Control of Parasites

Question 1

what are antiparasitic chemicals?

Answer 1

types of antimicrobials with crossover with antibacterial and antifungal chemical agents

Question 2

what do antiparasitic chemicals do? (3)

Answer 2

1. interfere with metabolism
2. interfere with reproduction
3. interfere with growth of parasitic agents

Question 3

what do antinematode agents specifically do?

Answer 3

affect adult reproduction so eggs can’t hatch and there are no larvae to continue the cycle

Question 4

what is the risk of using antiparasitic agents and why?

Answer 4

they have low selective toxicity because the eukaryotic parasite cells are very similar to our own eukaryotic cells, so there are extensive side effects

Question 5

what are the main kinds of antiprotozoals?

Answer 5

coccidiostats

Question 6

what do coccidostats work against? (coccidia types)

Answer 6

eimeria and isospora!!

Question 7

what are the 2 groups of coccidiostats?

Answer 7

1. polyetherionophore antibiotics: like monensin

2. nonpolyetherionophore antibiotics/synthetics/chemicals

Question 8

what do polyetherionophores do?

Answer 8

target ion channels to disrupt movement of ions across cell membranes, leading to an osmotic pressure imbalance that causes coccidia to die

Question 9

what is standard practice to avoid resistance to coccidiostats?

Answer 9

rotate between polyetherionophores and nonpolyetherionophores

Question 10

what Kind of effect does monensin, a polyetherionophore, have? how?

Answer 10

increases permeability in coccidia cell membranes to create an antibacterial effect

Question 11

in what 4 animals is monensin widely used preventatively?

Answer 11

1. rabbits
2. poultry
3. swine
4. ruminants

Question 12

how is monensin used in the US? why?

Answer 12

as a feed additive as a promotor of growth and feed conversion efficiency; the antibacterial effect leads to more efficient digestion

Question 13

how is monensin used in the EU?

Answer 13

only in poultry and rabbits where coccidiosis is systemic/widespread problem

Question 14

in what animals in monensin highly toxic?

Answer 14

horses

Question 15

what 2 things are countries trying to figure out with monensin? answer those questions

Answer 15

1. is monensin absorbed in meat/does it enter food? research says no because it can’t get inside of cells, can only target free-living parasites
2. is coccidia becoming resistant to monensin? it IS becoming an issue, so we have to be very careful in our usage (@US)

Question 16

where was most of the control of ectoparasites developed from?

Answer 16

pesticides on crops

Question 17

what are the 2 types of ectoparasite situations that determine how we treat it? tell how treat

Answer 17

1. parasites that live permanently in the host; we can treat the host directly
2. parasites that have only one life stage in the host; need to combine control of parasites and environment

Question 18

list and describe 3 methods of control of ectoparasites

Answer 18

1. biological control: used a lot now in crop to decrease pesticide use, like lady bugs eating parasites
2. off-host control: fumigate the area to kill eggs and larvae, here you can use pesiticides since not in direct contact with living host
3. insect growth retardants: block growth hormone of insects/parasites, inhibiting their development

Question 19

why are insect growth retardants completely safe to use on animals?

Answer 19

because animals use a different mechanism/hormone to grow, so no effect

Question 20

what are the 3 GENERAL classes of antihelmintics?

Answer 20

1. benzimidazoles
2. imidazothiazoles
3. macrolides, like ivermectin

Question 21

what is the problem with the fact that we only have three very general classes of antihelmintics?

Answer 21

drugs utulize similar mechanisms within each class, so resistance to one drug in the class by a parasite indicates likely resistance to all drugs in that class; the classes themselves are also all very similar, so resistance is a HUGE issue

Question 22

what are the 4 modes of action of antihelmintics?

Answer 22

1. inhibit tubulin polymerization, a structural/cytoskeleton protein that inhibition of leads to noviable cells
2. uncouple oxidative phosphorylation, so no energy production
3. inhibit enzymes in glycolytic pathways, so no energy production
4. neuromuscular coordinators, so paralyze parasite basically

Question 23

what is antiparasitic resistance?

Answer 23

the ability of parasites to survive doses of drugs that would normally kill parasites of the same species and life stage

Question 24

what happens reproductively when parasites mutate and develop resistance?

Answer 24

they produce eggs that are also resistant

Question 25

what does every exposure of an antiparasitic, especially antihelmintics, do?

Answer 25

exerts some selection pressure for resistance development

Question 26

what aare the 3 main goals in determining deworming strategies for livestock?

Answer 26

1. reduce the chance of developing resistant parasites 2. decrease operational expenses for livestock producers (antiparasitics are expensive) 3. decrease use of drugs in food animals

Question 27

how do you avoid parasitic resistance?

Answer 27

reduce exposure of anthelmintics to parasites and minimize the frequency of use

Question 28

what is the "golden rule" followed when determining a deworming strategy for livestock?

Answer 28

in a herd, 20% of animals will shed 80% of the parasite load

Question 29

how do livestock producers use the 20/80 rule when developing a treatment strategy?

Answer 29

don't have to treat entire herd, can use fecals (inexpensive) to find individual shedders and treat just them instead

Question 30

what are deworming protocols for livestock based on? (4)

Answer 30

type, location (geography and seasons), herd, and individual animals of an operation

Question 31

what do livestock producers in the southeast US have to do concering parasites?

Answer 31

manage parasites year round

Question 32

describe deworming strategies in equines (3)

Answer 32

1. moved away from the use of a rotational deworming every few weeks to just treating individuals 2. use fecal egg counts to determine which horses have a high enough parasite load to treat (lost the battle) 3. fecal egg counts above 500 should be treated based on species of eggs present

Question 33

give some general techniques (4) of parasite management in equines

Answer 33

1. clean and dispose of manure in the pasture 2. rotate pastures 3. keep housing/pasture density low 4. remove bot fly eggs from hair to prevent ingestion

Question 34

describe the 2 types of deworming strategies in small ruminants

Answer 34

1. FAMACHA scoring: eye mucosal inspection, tells anemia levels; indicates blood sucking (Haemonchus contortus parasite) 2. fecal egg count gives more specific recommendations and tells species present beyond blood sucker

Question 35

in the southeast US, what 2 parasites are of economic importance in small ruminants? fancy and common names please

Answer 35

1. Haemonchus contortus: barber pole worms | 2. Ostertagia circumcinta: brown stomach worm

Question 36

how are cattle deworming strategies different from equines and small ruminants?

Answer 36

is treated by management category, not by individual animal

Question 37

what "most likely to be affected" groups of cattle are dewormed? (3)

Answer 37

1. nursing calves 2. stockers (5-11 months of age) 3. replacement heifers all under 1 year old

Question 38

when does cattle immunity to worms develop?

Answer 38

1 year after weaning

Question 39

cattle producers use stratgic deworming programs with 4 core production aspects; what are they?

Answer 39

1. time of year grazing begins: if pasture freezes during winter, deworm before cows go out to keep pature parasite free 2. age/category 3. type of operations grazing system 4. grazing history of parasites: 6 month rule

Question 40

what is the 6 month rule concerning parasites and pastures?

Answer 40

if no animals have been on a pasture for over 6 months, it's probably parasite free; if animals have been there in the last six months, parasites are likely still there

Question 41

when do you deworm weanling cattle? (4)

Answer 41

1. their first grazing season 2. at weaning and anytime moved to a new pasture 3. when 6 month rule indicates pasture could have parasites 4. when stocking density is high

Question 42

what is rotational grazing?

Answer 42

only a portion of the pasture is grazed at a time while the remainder of the pasture "rests," allows free forms of parasites (eggs and oocysts) to be exposed to the environment and die before closing the cycle

Question 43

what is important to know when using rotational grazing?

Answer 43

the life cycle of the main parasites found in your pastures/animals