1-13. USES OF EPIDEMIOLOGY
In general, epidemiology has three principal uses in the field of preventive
a. First, it may provide the key to discovering the etiology, or causative origin, of
a disease whose exact cause is not yet known. For example, during the London
cholera epidemic of 1849-54, John Snow, an English physician, established that cholera
was caused by polluted water and not by "bad air" as most people at that time believed
to be the cause. His hypothesis was based upon a study of the occurrence of the
disease within the city and the source from which each affected family obtained its
b. Second, epidemiology is used to investigate epidemics of diseases in which
the causative agents are known, but the means of transmission are unknown. An
epidemic of infectious hepatitis at Holy Cross University in 1968 was traced to a polluted
water supply by means of the tools of epidemiology.
c. Third, epidemiology is a useful administrative tool in the implementation of a
preventive medicine program. It assists us in planning the type of health care facilities
needed, planning education programs, identifying high risk groups, identifying areas in
which to locate health care facilities, and in many other facets of preventive medicine.