Principles of Disease and Epidemiology – Chapter 14

Vocabulary flashcards summarizing the key terms and concepts from Chapter 14: Principles of Disease and Epidemiology.

Epidemiology

The study of disease patterns in populations and the design of strategies to control, prevent, or predict the spread of disease.

Epidemiologist

A scientist who investigates disease patterns and devises infection-control strategies.

Pathology

The scientific study of disease, including its causes, development, and effects on the body.

Etiology

The specific cause of a disease; in infectious diseases, the pathogen responsible.

Pathogenesis

The developmental process by which a disease originates and progresses in the host.

Infection

Invasion and colonization of the body by pathogenic microorganisms.

Disease

An abnormal condition in which the body is not performing normal functions, often following infection.

Normal microbiota (Resident microbiota)

Microorganisms that permanently colonize the human body and usually do not cause disease under normal conditions.

Transient microbiota

Microbes that are present in or on the body for days, weeks, or months but do not permanently colonize the host.

Opportunistic pathogen

A normally harmless microorganism that can cause disease when the host’s defenses are compromised or when it moves to a new body site.

Dysbiosis

An imbalance in the normal microbiota, often linked to diseases such as inflammatory bowel disease or chronic fatigue syndrome.

Microbial antagonism (Competitive exclusion)

Protection provided by normal microbiota through competition for nutrients, production of inhibitory substances, or alteration of local pH and oxygen levels.

Symbiosis

Any close relationship between two different organisms living together; includes commensalism, mutualism, and parasitism.

Commensalism

A symbiotic relationship in which one organism benefits while the other is unaffected (e.g., many skin microbes).

Mutualism

A symbiotic relationship in which both organisms benefit (e.g., Escherichia coli in the colon synthesizing vitamins for the host).

Parasitism

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

Koch’s postulates

Four criteria used to prove that a specific pathogen causes a specific infectious disease: (1) the pathogen is present in every case of the disease; (2) it can be isolated and grown in pure culture; (3) the cultured pathogen causes the disease in a healthy host; (4) it is re-isolated from the experimentally infected host.

Limitations of Koch’s postulates

Some pathogens cause multiple diseases, cannot be cultured outside the host, or infect only humans, making animal testing or pure culture steps impossible.