell phone because you know I'm not comfortable talking at my desk because I'm neurotic because I have toxoplasmosis.

Chuck

Yes.

Josh

Anyway --

Chuck

Because you play in cat poop.

Josh

Right so this Dr. Flegr, who is arguably the foremost authority on toxoplasmosis, he conducted that study and --

Chuck

And many more.

Josh

Right I think he conducted 11 and in nine of the 11 studies, there was a significant difference between people who are infected with toxoplasmosis and people who weren't.

Chuck

Yeah.

Josh

In humans, there's actually an equal and opposite effect defined by gender.

Chuck

This is what I thought was really interesting.

Josh

It's odd.

Chuck

It was almost dead opposite the way men and women were affected by this thing.

Josh

Yeah so -

Chuck

And women kind of got out ahead in this deal.

Josh

Yeah.

Chuck

Wouldn't you say so?

Josh

These are the women we love, the toxoplasmosis infected women.

Chuck

Those are my favorite.

Josh

Women who are T infected and not Chuck's car but the other kind. They tend to be warm hearted, outgoing, conscientious, moralistic. These are wonderful women.

Chuck

The salt of the earth.

Josh

Yeah, but also outgoing you know like everybody loves a gal who's willing to just try anything and you know, but also has a line which is moralistic so, yeah.

Chuck

Men though, men got the bad end of the stick. We tended to be stupider, but more loyal.

Josh

Is stupider a word? Are you toxoplasmatic?

Chuck

I am. Less intelligent, more loyal, frugal which was interesting and mild tempered.

Josh

And dogmatic. Did you say dogmatic?

Chuck

I did not.

Josh

So dogmatic meaning inflexible basically.

Chuck

Right, but they're both neurotic.

Josh

Basically guys who are infected with toxoplasmosis are jerks and women who are infected are cool.

Chuck

Right.

Josh

Yeah.

Chuck

But they're both neurotic. That was the one shared trait.

Josh

Right and so I talked to Dr. Flegr and I was asking, where are we as far as understanding how toxoplasmosis could affect us, physiologically our brain. And one thing I saw that kept coming up is neurotransmitters. He said the likeliest candidate is dopamine or dopamine as he put it.

Chuck

Oh, did he really?

Josh

He said it increases levels and he also has found that there are increased level of testosterone in men, lowered levels of testosterone in women who are infected with toxoplasmosis.

Chuck

That makes sense.

Josh

So he says in his opinion that would account for it. Again, he's a stickler on pointing out correlation, not causation. We are definitely at the correlation stage and understanding how toxoplasmosis can affect human behavior but he's finding some really cool stuff.

Chuck

Yeah, that's interesting about the, it kinda makes sense with the testosterone levels because they found that like we said earlier, 67 percent of Brazilians are infected with this stuff. In countries, they found where there were a lot of people infected with this; they were more likely to have masculine sex roles in this country.

Josh

Or more divergent gender roles, they're more pronounced distinction among genders.

Chuck

Exactly, the men go out and they're masculine, they do the hard work and the women -

Josh

They work inflexibly.

Chuck

Exactly.

Josh

And the women are just like, that's my man.

Chuck

Yeah, I thought very interesting.

Josh

Yeah, I mean think about it. If 80 percent of the population is infected with latent toxoplasmosis, then yeah this would conceivably alter cultures.

Chuck

Still a little hinky if you ask me.

Josh

I don't know man, it's still new research but I'm thinking it's starting to look like this parasite rules the world.

Chuck

Well it could be one factor -

Josh

Because we're ruled by toxoplasma, air ego toxoplasma rules the world.

Chuck

I think it's a bunch of factors, that's me.

Josh

Quiet.

Chuck

That's my camp.

Josh

So you know, Flegr also conducted a study back in 2002 in Prague where he -

Chuck

The driving test?

Josh

Um-hum, I think it was a 167 people who were identified as the causes of car accidents either as pedestrians or drivers.

Chuck

Yeah, which I thought was also interesting.

Josh

And he found that people with toxoplasmosis are 2.65 times more likely, that's almost three times as likely to be involved in a car accident as someone who's not infected.

Chuck

I think that goes back to the latent reaction time, wouldn't you think?

Josh

Could be.

Chuck

The delayed reaction.

Josh

Again though, well yeah. Yeah, how a red light affects our motor skills.

Chuck

Oops, crash.

Josh

Sure or if it makes us more reckless like if you're a man.

Chuck

Right.

Josh

Because we said that you're more willing to break rules if you're a man infected with toxoplasmosis.

Chuck

Right. Red light, screw it.

Josh

Exactly or this car will stop for me if I walk out in front of it, that kind of thing. But again, we're at the correlation not causation stage so -

Chuck

Everyone points that out.

Josh

It's entirely possible that people in Prague who have cats and would be more likely to be infected with toxoplasmosis are also more likely to zone out while driving thinking about how Princess Lady would look really good in a little cat tiara that you saw on line that morning.

Chuck

They said it could be a personality thing which I thought that was a little hinky too.

Josh

But there's also a correlation between schizophrenia and toxoplasmosis.

Chuck

Not hinky.

Josh

No, there's a definite link. And there's also a neurotransmitter called nitric oxide. This is not Flegr. Flegr actually said that he had not done much research on nitric oxide or nutric oxide as he called it. But actually some guys from Toledo, my home town.

Chuck

Really?

Josh

Some psychiatrists have been researching into it and there are increased levels of nitric oxide in schizophrenics and toxoplasmatics.

Chuck

And schizophrenics are more likely to own cats which I thought was odd. So says the University of Maryland.

Josh

Right, they own cats because the toxoplasmosis and the neighbor's dog tell them to.

Chuck

Right, actually not the University of Maryland, sorry Stanley Medical Research Center in Maryland.

Josh

I gotcha.

Chuck

Just wanted to clear that up.

Josh

So Chuck, what do you think? You think its still hinky?

Chuck

I think it's slightly hinky. I think there's something to it but I think it's some like I said, I think it's one of many factors probably. I don't think you can chalk up the machismo, the Brazilian man to cat poop.

Josh

Yeah, no.

Chuck

To cat poop, just yet.

Josh

So that's toxoplasmosis but if you are into parasites or this podcast has peeked your interest, Chuck and I would both strongly recommend that you watch that new show, Monster's Inside of Me on Animal Planet. What is it, Wednesday's at 9:00?

Chuck

Wednesday's at 9:00. It's a cool show. Cool graphics like CG, they get inside your body as if you were a parasite.

Josh

Yeah our parent company Discovery definitely threw some money at this one. It looks very cool.

Chuck

Definitely.

Josh

Yeah, so check that out. And we also have tons of cool stuff. You can also check out the Monster's Inside of Me website.

Chuck

Yeah, Robert Lamb.Josh: Robert Lamb wrote some really cool stuff and actually we have to give him a big thanks for pointing us in the right direction for research on this particular podcast. He knows what he's doing.

Chuck

He's parasitetastic.

Josh

Yeah and of course, howstuffworks.com has tons of stuff on it. And if you're interested you can also read all of our blog posts on it. There's like five million of them and each ones better than the last. Yeah, that's it for plug-in, isn't it?

Chuck

I think so, yeah plug heavy for a change.

Josh

Which means buddy, it is time for Listener Mail.

Chuck

So Josh, I'm just going call this We're Awesome Because We Saved a Women's Life.

Josh

Yeah this is crazy.

Chuck

It is, slightly hinky, but I'll take credit. Bonnie from Boulder, Colorado wrote in and Bonnie says this: Hi guys, stuff you should know just saved my life. The facts are these. I was driving home and just finished listening to your Hypermiling podcast. As a result I was only going 40 miles per hour on a stretch of highway where I usually go 60. All of a sudden, there was a pair of headlights right in front of me. Some genius was going the wrong way in the same lane of the highway as me. Short story even shorter, I ended up facing the wrong way on the highway. Thanks to some recent rain and some awful skidding and sliding, but due to the late hour, lack of other cars and my slow speed, I avoided hitting anything. Who knows if I would have had a head on collision and if I'd been going my normal speed, but I do know that thanks to you two and you're always enlightening podcasts, I will never have to know. Many thanks, you're immensely appreciative listener and fan. Bonnie of Boulder, Colorado.

Josh

Thank you Bonnie, that's awesome.

Chuck

Dude, honestly, what if would have been going 20 miles an hour that could have made all the difference.

Chuck

Oh yeah, definitely.

Josh

Even if it was just a fluke thing.

Chuck

I'll take credit.

Josh

Yeah, even it wasn't fluke; we still picked up an adventured servant for life.

Chuck

Yeah and personally, I think we should get a key to the City of Boulder so.

Josh

Yeah, I've been angling for one of those for a long time.

Chuck

The key to any city?

Josh

No, Boulder.

Chuck

Oh okay.

Josh

Yeah so this is our in for sure.

Chuck

Hope so.

Josh

Maybe a t-shirt even.

Chuck

Sure. Or Boulder is for Lovers -

Josh

I saved Bonnie's life and all I got is this lousy t-shirt.

Josh

That's a good one. If you have any good t-shirt ideas or any instances of how Chuck and I saved your life, you can send them in an email to stuffpodcast@howstuffworks.com.

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