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
1
Q
microspora
A
- Phylum: Microsporidia
- obligate, intracellular protozoan parasites
- spore-forming
- infecting every major animal group
2
Q
zoonotic microsporidia have to overcome 2 obstacles
A
- more advance immune systems
2. much higher body temps
3
Q
mammalian species
A
Enterocytozoon bieneusi
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)
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
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
7
Q
ectoparasite
A
flea living on a dog; flea feeds on dog’s blood which is detrimental to dog
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
9
Q
endoparasite
A
cestode platyhelminth living in intestine of fish and mammals
10
Q
parasitism
A
Ht - x or X
11
Q
commensalism
A
Ht +/- 0 (-x)
12
Q
mutualism
A
Ht + Y
13
Q
Helminths
A
- parasitic worms
- large
- multicellular
- vermiform or “worm-like” in form
14
Q
Phylum Nematoda
A
roundworms
15
Q
Phylum Platyhelminthes
A
flatworms
16
Q
Class Cestoda
A
tapeworms
17
Q
Class Trematoda
A
flukes: endoparasites
18
Q
Class Monogenea
A
skin flukes: ectoparasites
19
Q
Class Turbellaria
A
free-living flatworms, some parasitic forms
20
Q
Phylum Acanthocephala
A
thorny-headed worms
21
Q
Phylum Annelida
A
segmented worms
- not parasitic (leeches)
22
Q
Kingdom Protozoa
A
- Phylum Mastigophora (flagellates)
- Phylum Apicomplexa
- Phylum Ciliphora (ciliates)
23
Q
Kingdom Animalia
A
- Phylum Arthropoda insects/arachnids, copepods)
- Phylum Cnidaria (Myxozoa)
24
Q
parasitism
A
non-mutual non-symbiotic relationship btwn species, where one species (parasite) benefits at the expense of the other (host)
25
ectoparasite
live on their host
26
endoparasite
live in their host
27
parasites
- 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
28
parasites use the host for survival:
- food
- water
- heat
- habitat
- transmission
29
mode of infection
- oral
- skin penetration
- injection
- transplacental
30
oral mode of infection
- 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
intermediate host
- required host
| - serves as temporary but necessary host for continued development of essential life stages
32
paratenic host (transport hosts)
- non-required host
- no development of parasite occurs
- just transport only
33
aberrant (abnormal) host
host not usually used by parasites, development slow or incomplete
34
dead-end (incidental host)
- intermediate host that generally does not allow transmission to the definitive host
- preventing parasite from completing its development
35
direct life cycle
- 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
indirect life cycle
- 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
Dirofilaria immitis
indirect life cycle
38
Toxocara canis
Direct life cycle; Paratenic host
39
Toxocara canis
Direct life cycle; aberrant host (human)
40
indirect life cycle with Paratenic Host
feline host: worm life cycle involving snails and birds
41
Sexual
- genetic diversity
- longer life cycle
- must have at least 2 parasites (M&F)
42
Asexual
- lack of genetic diversity
- short life cycle
- one is enough!
43
Nematode life cycle
Direct life cycle; sexual repro
44
Toxoplasma gondii
Indirect life cycle; a/sexual repro
45
Benefits from host
survival
- heat
- food & water
- habitat
46
Heat
arrested development/hypobiotic stage
47
Hypobiosis
arrested development that has a seasonal basis
| - e.g. nematodes
48
Food
blood, mucosal lining, etc
49
Predilection site
preferred site in or on host
50
Aberrant site
site in or on host chichis not normal location
51
Parasite - host balance
- parasite
- host & host response
- environment
52
The parasite
- number of parasites
- location of parasites; migration
- transmission
53
The host response
- previous exposure
- type of host response (inflammatory, immune, etc.)
- nutritional status (health of host)
- age of the host (immune status)
54
parasite x host x environment
- 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
-iasis
presence of parasite
| - e.g. Coccidiasis
56
-osis
disease caused by parasite
| - e.g. Coccidiosis
57
Demodex (Arachnida)
- ectoparasitic mite
- present in low numbers in healthy dogs
- not usually contagious unless suppressed immune system
58
Blepharitis
- first documented case of Demodex in humans
| - prevalent in the old, and very under diagnosed in humans
59
Ectoparasites as vectors
Any organism (vertebrate or invertebrate) that functions as a carrier of an infectious agent btwn organisms of a different species)
60
Ectoparasites with high veterinary importance
- 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
Class: Monogenea
- 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
Class: Monogenea lifecycle
- direct life cycle
| - involving 1 host
63
Gyrodactylus
- class: monogenea
- viviparous
- some species extremely pathogenic
64
Udonella spp.
- Class: Monogenea
- ectoparasitic flatworm
- obligate parasite
- lost attachment hooks during evolution due to epibiosis
- ectocommensal
- ultimate 'hitchhikers'
65
epibiosis
?
66
phoresis
?
67
commensalism
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
ectocommensal
flagellates feeding on bacteria on surface of fish
| - not negatively impacting host
69
endocommensal
entamoeba sp. feeding on bacteria in human intestine
