Introduction to Infectious Diseases Flashcards

This set of vocabulary flashcards covers concepts from Chapter 18 including microbial pathogenesis, virulence strategies, transmission routes, epidemiological patterns, and historical case studies of infectious diseases.

Disease

A disturbance in the normal functioning of an organism.

Infectious disease

A disease caused by a microbe that can be transmitted from host to host.

Zoonotic disease

Infectious diseases of animals that can cause disease when transmitted to humans, such as rabies or West Nile fever.

Pathogenesis

The mechanism a microbe uses to cause the disease state.

Infection

The replication of a pathogen in or on its host.

Primary pathogen

A pathogen that tends to produce disease readily in healthy hosts.

Opportunistic pathogen

A pathogen that generally only causes disease when displaced to an unusual site or when the host has a weakened immune system.

Virulence

A measure of the severity of disease a pathogen can induce.

Case-to-Infection (CI) ratio

The proportion of infected individuals who develop the disease.

Attenuated strain

A strain of a pathogen that shows decreased virulence, often useful for vaccine development.

Avirulent strain

A strain of a pathogen that can no longer cause disease.

Carrier

An individual infected with a pathogenic microbe who never exhibits overt signs or symptoms of the disease (asymptomatic) but may still transmit the microbe.

Mary Mallon

A famous carrier case also known as Typhoid Mary.

Host Range

The group of organisms that a pathogen can infect, determined by its ability to attach, invade, and replicate.

Antigenic Variation

A strategy used by microbes like T. brucei and N. gonorrhoeae to evade host defenses by shifting their surface protein structures.

Latency

An evasion method where a virus such as Herpes simplex virus inserts its genome into host cells and stops replication until periodic reactivation occurs.

Restriction endonucleases

Bacterial enzymes used to digest phage DNA as a defense mechanism.

Exotoxins

Proteins produced and secreted by microbes that can have negative effects on host cells.

Endotoxins

Toxic components that are part of the microbial structure itself.

Transmission

The spread of an infectious agent from one host to another or from a natural source (reservoir) to a host.

Fomite

An inanimate object that carries an infectious agent between internal and susceptible individuals.

Horizontal transmission

Transmission of a pathogen between members of a species other than from parent to offspring.

Vertical transmission

The passing of a pathogen from parent to child, often in utero, during birth, or shortly after birth.

Epidemiology

The study of patterns of disease in populations.

Morbidity rate

The rate of disease in a population.

Mortality rate

The death rate of a disease.

Incidence

The number of new cases appearing in a population during a specific time period.

Prevalence

The total number of cases in a population at a particular time.

Endemic disease

A disease habitually present in a population, often resulting in cyclical patterns of incidence.

Epidemic

When the incidence of a disease rises significantly above the normally expected value.

Outbreak

An unexpected cluster of cases in a short time in a localized population.

Pandemic

A global epidemic.

Common-source epidemic

An epidemic arising from a single source of infection to which a population is exposed, characterized by a rapid increase and decrease in incidence.

Propagated epidemic

An epidemic where infection passes from one host to another, typically exhibiting a gradual increase in incidence over time.

John Snow

Considered the father of epidemiology for his work mapping the $1854$ London cholera outbreak to the Broad Street pump.

Koch's Postulates

A set of four rules used to prove that a specific microbe causes a specific disease.

Pathogenicity islands

Clusters of virulence factor genes within a pathogen's genome.

Borrelia burgdorferi

The bacterium that causes Lyme disease, normally residing in deer and mice.

Ixodes scapularis

The black-legged tick that acts as a vector organism for Lyme disease.

MRSA

Methicillin-resistant Staphylococcus aureus, a common microbe that has acquired resistance traits against elimination drugs.