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Parasitology > Principles of Parasitism (1) > Flashcards

Principles of Parasitism (1) Flashcards

1
Q

What is the cost of parasitism?

A

lost agricultural and human productivity
human and animal suffering and premature mortality

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2
Q

Parasitism has at least ____ time among the nematodes that infect vertebrates

A

4

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3
Q

Parasitism is a kind of ______ and is literally defined as _______

A

symbiosis
two organisms traveling together

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4
Q

What is a parasite?

A

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

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5
Q

How does a parasite use the host?

A

metabolic dependency on them for:
sustanance
survival
maturation
reproduction

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6
Q

What is another benefit for parasites to have inside a host?

A

shelter: a stable environment
protection from competition and predation from other organisms

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7
Q

Parasites live at the measurable expense of the host. In what ways?

A

hematocrit
fecundity
BCS
feed efficiency
time to conception

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8
Q

Disease resulting from parasitic association with the host is [primary/secondary]

A

secondary
damage done is just “collateral damage”

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9
Q

T/F: Parasites are subject to all constraints (fitness) of evolutionary biology

A

TRUE - must find a way to adapt and overcome fitness cost

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10
Q

What is fitness characterized by?

A

a parasite’s ability to colonize, resist environmental stress (drug, climate), survive host defenses, reproduce and disseminate its progeny

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11
Q

Parasite populations are ____ and dynamic

A

plastic

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12
Q

How do parasites have permanent alterations of their genetic composition to survive?

A

hypobiosis (arrested development)
vertical transmission of developmental stages - pass young to other host
shorter or abbreviated life cycle development
drug resistance
ability to colonize new hosts/sites within hosts

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13
Q

T/F: Parasitism is extremely comment in wildlife and domestic animals

A

TRUE

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14
Q

Where is parasitic disease relatively rare?

A

in natural settings
host populations

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15
Q

Most animals will eventually develop some degree of _______ to parasitic infections

A

acquired immunity

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16
Q

Parasitism in domestic livestock and companion animal populations is generally a consequence of ______

A

management

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17
Q

What is the rational control of parasitism and mitigation of disease?

A

disrupting transmission btwn parasites and their host population
development of host immunity
changes in modification/management of environemtn

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18
Q

How do parasites cause disease?

A

suck blood
feed on solid tissues directly
compete with host for ingested food
cause traumatic injury by mechanical obstructions
destroy host cells by growing in them
production of toxic substances that aid in ability to enter host tissues, feed or reproduce
cause host rxns like allergic & inflammatory
stimulate cancerous cell growth
carry (vector) additional diseases
reduce host resistance to other diseases

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19
Q

What is an obligatory parasite?

A

cannot complete lifecycle without spending part of all its time on or within a host

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20
Q

What is a facultative parasite?

A

not normally parasitic but becomes so when eaten or OPPORTUNISTICALLY enters a host through an orifice or wound
brain-eating amoeba

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21
Q

What is a endoparasite?

A

organisms living within host environment

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22
Q

What is an exoparasite?

A

organisms living on host (external environment)

23
Q

What is an aberrant parasite?

A

organisms found in locations where they do not normally occur
often result in diseased state
“ectopic infections”

24
Q

What are the 3 main parasitic associations?

A

accidental or incidental parasite
pseudoparasite
hyperparasite

25
Q

What is an accidental/incidental parastite

A

parasitic organisms that enter or attach to host species that are different from the one(s) with which they are normally associated
may not be able to survive in the host or often elicits a major pathological response from the host
repeated successful colonization of an accidental host can become the basis of “host switching” and development of a new host association

26
Q

What is a pseudo parasite?

A

diagnostic parasite stages or other artifacts that superficially resemble protozoan cysts or helminth eggs in the feces, blood, or urine of infected animal
misnomer

27
Q

What is a hyperparasite?

A

when a parasitic organism is host to another parasite species

28
Q

What are the host associations?

A

definitive host
intermediate host
paratenic host
reservoir host
- organisms where a parasite lives for part or all of its existence

29
Q

What is a definitive host?

A

where a parasite attains reproductive maturity

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

30
Q

What is an intermediate host?

A

in which a larval or intermediate stage parasite must undergo development to become infective for the definitive or final host
often an obligate or required developmental stage for completion of life cycle

31
Q

What is a reservoir host?

A

maintain a parasite in the population at sufficient levels to facilitate its transmission between susceptible hosts
- POPULATION parameter

32
Q

What is a paratenic host?

A

a facultative host used by a larval or intermediate stage parasite to facilitate transmission to the “definitive” or final host
facultative relationship (convenience and opportunity)

33
Q

What is an important distinction between paratenic and intermediate hosts?

A

in paratenic, parasites do not undergo development whereas in intermediate, they do

34
Q

What are vectors?

A

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

35
Q

What do biological vectors assume?

A

the existence of an obligate relationship for successful transmission and maintenance of the parasite species in the host population

36
Q

T/F: Mechanical vectors do not have an obligate role

A

TRUE

37
Q

Reservoir hosts may be _____, ______, or _______

A

definitive: adult parasites
intermediate: obligate development stages
paratenic: facultative developmental stages

38
Q

What are the two life cycles?

A

indirect
direct life cycle

39
Q

What is the direct life cycle?

A

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 stages

40
Q

What is an Indirect life cycle - obligate?

A

require intervention of an intermediate host
stages passed from host in feces/other tissues
infective to the “intermediate host” like have to go through flea to get to dog
indirect transmission to “definitive host”
may involve paratenic host - “bridge the ecological gap”

41
Q

What is a facultative indirect life cycle?

A

indirect transmission to definitive host
optional intervention of an intermediate or paratenic host
stages passed from host in feces/other tissues
infective to definitive host or the “optional host”
“bridge the ecological gap”

42
Q

What are the principles of transmission?

A

horizontal
vertical

43
Q

What is horizontal transmission?

A

parasites colonize susceptible individuals by usual routes
* infection across different generations of host populations NOT required

44
Q

What is vertical transmission?

A

transmission of parasites from mother to offspring by transplacental or lactogenic routes
trans-generational requirement
penal or perinatal

45
Q

What is host specificity?

A

high specificity (monospecific)
low specificity (heterospecific)

46
Q

What is high specificity or monospecific?

A

limited number of hosts capable of completing lifecycle

47
Q

What is low specificity or heterospecific?

A

wide variety of species capable of hosting parasite
typical of INTERMEDIATE and PARATENiC hosts

48
Q

What is endemic (enzootic)?

A

normal or usual distribution of parasites in a host population or geographical area

49
Q

What is an 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
Q

What is prevalence?

A

the occurrence of a parasite in an population defined by time and space

51
Q

What is incidence?

A

the rate at which new cases are added to a host population defined by time and space

52
Q

What are the morphological characteristics of nemotodes?

A

roundworms
bilaterally symmetrical, cylindrical, elongate
very small to huge
longitudinal muscles only
worm-like bodies covered with cuticles
dioecious (separate sexes)
pseudo-coelomate

53
Q

What is the pre-patent period also known as?

A

egg reappearance period

54
Q

What is the pre-patent period in nematodes?

A

time to reproductive maturity

Parasitology (31 decks)

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