Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 4 Livestock and One Health > Small Ruminants: Clinical Parasitology > Flashcards

Small Ruminants: Clinical Parasitology Flashcards

1
Q

What is the definition of anthelmintic resistance?

A

When a drug (anthelmintic) has lower then 95% efficacy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name the 5 species of nematodes that commonly infect sheep?

A
  • Nematodirus battus
  • Telodorsagia circumcincta
  • Trichostrongylus spp
  • Haemonchosis contorsus
  • Dictylocaulus filaria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do nematodes cause disease in sheep?

A
  • Damage lining of guts
  • Remove nutrients
  • Remove blood (haemorrhage)
  • Host immune response
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the generic clinical signs of nematode disease in sheep?

A
  • Reduced appetite
  • Poor weight gain/weight loss
  • Diarrhoea
  • Anaemia
  • Death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When do the following nematodes cause disease in sheep/lambs?:
1. Nematodirus battus
2. Telodorsagia circumcinta
3. Trichostrongylus spp
4. Haemonchus contortus

A
  1. Outbreaks of acute severe diarrhoea and death in lambs 6-12 weeks old
  2. Type 1- lambs first grazing, mid summer onwards, Type 2- yearlings winter months, emergence of hypobiotic larvae
  3. Black scour- lambs or replacments late summer/autumn
  4. Adults and lambs- mid spring to late autumn, non regen anaemia, sudden death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the basic life cycle of nematode parasites in sheep

A
  • L1 and L2 in faeces
  • L3 infective stage ingested
  • L4 and mature adults develop into adults

PPP- 16-21 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain this Graph

A
  • Jan- Mar: remaining over wintered pasture larvae slowly dying off
  • Feb-May: increase shedding from ewes due to Peri-parturient rise
  • April: lambs start grazing and has no immunity, buidling number on pastures
  • Declines over winter as lambs gain immunity

Peak of infectivity over summer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain this Graph

A
  • Jan- Mar: remaining over wintered pasture larvae slowly dying off
  • Feb-May: increase shedding from ewes due to Peri-parturient rise
  • April: lambs start grazing and has no immunity, buidling number on pastures
  • Declines over winter as lambs gain immunity

Peak of infectivity over summer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When do the following species peak?:
1. Telodorsagia
2. Trichostrongylus
3. Haemonchus

A
  1. Early summer
  2. Late summer
  3. Mid spring to late autumn
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which species of nematodes in sheep hypobiose?

A

Telodorsagia
Haemonchus contortus
Trichostrongylus axei

Interupted development of L4 inside sheep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the epidemiology of nematodirus battus differ?

A
  • Eggs shed by lambs one year and remain on pasture to infect next year (no hypobiosis)
  • Hatching occurs after period of chill
  • L3 hatch en masse in spring

Some now don’t require chill, cause clinical problems in autumn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. When should a lamb have developed immunity to nematodes by?
  2. What influences immunity to nematodes?
A
  1. Provided the lamb is exposed to nematodes: 5-6 months
  2. Influenced by:
    * Nutrition
    * Genetics
    * Stage of parturition- PPR, 2-4w before lambing, 6-8 w after, less in singles, reduced by higher protein diet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is nematode control a balance?

A

It is not possible to eliminate infections, therefore control is a balance of suficent exposure to develop immunity, but not too much to cause disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 5 groups of anthelmintic drugs?
What colour drench are each?

A

1- Benzimidazoles- white drench
2- Levamisole- yellow drench
3- Macrocyclic lactones- clear drench
4- Amino-acetonitrile- orange drench
5- Spiroindoles- purple drench

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Each anthelmintic has a different MOA. Match the following actions to the drugs:
* Block Cl- and GABA channel paralysis
* Nicotinic cholinergic paralysis
* ACH receptors, paralysis
* Tubulin binding, prevents uptake of glucose, ovicidal
* Ganglion blocking drugs, paralysis

A

3- MLs: block Cl- and GABA channels paralysis
5- spiroindoles: nicotinic cholinergic paraylsis
4 ADs: ACH receptors, paralysis
1 BZs- Tubulin binding, prevents uptake of glucose- ovicidal
2 LVs- Ganglion blocking drugs, paralysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the special features of BZs?

A
  • Broad spectrum round worms
  • Tape worms
  • Albendazole (also fluke)
  • N battus
  • Some hypobiosed larvae
  • Most resistance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the special features of MLs?

A
  • Round worms and mites
  • Moxidectin- persistent activity against telodorsagia, all injectable forms active against mange mites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the key factors that influence the development of anthelmintic resistance?

A
  • Treatment frequency
  • Proportion of population exposed to treatment ‘in refugia’
  • Under dosing
  • Biosecurity (new strains introduced)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How can anthelmintic resitance be suspected and tested?

A
  • Clinical signs- lambs growth rates reduced, diarrhoea, death
  • Test- FEC reduction (FEC reduced to 0 after drug
  • Drench test- post treatment FEC check
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe how to do a drench and FECRT test

A

Drench test- FEC 7-14 days post treatment
FECRT
* 10 lambs
* Weigh and mark
* Pre- treatment FEC
* Accurate dose drug
* 7-14 days post treatment
* Calculate mean reduction in FEC >95%

20
Q

What other tests can specialist labs do?

A
  • Egg hatch assay
  • Larval development test
  • Larval migration test
  • Adult motility
  • Larval feeding inhibition assay
  • BZ and LV
21
Q

What are the SCOPS principles?

Sustainable control of parasites

A
  1. Always make sure treatment is fully effective
  2. Reduce dependence on anthelmintic using managment and monitoring
  3. Avoid bringing in resistant worms and/or other parasites by following a robust quarantine routine. Test for anthelmintic resistance
  4. Minimise the selection for worms that are resistant to anthelmintics when you treat sheep
22
Q

How can you make sure treatment is fully effective?

A
  1. Avoid under-dosing- pick heaviest in group, weigh and dose to heaviest (if range then sub-group)
  2. Check dosing gun
  3. Test for resistance
  4. Choose correct product for task
23
Q

How can we make sure the correct anthelmintic is used for the task?

A
  • Broad spectrum for nematode parasites
  • Use all 5 groups- rotate through
  • Quarentine/biosecurity use new classes
  • Avoid combination products
  • Test for resistance
24
Q

When should anthelmintics be used?

A

Adult sheep should have immunity by the time sheep are adult (not haemonchus)
* Treat at lambing time- reduce pasture contamination for lambs, leave portion untreated (only thin, triplets etc)
* Treat at tupping time- only thin, ideally FEC first

Vaccination programme at high risk period for Haemonchus barbervax

25
Q

How can reliance on anthelmintics be reduced in grazing lambs?

A
  • Rotational grazing practices (crops, cattle, adult sheep)
  • Weaned lambs move to lower risk pastures
  • Good plane of nutrition (protein)
  • Manage concurrent disease (coccidiosis)
  • Genetic selection (EBV for resistance)
  • Vaccination- haemonchus barbervax
  • Target use of anthelmintics to when actually required
  • Monitoring treatments- FEC, forecasts
26
Q

How and when should samples be taken for FEC?

A
  • Sample groups of lambs every 2-4 weeks
  • Fresh dung less than 1 hour
  • Take at least 10 individual samples per group- 10% in larger groups
  • Healthy sheep- access to pasture/feed
  • Random samples
  • Air expelled from bag and sample cool
  • Interpret according to clinical signs for sheep

Not suitable for nematodirus monitoring

26
Q

How and when should samples be taken for FEC?

A
  • Sample groups of lambs every 2-4 weeks
  • Fresh dung less than 1 hour
  • Take at least 10 individual samples per group- 10% in larger groups
  • Healthy sheep- access to pasture/feed
  • Random samples
  • Air expelled from bag and sample cool
  • Interpret according to clinical signs for sheep- count depends on species

Not suitable for nematodirus monitoring

27
Q

Why can live weight gain monitoring be useful for anthelmintic use?

A

If lambs are growing at required growth rates they do not need to be wormed

28
Q

What is the FAMANCHA test used for?

A

Pallor or eye mucous membranes in sheep for haemonchosis

29
Q

Describe high, medium and low pasture risk for spring and late june

A

Spring:
* High- ewes and lambs last year, nematodirus carried in previous spring, store lambs previous autumn
* Medium- grazed only by adult non-lactating sheep
* Low- crops, cattle or conservation

Late June
* High- ewes and lambs in spring
* Medium- adult, non lactating sheep in spring, cattle or conservation
* Low- cattle or conservation in first half of grazing season, forage or crops

30
Q

How should bought in sheep be quarentined?

A
  • Dose- monopantel (zolvix) and/or derquantel and abametcin
  • Hold off pasture 24-48 hours for treatment to work
31
Q

How is the risk of selection resistance reduced when treating sheep?

A
  1. Don’t treat and move- leave a couple of days
  2. Only treat thin, triplet bearing and young sheep at lambing
  3. Avoid long acting products if possible
32
Q

What is ‘in refugia’
Why does it rapidly select for resistance?

A

When sheep are dosed with anthelmintics when the majority of the worm population is in the sheep

Autumn, winter, early spring

33
Q

What are the 3 problems with cestode infections in sheep?

A
  1. Carcass condemnations at abattoir
  2. Echinococcus granulosus zoonosis
  3. Clinical signs in sheep ‘Gid’ cysts in the brain
34
Q

For the following cestodes state the primary host, intermediate host and clinical significance:
1. Monezia expansa
2. Taenia hydatigena
3. Taenia ovis
4. Taenia multiceps
5. Echinococcus granulosus

A
35
Q

How can tapeworms in dogs be controlled?

A

Praziquantel every 6 weeks

36
Q

What affects epidemiology of fluke?

A

Rain-
* increases snail habitats,
* development of fluke eggs,
* miracidium finding snails
* dispercal of carcariae from snails

Temperature
* >10 for miracidia in egg
* >10 eggs to hach and for snails

37
Q

What causes either acute or chronic fasciolosis in sheep?

A

Acute- large numbers of metacercariae on pasture in late summer (very wet summer)
Chronic- less numbers ingested over summer and autumn

38
Q

Describe the life cycle of liver fluke?

A
  • Metacercariae ingested
  • Eggs shed
  • 2-6 weeks eggs to miracidium
  • Miracidium hatch to snail (in 24h)
  • Miracidium to cercaria emerge to be metacercaria
39
Q

What causes acute fluke disease and what does acute liver disease cause?

A

2-6 weeks after ingestion of very large numbers of metacercariae- Sep- Dec
* Severe haemorrhages- immature stage migration
* Sudden death
* Weakness
* Pale
* Dyspnoeic

40
Q

When is chronic fluke disease caused?
What is the clinical presentation?

A

Late autumn/winter/spring- small numbers of metacercariae ingested
* Blood feeding adults in bile ducts-
* aemorrhagic anaemia,
* hypoalbuminaemia
* Hepatic fibrosis and cholongitis
* Anaemia, weight loss, submandibular oedema, hepatomegaly, secondary clostridial disease

41
Q

How can fluke be diagnosed?

A
  • History and clinical signs
  • Parasite forecasts
  • PM
  • Abbattoir reports
  • FEC- 12 weeks post infection
  • Coproantigen ELISA similar time to FEC
  • Serum ELISA antibody- 2-4 weeks post infection- usefult for naive animals
  • Liver enzymes, haematology- not fluke specific
42
Q

What are the 5 drugs currently available to treat fluke?

A
  • Albendazole
  • Oxyclozanide
  • Nitroxynil
  • Closantel
  • Tricalbendazole
43
Q

What is the optimum time for the following drugs for fluke treatment?
Albendazole
Oxyclozanide
Nitroxynil
Closantel
Triclabendazole

A
  • Albendazole- spring/summer
  • Oxyclozanide- spring/summer
  • Nitroxynil- late autumn/winter
  • Clostantel- autumn
  • Triclabendazole- autumn- resistance
44
Q

How can fluke be avoided?

A

Manage environment- assess snail habitats, fence
improve pasture- drain

Biosecurity- some farms free, risk resistance. Clostantel on arrival

45
Q

How can fluke be monitored?

A
  • Inform how well drug is working
  • Guide to timing of doses- Abbatoir, serum Elisa, Coproantigen, FEC
  • Forecasting
  • PM sudden death
  • Clinical signs
46
Q

How should fluke be treated in an average rainfall year in known fluke area?

What should high risk farms/years additionally do?

A
  • Autumn against immature stages- TCBZ
  • Winter immature and adults- Clos/Nitrox
  • Late spring remove all adults- Alben

Additionally dose in november (TCBZ), june (TCBZ)

47
Q

How can drug resistance be prevented against fluke?

A

Rotational use of drugs- 3 classes
Only use TBCZ when necessary- autumn
Spring dose against adults- prevent egg output
Quarantine drenching
Closatnel/Nitroxynil
Test for resistance to TCB (increasing problem)

Year 4 Livestock and One Health (58 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions