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Parasitology > Introduction to Course > Flashcards

Introduction to Course Flashcards

1
Q

Why parasitology?

A
  • heavy representation: 30% OF EUKARYOTES ARE PARASITIC! (60% of nematodes, 40% of insects)
  • many relevant diseases of animals & humans
  • 50% CLINIC PROFITS from dispensing fees, HALF OF THESE ARE FROM PARASITICIDES
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2
Q

What can parasites affect?

A
  • clinical disease
  • sub-clinical disease / reduced production
  • aesthetics / human animal bond
  • animal welfare
  • public health
  • money
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3
Q

How productive are parasites?

A

very
- single female of H. contortus (barber’s pole worm) can produce up to 10,000 eggs/day
- it can suck up to 0.05 mL of blood per day (1000 female = 500ML)
- average 1mo lamb: 12kg = 50mL/kg = 600 mL

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4
Q

What can parasites survive?

A

harsh conditions
- Trichinella - case in US after eating undercooked SK bear meat
- meat was frozen for 45 days & they still got infected

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5
Q

What can parasites be resistant to?

A
  • parasites can develop resistance to drugs used to treat them (ex: malaria (Plasmodium genus), Ru nematodes, Ancylostoma in Ca
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6
Q

Who can parasites cause financial losses to?

A

Industry & small-scale producers
- production losses in cattle: 74 million pounds per year in UK (exclusive of veterinary car)
- largest animal health cost in Australian sheep industry ($11/ewe)
- most prevalent disease reported by US sheep farmers

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7
Q

What can parasites control?

A

Brains
- Dicrocoelium dendriticum (lancet liver fluke) is a parasitic worm that can manipulate ants into-zombie-like behaviour, climbing to the top of grass stalks & exposing themselves to the herbivore host

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8
Q

what is symbiosis?

A

Relationship btwn two organisms in close association with each other

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9
Q

What is mutualism?

A
  • relationship btwn two organisms where both benefit (Ex: bacteria inside the rumen)
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10
Q

What is commensalism?

A
  • relationship btwn two organisms where one organism benefits and the other doesn’t benefit but also isnt harmed (ex: amoeba inside the cecum/colon of cattle & sheep)
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11
Q

What is parasitism?

A
  • relationship btwn two organisms where one benefits and the other is harmed
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12
Q

What is the definition of parasitism?

A

an ecological relationship where the parasite:
- depends on the host for survival & benefits from the host
- has negative effects on the host
- has greater fecundity than the host
- has an over-dispersed host distribution

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13
Q

What are endoparasites?

A

internal, causing infections

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14
Q

What are ectoparasites?

A

external, causing infestations

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15
Q

What kind of distribution do parasites have?

A

overdispersed distribution
- a lot of hosts have zero or a few parasites while a few hosts have
a lot of parasites (20:80 rule)

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16
Q

Why can an overdispersed distribution of parasites be a challenge?

A

it can be challenging to test for in a herd or flock

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17
Q

How do hosts differ?

A
  • age, immune status, sex, size, genetics, resistance/resilience, behaviour, metabolism (insect attractants!), clinical presentation
18
Q

What 3 things do you need for parasitism?

A

environment, hosts, parasites

19
Q

What is the infective stage?

A

life cycle stage infective (can cause disease in) for host

20
Q

What is the shed stage?

A

stages that are passed by the host

21
Q

What is pre-patent period (PPP)?

A

time btwn infection & shedding of the next generation of parasites

22
Q

What is the patent period (patency)?

A

period of shedding

23
Q

What is prevalence?

A

proportion of infected hosts (like 1 out of 10)

24
Q

What is the intensity?

A

the number of parasites per host (often expressed by proxy of fecal egg counts)

25
Q

What is host specificity?

A

how restricted a parasite is to certain host spp (how picky it is!)

26
Q

What is a direct life cycle?

A

Shed stages -> go into environment (EE) -> become infective stages -> go into definitive host (DH) and live there as adult parasite until reproduction & shedding

27
Q

What is an indirect life cycle?

A

Shed stages -> go into environment (EE) -> go into intermediate host(s) & live there as a juvenile stages (no sexual reproduction, may be asexual reproduction) -> then go into definitive host (DH) and live there as adult parasite until reproduction & shedding

28
Q

How can hosts be classified?

A
  • definitive host (DH)
  • intermediate host (IH)
  • paratenic host
  • vector
  • transport
29
Q

What is a definitive host?

A
  • obligatory for ALL parasites (need this host to survive/reproduce)
  • the only host in a direct life cycle
  • if endoparasite undergoes sexual reproduction (helminths & coccidian protozoans), it occurs inside the DH
30
Q

What is an intermediate host?

A
  • obligatory for endoparasites w/ indirect life cycles - all cestodes & trematodes, some nematodes & protozoans
  • parasite undergoes development w/in IH (NEVER sexual reproduction; sometimes asexual reproduction (amplification))
31
Q

What is a paratenic host?

A
  • HELPFUL FOR TRANSMISSION, BUT NOT REQUIRED (facultative vs obligatory)
  • infection but no reproduction, no development
32
Q

What is a vector host?

A

MOBILE transport host, often an arthropod. can be biological, in which the pathogen undergoes development or amplification, or simply mechanical. many ectoparasites are vectors (ex: ticks); some endoparasites (ex: heartworm, malaria) are vector-borne

33
Q

What is a transport host?

A
  • HELPFUL FOR TRANSMISSION BUT NOT REQUIRED (facultative vs obligatory)
  • no infection, simply mechanical transport
34
Q

What is an oocyst?

A
  • a hardy, tick-walled spore, able to survive for lengthy periods outside a host
  • organisms that create oocysts include Eimeria, Isospora, Cryptosporidium, Toxoplasma
35
Q

What are sporozoites?

A

infective cell form

36
Q

What is a trophozoite?

A
  • G. nourishment
  • intracellular stage that feeds & grows
37
Q

What is a hypnozoite?

A
  • G. sleep
  • quiescent stage
38
Q

What is a bradyzoite?

A
  • G. bradys = slow
  • slow-growing form responsible for parasitic infections
39
Q

What is a tachyzoite?

A
  • G. tachys = fast
  • rapid growth & replication
40
Q

What are the types of asexual reproduction performed by parasites?

A
  • binary fission
  • schizogony
41
Q

What is schizogony?

A

trophozoites grow super large, while the nucleus divides many times, the structure is called SCHIZONT & when mature, the organisms are called MEROZOITES

42
Q

What type of sexual reproduction is performed by parasites?

A

gametogony

Parasitology (6 decks)

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