Recall that epidemiology is the study of the occurrence and distribution, cause and control, and treatment and prevention of disease and other morbid conditions. Epidemiologists rely on surveillance not only to spot the occurrence and distribution of disease, but to act as the baseline of data needed during investigations into the cause and control of outbreaks. Surveillance is the monitoring of a population’s morbidity and mortality through data collection, analysis, interpretation, and reporting. Surveillance results are used in health promotion and disease prevention programs. It is a primary activity of international, federal, state, and local-level public health agencies. Foremost, surveillance identifies indicators of endemic and epidemic diseases. The former means the usual incidence and prevalence of disease and other behaviors affecting health status; the latter represents the greater than expected incidence or sudden increase in prevalence of disease or other behaviors affecting health status (Lilienfeld and Stolley, 1994).