Lecture 1 Flashcards
definition of phoresis
‘to carry’ ; when two organisms are ‘traveling’ together
commensalism
one member benefits while the other is unaffected
example of commensalism
sea anomone provides protection against predators of the clown fish
mutualism
both symbionts gain something
example of mutualism
yucca plant and yucca moth; yucca moth lays its eggs in the yucca and the pollinator larvae feed exclusively on the seeds
parasitism
one organism is positively affected, and the other is negatively affected
why is parasitism difficult to define?
the word ‘harm’ is difficult to define
A parasite is…
a living eukaryotic organism. they are not a bacteria or virus
what are the categories of parasites?
- protozoans
- metazoans
- endoparasites
- ectoparasites
3 examples of metazoans
1) lone star tick
2) digenean trematode
3) roundworm
2 groups of endoparasites
1) protozoa
- flagellates
- amebae
- sporozoa
- ciliates
2) helminths
- nematodes
- trematoda
- cestoda
4 examples of unicellular endoparasites
1) leishmania
2) plasmodium
3) trypanosoma
4) Gardia
multicellular endoparasites
1) hookworm
2) tapeworm
3) tapeworm eggs
4) roundworm
5) pinworm
hemiparasite
a parasitic plant that derives some, or all of its sustenance from another plant (eg. mistletoe)
host
the organism in, or on, which the parasite lives
definitive host
the organism in which the parasite reaches sexual maturity
intermediate host
the organism in which the parasite completes part of its life cycle. usually the parasite undergoes a morphological or physiological change in this host
reservoir host
alternate animal host from which the parasite can be transmitted to humans (zoonosis) or domestic animals
accidental host
one that accidentally harbors a parasitic stage that is not usually parasitic in the particular species and cannot be transmitted
vector
a host that plays an active role in transmission of the parasite
infection
a parasite growing and multiplying within or on a host, often accompanied by an immune response
pathogenecity
ability of parasite to cause disease
virulence
- degree of pathogenicity
- the ability for the organism to invade, infect, grow, and cause damage despite the hosts defenses
general steps of parasitic infections
- encounter
- entry
- spread
- multiplication
- damage
- outcome
main modes of transmission
skin, respiratory, GI, urogenital symptoms, vector borne, blood transfusion, or organ transplant
external transmission
passive carriage of pathogen on body of vector. no growth of pathogen during transmission
internal transmission
carried within a vector. includes: harborage transmission and biologic transmission
harborage transmission
pathogen does not undergo changes within vector
biologic transmission
pathogen undergoes changes within vector
definition of infectivity
ability of the organism to establish a discrete, focal point of infection
definition of invasiveness
ability of an organism to spread to adjacent or other tissues of the host
penetration of host’s mucous membranes or epithelium can be ___ or ____
active or passive
examples of passive penetration:
skin lesions, insect bites, wounds
definition of protozoans
unicellular endoparasites that include flagellates, amoebas, malarial organisms
definition of helminths
multicellular parasitic worms that include flukes, tapeworms, and roundworms
definition of arthropods
multicellular ectoparasites that include insects (lice, fleas) and arachnids (ticks, mites) that are carriers (vectors) of diseases
