Principles of Disease and Epidemiology – Vocabulary Review

A comprehensive set of vocabulary flashcards covering key terms from the lecture on disease principles and epidemiology.

Pathology

The study of disease.

Etiology

The cause of a disease.

Pathogenesis

The manner in which a disease develops.

Infection

Invasion or colonization of the body by pathogens.

Infectious disease

Any change in health that results from an infection.

Human microbiome

The collection of microorganisms that live on and inside the human body.

Normal microbiota (normal flora)

Microbes that permanently colonize the host without causing disease under normal conditions.

Transient microbiota

Microbes that are present temporarily (days to months) and then disappear.

Symbiosis

A relationship between two organisms in which at least one depends on the other.

Commensalism

Symbiotic relationship where one organism benefits and the other is unaffected.

Mutualism

Symbiotic relationship in which both organisms benefit.

Parasitism

Symbiotic relationship in which one organism benefits at the expense of the other.

Opportunistic pathogen

A normally harmless microbe that can cause disease under certain conditions.

Microbial antagonism (competitive exclusion)

Competition by normal microbiota that prevents overgrowth of harmful microbes.

Koch’s postulates

Four criteria used to prove that a specific microbe causes a specific disease.

Symptom

Subjective change in body function felt by the patient (e.g., pain).

Sign

Objective, measurable change in the body caused by disease (e.g., fever).

Syndrome

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

Communicable disease

Disease that spreads from one host to another.

Contagious disease

Disease that is easily and rapidly spread from person to person.

Noncommunicable disease

Disease that is not transmitted from one host to another.

Incidence

Number of new cases of a disease in a population during a time period.

Prevalence

Total number of existing cases (old and new) at a given time.

Sporadic disease

Disease that occurs only occasionally.

Endemic disease

Disease constantly present in a population.

Epidemic disease

Disease acquired by many people in a short time within an area.

Pandemic disease

Worldwide epidemic.

Acute disease

Disease with rapid onset and short duration.

Chronic disease

Disease that develops slowly and lasts for a long period.

Subacute disease

Disease whose symptoms are intermediate between acute and chronic.

Latent disease

Disease in which the causative agent remains inactive for a time before producing symptoms.

Herd immunity

Resistance of a population to disease due to immunity of most members.

Local infection

Infection limited to a small area of the body.

Systemic (generalized) infection

Infection that spreads throughout the body via blood or lymph.

Focal infection

Systemic infection that began as a local infection.

Sepsis

Toxic inflammatory condition arising from the spread of microbes or their toxins.

Bacteremia

Presence of bacteria in the blood.

Toxemia

Presence of toxins in the blood.

Viremia

Presence of viruses in the blood.

Primary infection

Acute infection that causes the initial illness.

Secondary infection

Opportunistic infection after a primary infection.

Subclinical infection

Infection with no noticeable signs or symptoms.

Predisposing factor

Variable that makes the body more susceptible to disease or alters its course (e.g., age, nutrition).

Incubation period

Interval between initial infection and first signs or symptoms.

Prodromal period

Short period after incubation with early, mild symptoms.

Period of illness

Stage when disease is most severe and signs/symptoms peak.

Period of decline

Stage when signs and symptoms subside.

Period of convalescence

Stage when the body returns to its pre-disease state.

Reservoir of infection

Continual source of pathogens (human, animal, or nonliving).

Zoonosis

Disease transmitted from animals to humans.

Direct contact transmission

Person-to-person spread requiring close physical contact.

Congenital transmission

Pathogen passes from mother to fetus or newborn.

Indirect contact transmission

Spread via a nonliving object (fomite).

Droplet transmission

Spread via airborne droplets ≤1 meter.

Vehicle transmission

Spread via an inanimate reservoir such as air, water, or food.

Vector

Arthropod that transmits pathogens between hosts.

Mechanical transmission

Vector carries pathogen on its body surface (e.g., feet).

Biological transmission

Pathogen reproduces in vector and is transmitted via bite or feces.

Healthcare-associated infection (HAI)

Infection acquired while receiving treatment in a healthcare facility.

Compromised host

Individual with impaired resistance to infection due to disease, therapy, or burns.