Infection, Disease, and Epidemiology Flashcards

This set of vocabulary flashcards covers fundamentals of infection and disease, the stages of infectious illness, epidemiological classifications, types of infectious agents, and various reservoirs including specific bacterial examples.

Infection

A microbe growing or multiplying on or within a host.

Infectious disease

Any change in health where part or all of the host is incapable of functioning normally.

Disease

A broad term that encompasses any abnormal condition that affects the normal functioning of a living organism, including humans, caused by factors such as genetics, lifestyle choices, or environmental factors.

Pathogen

Any organism that causes disease.

Opportunistic pathogen

A pathogen that doesn't typically cause harm to a healthy individual with an intact immune system but can cause infections if the immune system is compromised or weakened.

Pathogenicity

The ability for a microorganism to cause disease in a susceptible host.

Virulence

A quantitative measure of the degree or severity of the pathogenicity of a microorganism, representing the extent of harm inflicted upon the host.

Incubation period

The period after pathogen entry but before the appearance of signs and symptoms.

Prodromal stage

The onset of signs and symptoms that are not clear enough for a diagnosis.

Illness period

The most severe point of disease regarding signs and symptoms, which sometimes culminates in death.

Convalescence

The stage where signs and symptoms of an infectious disease begin to disappear.

Signs

Objective changes in the body experienced by the patient.

Symptoms

Subjective changes experienced by the patient, such as pain or loss of appetite.

Transmission

The process by which an infection or disease travels from one host to another.

Epidemiology

The science that evaluates occurrence, determinants, distribution, and control of health and disease in a defined human population.

Sporadic disease

A disease that occurs occasionally or at irregular intervals, occurring one at a time and in areas separated geographically.

Endemic disease

A disease maintained at a relatively steady low-level frequency at a moderately regular interval, constantly present in a population or area.

Outbreak

A sudden, unexpected occurrence of a disease in a limited segment of the population.

Epidemic

A sudden increase in the level of disease above what is normally expected in a given population or area, typically within a smaller and more limited geographic area than an outbreak.

Pandemic

An epidemic occurrence within a large population over several countries or continents.

Hyperendemic disease

A disease that gradually increases in frequency above the endemic level but not to the epidemic level.

Common source epidemic

An epidemic with a rapid increase to a peak number of infected individuals followed by a rapid but more gradual decline, where cases are reported for approximately one incubation period.

Propagated epidemic

An epidemic showing a gradual rise followed by a gradual decline, with cases reported over a time interval equal to several incubation periods.

Bacteria

Single-celled (unicellular) prokaryote organisms with a primordial nucleus that lack a nucleus and membrane-enclosed intracellular structures.

Archaea

Single-celled prokaryotes with no nucleus that are genetically and metabolically very different from bacteria and are not known to cause disease.

Viruses

Acellular organisms composed of nucleic acid and a few proteins that must enter a cell to multiply.

Viroids

Infectious agents consisting of nucleic acid RNA with a protein coating that cause various plant diseases.

Prions

Protein without any nucleic acid, associated with mad cow disease and related disorders.

Fungi

Eukaryotic organisms containing a nucleus and membrane-bound organelles, which can be unicellular yeasts, mould, or mushrooms.

Protozoa

Large and diverse group of single-celled microscopic eukaryotic organisms with at least one nucleus and numerous intracellular structures.

Helminths

Multicellular eukaryotic animals (parasitic worms) that generally possess digestive, circulatory, nervous, excretory, and reproductive systems.

Reservoir

The habitat in which the infectious agent normally lives, grows, and multiplies.

Source

The individual or object from which the infectious agent is acquired.

Asymptomatic carrier

An individual with a subclinical infection showing no detectable symptoms but capable of transmitting the pathogen to others.

Asymptomatic chronic carriers

Asymptomatic individuals who continue to harbour a pathogen for moths or even years after the initial infection.

Latent viral infections

Occurrences where a viral pathogen becomes dormant in a cell, is not replicated, and displays no symptoms until it becomes active again.

Zoonoses

Animal diseases that can be transmitted to humans through close contact, secretions, or vectors.

Pseudomonas sp.

Gram-negative bacteria commonly found in soil and on plants that are important opportunistic pathogens naturally resistant to multiple antimicrobial agents.

Clostridium sp.

Gram-positive, anaerobic, spore-forming bacteria commonly found in soil.

Clostridium tetani

Bacteria that can be part of the bowel microbiota of animals and produce endospores that remain viable in soil, transferring to humans via contaminated injury.

Clostridium perfringens

Bacteria with widely distributed endospores that can cause gas gangrene through skin breakage or gastroenteritis if ingested in food.

Clostridium botulinum

Bacteria found in soil whose endospores can germinate in poorly preserved food under $AnO_2$ conditions to produce neurotoxins leading to botulism.

Legionella

A pathogen found in natural streams and isolated from the cooling towers of air-conditioning plants.