1. Internal parasite control in sheep
Fewer worms
More dollars

2. Course aim
Monitor and manage sheep worm populations to improve production, by:
Using worm egg counts to detect infestations early.
Becoming competent at the faecal egg count test.
Regular drench resistance tests.
Use of WormBoss in decision making.

3. Outline Setting the scene Types of internal parasites
Parasite damage to sheep
Introduction to WormBoss
Worm egg counting
Drench resistance

4. Setting the scene Worms cost the Australian sheep industry $369M/yr
This could increase to $700M by 2010
drench resistance
more production losses

5. Figure 1. National cost ($million) of major sheep health issues in Australia. (Source: Holmes et al. 2006)

6. Types of internal parasites
Strongyles or Round worms
Cestodes or Tapeworms
Trematodes or Liver flukes

7. Round worms (Strongyles)
Major cause of production losses in sheep
Summer dominant rainfall
Barbers Pole
Black Scour
Winter dominant rainfall
Brown Stomach
Lung worms

8. Round worms and site of infection
Round worm scientific name
Round worm common name
Abomasum
Haemonchus contortus
Teladorsagia circumcincta
Trichostrongylus axei
Barbers Pole
Brown Stomach
Stomach Hair
Small intestine
Trichostrongylus colubriformis
Trichostrongylus vitrinus
Nematodirus spathiger
Cooperia curticei
Bunostomum trigonocephalum
Strongyloides papillosus
Black Scour
Thin Necked Intestinal
Small Intestinal
Hook Worm
Strongyloides
Large intestine
Trichuris ovis
Oesophagostomum columbianum
Oesophagostomum venulosum
Chabertia ovina
Whip Worm
Nodule Worm
Large Bowel
Large Mouthed Bowel
Lungs
Dictyocaulus filaria
Muellerius capillaries
Large Lung
Small Lung
(Source: Cole 1980)

9. Life cycle of round worms
(Source: Cole 1980)

10. Epidemiology
Temperature and moisture are critical for the survival of worm eggs and larvae
Round worms require avg. daily temp. of 10oC and 50% humidity (50 – 75mm) to hatch
Except Barbers Pole – temp. above 15oC

11. Tape worms (Cestodes) Most common/important species Moniezia
live in intestines
no known ill effects
Echinococcus
Taenia

12. Liver flukes (Trematodes)
Only species in sheep is Fasciola hepatica
Complex life cycle and has a fresh water snail as an intermediate host
Live in bile ducts of liver

13. Parasite damage to sheep
Tissue damage
Competition for protein
Appetite reduction
Scouring
Anaemia (Barbers Pole)
(Source: )

14. Overall production effects
Parasites will cause a reduction in:
fertility
milking ability
meat production
wool production
wool soundness
immunity

15. Introduction to WormBoss
Developed by Sheep CRC and AWI
Recommendations:
monitor worm populations
regular drench resistance tests
use non-chemical management strategies
if unsure, seek professional advice

16. Exercise 1 – Using WormBoss
Select “know your worms”
List major summer and winter rainfall worms
Select one worm from each rainfall group and list its scientific and common name, distribution, location in sheep and affects on sheep

17. Worm egg counting
Number of worm eggs in a sample of sheep dung - “eggs per gram” (epg)
Can’t distinguish between different round worm species “strongyle eggs”
More accurate than visual assessment

18. Worm egg counting Useful to decide: if treatment is necessary
if previous treatments were effective
assess level of worm contamination being put into paddocks
which sheep are worm resistant

19. View of worm eggs
(Source: WormBoss website, Dr R Woodgate)

20. Worm egg typing
Larval culture and differentiation is required to differentiate between different worm species
(Source: WormBoss website, Dr R Woodgate)

21. Exercise 2 – Worm Egg Count Test
Aim of procedure
Materials
including use and care of microscopes
Method
Counting
Calculations
Interpreting results

22. Use and care of microscopes
Start at lowest magnification
Rotate the focus wheel so you know which direction lowers/raises microscope
Focus using coarse focus first, then fine tune
Don’t allow microscope head to come in contact with slide
Rest eyes regularly
Always clean immediately after use

23. WEC test method Weigh 2g faeces from each sample into mixing bowl
Add 60ml of saturated salt solution and mix
Pour through strainer to remove course material
Stir in a N-S E-W motion before allowing material to flow into pipette
Moisten counting chambers of slide
Fill the slide chambers from right to left and with the slide verandah facing away from operator
Allow about 1 min. between preparation and counting for eggs to float to top of slide

24. Counting the faecal eggs
See Egg Identification Sheet to identify different worm egg species
Place slide on microscope with verandah facing away from operator, use fine focus knob to focus slide
Begin counting using lines as a guide
For each sample, count and record number of eggs seen for each species

25. Egg identification (page 1)
3. Coccidia
1. Trichostrongylus (Black scour worm)
4. Moniezia (Tapeworm)
2. Haemonchus (Barbers Pole worm)
The images on this page were sourced from: 1. 2.
3. commons.wikimedia.org/wiki/Image:Coccidia.JPG 4.

26. Egg identification (page 2)
7. Fasciola (Liver Fluke)
5. Trichuris (Whipworm)
6. Nematodirus (Thin necked Intestinal worm)
9. Dictyocaulus (Lungworm)
The images on this page were sourced from:
5. w3.ufsm.br/parasitologia/arquivospagina/ovosdebovinos.htm 6.
7. cal.vet.upenn.edu/projects/parasit06/website/lab6.htm 8.

27. Calculation for FEC test
Number of eggs/gram of faeces =
number of eggs counted x total volume of mix (ml)
volume of counting chamber (ml) x wt of faeces in mix

28. Interpretation of FEC test results
Click on “Ask the Boss” and read
Click on “Consult the Boss” and follow the prompts
A report will be generated based on the information you enter

29. Drench resistance
Essential to know to be able to effectively manage worms
Occurs once worms can survive a dose of a drench that would have previously killed them
Measured by a Faecal Egg Count Reduction Test (FECRT)
Accepted industry definition = a reduction in worm egg count of less than 95%

30. Factors influencing development of drench resistance
Chemical group and persistency of the product involved
Frequency of treatments
Worm species involved
Environmental factors

31. How common is drench resistance?
Widespread, probably 90% or more of farms have a problem
Sheep worms have evolved resistance fairly quickly to each new drench group

32. Drench resistance testing
Essential to know the efficacy of drenches on your property
Assessed through a Faecal Egg Count Reduction Test (FECRT)
Should be conducted every 2 years

33. Exercise 3 – Setting up a FECRT
Select appropriate sheep
young, wormy and undrenched
at least 12 weeks old
Do a worm egg count
collect dung samples from min. 10 sheep
samples tested for enough worm species (min. 300 epg)

34. Setting up a FECRT Decide drenches to test Set up test groups
seek professional advice
depends on previous test results and property drench history
Set up test groups
at least 15 sheep in each group plus one control (undrenched) group
ID each group

35. Setting up a FECRT Drench each group Return sheep to paddock together
drench each group with correct drench
make sure:
no cross contamination of drenches
control group not drenched
correct drenching technique used
Return sheep to paddock together

36. Setting up a FECRT Collect faecal samples for worm egg counting
10-14 days after initial treatment collect 10 fresh faecal samples from each group including the control group
obtain a larval culture and differentiation on samples from each group

37. Setting up a FECRT Interpreting results
compare average no. of faecal eggs in each sheep group with that of the control
Fully effective drench = 95% worm egg reduction in relation to undrenched control group
% efficacy = (control – treatment) / control x 100