epidemiology

pop health

What is epidemiology?

The study of the occurrence and distribution of disease or health-altering events in populations to prevent, mitigate, or control health problems

What are the six core functions of epidemiology?

Surveillance, investigation, analytic studies, evaluation, linkages, and policy development

What is epidemiological surveillance?

Ongoing collection and interpretation of health information to monitor population health, identify problems, and evaluate interventions

What is the National Notifiable Disease Surveillance System (NNDSS)?

A CDC surveillance system that collects information about reportable diseases to support disease prevention and control

What is an epidemiological investigation?

A systematic inquiry following disease detection to identify the source of an outbreak

What is an endemic disease?

A disease consistently present within a specific population or geographic area

What is an epidemic?

A sudden increase in disease cases above what is normally expected within a population or geographic area

What is a pandemic?

An epidemic that spreads across multiple countries or continents

Malaria occurs consistently year-round in a particular country. What level of disease is this?

Endemic

A sudden increase in influenza cases occurs above the expected level. What is this?

Epidemic

An infectious disease spreads across multiple continents. What is this?

Pandemic

What is descriptive epidemiology?

The study of disease patterns based on person, place, and time

What questions does descriptive epidemiology answer?

Who, what, when, and where?

What is analytic epidemiology?

The study of potential causes of disease using comparisons between groups

What question does analytic epidemiology primarily answer?

Why is the disease occurring?

A nurse investigates why several people developed vomiting and diarrhea after attending a banquet. What type of epidemiology is this?

Analytic epidemiology

What is formative evaluation?

Evaluation conducted during program planning and implementation to assess and improve the intervention

What is summative evaluation?

Evaluation conducted on established programs to measure overall outcomes

What is the main difference between formative and summative evaluation?

Formative occurs during planning and implementation; summative evaluates overall outcomes of established programs

What is the epidemiological triangle?

A model describing how the agent, host, and environment interact to influence disease occurrence and transmission

What are the three components of the epidemiological triangle?

Agent, host, and environment

What is an agent?

A factor that causes or contributes to a health problem or disease

What are the five types of agents?

Biological, nutritional, chemical, physical, and psychological

What are examples of biological agents?

Bacteria, viruses, fungi, and protozoa

What are examples of chemical and physical agents?

Chemical: pesticides, asbestos, radiation. Physical: UV exposure, floods, earthquakes, and fires

What is a host?

A susceptible human or animal that harbors and nourishes a disease-causing agent

What host factors influence disease susceptibility?

Physical characteristics, genetics, psychological stress, coping mechanisms, diet, exercise, and sleep

What is the environment in the epidemiological triangle?

External conditions surrounding the host that influence vulnerability or resistance to disease

What are examples of environmental factors?

Climate, geography, poverty, culture, and access to healthcare

A nurse identifies Salmonella as the cause of an infection. Which component of the epidemiological triangle is Salmonella?

Agent

What is infectivity?

The ability of an infectious agent to replicate within a host

What is virulence?

The severity of disease caused by an infectious agent

How do exposure duration and dose influence disease severity?

Longer exposure or greater doses can increase symptom severity

What is the natural history of disease?

The expected progression of disease without intervention

What are the stages in the natural history of disease?

Susceptibility → Subclinical disease → Clinical disease → Recovery, disability, or death

What is the incubation period?

The time between exposure to an infectious agent and the onset of symptoms

What is the latency period?

The subclinical period between exposure and symptom onset in chronic disease

What is the main difference between incubation and latency periods?

Incubation applies to infectious diseases; latency applies to chronic diseases in this lecture

Why is the incubation period important in disease transmission?

Individuals may be asymptomatic but still capable of spreading infection

What is a reservoir?

An organism in which an infectious agent lives and multiplies

What is direct transmission?

Immediate transfer of an infectious agent from a reservoir to a host

What are examples of direct transmission?

Touching, kissing, biting, sexual contact, fecal-oral contact, and respiratory droplets

What is indirect transmission?

Transmission through air, contaminated food or water, fomites, or vectors

What is a fomite?

An inanimate object that carries an infectious agent, such as a doorknob or countertop

What is a vector?

A living carrier, such as an insect or tick, that transmits an infectious agent

A person develops malaria after exposure to infected mosquitoes. What type of transmission occurred?

Indirect transmission through a vector

What are the six links in the chain of infection?

Infectious agent → Reservoir → Portal of exit → Mode of transmission → Portal of entry → Susceptible host

What is incidence?

The number of new disease cases occurring within a specific time period among people at risk

What is prevalence?

The number of existing and new disease cases within a population at a specified time

What is the key difference between incidence and prevalence?

Incidence measures NEW cases; prevalence includes ALL existing and new cases

Who is included in the population at risk when determining incidence?

Only individuals who are susceptible to developing the disease

What is point prevalence?

The prevalence of a disease at one specific point in time

What is period prevalence?

The prevalence of a disease during a specified time span

A nurse wants to identify newly diagnosed cases of an illness. Which measure should be used?

Incidence

A nurse wants to determine how many community members currently have an illness. Which measure should be used?

Prevalence

What is reliability in screening?

The consistency of a measurement when repeated under the same conditions

What is validity in screening?

Whether a test accurately measures what it is intended to measure

What is the difference between reliability and validity?

Reliability = consistency

validity = accuracy

What factors can decrease screening reliability?

Variation in the trait measured, observer differences, and inconsistent instruments

What is sensitivity?

The ability of a screening test to correctly identify individuals who HAVE the disease (true positives)

What is specificity?

The ability of a screening test to correctly identify individuals who DO NOT have the disease (true negatives)

What is a false negative?

A test indicates that an individual does not have a disease when they actually do

What is a false positive?

A test indicates that an individual has a disease when they actually do not

What is the major concern with false-negative results?

Individuals with disease may remain undiagnosed and untreated

What are the potential consequences of false-positive results?

Unnecessary treatment, psychological distress, and increased healthcare costs

A screening test has high specificity. What does this indicate?

The test accurately identifies individuals who do not have the disease

Which screening characteristic is associated with identifying true positives?

Sensitivity

Which screening characteristic is associated with identifying true negatives?

Specificity

Which diseases must be reported IMMEDIATELY or ASAP within 3 hours (RED)?

• any suspected bioterrorist threat

• any unusual case or cluster of cases that may indicate a piblic health hazard

• anthrax

• ‘botulism/foodborne

• diphtheria

• Influenza A

• plague

• poliomyelitis

• severe acute respiratory syndrome (SARS)

• smallpox

Which diseases must be reported within 24 hrs (BLACK)?

• Botulism, infant, wound

• brucellosis

• cholera

• COVID

• E. coli infections

• foodborne or waterborne outbreaks

• haemophilus influenzae

• hantavirus pulmonary syndrome

• hemolytic uremic syndrome

• hepatitis A

• influenza, ICU admission

• measles

• mumps

• nisseria meningitidis

• outbreaks of public significance pertussis (whooping cough)

• Q fever

• rabies

• rubella

• S. aureus infections

• tularemia

• typhoid fever

• typhus

• varicella