Outside of Roanoke, Virginia, health officials scramble to find the origin of a deadly bacterial outbreak of pneumonia.

Health officials in Albuquerque, New Mexico face an outbreak of a rare and fatal blood disorder. Patients suffer sharp muscular pain, fatigue, fever and rashes. Twenty-one people die from the illness. Five other states report similar cases. The epidemic is spreading. The Center for Disease Control assists federal and state health officials in their hunt for the cause.

In late August of 1999, an infectious disease specialist in Queens, New York reports that she has two elderly patients with neurological disorders. More cases crop up in the following days, several patients die. Initial tests confirm that New York has been hit by an outbreak of the mosquito-borne illness, St. Louis encephalitis. Nearly a month later, exotic birds begin to die at the Bronx Zoo.

In August of 1998, Marilyn Miller is awakened by her son's frightened cries. She finds him suffering from a dangerously high fever and severe abdominal pains. As doctors work to stabilize him, she begins to feel the sickening symptoms herself. Doctor's suspect a food poisoning outbreak and direct her to call the Minnesota Department of Health.

On the tiny resort island of Martha's Vineyard, landscaper, Patrick Ryer, suffers from chills and high fever. Patrick has contracted Tularemia, a rare bacterial disease. Health officials alert residents and tourists who crowd the Vineyard over the summer holiday. Over the next month, ten more people are diagnosed with the disease, including other landscapers and children.

A hospital in Walkerton, Ontario is flooded with patients with the same alarming symptoms. All suffer from fever, nausea and gastrointestinal problems. Health officials suspect water contamination, but the Public Utilities Commission (PUC) reports that the water is safe. The next day, 20 more patients are admitted with the same symptoms.

In the summer of 2001, Debby Stoner's family begins to exhibit severe flu like symptoms. Upon visiting the family, who live in a small village on Maui, doctors discover that others are also suffering from strange symptoms including headaches, fevers and a bizarre red rash. Health officials are concerned they are dealing with a terrifying virus that is spread by mosquitoes.

During December of 1999, public health authorities in Alberta, Canada are notified of two cases of a rare form of bacterial meningitis. A third reported case claims the life of a seventeen-year-old. Soon after, six more cases are reported and another young life is taken. Health officials think a new strain of the bacteria may be invading the population.

In December of 1979, a young girl passes out on a bus in Wisconsin. She is taken to the hospital complaining of a sore throat, fever and aching muscles. Doctors believe she has the flu, until her blood pressure drops and her kidneys begin to fail. When additional women begin exhibiting similar symptoms, which bring them close to death, doctors fear an outbreak of toxic shock syndrome.

Canadian doctors are alarmed when a middle-aged woman dies of cryptococcal meningitis in 1999. Over the next few years, doctors see dozens of similar infections with pneumonia-like symptoms including shortness of breath, weight loss and severe headaches. Vancouver Island becomes home to the largest outbreak of the deadly fungus anywhere in the world.

In 1993, aquatic researcher Joanne Burkholder suffers an array of troubling symptoms while working in her North Carolina State University lab. A fellow researcher confides that he has recently been plagued by bizarre medical problems including memory loss, confusion, numbness and a burning sensation on the skin, symptoms identical to Burkholder's.

When an unpredictable germ terrifies Texas in 1998, the CDC and health officials alert all neighboring states and territories to be on the lookout for streptococcus outbreak, the same bacteria that causes strep throat. This new strain, however, will kill 33 people, causing flesh-eating viruses, introducing deadly toxins into the blood and introducing pneumonia.