host microbe relation

Mutualism

An obligatory and mutually beneficial relationship between two organisms.

Parasitism

An interrelationship in which the host organism provides the parasitic microbe with nutrients and a habitat.

Commensalism

A relationship where one organism receives benefits while its co-inhabitant is neither harmed nor benefited.

Satellitism

A form of commensalism where one member provides nutritional or protective factors needed by the other.

Contamination

The mere presence of microorganisms on body surfaces without necessarily penetrating defenses.

Infection

Occurs when a pathogenic organism successfully penetrates host defenses.

Disease

Occurs when an infection damages or disrupts tissues or organs.

Pathogen

Any parasitic organism that results in an infectious disease.

Pathogenicity

The general ability of a parasitic organism to cause a disease.

Virulence

The degree or intensity of pathogenicity, determined by the ability to establish in the host and cause damage.

Invasiveness

The ability of an organism to spread to adjacent tissues.

Infectivity

The ability of an organism to establish a focal point of infection.

Animal passage

The rapid transport of a pathogen through animals of a species susceptible to that pathogen.

Attenuation

The weakening of the disease-producing ability of a pathogen.

Transposal of virulence

A lab technique of exposing a pathogen to a new host to weaken its virulence in the original host.

Endogenous disease

A disease caused by the host's own microbiota because the host's resistance has dropped.

Exogenous disease

A disease originating from a source outside the body.

Normal microflora

Organisms that live on or in the body but do not normally cause disease.

Resident microflora

Microbes that are always present on or in the human body.

Transient microflora

Organisms that can be present under certain conditions in locations where resident microflora is found.

Primary pathogens

Microorganisms that can cause disease in a normal, healthy host regardless of immune strength or resident microbiota.

Opportunists

Resident and transient microflora that do not usually cause disease unless host defenses fail or they enter unusual body sites.

Communicable disease

A disease where an infected host transmits the infectious agent to another host directly or indirectly.

Zoonotic disease

A communicable disease transmitted from animals to humans.

Nosocomial infection

An infection acquired in a healthcare setting such as a hospital.

Iatrogenic disease

A disease or infection that results directly from a medical treatment or procedure.

Non-communicable disease

A disease that does not arise through transmission from host to host, often acquired through special circumstances.

Hyaluronidase

An exoenzyme that dissolves hyaluronic acid, causing tissue cells to come apart.

Coagulase

An exoenzyme that accelerates the coagulation of blood.

Streptokinase

An exoenzyme that dissolves blood clots.

Endotoxins

Toxins that are part of the cell wall in gram-negative organisms and released upon cell death.

Exotoxins

Toxins that are secreted into host tissues, such as hemolysins, leukocidins, neurotoxins, and enterotoxins.

Signs

Any objective evidence of disease that is noted by an observer.

Symptoms

Evidence of disease as subjectively sensed by the patient.

Syndromes

A disease identified or defined by a specific complex of signs and symptoms.

Sequelae

Remaining long-term effects after a disease, such as scars or heart valve damage.

Acute disease

A disease that is severe but short-lived.

Chronic disease

A disease that progresses and persists over a long period of time.

Incubation period

The time between initial infection and the appearance of signs and symptoms.

Prodromal phase

A short period during which nonspecific and mild symptoms appear.