14 Facts about Parasites - mental_floss on YouTube - List Show (314)

Hi, I'm Aaron Carroll, the host of Healthcare Triage

Over on our show, we're doing a month-long run on parasites that affect humans

The research for that show has pretty much ruined sleep for me. It's taking every bit of willpower I have not to scratch my head right now

We thought we'd share some of the pain with you. So, fair warning here, if insects or other creepy crawly things make you squeamish

you might want to watch something else. Still with us? Into the Breach

Did you know that bed bugs reproduce by traumatic insemination? After all, why use a female genital tract for its intended purpose when you have a sharp

penis-like thing that you can stab into a female's abdomen and just ejaculate there

It leaves the females with a gaping wound, which can get infected and leave them more

likely to die, but who cares? Not the male bedbugs, evidently. Get ready to fear everything, because that's the first of many fascinating, and sometimes

horrifying, things I'm gonna tell you about parasites today. Malaria is caused by the parasite Plasmodium

What's mind-blowing about this parasite is just how ridiculously deadly it is

The WHO has reported that malaria may have killed close to 200 million people in the

19th century alone. It still kills about 1.2 million people a year, and most of those are kids in Africa

There are experts who argue that malaria has killed about half of all human beings who

have ever lived. Really. Regardless, malaria kills way more people than almost any other infection, and yet we

freak out over things that are far, far less deadly way more often

Malaria's Plasmodium isn't the only horrible parasite that mosquitoes gift us with

There's also the Wuccararia bancrofti, a roundworm that causes filariasis. Once they get into your body, they first set up shop in your blood vessels

They're most commonly found in vessels in your peripheral circulation, which is sort of the outside as opposed to deep in your body, from about 10pm to 4am, meaning that

they're making some sort of decisions on where to hang out on your body at different

times of the day. Scientists think this is adaptive behavior to make them more likely to get into new mosquitoes

who might bite you at the periphery at night. Later in their lives, they move into your lymphatic system, where they grow and eventually

block it up. Then you get lymphedema and eventually elephantiasis, which most commonly affects the arms, legs

breasts, and scrotum, because why wouldn't it? There are other horrifying roundworms that cause filariasis

Take the loa loa worm. The larvae develop in horseflies, which can bite people and infect them

Then the larvae travel through our subcutaneous tissues At some point they stop and start to develop into adults If you lucky that be in your joints where they cause swelling and inflammation If you unlucky they get to your eye

If they do, they swim around in there and you can feel them swimming in your eye

If they get big enough, you can even see them in your eye

and they can live inside you for about 17 years. Tapeworms come in a number of varieties

but the ones that are more common in the United States come from beef. If you get one of these numbers

they can grow inside you to about 30 feet in length. The idea of a 30 foot worm is repulsive enough

but the thought of a 30 foot worm living in your belly is almost incomprehensible

Even if you get it treated, can you imagine passing that into the toilet

Can you? There's a flatworm of the genus, Riberia, that infects amphibians while they're tadpoles

Once it gets in there, it likes to head to the part of the tadpole that eventually becomes legs

Then it makes everything go wrong. Frogs infected with these larvae grow extra legs

that are tangled, weird looking, and monstrous. And when frogs like this are discovered

we often fear that they're living near radiation or toxins, but once again, parasites

Entamoeba histolytica is a single cell organism that can infect you for years

You usually get it from dirty water or unwashed food. Most times they stay in your gut and cause local disease

but sometimes they get out and invade other tissues, causing abscesses or pockets of infection

At the 1933 Chicago World's Fair there was an outbreak from contaminated drinking water

that infected about a thousand people and killed 58 of them from amoebas, single cell organisms

Although not a true amoeba, Nagleria falleri made news a couple years ago

because it killed a couple people in the United States. How? Ready for this

Neti pots. Yes, those things that some people use to wash out their sinuses

Turns out two people in Louisiana use tap water, which contain these guys

and they use the opportunity of being in their sinuses to work their way to the brain and murder human beings

I've never understood the allure of neti pots, to be honest, but the fact that they can let

brain-eating single-celled organisms into your skull pretty much sealed the deal that I won't be using them

Hookworms are the only worms that have teeth. Lucky them, unlucky you

because they use these teeth to latch onto your gut, where they can spend up to 15 years feeding and reproducing

And I mean reproducing, because the female hookworm can produce 20,000 eggs a day

for like 15 years. When you're infected, you can have thousands of these guys inside you

They can cause diarrhea weight loss difficulty breathing and even mental retardation in kids from blood loss and lack of oxygen to the brain Their Latin name is Nicator Americanis which literally means American murderer

Guinea worms prey only on humans. You get infected with them when you drink water

that's infested with their larvae. They mate inside your GI tract and then they start to grow

Eventually, female worms burrow their way out to the skin, where they create incredibly painful sores

by which they can exit the body. They exit very slowly, causing a burning pain as they do

There's no treatment for guinea worms. There's no vaccine. The best we can do, even today

is to wrap the part of the worm that's exposed around a stick and slowly pull it out

That can take weeks and it's not pleasant at all. One of the only things that soothes the pain

is to submerge the worm and the sore in water, which is of course exactly what you don't wanna do

as it allows the worm to release its larvae and start the cycle all over again

But here's some good news. In 1986, about 3.5 million people were infected worldwide

But today, thanks to efforts spearheaded by the Carter Center, by April 30th of this year

there had been only three documented cases in the whole world. It's thought that we might eradicate this parasite from the face of the Earth soon, which is amazing

Samothua exigua is insane. The parasite infects red snappers, the fish, by entering first through the gills

There it works its way to the bottom of the fish's tongue, where it latches on and starts to feed

As it grows, it takes more and more away from the tongue until the tongue withers away and falls off

At that point, it's about the size of the old tongue. So, it latches onto the muscles in the fish's mouth in such a way that the snapper starts to use the parasite as if it were a tongue

They can also change gender apparently, but that's not even interesting when you know the whole tongue thing

Horsehair worms, thankfully, don't mess with humans, which is awesome because they basically get their hosts to kill themselves

They mostly infect insects like grasshoppers. As larvae, they plant themselves on vegetation and form cysts for an unlucky grasshopper to eat

Inside the insect, they do the usual thing of feasting and growing right up until they want to mate

They need water for that. So what do they do? They release some compound that makes the grasshopper want water so badly that it'll jump right in

even though grasshoppers can't swim. The unlucky hoppers drown, and as they do, the horsehair worms come pouring out of their anuses

where they can mate and go about their happy lives. Let's talk about the emerald jewel wasp

otherwise known as the emerald cockroach wasp. Why? Because this wasp totally ruins a poor cockroach life When the female wasp is ready to reproduce she finds an unsuspecting cockroach lands on it and stings it right in the thoracic nervous system which paralyzes its front half This allows the wasp to deliver a second surgical sting right into the part of the brain which controls the cockroach escape reflex which basically turns it into a zombie

Then the wasp eats half of the roach's antennas. Why? No one really knows. Maybe for sustenance

And then it leads the now zombified roach back to its lair, by what remains of its antennas

When it arrives, it lays an egg on the roach and leaves the burrow and seals it with pebbles

to both lock in the roach and keep other predators out. The roach just lays there, like a zombie, alive, while the larva hatches, eats its way

inside and then consumes the cockroach's organs in an order which keeps the roach alive as

long as possible so that the larva has time to form a cocoon in its body

When it's done developing, it exits the dead roach and goes about its horrible emerald

jewel wasp life. That's not the only zombifying parasite. The dichrocyllium dendriticum is a fluke

that goes through a host of animals. They start their lives in snails

which get infested with the larva. The snails are smart though. They wall off the parasite and cysts and excrete them

But that's when things go south. Ants eat the cysts, which can contain hundreds of tiny little flukes

And most hang out and develop and do their usual thing. But one lucky fluke heads up

to the ant's subesophageal ganglion, where it takes control of the ant's nervous system

Somehow it knows to wait until it's night time, and then it forces the ant

by controlling its nervous system, to leave its home, climb up a blade of grass

as high as possible, and then bite down as hard as it can so it's stuck there

Why at night? Because evidently the sun and heat are harmful to the fluke

If the ant makes it till morning, the fluke will release its control and the ant scurries home

But it makes the ant do this every night, up the blade of grass, in the hope that eventually

a grazing animal, like a cow, will eat it. Then they infect that animal until they start their life cycle all over again

You made it the whole way? You rock! Leave it in the comments

Try not to get infected by parasites. Don't forget to be awesome