Lecture 47 - Pasture-based nematodes Flashcards

1
Q

what are the 3 modes of nematode transmission

A
  1. tracheal
  2. somatic
  3. mucosal
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2
Q

tracheal migration

A

migrate by the bloodstream to the liver and then to alveoli in the lungs which are coughed up and swallowed. adult worms mature in the small intestine

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3
Q

somatic migration

A

larvae will be transported to systemic circulation to various organs and somatic tissues where they encyst as arrested larvae

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4
Q

mucosal migration

A

after infection, larvae migrate to intestinal muscosa where they encyst as arrested larvae

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5
Q

premunition

A

parasitological feedback mechanism in which the adult population in the lumen inhibits reactivation and emergence of the arrested larvae

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6
Q

what is the danger of deworming

A

suddent death of the adult population allowing for arrested larvae to emerge and cause damage

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7
Q

why does resistance develop

A

too frequent dewormer use
underdosing of dewormer

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8
Q

refugia

A

portion of population of parasites that eludes the drug at the time of the treatment event that are still susceptible

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9
Q

what concept explains:

The portion of a population of parasites that eludes the dewormer at the time of a
treatment event. Also known as the portion of a worm population that is susceptible to a dewormer

A

refugia

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10
Q

what concept explains:

The ability of worms in a population to survive treatments that are generally effective against that species of worm.

A

resistance

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11
Q

what concept explains:

The loss of ________ may result in post-treatment pathology caused by the reactivation of arrested L4s after the elimination of adult worms via a deworming treatment

A

premunition

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12
Q

what concept explains:

An important biological event in the life cycle of Pasture-borne Nematodes, in which ingested larvae migrate to and may arrest in the wall of the host gut

A

mucosal migration

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13
Q

what concept explains:

A parasitological feedback mechanism in which the adult population in the lumen inhibits the
reactivation and emergence of the arrested larvae

A

premunition

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14
Q

what concept explains:

often caused by the overuse or underdosing of a dewormer

A

resistance

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15
Q

what is the goal of parasite control programs

A
  1. minimize the risk of parasitic disease
  2. delay further development of anthelmintic resistance
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16
Q

how are hosts infected by pasture-borne nematodes

A

ingest L3s on forage

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17
Q

what are 5 goals when controlling pasture-borne nematode

A
  1. promote refugia
  2. limit pathology
  3. reduce pasture contamination
  4. reduce the use of dewormers
  5. slow resistance
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18
Q

20% of the herd produces what percentage of pasture contamination

A

80%

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19
Q

In general, _____ are more likely to become heavily infected and seriously affected by parasites

A

young and naive hosts

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20
Q

what is salvage deworming

A

treatment to stop clinical pathology

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21
Q

what is selective/tactical deworming

A

treat hosts with subclinical pathology but not treatment of hosts showing no symptoms

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22
Q

strategic deworming

A

prevent future infections by reducing pasture contamination

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23
Q

scheduled deworming

A

deworm at regular intervals to eliminate maturing adults (spring and end of grazing season)

24
Q

what type of deworming is:

A subclinical horse with a FEC* above specified threshold

A

selective

25
Q

what type of deworming is:

Planned Deworming v/s the Periparturient Rise

A

strategic

26
Q

what type of deworming is:

Host showing severe clinical pathology

A

salvage

27
Q

what type of deworming is:

A subclinical goat with a FAMACHA score of D(4)

A

selective

28
Q

what type of deworming is:

Calf with intense diarrhea and anorexia

A

salvage

29
Q

what type of deworming is:

Has led to overuse of dewormers and resistance.

A

strategic

30
Q

what type of deworming is:

Used to promote refugia and delay resistance

A

selective

31
Q

what type of deworming is:

Deworming Based on PPP**

A

strategic

32
Q

what information does a fecal egg count provide

A
  • identifies hosts with high contamination potential
  • end of grazing season to check efficacy of control program
33
Q

what information does the fecal egg count reduction test provide

A
  • informs about resistance/efficacy
34
Q

why do you wait 10-14 days to collect a post-treatment fecal

A

to clear out dead worms/eggs and before new worms repopulate the gut

35
Q

T/F: there should be treatment only once the FEC has reached a specific threshold

A

TRUE

36
Q

what utilizes the McMasters technique

A

FEC and FECRT

37
Q

what is used to identify Hosts with High Contamination Potential

A

FEC

38
Q

Informs about the presence of Dewormer Resistance

A

FECRT

39
Q

When is the best time to check the efficacy of one’s pasture-borne nematode control program?
A. Beginning of Grazing Season
B. Middle of Grazing Season
C. End of Grazing Season

A

C. end of grazing season

40
Q

what larval stage is most susceptible to harsh conditions

A

L1 and L2

41
Q

describe L3s

A

retains protective sheath (less susceptible) but cannot feed

42
Q

what is a larval storm

A

rainstorm releases large numbers of L3 that have matured in fecal pat, pathology shows up in hosts soon after

43
Q

what are the treatment methods for pasture management

A
  1. removal
  2. compost
  3. drag?
44
Q

Which environmental conditions are most detrimental to the free-living stages (ova, L1s, L2s, L3s) of pasture-borne nematodes?

A

low humidity and high temperature

45
Q

The release of large numbers of L3s from fecal pats, which cause pathology in hosts soon after a rainstorm event following a dry period.

A

larval storms

46
Q

horizontal migration

A

across pasture

47
Q

vertical migration

A

up grass blades

48
Q

Which “Treat-&-Move Strategy” is most likely to produce a monoculture population of Resistant Nematodes?

A

treat & move

49
Q

Which “Treat-&-Move Strategy” inhibits the development of Refugia?

A

treat & move

50
Q

what pasture management:

Requires much fencing for multiple small pastures.

A

planned intensive grazing

51
Q

which practice is best to limit contamination of new pasture

a. treat & move
b. move, wait, treat
c. treat, wait, move

A

c. treat, wait, move

52
Q

interspecific co-grazing relies on what

A

host specificity

53
Q

intraspecific co-grazing relies on what

A

age-related immunity

ex: cow-calf grazing, forward grazing (fresh pasture grazed by calves first)

54
Q

what are two different types of pasture maintenance

A
  1. strip grazing
  2. rotational grazing
55
Q

reactivation of arrested L4s can be caused by

A
  1. spring rise (winter stressors)
  2. periparturient rise (decrease in female host immunity due to pregnancy and lactation)
56
Q

T/F: dewormers do not affect arrested L4 because they are metabolically inactive

A

TRUE