HAP 355 Midterm

Epidemiology

Epidemiology

Study and analysis of the distribution, patterns, and determinants of health & disease conditions in a defined population

Descriptive Epidemiology

Involves characterizations of the distribution of health-related states or events (person, place, time)

Analytic Epidemiology

Involves finding & quantifying associations, testing hypotheses, & identifying causes of health-related states or events

Efficacy

Ability of a program to produce a desired effect among participants in the program compared to those not in the program

Effectiveness

Ability of a program to produce benefits among those who are offered the program

Epidemics

Illness or behavior or health-related event in excess of normal

Endemics

Ongoing, usual, or constant presence of a disease in a community

Pandemics

Epidemic that affects the population of an extensive region

Common-source

Specific source

Common-source

specific source

Propagated

infections that are transmitted from one infested person to another

Case

a person in a population who has a disease, disorder, injury, or condition

Case defined

a standard set of criteria

Primary case

first disease case in the population

Index case

first disease brought to the attention of an epidemiologist

Secondary case

person infected after contact with a primary case

Suspect case

individual or groups who have signs and symptoms but not diagnosed

Case severity

how disabling or debilitating the illness is (hospital length of stay)

Epidemiology Triangle

model for understanding infectious disease

Fomite

inanimate object that can harbor a pathogen and is capable of being a means of transmission

Vector

invertebrate animal that transmits infection by conveying the pathogen from one host to another

Reservoir

habitat in which the agent normally lives, grows, & multiplies

Vehicle

a fomite intermediary that conveys the infectious agent from its reservoir to a susceptible host

Carrier

contains, spreads, or harbors an infectious organism

active carrier

exposed and harbors the pathogen

convalescent carrier

harbors the pathogen, recovery phase

healthy (passive) carrier

not ill, but exposed and harbors the pathogen

incubatory carrier

exposed, & harbors the pathogen, ability to transmit

intermittent carrier

exposed to and harbors, can spread pathogen

Direct

un-interrupted and immediate transfer from person to person

Indirect

transmission through airborne, vector-borne, and vehicle-borne routes

airborne

occurs when droplets or dust carry the pathogen to the host and cause infection

vector-borne

occurs when an arthropod conveys the infectious agent

vehicle-borne

involves an inanimate object that conveys an infection from the host

chain of infection

→ infectious agent → reservoir → portal of exit → mode of transmission → portal of entry → susceptible host →

advanced triangle of epidemiology

Hippocrates

Considered the first epidemiologist, he introduced terms like epidemic and endemic, emphasizing a rational perspective on diseases over supernatural beliefs.

John Graunt

An English statistician who developed vital statistics, including life tables and life expectancy calculations, and categorized deaths into acute and chronic causes.

Bernardino Ramazzini

Noted that diseases among workers stemmed from harmful materials and unnatural postures at work, laying the foundation for occupational health.

James Lind

Scottish naval surgeon who conducted an experimental study on scurvy, highlighting the impact of diet, time, and place on disease spread.

Edward Jenner

Rural physician who pioneered vaccination by using cowpox to protect against smallpox, a breakthrough in immunization.

John Snow

Known as the father of Epidemiology, he studied cholera transmission, incubation times, and water sources, contributing significantly to disease control.

Ignaz Semmelweis

Hungarian physician who advocated for hand hygiene to prevent childbed fever, a crucial step in understanding and preventing nosocomial infections.

Florence Nightingale

Revered as the mother of modern nursing, she revolutionized healthcare practices during the Crimean War and established the first nursing school.

Louis Pasteur

Renowned French scientist who developed vaccines for anthrax and other diseases, pioneering the field of microbiology and immunization.

Typhoid Mary

Refers to Mary Mallon, an Irish chef who unknowingly spread typhoid fever, highlighting the importance of asymptomatic carriers in disease transmission.

Communicable disease

Infectious diseases that are contagious or capable of being transmitted

Non-communicable disease

A disease not transmissible directly from one person to another

Vertical Transmission

Transmission from an individual to its offspring through sperm, placenta, milk, or vaginal fluid

Horizontal Transmission

Transmission of infectious agents from an infected person to a susceptible person

Characteristics of infectious disease agents

Viability, communicability, infectivity, pathogenicity, and virulence

Viability

Ability of the infectious agent to survive outside the host and thrive in the environment

Communicability

Ability of the infectious disease to be transmitted from one person to the next or spread in a population

Infectivity

Ability of an infectious agent to cause infection

Pathogenicity

Ability of an infectious agent to cause disease after infection

Virulence

Ability of an infectious agent to cause severe disease

Stages of Disease

Susceptibility, Pre-symptomatic Disease, Clinical Disease, Recovery, Disability, or Death

how the human body resists infection

resistance to infection

→ general resistance

→ immunity

—> active immunity (naturally or artificially acquired active immunity)

—> passive immunity (naturally or artificially acquired passive immunity)

Active Immunity

Body produces antibodies against a specific antigen for permanent immunity

Passive Immunity

Transfer of antibodies from another person for short-lived immunity

Herd immunity

Protection of the population from disease by immunity to limit major epidemics

Environmental Control

Measures like clean water, safer air, and control of vectors to prevent disease

Host-related Control

Quarantine for exposed persons, isolation for non-ill individuals with contagious diseases

Infection-control and prevention

Includes personal hygiene and antibiotic prophylaxis

Descriptive Epidemiology

Describes the extent of a public health problem according to person, place, and time

Population Pyramids

Used to track and compare changes in the population age distributions over time

Constrictive Pyramid

A population pyramid that comes in at the bottom, indicating an older population with low birth rates

Gender or Sex

Sex is biologically founded, while gender is a socially constructed notion

Time Trends

Examples include temperature measured at noon each day and the number of hospital admissions per day

Point Source Epidemic

Individual exposed to the same source over a limited time period

Surveillance

Systematic ongoing collection, analysis, interpretation, and dissemination of health data

Health Programs

Aimed at increasing vaccination levels, reducing smoking, and increasing physical activity

Confounding Factors

Always a threat in descriptive studies, analytic epidemiologic studies are better for minimizing the threat

Noninfectious acute conditions

Conditions that occur suddenly, such as car accidents or injuries.

Chronic disease epidemiology

Study of the distribution and determinants of chronic diseases in the human population for preventing and controlling health problems.

Risk factor

A variable associated with an increased likelihood of experiencing adverse health outcomes.

Exposure to radiation pathways

Inhalation, ingestion, and direct exposure to radioactive materials.

Toxicokinetics

Processes including absorption, distribution, biotransformation, and excretion of substances in the body.

Social environment and health

Factors like war, families, social networks, neighborhoods, and public health policies influencing health.

Behavior and chronic health problems

Lifestyles affecting modern diseases, including smoking, diet, body weight, sexual practices, and heredity.

Risk factors of breast cancer

Age, family history, geography, radiation exposure, obesity, breastfeeding, and mammography for screening.

Prevention behaviors

Healthy weight maintenance, dietary choices, alcohol consumption, fruit and vegetable intake, exercise, and protection from various risks.

Health Belief Model

Factors like perceived susceptibility, severity, benefits, barriers, cues to action, and self-efficacy in health decision-making.

Prevention and control of noninfectious diseases

Tailoring prevention programs to societies, cultures, and health determinants for effective control and reduced healthcare costs.

Priorities in disease prevention and control

Identifying impactful diseases, susceptible populations, responsive communities, overlooked diseases, and investigations for improved health states and economic benefits.