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 21 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.

When Patrick Ryer suffers from a sudden onset of chills and high fever, doctors discover he has rare summertime pneumonia. Where has it come from?

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