Epidemiology and Nosocomial Infections

Epidemiology

The study of factors and mechanisms involved in the frequency and spread of diseases within populations.

Etiology

The cause of a disease in a population.

Prevalence

The total number of existing cases with respect to the entire population, expressed as a percentage.

Incidence

The number of new cases over a certain time period divided by total susceptible persons.

Mortality Rate

The total number of deaths in a population due to a certain disease.

Morbidity Rate

The number of persons afflicted with infectious diseases.

Endemic

A disease present continually in a population with cases and severity too low to be a public health problem.

Epidemic

A disease that suddenly has a higher-than-normal incidence in a population.

Pandemic

An epidemic that spreads worldwide.

Sporadic

A disease that occurs in a random and unpredictable manner.

Common-source Epidemic

An epidemic arising from contact with contaminated substances.

Propagated Epidemic

An epidemic arising from direct person-to-person contact.

Reservoir

The primary habitat in the natural world from which a pathogen originates.

Source

The individual or object from which an infection is actually acquired.

Zoonoses

Infections indigenous to animals but naturally transmissible to humans.

Portal of Entry

Sites at which microorganisms can enter the body, such as skin, mucous membranes, or respiratory tract.

Direct Contact Transmission

Requires body contact between individuals, including horizontal touch and vertical parent-to-offspring transmission.

Fomites

Inanimate objects that can harbor and transmit infectious diseases via indirect contact.

Mechanical Vectors

Live animals that transport an infectious agent without being infected themselves.

Biological Vectors

Live animals that actively participate in a pathogen's life cycle.

Herd Immunity

The proportion of individuals in a community or population who are immune to a particular disease.

Quarantine

Prevents the spread of disease during the incubation period by restricting movement.

Nosocomial Infection

An infection acquired in a hospital or other medical facility.

Exogenous Infections

Nosocomial infections that enter the patient from the external environment.

Endogenous Infections

Nosocomial infections originating from the patient's own normal microflora.

Hand Washing

The single most important technique to reduce the spread of pathogens in healthcare settings.