Lectures 3-7 Descriptive Epidemiology Flashcards
What are the two “descriptions” of measurement used when determining the distribution of a disease?
Which of the 3 W’s are these measurements referring to?
- Frequencies of the Disease - Relative to the size of a population. For comparative purposes, the population size has to be similar
- Patterns of disease - Evaluating disease with respect to persons, place, and times
Determining Who/Where/When are the components of descriptive epidemiology.
What is the basic purpose of Descriptive Epidemiology?
Descriptive Epidemiology can be used to determine if a location is experiencing disease occurrence More Frequently Than Usual, or more than other locations.
What are Surveillance Systems? Name the 3 main types of surveillance systems.
- The study of determining whether or not there is disease in a population.
Three types include Passive Surveillance Systems, Active Surveillance Systems, and Syndromic Surveillance systems.
Briefly describe passive surveillance systems
Relies on standardized reports of disease to come in from healthcare systems such as clinics and hospitals. These systems are required by law to follow regulations on reporting these conditions.
- The Public health system passively waits for reports to come in, in order totrack disease frequency/occurrence over time and within populations
Briefly describe Active Surveillance Systems
Public health officials actively go into communities to search out new disease cases/conditions
Describe Syndromic Surveillance Systems
This system looks for pre-defined signs or symptoms of patients related to trackable but rare conditions or diseases. Asking physicians/hospitals to keep an eye out for red-flag syndromic symptoms, such as fever/body-aches during flu season would count as this.
- Biosurveillance can consist of humans, animals, plants, or environmental factors
List the 4 stages of clinical disease, including any significant events that occur during them
- Stage of Susceptibility - Patient is at risk, but uninfected. Stage ends at first exposure.
- Stage of Subclinical Disease - From the time of exposure to first onset of symptoms. Pathological changes can occur before symptoms.
- Stage of Clinical Disease - Technically the duration of the disease after first symptoms. Diagnosis usually occurs shortly into this stage.
- Stage of Recovery, Disability, or Death
What is the induction period? Latency Period? Incubation Period?
Induction - Time Between Disease Exposure and Disease Onset
Latency - Time between Onset of Disease (?) and First Symptoms or Signs
Incubation - Similar to Induction, Incubation is meant more for infectious diseases, while induction is more broad-based and includes chronic diseases
What is the most important aspect of the disease that must be determined before descriptive epidemiology procedures can begin?
Describe CSTE and NNDSS
CASE definitions - A set of uniform criteria for respective diseases for public health surveillance. Enables consistency across multiple states and divisions of epidemiology.
The CDC-run Council for State or Territorial Epidemiology (CSTE) recommends diseases be reported to National Notifiable Diseases Surveillance System (NNDSS), whereupon the CSTE updates their list of case definitions for infections and non-infectious diseases uniformly every year.
Why are case Definitions Important?
What’s the difference between probable case definitions and confirmed?
It is important for epidemiologists to carefully and consistently define and execute how diseases will be diagnosed, and then to properly and Accurately count the frequency.
It’s not confirmed until laboratory/diagnostic evaluations have definitive results. Probable case definitions are used more commonly for more extreme diseases.
What is the difference between an epidemic, and an outbreak. Describe both.
Epidemic - Occurrence of a disease is significantly higher than normal. The community can be as small of a population as a zip code, or as large as a country, but the community and period must be clearly defined. The goal is to capture disease as early as possible.
Outbreak - Similar to an epidemic, but a more localized increase in disease occurrence, such as a school; Sometimes referred to as a Cluster
What are general rules of thumb with seasonal epidemics
Seasonal Outbreaks can’t really be considered epidemics unless they’re compared with Last Year’s Averages. It can’t “just” be compared with last year’s numbers because it’s always possible that last year involved an outlier or abnormal frequency of some kind.
Name the 3 escalating categorizations for Epidemic Severity and describe their characteristics
- Endemic - Standard category for the constant presence of a disease in excess of a normal level in a localized region.
- Emergency of International Concern - Epidemic that alerts the entire world to the need for higher vigilance of a disease. Included Polio scare of 2014
- Pandemic - Epidemic that is spread world-wide. Included the H1N1 Pandemic of 2009.
What is the epidemic curve?
A visual time-based depiction of the spread of a disease during an outbreak or epidemic. Must visually depict the Shape of the disease spread. Includes a Common/Point Source (Beginning) that is either intermittent thereafter, or continuous. (Suggests the disease is mostly spread from a single person, or single source)
A propagated source (more of a steady bell curve increase) suggests that it’s contagiously spread person-to-person
What are some “points” in the epidemic curve that one should look for to help determine magnitude and timing of disease?
Sentinel (Initial) index case
Peaks
Outliers
Start/Stop Duration (Time)
