Evidence-Based Practice for Nurses

8.2 Infectious Diseases

and Outbreak Investigations

By the end of this section, you will be able to:

‹ Discuss infectious disease using the epidemiologic triangle

‹ Describe transmission

‹ Describe the steps to an outbreak investigation

Because epidemiology is the study of the distribution and
determinants of disease in human populations, epidemiolo-
gists are by nature concerned with infectious diseases. Their
goal is to control infectious diseases and to eradicate them
when possible. Endemic diseases, which are diseases that
are localized to a particular geographic area, are controlled
to prevent epidemics or pandemics. Eradication of a disease
occurs when the infectious agent no longer exists in the
human population. For a disease to be eradicated, there
needs to be 3 years of data to support that the population is disease free with no
newly occurring cases. Smallpox is the only disease that has been eradicated.

Epidemiologists view disease through the lens of the epidemiologic triangle
(see Figure 8-1). The host is the human, the agent is the organism, and the
environment is the world in which we live. Each one of these components
contributes to the control of infectious diseases.

To better understand and control infectious diseases, nurses must understand
the transmission cycle. Transmission of disease occurs through both direct and

FYI

Epidemiologic principles provide the foun-

dation for public health and are useful for

supporting evidence-based practice. They

are used to determine the effect and extent

of disease in a population. Knowing these

determinations is important for decision

making regarding prevention, treatment,

control, and research of disease in populations.

FIGURE 8-1 The Epidemiologic Triangle

Agent Environment

Host

8.2 Infectious Diseases and Outbreak Investigations 195