A teenage girl begins having strange mood swings from anti-NMDA receptor encephalitis; an elderly mother gets chills, hand numbness, wrist pain, and oozing blisters from Vibrio vulnificus she got from being pricked by a crab while making a stew; an athletic military veteran from the Afghan war competing in reality shows returns home from Fiji feeling hotness, a pinching sensation in her arms and toes, and hallucinations from rat lungworm she got from eating a slug in a reality show in the jungle

A 6-year-old boy suffers a nasty cough, fever, and vomiting from valley fever; a newlywed husband becomes paralyzed from the waist down due to the West Nile virus; an international journalist suffers extreme stomach cramps, night sweats, chills, nausea, and fever from Entamoeba histolytica.

A 23-year-old athlete/construction worker suffers multiple grand mal seizures and high fevers from eastern equine encephalitis; a hard-edged tough guy suffers severe stomach pains and loss of appetite from accidentally swallowing a grill bristle; a 17-year-old cheerleader who recently got her driver's license suffers a swollen, itchy eye and excruciating eye pains from Acanthamoeba keratitis she got from contact lenses.

A contractor gets hit in the head with a tool, and later starts getting a pounding headache, dizziness, spotty vision, and nausea from having a nail punctured into his brain; a football player in college gets extreme headaches, a stuffy nose, and blurred vision from Aspergillus fungi entering his brain; in 2012, an 8-year-old boy suffers constant vomiting, fatigue, seizures, and eventually dies from amoebic meningitis after being infected with Naegleria fowleri.

A Canadian science-lover and traveler suffers a painful lesion caused by botfly larvae; a video game programmer gets suffers from constant vomiting and coughing. When doctors find a large mass in his chest, it is discovered that he has histoplasmosis, which was contracted from inhaling bat droppings in a cave; a 15-year-old girl gets an extremely sore throat, a headache, nausea, and body pains from Lemierre's syndrome.

A war veteran suffers fatigue, high fevers, night sweats, strange rashes, bloody urine and jaundice from babesiosis; a 15-month-old baby girl suffers fever, dry mouth, vomiting and bloody diarrhea from E. coli O157:H7, whom she got from drinking raw milk; a biologist suffers extreme fatigue, back pains, anxiety, and vertigo from Aspergillus-contaminated breast implants

The second episode of the series to be Christmas-themed – a saleswoman gets a stabbing headaches and a constant burning sensation in her right eye from a Dirofilaria immitis worm that is in her eye; a store manager gets stomach pains, fatigue, nausea, vomiting and even a constantly moving stomach from a surgical sponge being left and forming a hole in his colon; a grandmother working in the forest service gets abdomen pains, fatigue, and pneumonia from Strongyloides stercoralis worms invading her intestines.

A teenager gets coughing, shoulder pains, dizziness, and nausea from Cryptococcus gattii fungi invading her lungs; a saleswoman gets extreme pain in her breast from a brown recluse spider (Loxosceles reclusa) bite; a religious youth organizer gets swelling of multiple parts of the body over the course of three years from the Loa loa worm.

A Canadian 13-month-old toddler gets breathing difficulties and mild vomiting from accidentally swallowing a button battery (for what the doctors originally thought was a coin); a college freshwoman gets migraines, nausea, on-and-off blindness, hallucination-like partial seizures, repulsive taste and two lesions in her brain from infection with Taenia solium; in 2008, a 6-year-old girl gets a headache, a rash, high fevers, and dies from Rocky Mountain spotted fever.

A 29-year-old man gets tooth pain and almost dies of necrotizing fasciitis caused by the bacteria Streptococcus intermedius and Peptostreptococcus; a female financial adviser gets fatigue, joint pain, mental confusion, hair loss, and muscle weakness for over three years from Lyme disease; a 7-year-old boy gets a loss of appetite, abdominal pains, a fever, diarrhea, constant vomiting, and weight loss from Cryptosporidium.