Frequency of Disease
Epidemiology is important concerning causes and frequency of disease. The vocabulary of the frequency of disease is as follows..
INCIDENCE is the number of new cases in a certain population.
PREVALENCE includes both the number of old and the number of new cases combined.
(Both of the previous are expressed as a ratio of the number of cases divided by the number of people at risk)
Incidence = # of new cases/# of people at risk
Prevalence = # of old and new cases/# of people at risk
SPORATIC disease is considered when only a few cases occur within a population .
ENDEMIC diseases occur at a regular frequency within geographical distribution.
EPIDEMIC disease occurs at a greater frequency than usual within a population or area.
PANDEMIC disease is referred to as one that occurs simultaneously on more than one continent. (AIDS is considered pandemic worldwide)