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.

When doctors cannot find anything in his mouth, biology professor John Allen takes matters into his own hands and extracts a rare parasite called Gongylonema pulchrum.

A school girl cannot understand why she's finding it so hard to breathe, until the is revealed that there is a fungus spreading throughout her lungs.

Brenda's painful headaches have sent her to the hospital, where doctors make a surprising diagnosis.

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

When one woman checks a wound on her leg and sees a tube-like creature MOVE and retract into her body - she heads back to the doctor immediately.

After suffering from an array of symptoms for months, Al Ceccarelli is diagnosed with Strongyloides, a disease caused by parasitic worms found in tropical climates.

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.

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.

A fishing trip turns into the vacation from hell when Rick's ankle injury turns into a matter of life or death.

Lauren is a happy 7-year-old girl… until she begins suffering from tics, anxiety and manic episodes. Her symptoms build up to a terrifying breaking point.

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.

When a Dad and soldier has been hospitalized for extreme pain, jaundice and fever, doctors finally diagnose him with a very frightening parasite: 'Babesia.'

After spending two months in a coma as a result of a Group A Streptococcus infection, Katy wakes up to the devastating news that all four limbs had to be amputated in order to keep her alive.

A young woman's life has been deeply affected for five years by fatigue and illness, when the cause of Lyme Disease is finally discovered.

SNEAK PEEK: When a 15-month-old girl has a fever and bloody diarrhea, her frantic parents race her to the hospital. WHAT could be ailing this poor baby?

After complaining about pain on his head, 8-year-old Andrew is rushed to the ER, where doctors remove a botfly larva from his scalp.