A four-year-old is drowning in his own mucus; the wound on a seven-year-old's knee has a vile cause; a college student has bizarre dreams before being hospitalized.

The lives of three families are twisted in knots. A mysterious infection brings a tough ultra-marathoner to his knees. A teenager contracts one of the most feared diseases on the planet. And a woman's brain is practically set on fire.

A man's leg is torn apart by an infection; a rare brain infection pushes a 7-year-old girl towards suicide; another infection lands a woman in the hospital.

A couple's home turns into a living nightmare; an insidious creature takes a man's spleen; a domestic pet takes a boy to the edge of death.

A baby boy faces near death from a common household item; a parasite eats a man's lungs; a female boxer fights for her life.

A 2-year-old girl writhes in pain and is near death; a neuro-psychiatrist suffers multi-organ failure; a woman's life hangs by a thread.

A mysterious infection eats a college student's eyeball; a 6-month-old is paralyzed in 24 hours; a mother giving birth gets a nasty surprise.

In California, a mysterious infection is shutting down a teenager's lungs; in Hawaii, a personal trainer is afflicted with nerve pain when something attacks her body; and in Michigan, a parasite is eating the blood of a health worker.

A cut on his knee makes a teenager feverish and fatigued; a couple move into their new home in New Mexico to rashes, breathing difficulties, and memory loss; and in Hawaii, worms are destroying an 8-year-old's retinas.

A Christmas baby gets a brain infection in utero; a woman suffers an infection during Hanukkah; and seizures ruin a schoolteacher's Thanksgiving and Christmas.