Outbreak investigations are a classic method in epidemiology; they have determined the causes of new epidemics such as Legionnaires' disease, Hanta virus, Ebola virus, SARS, and E. coli O157:H7. An outbreak investigation is designed primarily to identify the sources of unusual diseases or unusual numbers of cases of disease, as well as to prevent additional cases (Reingold 1998). The steps in an epidemiological outbreak investigation include finding cases, verifying diagnoses, and comparing rates with background expectations; interviewing both cases and controls about onset and exposure; establishing causes; and developing measures of control.

Disease outbreaks are almost always newsworthy and a topic of great public concern. The public reads many sensational tales of disease and heroism, real and imagined, with titles like The Coming Plague, The Hot Zone, Outbreak, The Demon in the Freezer, The Andromeda Strain, and Plague Time. But there are other, somewhat less thrilling, stories to be told about new pathogens.