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Words from lesson 1


an organism that lives within, upon, or at the expense of another organism, known as the host.

medical parasitology

area of microbiology concerned with invertebrate organisms capable of producing diseases in humans


Stages of development that a parasite goes through during its life includes growth and development reproduction and transmission routes

Infective stage

the stage of the parasite at which it is capable of entering the host and continuing development within the host

Diagnostic stage

the stage at which a parasite may be detected in human body secretions, discharges, feces, blood or tissue by chemical means or microscopic observation as an aid to diagnosis


Multicellular organisms; wormlike invertebrates, includes roundworms and flatworms








unicellular organisms
includes: Ameba, Flagellates, Ciliates, Apicomplexa(Sporozoa)

Accidental (or incidental) host

infection of a host other than the normal host species; a parasite may or may not continue full development in an accidental host.


a host harboring a parasite but exhibiting no clinical signs or symtons


the association of 2 different species of organisms in which one partner is benefited and the other is neither benefited or injured

Definitive host

the animal in which a parasite passes its adult existence, sexual reproductive phase, or both

Facultative parasite

an organism capable of living an independent or a parasitic existence; not an obligatory parasite, but potentially parasitic


the species of animal or plant that harbors a parasite and provides some metabolic resources to the parasitic species

Intermediate host

the animal in which a parasite passes its larval stage or asexual reproductive phase

Obligatory parasite

a parasite that cannot live apart from its host


the association of 2 different species of organisms in which the smaller species lives on or within the other and has a metabolic dependence on the larger host species

Reservoir host

an animal that harbors a species of parasite that is also parasitic for human and from which a human may become infective


the association of two different species of organisms exhibiting metabolic dependence by their relationship


any arthropods or other living carriers that transport a pathogenic microorganism from an infected to a non-infected host


a disease involving a parasite that has accidentally infected a human; the normal host for the parasite is an animal


eggs stay in perianal area, mature, crawl back into intestines


albuminous layer


refers to the mammilated outer coat mammilated


refers to the mammilated outer coat non-mammilated

Rhabditiform larva

the feeding but non-infective larval stage, stage that hatches from the egg

Filariform larva

larval stage infective for the definitive host

Indirect life cycle

other rhabditiform larvae may molt into free-living males and females, female lay eggs that hatch into filariform larvae


development of filariform (infective) larvae occurs in intestine, starts lifecycle in same person

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