After a woman suffers having cysts surgically removed from her right breast, things get even worse when surgical sponges are accidentally left inside of her.

A dream vacation to South America becomes a nightmare when a man's face begins to be eaten away by a parasite.

Tara keeps feeling stabbing pains in her scalp, so she investigates the Internet for answers. What she finds is almost unbelievable - botflies. She decides to cut open her scalp.

Boil-like legions lead to a diagnosis of lung cancer, just in time for Christmas. But during surgery, doctors are surprised to find a different sort of infection.

Found in contaminated food and water, Entamoeba histolytica is a parasite that feeds on living cells in the human gut.

After eating some raw sushi, a woman begins a fight for her life as a mass containing parasitic worms creates a blockage in her colon. The woman has Anisakiasis, a disease caused by Anisakis worms.

A disease begins eating a boy's face from the inside, forcing doctors to begin removing the infected flesh to save his life.

A happily married couple's trip to New York becomes a nightmare when they learn that they have been infected with the Bubonic Plague, not only putting their lives in danger but anyone who comes into contact with them.

Leishmaniasis kills skin cells in mass numbers, causing prominent skin sores. In extreme cases, it attacks the face itself, leaving the victim disfigured.

The Leishmania parsite feeds directly on the vital organs from the inside-out. It's spread through infected sand flies.

Acanthamoeba is a voracious parasite that enters the body through the skin or the nose, then devours brain cells.

While swimming with a friend a man has a seizure and collapses. Shortly after, he finds out that a pork tapeworm has been slowly eating away at his brain!

Even dead, the larvae of parasitic roundworms can cause river blindness, or Onchocerciasis. These parasites are transmitted through the saliva of blackflies.

Burrowing through the skin and internal organs, gnathostoma worms can eventually cause paralysis and death.

The pork tapeworm is a particularly vicious parasite because it can end up in the most important organ in the human body: the brain.

A fitness fanatic cannot understand why he is too fatigued to work out until he learns an infection in his colon has created a tear, causing e-coli to spread through his body.

The pork tapeworm is a particularly vicious parasite because it can end up in the most important organ in the human body: the brain.

Armed with jagged teeth used to hook onto its host, the hookworm can be transmitted from your household cat onto a human.

Found in contaminated food and water, Entamoeba histolytica is a parasite that feeds on living cells in the human gut.

Acanthamoeba is a voracious parasite that enters the body through the skin or the nose, then devours brain cells.

Even dead, the larvae of parasitic roundworms can cause river blindness, or Onchocerciasis. These parasites are transmitted through the saliva of blackflies.

Found inside undercooked wild game and pork, Trichanella spiralis is a parasitic worm that can cut through human muscles and tissue.

The Leishmania parsite feeds directly on the vital organs from the inside-out. It's spread through infected sand flies.

After taking a trip to a local water park, a man is fighting for his life while a parasite eats his intestines from the inside out.

While swimming with a friend a man has a seizure and collapses. Shortly after, he finds out that a pork tapeworm has been slowly eating away at his brain!

After eating some raw sushi, a woman begins a fight for her life as a mass containing parasitic worms creates a blockage in her colon. The woman has Anisakiasis, a disease caused by Anisakis worms.

What happens when humans fall prey to parasites? Explore the shocking, gruesome and sometimes deadly details of parasitic infection on Monsters Inside Me. Returns Friday, Oct. 5 at 8PM E/P!

Burrowing through the skin and internal organs, gnathostoma worms can eventually cause paralysis and death.

Unclean sheets and linens carry human scabies mites, which feed on human skin, causing intense itching. The condition is called scabies, or simply "the itch."

A young woman contracts a parasite, Trichinella spiralis, after eating infected meat. The condition, called trichinosis, can cause paralysis as the worms burrow through her muscles.

Some of the most horrifying creatures on the planet are ones that are too small to see! Get a glimpse of these monsters in the new show "Monsters Inside Me", premiering Wednesday, July 1 at 9 p.m. only on Animal Planet!

Anisakis worms, common in marine mammals, don't fair so well in the human body. The dead worms can create an inflammatory condition in the gut called Anisakiasis.