Epidemiology of Disease

Infection vs Disease
Presence or absence of the etiological agent is the
main determining factor in the epidemiology of
infectious disease
Infectious disease cannot occur without a causative agent
BUT, disease need not always result from the presence of
the agent
Critical epidemiological distinction between
infection and disease
Infection – invasion of a living organism (host) by another
living organism (agent)
Disease - derangement in a part (or whole body) of host