4 Terrifying Parasites Found in Humans | What the Stuff?!

(playful music) (moves into upbeat music) – Parasites are organisms that survive by mooching off a living
host body, like yours. From single-celled protozoa that exist harmoniously within us to fleas that suck our blood to tapeworms that set up shop
in our intestinal tracts, humans play hosts to
millions of common parasites every year, but some are incredibly rare. (upbeat music) The sparganum worm, ah, yes, it’s hungry for human flesh, can grow to be almost a foot long, and may live for 20 years in your body. Charming sparganum. Though common in animals, the recorded infection rate in humans is something like one to two
dozen cases per year worldwide. Maybe because it doesn’t
always symptoms in its host depending on where in
your body it settles. But if it invades your brain,
inner ear, spinal cord, or eyes, it can cause symptoms
from headache and vertigo to blindness and paralysis. The moral of the story, avoid undercooked meat
and untreated water, and definitely don’t use
raw frog meat in poultices on your wounds or eyes. (upbeat music) The Gnathostoma spinigerum worm. These critters actually
aren’t able to reproduce inside a human body the way
they do inside other hosts like freshwater fish
and tasty crustaceans. Well, that’s good news for you. It’s bad for the parasite. Once you’re infected,
they live out their lonely 10-to-12-year life cycle
migrating throughout your body, causing swelling under your skin. This condition, gnathostomiasis,
has begun emerging outside of its common habitat
in the tropics of Asia. Cooking your protein of choice
to an internal temperature of at least 145 degrees Fahrenheit, that’s about 63 degrees Celsius,
will help keep you safe. (upbeat music) The Naegleria fowleri amoeba. This single-celled,
heat-loving parasite is found in warm freshwater lakes,
ponds, rivers, and hot springs. It infects humans by
entering through your nose. Then crawls straight into your brain through your olfactory nerves,
causing a swelling infection called primary amoebic
meningoencephalitis. At first, this seems like
bacterial meningitis, headaches, nausea, and a stiff neck, but it quickly morphs into
something much more serious. Think seizures and hallucinations. It can kill you in less than a week. The good news, of the hundreds of millions of potential exposures
every year in the U.S., only zero to eight cases are reported, and it’s more common here than anywhere else in the world. (upbeat music) The candiru catfish. Wait, catfish? What the stuff? Yes, this tiny Amazon river
fish, a relative of the catfish beloved as a food source
in the U.S., is a parasite. They’re usually less than three inches or eight centimeters in length, and they want to suck your blood. Well, they want to suck fish blood really, so they’ve adapted a
keen nose for nitrogen, which fish excrete through their gills. The candiru senses that nitrogen, gets in through the gills
and feeds off of the fish. But humans also excrete
nitrogen in our urine, and since candiru don’t
notice the difference between a gill and a urethra, well, just remember to use the bathroom before you go swimming
in the Amazon River. And that’s all the time we have today to talk about parasites and stuff, but if you’d like to learn
more, check out our article 10 Rare Parasites on HowStuffWorks.com. And, hey, if you liked this video, let us know in the
comments and hit subscribe so that you won’t miss the next one. Charming sparga, spar, (speaks gibberish). This one is… Pronunciation? Gna, gna… Gnathostoma spinigerum. We can’t stop. We can’t stop! (horns honking)

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