Diagnosis: Unknown

Doctors in Virginia treat six cases of pneumonia in one night, while tests confirm an outbreak of legionnaire's disease.

A fatal blood disorder kills twenty-one in New Mexico and five other states report symptoms; it takes six months of investigation to reveal the cause.

After a specialist reports two patients with neurological disorders, further cases appear and several die; tests confirm the source of the outbreak.

When apparently unrelated outbreaks of shigellosis strike, the source is traced back to a strain of bacteria from food served at local restaurants.

A man is diagnosed with tularemia, a disease that's so infectious it's on the US government's list of bioterrorism agents.

An Ontario hospital is flooded with patients afflicted with fever, nausea and gastrointestinal problems caused by a deadly strain of E coli.