EXAM 1 Flashcards
What is epidemiology
Study of the distribution and determinants of ideas w frequency in human populations and the application of this study to control health problems.
Descriptive epidemiology
Person, place, and time
Burden (saturation)
How many individuals are impacted
What is rate?
Number of events divided by size of the population
Why is rate necessary?
It allows valid comparisons across different populations
Analytical epidemiology
Agent, host, and environment
Disease frequency
Quantifying how often a disease arises in a population (case definition, method to count cases, determining size of population
Population
Group of people with a common characteristic such as place of residence, gender, age, or use or certain medical services/resources
Disease control
Done to prevent the spread of a disease and/or decrease in the incidence
How is disease control accomplished?
Through epidemiological research and surveillance
What is an epidemiologist?
Publix health scientist who is responsible for carrying out all useful and effective activities needed for successful epidemiology practice
Purposes of epidemiology
- Identify etiology (cause) of disease and the risk factors associated
- Determine the extent of the disease found in the community
- Study natural history
- Evaluate both existing and new preventive and therapeutic measures and modes of health care delivery
- Provide foundation for developing (public) policy and making regulatory decisions
Public health
A multidisciplinary field whose goal is to promote the health of the population through organized community efforts
Types of prevention
Primary, secondary, tertiary
Primary prevention
Action to prevent the development of a disease in a person who is well and does NOT have disease
Ex: hand washing, education, vaccines
Secondary prevention
People who have developed the disease — screening and early intervention
Ex: mammogram, colonoscopy, pap smear
Tertiary prevention
Goal is to slow or block the progression of a disease, thereby reducing impairments and disabilities
Ex: radiation and chemo, surgery, rehab, antibiotics
List the 5 individuals most important in epidemiology
Hippocrates
James Lind
Edward Jenner
William Farr
John Snow
Hippocrates
Father of medicine
First recorded epidemiologist
Made observations about the cause and spread of disease in populations
James Lind
Delt with scurvy
Made sure cases were as similar as possible
Edward Jenner
Smallpox
came up with the idea of vaccination/immunization
William Farr
founders of modern epidemiology
Compiled the data for the first census Bureau
Used data to form hypotheses about causes and preventions of diseases
quantified and arranged mortality data
John Snow
Father of epidemiology
Believed that cholera was transmitted through contaminated water
epidemiological triad of disease
host, agent, environment
host
genetics, behavior/lifestyle, habits
agent
microorganism must be present for infection to occur (bacteria, viruses, etc)
ability to live outside host, acclimate harsh conditions, and modify antigenicity
environment
residential exposures
occupational exposures
susceptibility
host must be susceptible for an interaction to take place–determined by a variety of factors
factors that cause human disease
biological
physical
chemical
others
transmission
different organisms (agents) spread in different ways
factors/characteristics for determining outbreak
rate of growth of the agent
transmission route
different types of transmission routes
oral, inhalation, dermal, injection, transplacental
modes of transmission
direct vs indirect
direct transmission
person to person (STIs)
indirect transmission
vehicle or vector (malaria)
carrier status
individual harbors the organism but is not infected as measured by serologic studies (no evidence of antibody response)
–can still effect others
–acute or chronic
–no signs of clinical illness
Ex: typhoid Mary
endemic
habitual presence of a disease within a given geographical area–usual occurrence of a disease within such an area
epidemic
occurrence in a community or region of a group of illnesses of similar nature–clearly in excess of normal expectancy derived from common or from a propagated source
pandemic
worldwide epidemic
herd immunity
resistance of a group to an attack by a disease to which a large proportion of the members of the group are immune–critical percentage of the population is immune
incubation period
a period of subclinical or in apparent pathologic changes following exposure, ending with the onset of symptoms of infectious disease – interval from receipt of infection to the time of onset of clinical illness
why don’t diseases develop immediately?
may reflect the time needed for the organism to replicate
dose of infectious agent may influence the length of the incubation period
isolation
individuals who are ILL or symptomatic
quarantine
individuals who come in close contact with a case, but do not show symptoms or signs of illness and not tested positive
what are the three major characteristics in epidemiology?
person, place, and time
person
inherent characteristics (age, race, sex)
acquired characteristics (marital status)
activities occupation, leisure activities)
condition which one lives under (socioeconomic status)
place
place of residence
birthplace
place of employment
country, state, city
school district
time
disease rates change overtime
–seasonal changes
–secular trends (long-term trends that help to predict future incidence of a disease)
measures of frequency
ratios, proportions, rates
ratio
relative magnitude of two quantities or a comparison of any two values – one number divided by another
number of items/events/persons in another group
ratio formula
proportion
one number divided by another, but the entities represented by these numbers are related to one another–often expressed as a percentage
number of items/events/persons with a particular characteristic
————————— X 10^2
total number of items/events/persons of which the numerator is a subset
proportion formula
the numerator of a proportion is always a subset of the denominator
(true or false)
true
rate
measure of risk–measure of the frequency that an event occurs
number of individuals who are ill at a specific time and in a specific location
————————— X 10^n
total in the population at that specific time and in that specific location
rate formula
morbidity
any departure, subjective or objective from a state of physiological or psychological well-being–diseases, injuries and disabilities
measures of morbidity
incidence, prevalence, attack rates (type of incidence)
incidence
number of NEW cases of a disease that occurs in a location (place) during a specified period of time in a population at risk for developing the disease
incidence is a measure of risk (true or false)
true
cumulative incidence
period of time when all the individuals in a population are at risk regardless of exposure or other characteristics
number of new cases of an outcome occurring in the population during a specific period of time in a specific location
————————— X 10^n
number of persons at risk of the outcome during that specific time period in a specific location
incidence formula
prevalence
number of affected persons present in the population at a specific time divided by the number of persons in the population at that time
prevalence does NOT take into account the duration of disease (true or false)
true
point prevalence
how many people have the disease at a point in time
period prevalence
how many people have had the disease at any time during a certain period
number of cases of an outcome disease present in the population at a specified time and location
————————- X 10^n
number of persons in the population at that specified time and location
prevalence formula
attack rates
defines who is at risk–useful for comparing the risk of an outcome in groups with different exposures
types of attack rates
crude attack rates, attack rates, food-specific attack rates
number of persons ill with the outcome
———————— X 10^2
number of persons attending the event
crude attack rate formula
number of people at risk in whom a certain outcome develops
————————– X 10^2
total number of people at risk
attack rate formula
number of people who ate a certain food and became ill
————————— X 10^2
total number of people who ate that food
food-specific attack rate
mortality
measure of disease severity
why study mortality
-determine whether the treatment for a disease has become more effective overtime
-serves as a substitute for prevalence rate when disease is deadly
crude mortality rate (crude death rate, annual death rate, mortality rate)
sometimes use the population at the midyear point because people move in and out of a specific area
number of deaths in a specific location at a specific time period
————————— X 10^n
total population at that same location and during the same time period
crude mortality rate formula
cause-specific mortality rate
mortality rate from a specified cause for a population
number of individuals who die of a specific cause/outcome in a specific location during a specific time period
————————– X 10^n
total population at that same location and during the same time period
cause specific mortality formula
case-fatality rate
proportion of individuals with a particular condition who die from that condition–must have the illness and must die of the illness
number of cause-specific deaths among the incident cases
————————— X 10^2
number of incident cases
case fatality rate formula
proportionate mortality
describes the proportion of deaths in a specified population over a period of time attributable to different causes–expressed as a percentage
deaths due to a particular cause
————————– X 10^2
deaths from all causes
proportionate mortality formula
survival rate
measure of prognosis–measures probability of surviving a specified period of time–expressed as a percent
number of newly diagnosed patients with a given disease - number of deaths observed among patients in a specified time period
————————— X 10^n
number of newly diagnosed patients with the disease in the same time period
survival rate formula
problems with mortality data
-most information comes from death certificates
-hard to compare two entities
-age
when a disease is mild and NOT fatal, mortality is NOT a good measure (true or false)
true
why look at mortality rates
-good reflection of incidence
-if CFR is high
-duration of disease is short
