normal expectancy; the community or

normal expectancy; the community or region, and the time period in which cases
occur, are specified precisely” (WHO). Epidemics are limited in space and time.
Gradually they end and incidence rates decline with time because of recovery, secondary
complications, or death. Immunity plays an important role in the recovery
process. If there is only a minor change in the antigen, the exposed and unaffected
may be vaccinated, the infected may be treated with drugs, drug prophylaxis can be
offered to the exposed, and secondary complications arising as a result of the disease
can be addressed. For example, individuals infected with influenza virus generally
present with upper respiratory tract signs and symptoms such as sneezing and
coughing and constitutional symptoms including fever, muscle aches, and fatigue.
Acute respiratory distress syndrome can result, and the patient may die. Effective
healthcare communication and timely action can stop the progression of disease,
saving thousands of lives.
Epidemic Curve
The graphic representation of new cases originating because of the rapid transmission
of a disease in an area during an interval of time is called an epidemic curve, or epicurve.
Assimilating data to produce this graphic is time consuming on the part of epidemiologists.
When retrospectively analyzed, the curve provides valuable information.
For example, the incubation period of a disease can be calculated if the time of exposure
is approximately known. The planning of responses to epidemics depends on the
magnitude of the situation and may be associated with the number of cases that can be
tracked on the graph. Looking at the pattern of the curve, one may be able to determine
whether individuals were exposed to the source at one time or continuously