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Veterinary Parasitology > Lecture 1 - Principals of Parasitism > Flashcards

Lecture 1 - Principals of Parasitism Flashcards

1
Q

Significant costs of parasitism

A
  1. lost of agricultral & human productivity
  2. human/animal suffering & premature mortality
  3. rational efforts of parasitism control depend on understanding of parasitism
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2
Q

Independent evolution is at least _____ times among the nematodes that infect vertebrates

A

4

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3
Q

definition of parasite

A

an organism that is metabolically dependent and survives at the expense of another organism

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4
Q

commensalism vs. parasitism

A

host not harmed nor helped vs. survives @ expense of host

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5
Q

What do parasites depend on the host for

A

Metabolic dependency- sustenance (nutrition), survival, maturation, reproduction
Shelter- stable environment and protection for competition and predation by other organisms

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6
Q

What effect can parasites have on the host

A

hematocrit, fecundity, BCS, feed efficiency, time to conception

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7
Q

T/F disease resulting from parasitism is secondary

A

TRUE; parasites exist to perpetuate the species

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8
Q

How are parasites subject to fitness of evolutionary biology?

A

parasites that kill their host must find way to adapt and overcome the fitness cost

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9
Q

Fitness is characterized by parasites ability to

A
  1. colonize
  2. ability to resist environmental stresses
  3. survive host defenses
  4. reproduce and disseminate its progeny
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10
Q

What environmental stressors must parasites overcome

A

drug resistance & seasonal climatic extremes (hard freeze)

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11
Q

What host defenses must parasites overcome

A

immunomodulation and immune avoidance

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12
Q

Parasites have ability to alter their ____________________ to enhance the odds for survival and reproduction

A

biologic functions

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13
Q

Parasite populations are ________and _______

A

plastic and dynamic

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14
Q

Parasites have the capacity to respond to a variety of conditions and stimuli
(selection pressures) by ________________

A

permanent alterations of their genetic composition

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15
Q

How do parasites respond to selection pressures by alterations of their genetic composition?

A

hypobiosis, vertical transmission of developmental stages, shorter or abbreviated lifecycle development

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16
Q

hypobiosis

A

arrested development

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17
Q

How are parasite populations dynamic?

A
  1. permanent alterations of their genetic composition
  2. drug resistance
  3. ability to colonize new hosts/sites within hosts
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18
Q

Why are puppies born with roundworms?

A

cross placenta @ 42 days gestation

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19
Q

Most animals eventually develop some degree of
___________________ to parasitic infections

A

aquired immunity

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20
Q

acquired immunity with parasitsm

A

mechanisms to mitigate associated disease

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21
Q

Parasitic diseases in domestic livestock and companion animal populations is generally a consequence of __________-

A

management

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22
Q

1 cause of death in whitetail deer

A

lead poisoning

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23
Q

Parasitic disease is usually related to the

A

number of parasites infecting the host

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24
Q

What is it called when their is a large number of parasites in a living/grazing environments

A

hyper-contamination

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25
Q

What is it called when the host dies by depletion of host resourses

A

hyper-infection

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26
Q

How we can control parasitism and mitigate disease

A
  1. disrupt transmission between parasites and their host
  2. development of host immunity
  3. changes in management/modification of environment
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27
Q

How can we enhance host immunity?

A

vaccination and low levels of exposure

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28
Q

What is premunition

A

low levels of exposure

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29
Q

How can we disrrupt transmission between parasites and their host population?

A

breaking the life cycle of infection and reinfection RARELY achieved by meds alone

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30
Q

How can we modify environment to mitigate parasites

A
  1. protected environment for neonates
  2. reduced environmental contamination with infective stages
  3. selective breeding
  4. better nutrition
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31
Q

How do we create a protected environment for neonates

A

clean pasture for babies with no established immunity

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32
Q

How does better nutrition mitigate parasites

A

avoid the effects of parasitic disease

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33
Q

How can parasites cause disease?

A
  1. suck blood
  2. feed on solid tissues directly or after liquifying
  3. compete with host for ingested food
  4. traumatic injury by mechanical obstructions
  5. destroy host cells by growing in them
  6. production of toxic substances
  7. cause various host reactions
  8. stimulate cancerous growth
  9. carry additional diseases (parasites, viruses, bacteria)
  10. reduce host resistance to other diseases and parasites
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34
Q

What parasites suck blood

A

mosquitos, hookworms

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35
Q

What parasites suck lymph

A

midges

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36
Q

What parasites are exudates

A

lungworms

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37
Q

What parasites feed on solid tissues directly

A

giant kidney worms, liver flukes

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38
Q

What parasites feed on solid tissues after lysing and liquifying them

A

chiggers, amoebas

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39
Q

What parasites ingest intestinal contents

A

ascarids

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40
Q

What parasites absorb contens through the body wall

A

tapeworms

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41
Q

What parasites obstruct the intestines

A

ascarids

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42
Q

What parasites obstruct bile ducts

A

ascarids, fringed tapeworm

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43
Q

What parasites obstruct blood vessels

A

dog heartworm

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44
Q

What parasites obstruct lymph channels

A

filariids

45
Q

What parasites obstruct bronchi

A

lungworms

46
Q

How do hydatid cysts harm the hosts

A

pressure atrophy against body organs

47
Q

What parasites destroy host cells by growing in them

A

coccidia, malaria

48
Q

What toxic substances can parasites produce to aid their ability to enter host tissues, feed, reproduce

A

hemolysis, histolysins, anticoagulants

49
Q

What host reactions can parasites cause

A

allergic, inflammatory, hypertrophy, hyperplasia, and nodule formation

50
Q

What parasite stimulates the development of cancerous cell growth

A

Spirocerca lupi

51
Q

What diseases do the following parasites carry?
Mosquitos
lungworms
flukes

A

mosquitos- heartworm and malaria, lungworms- swine influenza, flukes- salmon poisoning

52
Q

What is an obligatory parasite

A

cannot complete its life cycle without spending part of all of its time on or within host

53
Q

What is a facultative parasite

A

not normally parasitic by become so when eaten or
opportunisitically enter a host through and orifice or
wound

54
Q

Example of facultative parasite

A

– Naegleria fowleri causative agent of Primary Amoebic
Meningoencephalitis (PAM) “Brain eating amoebae”
– Halicephalobus a causative agent of encephalitis in
horses

55
Q

How does Naegleria fowleri cause disease

A

warm water->nasal passage->brain

56
Q

Where does Halicephalobus enter

A

brain and kidney

57
Q

ndoparasite

A

Organisms living within a host environment

58
Q

Ectoparasite

A

– Organisms living on host (external environment)

59
Q

Abberant parasite

A

Organisms found in locations where they do not
normally occur

60
Q

Example of Abberant parasites

A

“Ectopic infections”
* Toxocara larvae in the eye of its host,
* Dirofilaria immitis in the brain of a tiger
* Paragonimus in the liver

61
Q

How do parasites cause disease in their
host?

A

They feed on host resources and
impact the host physically and
immunologically

62
Q

Accidental or Incidental parasite

A

Parasitic organisms that enter or attach to host species that are different from the one(s) with which they are normally associated

63
Q

Why may accidental parasites not be able to survive in host?

A

often elicits a major pathological response from the host.

64
Q

Repeated successful colonization of an accidental host can cause

A

host switching, development of new host association

65
Q

Pseudoparasite

A

Diagnostic parasite stages or other artifacts (plant pollen, fungi,
arthropods) that superficially resemble protozoan cysts or helminth eggs in the feces, blood, or urine of an examined animal

66
Q

Why is pseudoparasite a misnomer

A

“pseudo‐parasite products” are not associated with
a true host‐parasite association

67
Q

Example of pseudoparasite

A

Eimeria oocysts passed in dog feces, various pollen mistakenly attributed to parasitic species infecting a host

68
Q

Hyperparasite

A

When a parasitic organism is host to another parasite species

69
Q

Examples of hyperparasite

A

-Mosquito that is host to Plasmodium sp. or Dirofilaria immitis
-Flea that is host to Dipylidium caninum

70
Q

Definitive Host

A

Where a parasite attains reproductive maturity

71
Q

What is definitive host evidenced by

A

circulation or passage (in feces or other host tissues) of progeny capable of colonizing additional host species

72
Q

Intermediate Host

A

in which a larval or intermediate stage parasite must
undergo development to become infective for the
“definitive or final host

73
Q

Paratenic Host

A

A facultative host used by a larval or intermediate stage
parasite to facilitate transmission to the “definitive or final
host, DO NOT undergo development

74
Q

What is the distinguishing factor between paratenic and intermediate hosts?

A

parasites do not undergo development in paratenic hosts

75
Q

What often bridges an ecological gap between passage of
infective stages and successful transmission and
establishment in a new host for completion of a lifecycle
and perpetuation of the parasite population?

A

paratenic host

76
Q

reservoir hosts

A

Maintain a parasite in the population at sufficient levels to
facilitate its transmission between susceptible hosts

77
Q

reservoir host for zoonotic parasites and infectious diseases

A

animals (Lyme disease deer, white-footed mouse)

78
Q

Reservoir hosts for Dirofilaria immitis

A

coyotes, and stray/unprotected canines

79
Q

Reservoir hosts may be …..

A
  1. definitive (adult parasites)
  2. intermediate (obligate developmental stages)
  3. Paratentic (facultative developmental stages)
80
Q

Reservoir hosts are a _________ parameter rather than a _________ parameter

A

population; individual

81
Q

vectors

A

Organisms that facilitate transmission of infective
parasite stages between different individuals of a
host population

82
Q

Biological Vectors assume the existence of an
___________________________ for successful transmission and
maintenance of the parasite species in the host
population

A

obligate relationship

83
Q

vectors often also play a role as _____________

A

intermediate/paratenic hosts

84
Q

Which vectors have an obligate relationship

A

biological

85
Q

2 types of vectors

A

biological and mechanical

86
Q

example of mechanical vectors

A

flying syringe, transport on feet

87
Q

Direct life cycle

A

parasites infect host directly

88
Q

Direct Lifecycle
– Parasites infect host directly
– Stages passed from host in
feces/other tissues
– Infective to another “Definitive
host” (dog to dog)
– May require period of
development to infective stage
* Larval development ____________
* Free living larval stages in
_____

A
  1. w/in eggs
  2. environment
89
Q

obligate indirect life cycle require intervention of an

A

intermediate host

90
Q

obligate indirect life cycle is infective to the

A

intermediate host

91
Q

obligate indirect life cycle have obligate requirement for development to

A

infective stage

92
Q

obligate indirect life cycle have indirect transmission to

A

definitive host

93
Q

obligate indirect life cycle may involve

A

paratenic host

94
Q

facultative indirect lifecycle indirect transmission to

A

definitive host

95
Q

facultative indirect lifecycle optional intervention of an

A

intermediate or paratenic host

96
Q

facultative indirect lifecycle stages passed from host in

A

feces/other tissues

97
Q

facultative indirect lifecycle infective to

A

definitive host or the “optional host”

98
Q

horizontal transmission

A

-Parasites colonize susceptible individuals by usual routes
– Infection across different generations of host population not required

99
Q

vertical transmission

A

-Transmission of parasites from mother to offspring by transplacental or lactogenic routes
– Trans‐generational requirement
– Prenatal or perinatal

100
Q

2 types of host specificity

A

monospecific and heterospecific

101
Q

monospecfic host

A
  • limited number of hosts capable of completing lifecycle
  • Pinworms in primate hosts
102
Q

heterospecific

A
  • wide variety of species capable of hosting parasite
  • Typical of intermediate and paratentic hosts
  • Toxoplasma gondii, Baylisascaris procyonis
103
Q

zoonotic

A

animal to human

104
Q

anthroponotic

A

human to animal

105
Q

endemic (enzootic)

A

The normal or usual distribution of parasites in a host population or
geographic area (Eimeria sp. is endemic in Tennessee cattle)

106
Q

Epidemic (epizootic)

A
  • An excess number of parasite cases, far exceeding the normal or usual distribution in a host population
  • Temporal and Spatial characteristics
  • “ 50% of last years kid crop were aborted in an epizootic of
    toxoplasmosis “
107
Q

prevalance

A

The occurrence of a parasite in a population defined by time &
space

108
Q

Incidence

A

The rate at which new cases are added to a host population defined
by time & space

Veterinary Parasitology (1 decks)

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