Lecture 17: Principles of Disease & Epidemiology

Vocabulary flashcards covering key terms and concepts from the lecture notes.

Symbiosis

Life Together: A close relationship between two different organisms.

Commensalism

A symbiotic relationship where one organism benefits and the other is neither harmed nor helped (+, 0).

Mutualism

A symbiotic relationship where both organisms benefit (+, +).

Parasitism

A symbiotic relationship where one organism benefits at the expense of the other (+, -).

Normal Flora / Normal Microbiota

Microorganisms that colonize the body but do not produce disease under normal conditions; provide protection via microbial antagonism or competitive exclusion.

Pathology

Scientific study of disease.

Etiology

Cause of disease.

Pathogenesis

Origin and development of disease.

Virulence

Degree of pathogenicity.

Virulence factors

Molecules produced by a pathogen that allow it to thrive.

etiology of infectious disease is determined by

Kochs postulates

difficulties: microbe difficult to grow, fastidious

Colonization

The presence of microorganisms in a host.

Infection

When a pathogen enters and begins to grow in/on a host..

Disease

An abnormal state in which the body is not functioning normally

Disease signs

discovered by physician

Disease symptoms

reported by patient

Disease syndrome

A specific group of signs and symptoms that accompany a particular disease.

Primary infection

An acute infection that causes the initial illness

Secondary infection

occurs during or after primary infection

Primary pathogen

A pathogen that can cause disease in a healthy host.

Opportunistic pathogen

A pathogen that causes disease only when the host's defenses are compromised or in an unusual location.

Immunocompromised hosts

Individuals with weakened immune systems.

Incidence

Number of new cases of a disease in a given area or population during a specified period of time.

number of new cases/number of people at risk

Prevalence

Total number of existing cases (new and old) of a disease in a given area or population at a specific time.

number of old and new cases/number of people at risk

Sporadic disease

Occurs occasionally.

Endemic

Disease constantly present in a population.

ex. common cold

Epidemic

Many in a given area acquire a certain disease in a short period.

Pandemic disease

An epidemic disease that occurs worldwide.

Acute disease

Develops rapidly but lasts a short time.

Chronic disease

Develops more slowly, reaction less severe, but lasts a long time.

Latent disease

Causative agent remains inactive for a while, then activates.

Disease carriers

Individuals who harbor pathogens and transmit them to others without showing noticeable illness.

Subclinical infection

Infection that does not cause any noticeable illness.

Local infection

An infection that is confined to a specific area of the body.

ex. abscess, boils

Systemic infection

An infection that has spread throughout the body.

measles

Sepsis

Toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection.

Bacteremia

Presence of bacteria in the blood.

Viremia

Presence of viruses in the blood.

Toxemia

Presence of toxins in the blood.

Septicemia

Systemic infection arising from multiplication of pathogens in the blood.

Incubation period

The time between exposure to an infectious agent and the first signs or symptoms of disease.

Prodromal stage

Short period after incubation; early, mild symptoms

Period of invasion

The period during which the infectious agent multiplies rapidly and is at its highest levels, producing the most intense signs and symptoms.

Convalescent period

The stage of recovery from an illness.

Reservoir

Source which harbors disease causing organism; serves as potential source for disease outbreak.

symptomatic reservoirs

coughing, sneezing

asymptomatic resevoirs

carrier, no symptoms

non human - Zoonoses

Diseases transmitted from animals to humans.

animal reservoirs

environmental reservoirs

soil and water

ex. malaria, lyme disease

Communicable disease

A disease that is spread from one host to another.

Contagious disease

A disease that is easily spread from one host to another.

Noncommunicable disease

A disease that is not transmitted from one host to another.

Fomite

An inanimate object that transmits disease.

Vehicle Transmission

Transmission of pathogens via a medium such as water, food, or air.

Mechanical Vector

Arthropod carries pathogen on feet or other body parts.

ex. fly

Biological Vector

Pathogen reproduces in vector; transmitted via bites or feces.

ex. mosquito

Nosocomial Infection

Hospital-acquired infection.

#1 method of control: handwashing

Emerging Infectious Diseases (EIDs)

Diseases that are new, increasing in incidence, or showing a potential to increase in the near future.

factors contributing to EID

complacency and breakdown in public health care system

changes in human behavior

pop. expansion and development

mass distribution and food importation

wars and civil unrest

excessive and inappropriate use of antibiotics

increasing pop. of immunocompromised pts.

global travel

John Snow

father of epidemiology

figured out why a group of people were contracting cholera by mapping cases and identifying a contaminated water source.

Ignaz Semmelweis

savior of mothers

promoted handwashing between births as it may have caused childbirth fever in mothers

colleagues deemed him insane and casted him out where he fought back and called them out as murderers

threw him in insane asylum and after he died, only then did they test his theory in which cases dropped

Florence Nightingale

pioneered nursing and healthcare

compiled stats. demonstrating that disease, poor food, and unsanitary conditions were killing soldiers

Epidemiology

Science of disease transmission; includes microbiology, ecology, statistics, sociology, psychology.

Descriptive Epidemiology

Describes occurrence of disease; identifies people at risk, place, and time.

retrospective: directed to past

prospective: in the future

Analytical Epidemiology

Analyzes disease trends or outbreaks to determine cause and identify factors that might precede disease.

Experimental Epidemiology

Tests a hypothesis; evaluates the effectiveness of drugs or vaccines.

Case Reporting

Reports specific case(s) of disease outbreak.

Morbidity

Incidence of a specific notifiable disease.

Mortality

Deaths from notifiable diseases.

Incidence rate

Number of new cases of a disease during specified period.

Prevalence rate

Number of people who develop a disease at a specified time, regardless of when it first appeared.