chapter 1-4 Flashcards
what is epidemiology and how is it used in the real world
is commonly refered to as the foundation of public health because it is important information for improving the health and soical conditions concerned with the collection health of a group of individuals who share one or more observable personal characteristic
is the study of the distribution and determinants of health related states or events in human populations and the application of this study to prevent and control health population
how does epidemiology differ from clinical medicine
epidemiology - you are dealing with an entire population but in clinical medicine you are dealing with one patient
what are the aims epidemiology
describe the distribution ,the pattern and the history of disease in a population.
what is surveillance and the different types of surveillance
surveillance - the collection of data pertaining to the occurrences of specific disease disease injury and events
active - outbreak real time rare disease
passive - creating system to collect data
sentinel - a warning system high specific cause of disease social media
epidemic
a widespread occurrence of an infectious disease in a community at a particular time.
example - sickle cell in Africa
pandemic
this is going to occur worldwide
example COVID19
syndemic
when there are two or more disease in a population
example COVID 19 and racism and violence
epidemic threshold
is the number of cases or deaths that would support the conclusion that an epidemic was underway
worst disease outbreak in U.S history
smallpox ,yellow fever ,cholera,tyhoid fever ,spanish flu ,D phtheria polio ,measles ,cryptopordium ,whooping cough ,AIDS
describe why a standard case definition and adequate levels of reporting are important in epidemiologic investigations
it is ensured that every case is equivalent regardless of when or where it occurred or who identified it
allows for standardization of the cases of interests both with ongoing outbreak investigation and possibly between outbreak investigations that differ over time or geographic location
morbidity and mortality
morbidity - number of illness
mortality - number of deaths
what is application of epidemiologic triangle
it is consists of an external agent a susceptible host and an environment that brings the host and agent together
asthma =vector
host - age race ,gender ,genetic profile cytokine and lung injury response to acute infection
environment - microbiome ,SHS ,LPS and vitamin E antibiotics
agent - viral genomics ,virulence factors
what are the determinants of health
determinant - is a collective or individual risk factor or set of factors that is casually related to a health condition outcome or other defined characteristics
example biologic agent (bacteria and Viruses ),chemical agents Toxic pesticides and less specific factors stress and lifestyle
examples may include social conditions or events relationships ,neighborhoods ,communities ,institutions healthcare ,economic political and cultural factors
how are health outcomes measured
reflect the impact of the healthcare service or intervention on the health status of patients
examples - patients who died from surgery
the rate of surgical complications or hospital acquired infections
routes of transmission and the modes of transmission
direct transmission is the uninterrupted and immediate transfer of an infectious agent from one person to another requires physical contact between the infected host and a susceptible person and the physical transfer pf a pathogen
examples - HIV and AIDS Gonorrhea
indirect transmission - occurs when an agent is transferred or carried by some intermediate item organism means or process to host resulting in disease
Airborne tramissions - occurs when droplets or dust particles carry the pathogen to the host and causes pertusis ,pnenumoccal ,pneumonia and diphtheria rubella
vector borne transmission - occurs when an arthropod mosquito ,fleas and tick and lice conveys the infectious agents and it is response for the transmission of the pathogen to the host.
what is bioterrorism and types of bioterrorism agents and examples
terrorism involving the releasing of toxic biological agents
examples Anthrax ,Botulism and Plague
are pathogenic organisms or biological toxins that are used to produce death and disease in human animals or plants for terrorist purposes
what are the current leading causes of death in the U.S
heart disease ,cancer and COVID 19
what are the three levels of prevention used in public health and epidemiology
primary prevention -intervening before health effects occur, through. measures such as vaccinations, altering risky behaviors
example - west Nile virus - protect yourself from mosquito bites
secondary prevention-screening to identify diseases in the earliest. stages, before the onset of signs and symptoms, through measures such. as mammography and regular blood pressure testing
example - a void mosquito bites by wearing long pants and sleeves and socks and shoes
tertiary prevention-prevention of complications in people who have already developed disease, and in whom disease prevention is no longer an option.
example -repair any damaged window and door screens, remove standing water from areas around your home
no vaccinations for west Nile virus
what is the difference between active and passive primary prevention
active necessitates behavior change on the part of the subject
example - vaccinations ,wearing helmets or seatbelts
passive - does not require behavioral change
example - fortifications of milk and bread products
distribution
the occurrence of disease and other health outcomes varies in a populations within subgroups of the populations more frequently affected then others
central activity in epidemiology
counting the number of disease
rehabitiation
any attempt to restore an afflicted person to a useful productive and satisfying lifestyle
vehicle borne transmission
involves an inanimate object that conveys an infectious agent to a host
for example this occurs when a pathogen such as cholera or shigellosis is carried in drinking water and swimming pools
mechanical transmission
such as when the pathogen spreads using a host ( fly flea and louse or rat) as a mechanism for a ride for nourishment or as part of a physical transfer process
biological transmission
is when the pathogen undergoes changes as part of the lifestyle while within the host and vector before transmitting to other host
chain of infection
More specifically, transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host.
formite
is an inanimate nonliving object such as a piece of clothing a door handle and utensil that can harbor an infectious agent and is capable by the means of transmission
vector
is an invertebrate animals that transmit infection by conveying the infectious agent from one host to other
reservior
is the habitat living or nonliving in or which an infectious agent lives and grows and multiples on which it depends on its survival nature
active carrier
an individual who has been exposed to and harbors a disease causing organism and who has done so for some time
convalescent carrier
an individual who harbors a pathogen and who although in the recovery phase of the course of the disease is still infectious
healthy carrier
an individual who has been exposed to and harbors a pathogen but has not become ill or shown any of the symptoms of the disease
incubatory carrier
an individual who has been exposure to and harbors pathogen is in the beginning stages of the disease and is displaying symptoms and the ability to transmit the disease
intermittent carrier
an individual who has been exposed to and harbors a pathogen and who can spread the disease in different places or at different intervals
case severity
found by looking at several variables that are effective measures of it
case
is a person in a population who has been identified as having the particular disease
case definition
ensures that cases are consistently diagnosed regardless of where or when they were identified and who diagnosed the case
primary case
first disease case in the population
secondary case
a person who becomes infected and ill after a disease has been introduced into a population and who is infected as a result from the primary case
index case
the first case brought to the attention of the epidemiologist
suspect case
is an individual who has all the signs and symptoms of a disease or condition but has not be diagnosed to having the disease or the cause of symptoms by the primary suspect.
mixed epidemic
occurs when victims of a common source epidemic have person to person contact with others and spread the disease resulting in a propagated outbreak
common source epidemic
arises from a specific scource
propagated epidemic
arises from the infections transmitted from one infected person to other
efficacy
refers to the ability of the program to produce a desired effect among those who participate in the program and those who do not
effectiveness
refers to the ability of the program to produce benefits among those who offered the program
know the key landmarks in history
Hippocrates wrote Epidemic I, Epidemic III, and“On Airs, Waters, and Places” in 400 BC
Disease associated with physical environment
Move from supernatural to environmental explanations for disease
Edward Jenner
smallpox vaccination
Benjamin jesty
a farmer/dairyman in the mid 1700s noticed his milkmaids never got smallpox but cowpox
exposure his wife and children to cowpox
variolation - Chinese has observed for centuries that getting a weaker strain of smallpox was protective against a stronger strain of the disease
smallpox virus
caused by variola virus
chicken pox is a varicella virus
shingles is a varicella zoster virus
john graunt
father of statistics in epidemiology
looked at death record and discovered different patterns
william farr
Compiler of Abstracts” and one of the founder of medical statistics
Development of a more sophisticated system to code medical conditions
Provided the foundation for the International Classification of Diseases
John snow
father of epidemiology ,cholera outbreaks ,miasma and broad street in London mapping where individuals get water and also took out water handle
Used a spot map of cases and tabulation of fatal attacks and death
Evaluated deaths from two water sources to determine origin of water contamination and increased deaths
Worked with William Farr
Koch postulates
postulates:
1. Microorganisms must be observed in every case of disease
2. Isolated and grown in pure culture
3. Pure culture must reproduce disease
4. Microorganisms must be observed in, and recovered from, diseased animals
Proving a causal relationship between a microbe and disease
Ignaz Semmelweis
Mid-19th century, Viennese hospital
Postulated that medical students and physicians had contaminated their hands during autopsies
Introduced the practice of hand washing
the development made of certain study designs such as natural experiments
intervention - naturally occurring situation
control conditions - determined by nature or by factors outside of the investigators
epidemiologist role - analyze and collect data
contemporary examples in epidemiology
Seat belt law- Did seat belt use reduce fatalities from motor vehicle accidents?
Tobacco tax (Sin Tax) – Did the increase in cigarette price decrease the use of cigarettes?
Helmet Law – Did requiring the use of helmets by motorcyclists reduce the number of head injuries?
Legislative ban on smoking in public places – Did the number of CVD reduce?
atomic theory
the belief that everything is made up of tiny particles
scurvy
a disease marked by spongy and bleeding gums and bleeding under the skin and extreme weakness
influenza pandemic
Mortality – 50-100 million persons
20 – 40-year-olds most susceptible
2.5% case-fatality rate versus 0.1% for other influenza pandemics
the black death
Bubonic Plaque
1346- 1352
25%-33% population of Europe claimed
childbed fever
a uterine infection usually of the placental site after birth
cholera
is an acute infectious disease characterized by watery diarrhea ,loss of fluid and electrolytes dehydration and collapse
anthrax
plague by farmers caused by serious bacterial infection usually fatal destroyed them economically
multifactorial etiology
the promotion of the idea that some diseases especially chronic disease
typhoid fever
is an infectious disease continued fever physical and mental depression ,rosed colored spots on the chest
vitamins
are organic components in foods that are needed in very small amounts for metabolism growth and maintaining good health
1964 united states general
issued a warning that smoking can cause cancer
infectivity
The capacity of an agent to produce infection or disease
Measured by the secondary attack rate
pathogenicity
The capacity of the agent to cause disease in the infected host
Measured by the proportion of individuals with clinically apparent disease
virulence
Refers to the severity of the disease
Measured by the proportion of severe or fatal cases
If fatal, use case fatality rate
toxigencity
The capacity of the agent to produce a toxin or poison
resistance
The ability of the agent to survive adverse environmental conditions.
Antigenicity
The ability of the agent to induce antibody production in the host.
host
A person (or animal) who permits lodgment of an infectious disease agent under natural conditions.
inapparent infection
No symptoms of infection present
Important because disease can be transmitted to unsuspecting hosts
In asymptomatic individuals, clinicians can look for serologic evidence of infection
colonization
-agents multiply on the surface of the body without invoking tissue or immune response.
infestation
the presence of a living infectious agent on the body’s exterior surface, upon which a local reaction may be invoked.
what is representativeness
degree to which the sample population resemble the population from which the data have been taken
generalizability(external validity)
ability to apply the finding of the study to the population that did not participate in the study the general population
thoroughness
the extent to which all the cases of a health phenomenon have been identified
when is confidentiality important
Privacy Act of 1974
Prohibits the release of confidential data without the consent of the individual – Protects data from federal agencies only, allows access of data if its your own
Freedom of Information Act
Mandates the release of government information to the public, except for personal and medical files
The Public Health Service Act
Protects confidentiality of information collected by some federal agencies – all NCHS systems
For conditions that might be stigmatizing, such as reproductive, sexual, public health, and psychiatric health concerns
know the acts and laws related to protecting individuals information
the HIPAA privacy rule
Refers to the Health Insurance Portability and Accountability Act of 1996
Sections of HIPAA “…require the Secretary of HHS to publicize standards for the electronic exchange, privacy and security of health information…”
Categories of protected health information pertain to individually identifiable data
what statistics are derived from vital statistics
national vital statistics system
births, deaths, marriages, divorces, and fetal deaths. They also record information about the cause of death, or details of the birth.
what data is on a death certificate
cause of death, location of death, time of death and some other personal information about the deceased.
what are the strengths and limitations of mortality data
Factors inherent in the data may limit their usefulness
Examples of limitations:
Death certificates – useful for identifying cause?
Cross-sectional data – ability to ascertain cause?
Representative of BRFSS data?
Insurance data to assess health disparities?
disease registries such as SEER are good for what type of data
collects cancer data from different cancer registries across the U.S
provides information about trends in cancer incidence mortality and survival
if I wanted info on characteristics of the U.S population where would I go in order to find that data
The United States Census Bureau
identify sources to obtain epidemiological data
Behavioral Risk Factor Surveillance System
Gathers data primarily applicable to chronic diseases on behaviorally related phenomenon (e.g., risk behaviors)
Largest telephone based survey in the world
U.S bureau Census - provides information on the general social and economic characteristic’s of the U.S population
National center for health statistics- Scope of information is extensive.
Examples of sources of data collection systems and surveys:
National Health Interview Survey (NHIS)
National Health and Nutrition Examination Survey (NHANES)
National Vital Statistics System (NVSS)
National Health Interview Survey-The NCHS conducts the NHIS, which has been in operation since 1957.
Data from the NHIS are used for monitoring how well the nation is progressing toward specific health objectives as well as for tracking people’s health status and access to health care.
The goal of the survey is to collect data from a representative sample of the U.S. population.
National Health and Nutrition Examination Survey (NHANES-Evolved from the National Health Survey Act of 1956
The act provided for the creation of studies to characterize illness and disability in the United States.
A special feature of NHANES
Collection of information from physical examinations coupled with interviews
Operates as a continuous survey with data released in 2-year cycles (since 1999).
Patient databases from provider groups, health insurance plans, and other insurers
Clinical data (e.g., from clinical laboratories, physicians’ records, hospitals, and special clinics)
School health records
Information from absenteeism reports
Armed forces records
what are the possible value and limitations which hospital ,absentee or insurance data
Capturing Accurate Data. In a study at an ophthalmology clinic, EHR data matched patient-reported data in 23.5 percent of records. …
Fragmented Patient Care. …
Data Privacy & Security. …
Data Visualization. …
Document Processing and Analysis.
what is a census tract and how many residents are considered in the track
census tract - are small relatively permanent statistical subdivisions of a county or statistically equivalent entity that can be updated by local participants prior to each decennial census as part of the Census Bureau
demographic transition
shift from high birth and death rates found in societies to lower birth and death rates in developed countries
epidemiologic transition
shift in the pattern of morbidly and mortality from infectious and communicable disease to chronic degrative disease
incubation period
the time interval between exposure to an infectious agent and the appearance of the first signs and symptoms of the disease
zoonoses
infectious disease that are potentially the transmittable to humanism by vertebrate animals
examples - rabies and the plague
infectivity
The proportion of persons exposed to an infectious agent who become infected by it.
herd immunity
greater likelihood of spread = greater percent of the population that must be vaccinated A situation in which a sufficient proportion of population is immune to an infectious disease through vaccination and prior illness
immunity - is not 0 but really low
what is the natural history of the disease
natural course of disease progression from being to find clinical end points
research is being utilized identify where in a disease natural history effective intervention might be implemented
know the difference between active and passive immunity
active - natural active results from an infection by agent artificial active results from an injection with a vaccine
passive immunity - natural passive performed antibodies are passed to the fetus during pregnancy and provide short term immunity in the newborn
Classify acute and chronic disease to infectivity and communicability
acute - something with an sudden onset and occurs in rapid speed
chronic - something that occurs in a slow mild rush and it is the most deathly
What are the clinical endpoints in a disease
Recovery
Disability
Death
know examples of direct and indirect transmission
direct contact - touching ,kissing ,sexual contact contact with secretions or contact with body lesions
indirect contact infections spread when an infected person sneezes or coughs sending infectious droplets to the air
what is the role of the environment in disease transmission
the home environment particular in the kitchen and bathroom it serves as a reservoir of a large number of microorganisms particularly in any Enterobacteriaceae and infectious diseases
know the five categories of disease
physical diseases
mental diseases
infectious disease
non - infectious disease
deficiency disease
inherited disease
generative disease and social disease and self inflicted disease
describe notifiable diseases reported in the United states
cholera
cryptosporidiosis
Giardiasis
Hepatitis A
Malaria
Legionellosis
Salmonellosis
identify common sources and modes of disease transmission
vertical transmission - refers to transmission from an individual to its offspring through sperm ,placenta and milk or vaginal organs
horizontal transmission - refers to the transmission of an infected individual to a susceptible contemporary involves direct transmission sexually transmitted diseases food borne or blood borne
direct contact, droplets, a vector such as a mosquito, a vehicle such as food, or the airborne route.
Airborne -Respiratory
Common cold, influenza, COVID-19, Measles, Smallpox
Intestinal
Cholera, Giardiasis, Hepatitis
Open Sores - Lesions
AIDS, Gonorrhea
Zoonoses – Vectors-borne
Rabies, Ebola, Lyme disease, Malaria, Yellow Fever
Fomites
Common colds, influenza, Meningitis
Absorption
Skin and mucus membranes
Inhalation
Respiratory through air droplets
Ingestion
Gastrointestinal through consumption of food or drink
Injection
From needle or other object
Portal of Exit
Site where infectious agents leave the body, e.g., respiratory system, skin lesions.
Portal of Entry
Locus of access to the human body, e.g., mouth and digestive system
vehicles
contaminated water, infected blood, food.
formites
-inanimate objects laden with disease-causing agents.
vectors
living insects or animals involved with transmission of the disease agent.
know the examples of agents of infectious disease including their characteristics and infections diseases under each control mechanisms and carriers of agent discussed in class
bacteria -Tuberculosis (TB), salmonellosis and streptococcal
rickettsia -Typhus fever, Rocky Mountain spotted fever , Q-Fever
virus Hepatitis A, Herpes, Influenza and HIV
Mycoses (Fungi) -Coccidioidomycosis, ringworm, athlete’s foot
Protozoa -Malaria, amebiasis, bebeiosis
Helminths -Roundworm, pinworm, tapeworms
Ro or Rnaught
Expected number of secondary cases produced by a single infection in a completely susceptible population
number 15
why use descriptive or analytic studies
descriptive studies -used to identify a health problem that may exist. Characterize the amount and distribution of disease.
To evaluate and compare trends in health and disease.
To provide a basis for planning, provision, and evaluation of health services.
To identify problems for analytic studies
Creation of hypotheses
analytic studies - follow descriptive studies, and are used to identify the cause of the health problem.
describe the uses strengths and limitations of selective descriptive study designs
case reports -simplest category, individual profile
Case series- summarize characteristics of patients (small group) from major clinical settings.
- cross sectional studies -surveys of the population, collect data from individuals in a population
ecological studies -makes comparisons between two variables of interests at the aggregate level on the population (e.g., obesity and high fat diet)
case reports and case series pros and cons
pros - Inexpensive
Reporting sentinel events / rare events areas for new research
Recognition of epidemics
cons -Not representative
Lack a comparison group (control)
Cannot establish a cause-effect relationship
cross sectional study limitations and strength
limitations-Hard to detangle risk factors from factors associated with survivor
Cannot study low prevalence diseases
Cannot determine temporality of exposure and disease (or causation)
Possible response bias
strengths - prevalence study ,exposure and disease measures obtained at individual levels
both probability and non probability used
ecological studies advantage vs disadvantage
advantages - quick and simple ,inexpensive good approach for generating hypotheses when a disease is an unknown ecology
disadvantages - Lack of motivation for change in the environment.
Changing lifestyles can be extremely difficult.
Not all diseases can be prevented.
Many people are in denial and do not believe they are at risk.
understand the four common measures and provide an example for each
measures of disease frequency - to quantify health events or health characteristics in order to describe and compare populations
risk -if 1 in 10 people exposed to a substance gets sick, the exposed AR is 0.1. If 1 in 100 people who are not exposed get sick, the unexposed AR is 0.01.
rate -70 new cases of breast cancer per 1,000 women per year.
prevalence -1980 the Framingham Het Study examined 2,477 subjects for cataracts and found that 310 had them. So, the prevalence was 310/2,477 = 0.125
incidence rate- 795,000 new strokes in the United States, annually
difference between crude and adjusted rates and application
crude -refers to rates that are NOT adjusted for other population factors (e.g., Age differences between populations)
Make comparisons carefully!
Age-adjusted rates is most appropriate
Commonly expressed per 1,000 or per100,000
a crude death rate of 9.5 (per 1000 people) in a population of 1 million would imply 9500 deaths per year in the entire population.
adjusted rates - an artificially created figure that enables comparison across time and space. It should only be compared with another adjusted rate that was computed using the same “standard” population.
per 100,000 population
understand the relationship between prevalence and incidence
New cases
Measures changes in disease occurrence
Used for investigating the cause of disease
formula -The # NEW cases occurring
Total Population at risk at some designated time
prevalence -formula
The # of EXISTING cases divide by Total population at some designated time
Existing cases
Measures how much disease in a population (a snapshot)
Used for description, planning health care needs
attack rates
Alternative form of incidence rate
Used for diseases observed in a population for a short time period.
Not a true rate because time dimension often uncertain
formula - ar - ill times 100
divided by ill plus well
what are the applications and uses of prevalence data
uses - Describing the burden of a health problem in a population
Estimating the frequency of an exposure
Determining allocation of health resources such as facilities and personnel
Example of a proportion (not a rate)
the prevalence of type 2 diabetes among children age 2 to 12 equals the number of children age 2 to 12 years with type 2 diabetes divided by the total number of children within that age range
point prevalence vs period prevalence
point prevalence -the prevalence measured at a particular point in time.
Number of persons ill per 1,000
/Total number in the group
period prevalence - prevalence measured over an interval of time.
Number of persons ill /
Average population
arithmetic mean
is the measure of central location that is more familiar due to many desirable statistical properties
ecologic fallacy
is an error that results when an association between aggregated level variables is used to draw a conclusion about the association doesn’t exist.
response bias
a type of selection bias in which those who respond to a questionnaire are systematic those who don’t respond
serial survey
a cross-sectional survey that is routinely conducted
nominal data
unordered categories or classes gender and race and ethnicity and martial status occupation
ordinal data
additional information provided by the order among categories or a stage or grade of cancer
discrete
integers or counts that differ by fixing amounts with no intermediate values possible
ratio
- the values of x and y are distinct such that the values of x are not contained in y
proportion - x is contained in y
proportion
x is contained in y
incidence density rate
the denominator is the time each person is observed instead of the number of people
person time rate
denominator of the incidence rate is the sum of the time each person was observed
Secondary attack rate -
the epidemiologist is interested in the rate of new cases occurring among contacts of known cases
variance
is the average of the squared differences of the observations from the mean
