A baby falls mysteriously ill and struggles to breathe; a man has something living in an embarrassing place; a woman's weight gain confounds experts.

A mysterious infection brings a football player to his knees; parasites devour a stay-at-home mom's eyeball; a marina dock master is attacked by sea creatures.

A family's cruise ship vacation turns into a nightmare when their two-year-old swallows a sinister monster; a mother of two is plagued with a mysterious infection.

A man breaks out in a mysterious painful rash; a woman experiences bouts of piercing pain in her throat; a teen girl is left debilitated by strange spells of dizziness and fatigue.

A four-year-old boy is plagued by crippling pain; a college student with a small cut finds herself fighting for her life; a woman is driven to insanity by an intruder in her own body.

A young girl is brought to the hospital with stabbing pains in her scalp; a mother's mysterious symptoms threaten to tear a family apart; a deadly invader turns a relaxing vacation into a nightmare.

A man falls comatose; a college student's deadly sore throat; a woman's bizarre symptoms confound experts.

A man experiences strange swelling around his eye; a young girl falls mysteriously ill; a bizarre set of symptoms leave a young woman on the edge of madness.

A professor becomes an unsuspecting host; an infant falls mysteriously ill; a father is brought to the brink.

Doctors discover an invader in a young man's brain; a new mother is in critical condition; a young boy's illness defies antibiotics.

A toddler falls into a trance-like state; a strange condition strikes a boy; a woman's symptoms push her to madness.