PATHOGENIC MICROBIOLOGY

Host-Parasite Interaction
Basic Definitions

INDEPENDENCE:

living free from the influence, guidance, or control by another organism

SYMBIOSIS:

a relationship in which two dissimilar organisms (SYMBIOTES, SYMBIONTS) live in close association with one another

MUTUALISM:

mutually beneficial relationship between two species

COMMENSALISM:

a relationship between two species in which one is benefited and the other is not affected, neither negatively nor positively

PARASITISM:

a relationship between two species in which one benefits (parasite) from the other (host); usually involves some detriment to the host

BENIGN:

referring to a non-life or non-health threatening condition = COMMENSALISM

MALIGNANT:

a disease tending to become progressively worse (MORBIDITY=illness) and potentially result in death (MORTALITY=death)

CARRIER:

a symptomless individual who is host to a pathogenic microorganims and who has the potential to pass the pathogen to others

PATHOGENICITY:

the quality of producing or the ability to produce pathologic changes or disease

VIRULENCE:

a measure of pathogenicity; a measurement of the degree of disease producing ability of a microorganism as indicated by the severity of the disease produced; a measure of the dosage required to caused a specific degree of pathogenicity --- one general standard is the LD50

DOSAGE:

the number of pathogenic microorganisms entering the host

LD50:

the number of microorganisms required to cause lethality in 50% of the test host

TRUE PATHOGEN:

any microorganism capable of causing disease; an infecting agent

OPPORTUNISTIC PATHOGEN:

a usually harmless microorganism that becomes pathogenic under favorable conditions

INFECTION:

the colonization and/or invasion and multiplication of pathogenic microrganisms in the host with or without the manifestation of disease

COLONIZATION:

the successful occupation of a new habitat by a species not normally found in this niche

MULTIPLICATION:

the ability of a microorganism to reproduce during an infection

DISEASE:

an abnormal condition of body function(s) or structure that is considered to be harmful to the affected individual (host); any deviation from or interruption of the normal structure or function of any part, organ, or system of the body

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