Lecture 3-6 - Descriptive Epidemiology & Measures of Disease Frequency Flashcards
What are the different types of surveillance systems?
- passive surveillance
- active surveillance
- syndromic surveillance
What is the passive surveillance system?
Regulations requiring the healthcare system to report certain diseases/conditions.
What is the active surveillance system?
When public health officials go into communities to search for new cases of disease.
What is the syndromic surveillance system?
Looks at pre-defined signs and symptoms which are related to rare but traceable diseases.
What is the induction/incubation period of a disease?
The time between exposure and onset of symptoms; subclinical stage
What is the latency period of a disease?
The time between onset of symptoms and diagnosis.
What is a case definition?
A set of uniform criteria that are used to define a disease/condition so there may be consistency in reporting.
What are the categories of case definitions?
- confirmed
- probable
Define epidemic.
Increased occurrence of disease form normal.
Define outbreak.
Increase occurrence of disease from normal localized to a specific area.
Define endemic.
The normal prevalence of a disease in a certain area exceeds what is normal for other areas.
Define emergency of international concern.
An epidemic that requires the global community to be on alert; pre-pandemic.
Define pandemic.
An epidemic on a global scale
What is the Epi curve?
A graphical depiction of number of cases by date in an area during an outbreak or epidemic.
What is a proportion?
Division of two related numbers; part-over-whole
What is a ratio?
Division of two unrelated numbers; numerator is not part of the denominator.
What is a rate?
A proportion with time in the denominator.
What factors must be taken into account when comparing measures of disease frequency between different groups?
- number of people affected
- the size of the source population
- duration the population was followed
What must be done when comparing measures of disease frequency between groups if the population size or duration the population was followed are not the same?
You must standardize
What is incidence and how do you calculate it?
The number of new cases of disease.
-# of new cases of disease / total population at risk
What is prevalence and how do you calculate it?
Total case of disease, both existing cases and new cases.
-(# of existing cases + # of new cases) / total population at risk
What is crude morbidity rate?
The percentage of people in the population that have any disease over a period of time.
-# of people with disease / total population
What is crude mortality rate?
The percentage the population that dies within a period of time.
of deaths / total population
What is cause-specific morbidity rate?
The percentage of people with a specific disease in a population over a period of time.
-# of people with specific disease / total population
What is cause-specific mortality rate?
The percentage of people who die from a certain disease in the population over a period of time.
-# of deaths due to a specific disease / total population
What is case-fatality rate?
Percentage of people with a specific disease that die from their disease.
-# of deaths due to a specific disease / the number of people with the disease
What is cause-specific survival rate?
The percentage of people with a certain disease still alive over a period of time.
-# of people alive with a specific disease / total of people who have the disease
What is proportional mortality rate?
The percentage of deaths due to a certain disease over a period of time.
-# of deaths due to a specific disease / # of deaths
What is live birth rate?
of live births / 1,000 population
What is fertility rate?
of live births / 1,000 women of child bearing age (15-44)
What is neonatal mortality rate?
of deaths <28 days of age / 1,000 live births
What is postnatal mortality rate?
of deaths >28 days of age but <1 year of age / 1,000 live births
What is infant mortality rate?
of deaths <1 of age / 1,000 live births
What is maternal mortality ratio?
of female deaths related to childbirth / 100,000 live births
What is infectivity?
The ability of an infectious disease to infect a patient.
-# infected / # at risk
What is pathogenicity?
The ability of an infectious disease to cause clinical disease.
-# with clinical disease / # infected
What is virulence?
The ability of an infection disease to be lethal.
- # of deaths / # with clinical disease
- case-fatality rate
