Parasites: General Concepts & Ectoparasites Flashcards

- key concepts with parasites - mode of infection - types of hosts - life cycle - parasite fitness/survival - food - life cycle strategies - host-parasite balance

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1
Q

microspora

A
  • Phylum: Microsporidia
  • obligate, intracellular protozoan parasites
  • spore-forming
  • infecting every major animal group
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2
Q

zoonotic microsporidia have to overcome 2 obstacles

A
  1. more advance immune systems

2. much higher body temps

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3
Q

mammalian species

A

Enterocytozoon bieneusi

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4
Q

facultative parasite

A

organism that may become parasitic, but does not require a host for completion of its life cycle
- e.g. Blastomyces dermatitidis, Blastomycosis (fungi)

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5
Q

opportunistic infection

A

infection caused by pathogens (bacteria, viruses, fungi, or protozoa) that take advantage of an opportunity not normally available such as host weakened immune system, altered microbiota or breached integumentary barriers

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6
Q

parasitism

A

when organism for all or part of its life derives at least some, but often all of it’s food from a living organism of another species (host)
- ONE WHO EATS AT ANOTHER’S TABLE

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7
Q

ectoparasite

A

flea living on a dog; flea feeds on dog’s blood which is detrimental to dog

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8
Q

ectoparasite

A
caligid copepod (sea lice) living on skin of fish
- but these parasites spend part of their life cycle as free-living
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9
Q

endoparasite

A

cestode platyhelminth living in intestine of fish and mammals

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10
Q

parasitism

A

Ht - x or X

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11
Q

commensalism

A

Ht +/- 0 (-x)

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12
Q

mutualism

A

Ht + Y

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13
Q

Helminths

A
  • parasitic worms
  • large
  • multicellular
  • vermiform or “worm-like” in form
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14
Q

Phylum Nematoda

A

roundworms

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15
Q

Phylum Platyhelminthes

A

flatworms

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16
Q

Class Cestoda

A

tapeworms

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17
Q

Class Trematoda

A

flukes: endoparasites

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18
Q

Class Monogenea

A

skin flukes: ectoparasites

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19
Q

Class Turbellaria

A

free-living flatworms, some parasitic forms

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20
Q

Phylum Acanthocephala

A

thorny-headed worms

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21
Q

Phylum Annelida

A

segmented worms

- not parasitic (leeches)

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22
Q

Kingdom Protozoa

A
  • Phylum Mastigophora (flagellates)
  • Phylum Apicomplexa
  • Phylum Ciliphora (ciliates)
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23
Q

Kingdom Animalia

A
  • Phylum Arthropoda insects/arachnids, copepods)

- Phylum Cnidaria (Myxozoa)

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24
Q

parasitism

A

non-mutual non-symbiotic relationship btwn species, where one species (parasite) benefits at the expense of the other (host)

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25
Q

ectoparasite

A

live on their host

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26
Q

endoparasite

A

live in their host

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27
Q

parasites

A
  • smaller than their host
  • reduce host biological fitness to some extent (pathogenicity/virulence)
  • typically do not kill their host
  • reproduce at a faster rate than their host
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28
Q

parasites use the host for survival:

A
  • food
  • water
  • heat
  • habitat
  • transmission
29
Q

mode of infection

A
  • oral
  • skin penetration
  • injection
  • transplacental
30
Q

oral mode of infection

A
  • spore in environment
  • oocyst/eggs in environment
  • larvae in environment
  • larvae in intermediate host and paratenic host
  • cyst in other host
  • larvae in milk
31
Q

intermediate host

A
  • required host

- serves as temporary but necessary host for continued development of essential life stages

32
Q

paratenic host (transport hosts)

A
  • non-required host
  • no development of parasite occurs
  • just transport only
33
Q

aberrant (abnormal) host

A

host not usually used by parasites, development slow or incomplete

34
Q

dead-end (incidental host)

A
  • intermediate host that generally does not allow transmission to the definitive host
  • preventing parasite from completing its development
35
Q

direct life cycle

A
  • only 1 host required to complete life cycle
  • stages in this host and environment
  • host specific or broad host spectrum (non-specific)
  • definitive host
  • parasites that sexually reproduce without an intermediate host have direct life cycles
36
Q

indirect life cycle

A
  • 2 or more hosts required to complete the life cycle
  • host specific or broad host spectrum (non-specific)
  • final host: sexual repro
  • intermediate host
  • involves stages in the hosts & environment
37
Q

Dirofilaria immitis

A

indirect life cycle

38
Q

Toxocara canis

A

Direct life cycle; Paratenic host

39
Q

Toxocara canis

A

Direct life cycle; aberrant host (human)

40
Q

indirect life cycle with Paratenic Host

A

feline host: worm life cycle involving snails and birds

41
Q

Sexual

A
  • genetic diversity
  • longer life cycle
  • must have at least 2 parasites (M&F)
42
Q

Asexual

A
  • lack of genetic diversity
  • short life cycle
  • one is enough!
43
Q

Nematode life cycle

A

Direct life cycle; sexual repro

44
Q

Toxoplasma gondii

A

Indirect life cycle; a/sexual repro

45
Q

Benefits from host

A

survival

  • heat
  • food & water
  • habitat
46
Q

Heat

A

arrested development/hypobiotic stage

47
Q

Hypobiosis

A

arrested development that has a seasonal basis

- e.g. nematodes

48
Q

Food

A

blood, mucosal lining, etc

49
Q

Predilection site

A

preferred site in or on host

50
Q

Aberrant site

A

site in or on host chichis not normal location

51
Q

Parasite - host balance

A
  • parasite
  • host & host response
  • environment
52
Q

The parasite

A
  • number of parasites
  • location of parasites; migration
  • transmission
53
Q

The host response

A
  • previous exposure
  • type of host response (inflammatory, immune, etc.)
  • nutritional status (health of host)
  • age of the host (immune status)
54
Q

parasite x host x environment

A
  • environmental factors that
    • increase parasites
    • increase hypobiosis
    • decrease immunity
  • management
  • geographical location
  • weather
  • physical presence, activity or production of toxic products
  • size, numbers and behavior of parasites
  • how and how much the parasite feeds
  • the host’s response
55
Q

-iasis

A

presence of parasite

- e.g. Coccidiasis

56
Q

-osis

A

disease caused by parasite

- e.g. Coccidiosis

57
Q

Demodex (Arachnida)

A
  • ectoparasitic mite
  • present in low numbers in healthy dogs
  • not usually contagious unless suppressed immune system
58
Q

Blepharitis

A
  • first documented case of Demodex in humans

- prevalent in the old, and very under diagnosed in humans

59
Q

Ectoparasites as vectors

A

Any organism (vertebrate or invertebrate) that functions as a carrier of an infectious agent btwn organisms of a different species)

60
Q

Ectoparasites with high veterinary importance

A
  • Ehrlichia: genus of rickettsial bacteria that is transmitted to vertebrates by ticks
  • Anaplasma phagocytophilum: bacterial infection of the white blood cells (neutrophils) that’s transmitted by deer tick
  • heart worm: parasitic roundworm that is spread from host to host through mosquitos
61
Q

Class: Monogenea

A
  • ectoparasitic flatworms
  • Phylum: Platyhelminthes
  • no true body cavity or coelom
  • can be quite large
  • simple digestive system: mouth, pharynx, and intestine (no anus)
  • poorly developed suckers, attachment vis hooks
  • hermaphroditic, mostly producing eggs, some are viviparous
  • ancestrally related to Turbellaria (free-living flatworms) and closest to modern cestodes
62
Q

Class: Monogenea lifecycle

A
  • direct life cycle

- involving 1 host

63
Q

Gyrodactylus

A
  • class: monogenea
  • viviparous
  • some species extremely pathogenic
64
Q

Udonella spp.

A
  • Class: Monogenea
  • ectoparasitic flatworm
  • obligate parasite
  • lost attachment hooks during evolution due to epibiosis
  • ectocommensal
  • ultimate ‘hitchhikers’
65
Q

epibiosis

A

?

66
Q

phoresis

A

?

67
Q

commensalism

A

when smaller symbiont feeds on the food available in or on the surface of the host for whom it is unusable or unwanted (host neither benefits or is harmed)

68
Q

ectocommensal

A

flagellates feeding on bacteria on surface of fish

- not negatively impacting host

69
Q

endocommensal

A

entamoeba sp. feeding on bacteria in human intestine