Buccinum polare, a species of sea snail
A healthy human body is chock-full of good things. Peer under the hood and it's an engine comprised of indispensable internal organs and useful liquids such as, well, blood. Save for a few vestigial oddities, all are necessary. But sometimes the body takes on unwelcome visitors from beyond its borders, and that's when things can get a bit gnarly.
Take a look at a few of nature's critters that have no qualms about setting up shop on our insides, and sometimes even making a meal out of us.
Just this month, in Orange County, Calif., a 4-year-old boy made a strange discovery: There was a sea snail in his knee. He'd gone on a family camping trip and cut his knee. His parents patched up the wound, but not before a snail egg found its way into the cut. A few weeks later, the wound had grown into something that looked decidedly pus-filled to his mom. She squeezed it and out popped a snail! (It lived for one more day before shuffling off this mortal coil, but the boy kept its shell.)
Earlier this year, a British tourist returned from a trip to Peru, but home didn't provide her much comfort. She started getting headaches, sharp pain in the side of her face and even a mysterious discharge from one of her ears. She also heard (steel yourselves!) unexplained scratching sounds. Turns out her ear was filled with flesh-eating worms -- larvae of the screwworm fly (that would be Cochliomyia hominivorax, for the classification-minded.)
The woman, Rochelle Harris, had been pestered by flies at one point during her Peru trip. One of them had enough time to deposit its eggs in her ear. The maggots feasted, making a small hole in her ear canal, but Harris had no lasting damage from her accidental exercise in larvae hosting.
File this one under definitely maybe. Though science has yet to confirm conclusively this behavior, the candiru, a tiny Amazonian catfish, is said by some to be drawn to human urine and will attack through the urethra.
Maxing out at about 3 inches (7.6 centimeters) candiru feed on blood and keep their senses attuned for nitrogen, which is excreted in, you guessed it, human urine. The idea is that the catfish will head for the urethra and make a new parasitic home, if the right swimmer with the right level of bladder urgency appears. Urban legend or not, people may want to resist the urge "go" while swimming in the Amazon.
An adult specimen of the pork tapeworm, Taenia solium, from the intestine of a human.
A fully functional brain is a wonderful thing -- ask anyone who owns one. But it's less wonderful when it's being eaten by a worm.
In 2008 a Phoenix woman, Rosemary Alvarez, thought she was having surgery for removal of a brain tumor, and so did her surgeon. What the doctor found, instead, was a parasitic worm -- Taenia solium, a.k.a. a pork tapeworm -- feasting on her brain. Leading up to the surgery, it looked for all the world like a brain tumor, but it turned out Alvarez had been served food tainted with the feces of a person infected with the parasite. Her surgery was a success and the worm -- by no means the only troublesome tapeworm out there -- was evicted from the premises.
An image of Trophozoites of N. fowleri in brain tissue, stained.
The nose is the point of ingress for another "brain-eater," an amoeba called Naegleria fowleri. The organism lives in warm, fresh water and has killed several people in recent years. It travels to the brain once it enters the nose, causing fatal swelling. Infections are rare -- only 128 cases since 1962 -- but the odds of survival are extremely poor once the amoeba has found its way into the body.
For those not comforted by the long odds of infection, the bottom line for staying safe from these beasties while frolicking in fresh waters is to wear nose clips.