Hosa Epidemiology


Terms in this set (...)

The number of new cases per person per unit of time
The proportion of the population at a given time that has a case
Case Fatality Rate
Ratio of fatal cases to total cases
Risk factor
A definable element of exposure that captures at least one part of the pathway by which the cause increases the risk that a member of the population will meet the criteria of a case.
Observational Study
Study in which events occur without the scientist having controlled starting conditions. Resembles the studies of geology and astronomy.
The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study is the control of health problems.
5 Ws of Descriptive Epidemiology
Diagnosis or health event (what), Person (who), Place (where), Time (when) and Modes of Transmission (why/how)
Not only the number of health events, but also the relationship of that number to the size of the population.
The occurrence of health-related events by time, place and person.
Descriptive Epidemiology
Characterizing health events by time, place, and person.
The causes and other factors that influence the occurrence of disease and other health-related events.
Analytic Epidemiology
Provides the "why" and "how" disease and other health events spread/occur.
Public Health Surveillance
The ongoing, systematic collection, analysis, interpretation, and dissemination of health data to help guide public health decision making and action.
Field Investigation
Characterizes the extent of the epidemic and attempts to identify its cause.
Shoe Leather Epidemiology
Slang; the objective is to learn more about the natural history, clinical spectrum, descriptive epidemiology, and risk factors of the disease before determining what disease intervention methods might be appropriate.
Analytic Studies
A study with the purpose of identifying and quantifying the relationship between an exposure and an outcome and to test hypotheses about causal relationships by comparing case-patients and those in an appropriate comparison group (control).
Includes determining the appropriate research strategy and study design, writing justifications and protocols, calculating sample sizes, deciding on criteria for subject selection (e.g., developing case definitions), choosing an appropriate comparison group, and designing questionnaires.
Involves securing appropriate clearances and approvals, adhering to appropriate ethical principles, abstracting records, tracking down and interviewing subjects, collecting and handling specimens, and managing the data.
Begins with describing the characteristics of the subjects. It progresses to calculation of rates, creation of comparative tables (e.g. two-by-two tables), and computations of measures of association (e.g., chi-square test), confidence intervals, and the like.
Involves putting the study findings into perspective, identifying the key take-home messages, and making sound recommendations. Doing so requires the epidemiologist be knowledgeable about the subject matter and the strengths and weaknesses of the study.
The process of determining, as systematically and objectively as possible, the relevance, effectiveness, efficiency, and impact of activities with respect to establish goals.
Refers to the ability of a program to produce the intended or expected results in the field.
The ability to produce results under ideal conditions.
Refers to the ability of the program to produce the intended results with a minimum expenditure of time and resources.
Formative Evaluation
Evaluation that focuses on plans.
Process Evaluation
Evaluation that focuses on operations.
Summative Evaluation
Evaluation that focuses on impact.
Working in conjunction with members of other disciplines.
Case Definition
A set of standard criteria for classifying whether a person has a particular disease, syndrome, or other health condition.
The number of cases divided by the size of the population per unit of time.
Secular trends
Long term trends; Assess the prevailing direction of disease occurrence (increasing, decreasing, or essentially flat).
Epidemic Curve
A graph used to show the time course for a disease outbreak or epidemic.
Experimental Study
In this type of study, the investigator determines through a controlled process the exposure for each individual (clinical trial) or community (community trial), and then tracks the the individual or communities over time to detect the effects of the exposure.
Cohort Study
In this type of study, and epidemiologist records whether each study participant is exposed or not, and then tracks the participants to see if they develop the disease of interest. Similar to an experimental study, but observes rather than determines the exposure status.
Prospective Cohort Study
A kind of cohort study that observes the exposure status, and tracks the participants to see if they develop the disease in question; Also called a follow-up study
Retrospective Cohort Study
In this type of study, both the exposure and the outcomes have already occurred.
Case-Control Study
In this type of study, epidemiologists start by enrolling a group of people with a disease and a group of people with out that disease (controls). Investigators then compare previous exposures between the two groups.
A person with the disease of interest. Not called a case because case refers to occurrence of disease rather than a person.
Cross-Sectional Study
In this type of study, a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously. It tends to assess the presence (prevalence) of the health outcome at that point in time without regard to duration.
Epidemiologic Triad
Model of disease causation consisting of an external agent, a susceptible host, and an environment that brings the host and agent together. Works best for infectious diseases.
An infectious microorganism or parasite, chemical contaminants, or physical force that causes disease or injury.
The human who contracts the disease.
Refers to the intrinsic factors that effect the agent and the opportunity for exposure.
Causal Pie
A model of disease causation that accounts for the multifactorial nature of causation that represents each individual factor as a piece of the pie. After all the piece fall into place - disease occurs.
Necessary Cause
A component that appears in every pie or pathway. Without it, a disease will not occur.
Incubation Period
Name for the time from exposure to onset of disease symptoms for infectious diseases
Latency Period
Name for the time from exposure to onset of disease symptoms for chronic diseases.
Spectrum of Disease
The range of manifestations a disease process can take (e.g., from asymptomatic to mild clinical illness to severe illness and death).
The proportion of exposed person who become infected.
The proportion of infected individuals who develop a clinically apparent disease.
The proportion of the population of clinically apparent cases that are fatal.
Case-patients that are asymptomatic, but can still transmit disease.
The habitat in which the agent normally lives, grows, and multiplies.
An infectious disease that is transmissible under natural conditions from vertebrate animals to humans.
Portal of Exit
The path by which a pathogen leaves its host
Direct Transmission
Transmission in which an infectious agent is transferred from a reservoir to a susceptible host by direct contact or droplet spread
Indirect Transmission
Refers to the transfer of an infectious agent from a reservoir to a host by suspended air particles, inanimate objects (vehicles), or animate intermediaries (vectors).
Direct Contact
Contact that occurs through skin-to-skin contact, kissing, and sexual intercourse. Can also refer to contact with soil or vegetation harboring infectious organisms
Droplet Spread
Refers to spray with relatively large, short-range aerosols produced by sneezing, coughing, or even talking.
Airborne Transmission
Occurs when infectious agents are carried by dust or droplet nuclei suspended in air
Vehicles of Transmission
Include food, water, biologic products (blood), and fomites (inanimate objects such as handkerchiefs, bedding, or surgical scalpels).
Vectors of Transmission
Examples include mosquitoes, fleas, and ticks that may carry an infectious agent through purely mechanical means or may support growth or changes in the agent
Portal of Entry
Refers to the manner in which a pathogen enters a susceptible host.
Herd Immunity
The concept that suggests that if a high enough proportion of the population are resistant to the agent, then the few that are susceptible will be protected by the resistant majority, since the pathogen will be unlikely to "find" those few susceptible individual.
The constant presence of an agent or health condition within a given geographic area or population; can also refer to the usual prevalence of an agent or condition.; Baseline
Refers to a disease that occurs infrequently and irregularly
Refers to persistent, high levels of disease occurrence.
Refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area.
Refers to a sudden increase in the number of cases of disease above the baseline, often limited to a more limited geographic area.
Refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected, even though the expected number may not be known.
Refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people
Common-Source Outbreak
Outbreak in which a group of persons are all exposed to an infectious agent or a toxin from the same source.
Point-Source Outbreak
Outbreak in which a group of persons are all exposed to an infectious agent or a toxin over a relatively brief period of time so that everyone who becomes ill does so within one incubation period.
Continuous Common-Source Outbreak
Outbreaks in which case-patients may have been exposed over a period of days, weeks, or longer, resulting in the flattening and widening of the peaks of the epidemic curve. The range of exposures and range of incubation periods are longer.
Intermittent Common-Source Outbreak
The epidemic curve of this type of outbreak often shows its intermittent nature of this exposure.
Propagated Outbreak
Results from transmission from one person to another. Cases occur over more than one incubation period.
Mixed Epidemic
Epidemic that starts out with a common-source outbreak, followed by person-to-person spread (propagated outbreak).
The when (time), place (where), and person (who) of the case.
Public Health Surveillence
Includes includes the collection, analysis, and dissemination of public health information to help guide public health decision making and action
Any characteristic that differs from person to person, such as height, sex, smallpox vaccination status, or physical activity pattern.
The number or descriptor that applies to a particular person, such as 5'6" (168 cm), female, and never vaccinated.
Attack Rate
The proportion of the population that develops illness during an outbreak; Incidence proportion
Prevalence Rate
The proportion of the population that has a health condition at a point in time
Case-Fatality Rate
The proportion of persons with the disease who die from it.
Secondary Attack Rate
Sometimes used to calculate the difference between community transmission of illness versus transmission of illness in a household, barracks, or other closed population.
Point Prevalence
The prevalence measured at a particular point in time. It is the proportion of persons with a particular disease or attribute on a particular date.
Period Prevalence
The prevalence measured over an interval of time. It is the proportion of persons with a particular disease or attribute at any time during the interval.
Proportionate Mortality Rate
Used to compare deaths in a population of interest (say, a workplace) with the proportionate mortality in the broader population.
Years of Potential Life Lost
Calculated as the sum of the differences between a predetermined end point and the ages of death for those who died before that end point.
Measures of Association
Quantifies the relationship between exposure and disease among the two groups
Relative Risk
Compares the risk of a health event (disease, injury, risk factor, or death) among one group with the risk among another group.
Rate Ratio
Compares the incidence rates, person-time rates, or mortality rates of two groups.
Odds Ratio
Quantifies the relationship between an exposure with two categories and health outcome; Cross-Product Ratio
Attributable Proportion
A measure of the public health impact of a causative factor.
Ordinal Variable
Has an intrinsic order, but differences between levels are not relevant.
Discrete Variable
Values are integers (can only be .
Continuous Variables
Can have any value in a range (includes fractions and decimals)
Contingency Table
A two-variable table with data categorized jointly by two variables.
Term applied to almost any effort to monitor, observe, or determine health status, diseases, or risk factors within a population
Syndromic Surveillence
Situation in which the criteria for identifying and counting occurrences of a disease consist of a constellation of signs and symptoms, chief complaints or presumptive diagnoses, or other characteristics of the disease, rather than specific clinical or laboratory diagnostic criteria.
Step 1 of an Outbreak Investigation
Prepare for field work
Step 2 of an Outbreak Investigation
Establish the existence of an outbreak
Step 3 of an Outbreak Investigation
Verify the diagnosis
Step 4 of an Outbreak Investigation
Construct a working case definition
Step 5 of an Outbreak Investigation
Find cases systematically and record information
Step 6 of an Outbreak Investigation
Perform descriptive epidemiology
Step 7 of an Outbreak Investigation
Develop hypotheses
Step 8 of an Outbreak Investigation
Evaluate hypotheses epidemiologically
Step 9 of an Outbreak Investigation
As necessary, reconsider, refine, and re-evaluate hypotheses
Step 10 of an Outbreak Investigation
Compare and reconcile with laboratory and/or environmental studies
Step 11 of an Outbreak Investigation
Implement control and prevention measures
Step 12 of an Outbreak Investigation
Initiate or maintain surveillance
Step 13 of an Outbreak Investigation
Communicate findings
Null Hypothesis
Assuming that the exposure is not related to the disease
Alternative Hypthesis
Assuming that the exposure is related to the disease.
The distortion of the association between an exposure and a health outcome by a third variable that is related to both.
An inanimate object that can be the vehicle for transmission of an infectious agent (e.g., bedding, towels, or surgical instruments).
Without apparent symptoms.
Conditional Probability
The probability of an event given (or conditional upon) the occurrence of another event, e.g. the probability of disease Y given exposure to factor X.
Disease Transmission
The process of spread of a disease agent through a population.
The generic term used to describe the effective presence of any agent or factor that is thought to cause disease, e.g. toxic chemicals, dietary habits, activity levels, microorganisms.
The degree to which there is variation in a measurement.
The degree to which the measurement is , on average, correct.
Racial and Ethnic Health Disparities
This phrase is used to describe differences in disease rates by race/ethnicity
The process of early diagnosis of a disease.
Ecologic Study
Study in which the rate of the condition and the prevalence of a given risk factor in one population are compared with those in other populations or across different time periods.
Risk Difference
The arithmetic difference in the incidence of the disease in those with the risk factor and the incidence of disease in those without it.
Exposure occurring before the outcome.
An aspect of the design or execution of a study that yields misleading results.
Bayes' Theorem
Shows how the probability of a condition given a test result can be deduced from the probability of that test result given the condition.
Dose Response
The incremental increase in risk associated with increase in degree of exposure to the risk factor.
Includes: surveillance, observation, hypothesis testing, analytic research and experiments.
Health-related States and Events
Refer to: diseases, causes of death, behaviors such as use of tobacco, positive health states, reactions to preventive regimes and provision and use of health services.
Specified Populations
Include those with identifiable characteristics, such as occupational groups.
Application to Prevention and Control
The aims of public health—to promote, protect, and restore health.
Public Health
Refers to collective actions to improve population health.
Molecular Epidemiology
Measures exposure to specific substances and early biological response evaluating host characteristics mediating response to external agents, and using biochemical markers of a specific effect to refine disease categories.
Genetic Epidemiology
Deals with the etiology, distribution, and control of disease in groups of relatives, and with inherited causes of disease in populations.
Public Health Genetics
Include population screening programs, organizing and evaluating services for patients with genetic disorders, and the impact of genetics on medical practice.
The only disease to be completely eradicated due to vaccines.
Minamata Disease
One of the first reported epidemics of disease caused by environmental pollution.
A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.
Proportional Mortality
A ratio comparing the number of deaths from a given cause per 100 or 1000 total deaths in the same period.
Life Expectancy
The average number of years an individual of a given age is expected to live if current mortality rates continue
Age-Standardized Death Rate
A summary measure of the death rate that a population would have if it had a standard age structure; age adjusted rate.
Any loss or abnormality of psychological, physiological or
anatomical structure or function.
Any restriction or lack (resulting from an impairment) of ability to perform an activity in the manner or within the range considered normal for a human being
a disadvantage for a given individual, resulting from an impairment or a disability, that limits or prevents the fulfillment of a role that is normal (depending on age, sex, and social and cultural factors) for that individual.
Health Indicator
A variable that can be measured directly to reflect the state of health of people within a community.
Risk Factor
Refers to an aspect of personal habits or an environmental exposure, that is associated with an increased probability of occurrence of a disease.
Attributable Fraction
The proportion of all cases that can be attributed to a particular exposure; etiological fraction
Ecological Study
A study that compares groups rather than individuals; correlational study
A classic example of a case-control study that discovered the relationship and limb defects in Germany in 1959 and 1960.
Field Trials
Involve people who are healthy but presumed
to be at risk, data collection takes place "in the field," usually among non-institutionalized people in the general population
Random Error
When a value of the sample measurement diverges - due to chance alone - from that of the true population value
Selection Bias
Occurs when there is a systematic difference between the characteristics of the people selected for a study and the characteristics of those who are not.
Healthy Worker Bias
A selection bias in occupational epidemiology in which a worker must be healthy enough to continue working, the severely ill and disabled are usually excluded from employment.
Measurement Bias
Occurs when the individual measurements or classifications of disease or exposure are inaccurate - that is, they do not measure correctly what they are supposed to measure.
Recall Bias
An important kind of measurement bias in retrospective studies in which there is a differential recall
of information by cases and controls; for instance, cases may be more likely to recall past exposure, especially if it is widely known to be associated with the disease under
An expression of the degree to which a test is capable of measuring what it is intended to measure
Infectious Disease
A disease that is caused by the invasion of a host by agents whose activities harm the host's tissues and can be transmitted to other individuals.
A microorganism that are capable of causing disease.
Results when a pathogen invades and begins growing within a host
When tissue function is impaired as a consequence of the invasion and growth of a pathogen.
Unicellular prokaryotes that have no organized internal membranous structures such as nuclei, mitochondria, or lysosomes.
Infectious agents that are not organisms in themselves because, apart from a host cell, they have no metabolism and cannot reproduce. It is composed of a genome of nucleic acid that is surrounded by a protein coat called a capsid.
Eukaryotic, heterotrophic organisms that have rigid cellulose- or chitin-based cell walls and reproduce primarily by forming spores.
Unicellular, heterotrophic eukaryotes that include the familiar amoeba and paramecium.
Simple, invertebrate animals, some of which are infectious parasites. They are multicellular and have differentiated tissues.
Infectious particles that consisting only of protein such as Creutzfeldt-Jakob disease (in humans), scrapie (in sheep), and "mad cow disease" (in cattle).
Vertical Transmission
Transmission from parent to child during the processes of reproduction (through sperm or egg cells), fetal development, or birth.
Nonspecific Mechanisms
The body's primary defense against disease. These mechanisms include anatomical barriers to invading pathogens, physiological deterrents to pathogens, the inflammatory response and the presence of normal flora.
Specific Mechanisms
The immune response that enables the body to target particular pathogens and pathogen-infected cells for destruction.
Threshold Proportion
The proportion of the population needed for herd immunity to be effective.
Alexander Fleming
The discoverer of penicillin.
Extra-chromosomal genetic material that can be transferred between bacteria.
Emerging Infectious Diseases
Diseases that (1) have not occurred in humans before (this type of emergence is difficult to establish and is probably rare); (2) have occurred previously but affected only small numbers of people in isolated places (AIDS and Ebola hemorrhagic fever are examples); or (3) have occurred throughout human history but have only recently been recognized as distinct diseases due to an infectious agent (Lyme disease and gastric ulcers are examples)
Re-emerging Infectious Diseases
Diseases that once were major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population
The analysis of data and its application to health care. Includes jobs that include Biostatistician, Medical and Health Services Manager, & Health Informatics Specialist
Community Health
Considered the many dynamics that may be at play influencing the overall health of a particular community or region. Includes jobs such as Health Care Administrator, Health Educator, & Community Health Worker
Field of Epidemiology
Monitor the spread of diseases and work to understand their causes and develop solutions. Often employed by government agencies such as local health departments, the Department of Health and Human Services and the Centers for Disease Control and Prevention. However, they may also find jobs with international organizations or private companies such as pharmaceutical companies. Some epidemiologists work independently as consultants.
Environmental Health
Deal with topics such as indoor and outdoor pollution, climate change, electromagnetic fields and other external factors such as water quality that can affect a population's health. May include social environment, dealing with factors such as neighborhood safety, political empowerment and socioeconomic factors.
Global Health
A combination of research and education to serve populations around the world. Jobs can be found with non-profit or government agencies although private companies may also hire global health experts.
Health Policy and Management
Responsible for crafting policies that ensure access to medical care and provide uniform services across various populations.
Health Promotion and Communication
Part public health and part public relations, this field often efforts to encourage health lifestyles. Their job duties may be diverse and include creating and implementing wellness programs, developing marketing campaigns, completing grant applications and working with a team to formulate a comprehensive response to a health concern or crisis.
Maternal and Child Health
Concentrates on reproductive health, infant care and how best to protect the health of mothers and their children. It is a global priority, but workers may also work domestically. Areas of focus may include birth outcomes and adolescent mental health among others.
Minority Health and Health Disparities
Professionals in this field are committed to understanding why there is unequal access to health services and then working to alleviate those imbalances. Jobs in the field may require individuals to develop ways to better distribute available resources and improve health knowledge among underserved communities.
Social and Behavioral Health
This area includes a focus on the social influences impacting a population's overall health. However, social and behavioral health workers may have a greater emphasis on understanding how individual thought processes can affect health.
Main Objectives of Disaster Epidemiology
1. Prevent or reduce the number of deaths, illnesses, and injuries caused by disasters,
2. Provide timely and accurate health information for decision-makers,
3. Improve prevention and mitigation strategies for future disasters by collecting information for future response preparation.
Community Assessment for Public Health Emergency Response. An epidemiologic technique designed to provide quickly and at low cost, household-based information about an affected community's needs after a disaster in a simple format to decision-makers.
A serious disruption of the functioning of society, causing widespread human, material or environmental losses, that exceeds the local capacity to respond, and calls for external assistance.
Disaster Epidemiology
The use of epidemiology to assess the short- and long-term adverse health effects of disasters and to predict consequences of future disasters.
Why Data Should Be Collected During a Disaster
Provides situational awareness, let's us know the needs, allows us to plan the response, and gather appropriate resources. We want to prevent further morbidity and mortality by addressing both immediate and long-term needs, adjusting priorities, allocating resources, and projecting and planning for future needs. We also use data to identify risk factors and improve prevention and mitigation strategies for future disasters.
Public Health Surveillance
The systematic collection, analysis, and interpretation of deaths, injuries, and illnesses in order to provide information about any adverse health effects related to a disaster event in a community.
CDC Mission
CDC works 24/7 to protect America from health, safety and security threats, both foreign and in the U.S. Whether diseases start at home or abroad, are chronic or acute, curable or preventable, human error or deliberate attack, CDC fights disease and supports communities and citizens to do the same.

CDC increases the health security of our nation. As the nation's health protection agency, CDC saves lives and protects people from health threats. To accomplish our mission, CDC conducts critical science and provides health information that protects our nation against expensive and dangerous health threats, and responds when these arise.
CDC Role
- Detecting and responding to new and emerging health threats
- Tackling the biggest health problems causing death and disability for Americans
- Putting science and advanced technology into action to prevent disease
- Promoting healthy and safe behaviors, communities and environment
- Developing leaders and training the public health workforce, including disease detectives
- Taking the health pulse of our nation
Causes, risk factors, modes of transmission (why and how)