Community Midterm Flashcards
Endemic
Habitual presence of disease in a defined geographic area. High background rate of disease. (ie obesity, some STIs, malaria in some parts of the world, lyme disease in certain regions)
Epidemic
The occurrence in a community or region of a group of illnesses of similar nature, clearly in excess of normal expectancy, and derived from a common or propagated source. (AKA outbreak!)
Pandemic
Widespread, often global
What to do when there is an outbreak investigation?
- Establish and verify diagnosis of reported cases
- Search for additional cases - collect daata
- Describe and orient date in terms of time, place, person
- Formulate and test hypothesis
- Refine hypotheses and carry out additional studies (sometimes)
- Implement control and prevention measures
- Evaluate control measures
- Communicate findings
Epidemic curves can tell you…
- Distribution of the times of onset of the disease
- Type of disease process
- Pattern of spread
- Magnitude
- Time trend
- Exposure and/or incubation period
Epidemic Curves (4 types)
Person to person: Propagated
Common source: Point Source, Continuous, Intermittent
Point Source
Outbreak that is short term, and a one time exposure.
Continuous
Common source that is a contributing factor, but the exposure happens over a prolonged period of time. Ex: contamination in the water, continue to get sick until you remove the source of infection.
Intermittent Source
Common source, but spread out over time. Ex: Salmonella. Small peaks, then no outbreak, then another few cases, then no outbreak. Peaks not getting bigger, staying spread apart.
Propagated
One person gets disease, infects a group of people, they infect more people. Peaks get bigger and bigger as exponentially more people become infected. Communicable disease. Ends due to herd immunity, generally.
Attack Rate Formula
of people who ate a certain food and became ill/total # of people who ate that food
- numerator: cases, case definition
- denominator: population at risk
- calculate attack rate
Screening
Primary objective: detection of a disease in its early stages to treat it and deter its progression
Secondary objective: reduce cost of disease management by avoiding costly interventions at later stages.
Types of Screening (3)
Mass - to an entire population (cholesterol screening at a health fair)
Selective (targeted) - for high risk populations (TB in health care workers)
Periodic - screen a discreet but well subgroup of the population on a regular basis over time for predictable risks or problems (cervical cancer screening, lead screening)
Advantages of Screening
Simplicity
Target individuals or groups
Options of one-test or multiple-test screening
Opportunity for health education
Disadvantages of Screening
Not 100% accurate. Will be fas positives and false negatives.
Implications of Screening
False Positive: undue worry, stigma, more invasive testing, unnecessary treatment
False Negative: may lose opportunity for early intervention, may engage in risky behavior due to “negative” status
Selection of a Screenable Disease
Significance: is it really a public health concern? Level of threat? How many people are affected?
Detection: can we screen for this disease?
Should screening be done? What does the evidence say? What is the benefit of knowing? Is treatment available/really needed?
Sensitivity
True Positives/
(True Positives + False Negatives)
Has N in word but has to do with Positives!
Specificity
True Negatives/
(True Negatives + False Positives)
Has P in word but has to do with Negatives!
True Positives
Person has the disease and the test says they do
False Positive
Person doesn’t have the disease but the test says they do
True Negative
Person doesn’t have disease, test says they don’t
False Negative
Person does have the disease, test says they do
