Resistance

Question 1

Define resistance.

Answer 1

When there is a greater frequency of individuals within a population that are able to tolerate doses of compound than in a normal population of the same species and is heritable and due to a drug exposure

Question 2

True or False: All parasites present in the environment are in refugia, if they are also not exposed to a drug.

Answer 2

True

Question 3

True or False: Resistance is directly caused by the drug exposure.

Answer 3

False, there are already helminths in the environment that are able to survive drug treatment

Question 4

Drug exposure results in the an increase in the genetic levels of _________ populations.

Answer 4

Resistant

Question 5

Define refugia.

Answer 5

An area in which a population of organisms can survive through a period of unfavorable conditions

Question 6

Why would strategic treatments lead to a decrease in refugia?

Answer 6

Strategic treatments implies that the entire herd or flock is being treated at a specific time or times of the year, which leads to more rapid resistance since only the resistant parasites will be present as the susceptible microorganisms die off

Question 7

Why would tactical treatments lead to a decrease in refugia?

Answer 7

Tactical treatments involve treating an entire herd or flock when you would anticipate a larger parasitic burden, and leads to resistance

Question 8

Which form of treatment would lead to the fastest resistance populations?

Answer 8

Strategic

Question 9

True or False: In targeted selective treatments (TST), only the needy animals alone are treated thereby reducing the cost of treatment, drug residues in milk and meat, and the spread of drug resistant genes.

Answer 9

True

Question 10

Why do selective treatments not lead to resistance?

Answer 10

Only the affected animals of a herd or flock are treated, thereby reducing the growth of resistant populations as they are diluted with susceptible parasites, and those animals with resistant and susceptible parasites are left untreated

Question 11

Why would treating when there are few larvae on the pasture after good rains?

Answer 11

This would be considered a form of tactical treatment, which would lead to increased resistance as you’d expect an increased worm burden across the whole herd or flock

Question 12

Why would treating when there is a drought lead to increased resistance?

Answer 12

The entire herd or flock would only produce resistant parasites, and likely due to desiccation, only a small percentage of resistant parasites would be ingested

Question 13

The pest density at which management action should be taken to prevent an increasing pest population from reaching the economic injury level, is called?

Answer 13

The economic threshold

Question 14

If the efficacy of the anthelmintic falls below 90 percent after completing the proper testing protocol, you should not do -?
A) Use a different class of anthelmintic or combination of two compounds of different class
B) Repeat screening test under new treatment
C) Consider an additional diagnostic investigation
D) Use an alternate treatment
E) None of the above

Answer 14

E) None of the above

Question 15

What is an FECRT?

Answer 15

A more structured on-farm test that can be conducted in which a number of different anthelmintics are tested against a control, and can be used to determine the anthelmintic resistance status of the animals.

Question 16

True or False: There is resistance with almost all of the trichostrongylids.

Answer 16

True

Question 17

Which of the following is not associated with an integrated parasite management?
A) To decrease the rate of parasitic resistant populations in herds or flocks
B) Maintain parasites below the economic threshold to ensure losses do not exceed treatment costs
C) Prevent clinical disease and production losses through selective treatments
D) Monitoring and treating only afflicted animals based on diagnostics like FAMACHA and FEC

Answer 17

D) Monitoring and treating only afflicted animals based on diagnostics like FAMACHA and FEC

Question 18

True or False: High shedders, or those with increased parasitic burdens, will display clinical signs of disease.

Answer 18

False, dependent on various factors

Question 19

Why would breeding for host resistance and resilience be encouraged in integrated parasite management techniques?

Answer 19

An increased host’s resistance (an animal’s response to decrease the parasitic burden) and resilience (an animal’s adaptability to different environments) are favored to prevent parasitic infections.

Question 20

Define host tolerance.

Answer 20

An animal’s performance level at an increasing parasite burden.

Question 21

What effect does nutrition have on parasitic management?

Answer 21

It aids in supporting the immune system, which can lead to the decreased parasitic establishment and fecundity.

Question 22

Define fecund.

Answer 22

Producing, or the ability to produce offspring.

Question 23

What can be done to protect refugia in regards to pasture management?

Answer 23

Rotational and mixed grazing (followers follow leaders, or vice versa; the mixing of species), resting the pasture (allows larvae to die off), and alternating between crops and grazing pastures (to improve chance of eliminating eggs and early helminth seages via natural factors - desiccation, etc.).

Question 24

In order to ensure appropriate efficacy of a antihelminthic administered, it is important to retest treated populations how many days after?

Answer 24

10 - 14 days

Question 25

Which form of treatment will lead to more rapid resistance?
A) Tactical
B) Strategic
C) Selective

Answer 25

B) Strategic

Question 26

What is the Five Point Check System used for?

Answer 26

Allows farmers to identify several diseases and parasites in their small livestock

Question 27

What is being monitored in the Five Point Check system in small livestock (sheep, goats)?

Answer 27

• Back (body condition)
• Tail (soiling, dag)
• Eye (anemia)
• Nose (nasal discharge) = Oestrus ovis in sheep, worse
• Jaw (bottle jaw, edema)