Background
Definition of Disease
Infection that results in signs (objective) and symptoms (subjective).
Types of Surveillance
Passive Active Syndromic Sentinel
Public Health Approach –
primary role is in control and prevention of disease in populations or groups of individuals, some activities (e.g., diagnosing cases associated with outbreaks and treating persons with communicable diseases such as tuberculosis or syphilis) may overlap with those in clinical medicine.
Mortality
The rate of death in a population.
Syndromic
Signs of the disease (such as school absences or prescription drug sales) are monitored as a proxy for the disease itself. The symptom must be infrequent and severe enough to warrant investigation of each identified case, and must be unique. This form of surveillance is often used when timeliness is key, diagnosis is difficult or time-consuming, or when detecting and defining the scope of an outbreak.
Odds Ratio
used in case-control study
Infectivity
The property of establishing infection following exposure.
Sentinel
Professionals selected to represent a specific geographic area or group report health events to health agencies. This is used when high-quality data can't be obtained through passive surveillance. It involves monitoring trends or key health indicators and a limited network of reporting sites. Advantages include being able to implement intervention earlier and not being as reliant on doctors to diagnose disease. One downside to sentinel surveillance is that it's not as effective for detecting rare diseases or diseases that occur the outside the catchment areas of the sentinel sites.
Attack Rate
the rate that a group experienced an outcome or illness equal to the number sick divided by the total in that group. (There should be a high attack rate in those exposed and a low attack rate in those unexposed.)
Asymptomatic
Displays no signs or symptoms, but is infected and can carry the disease
Passive
Diseases are reported by healthcare providers. This type of surveillance, though simple and inexpensive, is often limited by incomplete reporting and quality variation in reporting.
Chi-Square
used to determine the statistical significance of the difference indicated by the relative risk or odds ratio. Chi-Square compares your observed values (a, b, c, and d) with the expected values for those same groups.