1. Internal Parasite Information
Anne Oakenful– Diagnostic & Analytical Services – Oct 09

2. Internal Parasites
Internal parasites (worms and fluke) are estimated to be costing the Australian sheep industry $369m per year.
This cost includes mortalities and production losses (reduced wool cut, stained wool, lowered staple strength), as well as the direct costs of control (mainly drenches and labour)

3. Types of Internal Parasites
4 main groups
Nematodes (roundworms)
Trematodes (fluke)
Cestodes (tapeworms)
Protozoans (coccidia)

4. Haemonchus spp. (Barber’s Pole worm)
Nematodes
commonly known as round worms eg:
Haemonchus spp. (Barber’s Pole worm)
Ostertagia circumcincta (Small Brown Stomach worm)
Trichostrongylus spp (Black Scour worm).
by far the most economically important group of internal parasites

5. Life cycles…. Nematodes
Most common internal parasite of domestic livestock
Naturally carry low worm burdens
Animals need to be exposed to develop resistance
Become a problem when numbers increase to cause production losses and or animal have other diseases

6. Life cycle… Nematodes cont…

7. Barber’s Pole Worm
quite large worm (20 to 30mm) found in the abomasum.
Adult females have a characteristic barbers pole appearance like red and white twisted wire. The male is smaller (around 15mm)
sucks blood from the lining of the stomach which causes anaemia.
adults suck around 0.05ml of blood per worm. A burden of 1000 worms may remove 50ml of blood (egg count would be around 5000epg)
Sign of heavy infection include
lack stamina, pale gums and conjunctiva, bottle-jaw, constipation.
faecal worm egg counts are usually high before symptoms show (could be over 10,000 epg).
a subclinical (no visible signs of worms) infestation can reduce weight gains by 30%, wool growth by 10% and milk production by 30%.
Information sourced from Wormboss .com.au

8. Brown Stomach worm
occurs in most sheep areas of Australia and is a major parasite in winter rainfall districts.
small (10mm) red-brown worm just visible on the lining of the abomasum.
very resilient, can survive freezing on the pasture and dry conditions.
adults can arrested or inhibited for varying lengths of time
Adult female brown stomach worms lay eggs per day.
damage the lining of the stomach as they mature from larvae to adult worms.
heavy infections cause rapid loose of condition, profuse scours occasionally death.
animals with fewer worms are unthrifty and daggy.
Mixed infections of brown stomach worm and black scour worm are more lethal than infection with only one of the worms.
Infection caused whitish nodules on the abomasum lining.
production-loss occurs in the absence of obvious disease.
a subclinical infestation can reduce weight gains by 35%, wool growth by 20% and milk production by 20%.
Information sourced from Wormboss .com.au

9. Black scour worm
Black scour worms occur in all sheep production districts of Australia.
Adult female black scour worms lay 100 – 200 eggs per day.
Black scour worms live in the first three metres of the small intestine of the sheep and cause damage to the lining of the gut.
the larvae burrow into the wall of the small intestine and undergo a moult to become an immature worm.
heavy infections cause rapid lose condition, scours, which may be black. The animal can dehydrate and may die.
A subclinical infestation can reduce weight gains by 35%, wool growth by 10% and milk production by 20%.
Damage to the intestinal wall leads to problems with nutrient absorbtion.
Information sourced from Wormboss .com.au

10. Trematodes
include Fasciola hepatica (liver fluke) and Paramphistomes (stomach fluke).
The most economically important fluke for livestock is liver fluke.
This parasite causes substantial economic lost in certain geographical areas in Australia.

11. Life cycle… Liver fluke
Cost sheep and cattle industry around $50-80 million a year
Reduced production and quality of wool
reduced lambing percentages
Poor growth rates
Reduced milk production
Have indirect life cycle that relies on freshwater snail (lymnaeid snail) as intermediate host.
Infection only occurs where snail is found

12. Life cycle… Liver fluke cont...
Adult flukes
in bile ducts
Metacercariae ingested
Fluke eggs in faeces
Metacercariae on vegetation
Lymnaeid snail (intermediate host)
Miracidia
Cercariae leave snail
sporocyst
cercariae
rediae

13. Life cycle… Liver fluke cont...
Diagnosis
Faecal sedimentation test
Only detects adult infections producing eggs
Blood ELISA
Very reliable
Detects infection from 4 weeks

14. Protozoans Coccidia can affect all domestic animals.
Most are host specific.
Eimeria is the main coccidia infecting sheep and cattle.
Cryptosporidium is another protozoan that can affect sheep and cattle.

15. Life cycle… Coccida Generally host specific
Cause disease by invading cells of intestinal wall
Can be present in low numbers with no ill-effect
Animals develop immunity as they mature
Immunity levels can drop if under stress (overcrowding, nutritional, weaning etc)

16. Life cycle… Coccida cont…
Common signs of infection
Diarrhoea (severe and containing blood)
Rough coat
Poor weight gain
Weight loss
Weakness
Lower milk/meat/fibre production

17. Life cycle… Coccida cont..
Coccidia multiply in intestine and form new oocysts (10 days approx.)
24-48 hours in summer
May take weeks in winter
Oocysts in droppings
Infective oocysts

18. Life cycle… Coccida cont..
In cattle infection called ‘black scours’
Profuse, dark, foul smelly diarrhoea
Animals infected by
Contaminated food, water or bedding
Licking contaminated hair or udders

19. Life cycle… Coccida cont..
Reduce infections by:
Using feed and water troughs
Reduce overstocking, especially on damp pastures
Avoid holding animals in yards for long periods
Avoid mixing young and old stock together

20. Faecal Egg Counts
Is the most routinely performed test to estimate the worm population in an animal.
Strongyle eggs float in saturated solutions of salt.
If you use known quantities of samples and reagents, the number of parasite eggs per gram of faeces can be determined

21. Collecting the sample Samples collected from :
The ground - holding the animals in the corner of a paddock for 5-10 minutes and allowing them to drift away
Directly from the rectum - insert gloved finger into rectum and gently move finger around until faeces is released. (should happen within 30 seconds)

22. Wormtest kits Are a valuable tool for worm control Can be used to
Monitor worm burdens
Determine if a drench is require
Determine if the drench used was effective (drench resistance)
Determine how “worming” a paddock is
Determine the species of worms present in the animal (if worm type conducted)
Base management decision on results

23. What happens in the lab
Weigh out known sample amount and add saturated salt solution
Subsample loaded into special chamber and then eggs are counted under the microscope.
Results are multiplied by 40 to give the number of eggs per gram of faeces (epg)

24. Identifying Eggs
Strongyles have a number of species that produce eggs of the same relative size.
Need to hatch the eggs to identify larvae

25. Identifying eggs cont…

26. New Dipstick test
Australian Sheep Industry CRC have developed the dipstick test to detect when sheep should be treated to prevent Barber’s Pole worm disease (haemonchosis) outbreaks
Can use the test in conjunction with faecal egg counts
Test gives results before worm egg counts rise as immature worms are detected a week before they produce eggs

27. Dipstick Test cont…
The basis of the test is that Barber’s Pole worms are blood-sucking internal parasites. As they feed on the abomasum some blood passes through the digestive tract.
The test detects haemoglobin (a product of blood breakdown) and changes colour according to the amount of blood in the sample

28. Dipstick Stick cont…. Major benefits include:
Results are available within 30 minutes on farm
Burdens are detected before egg production begins
The test is easily accessible and able to be kept on hand
The test is reliable, accurate and inexpensive

29. Dipstick Stick cont…
In warmer months the dipstick test can be used weekly to predict risks
Training days for users will be conducted in coming months
At present the test is only been evaluated for sheep
Interested graziers should contact their local Merial or Ancare Territory Manager or their local reseller for further information

30. Egg Count Result Interpretation
It is very difficult to give hard and fast rules on interpreting egg counts
There are so many variables to consider including:
age of the animals
physiological status
host species
nutritional status
forecasting
management factors
the worm mix

31. Age of the animal
Adult dry animals in good condition tolerate worms much better than young or poor animals.
In the case of extensively grazed cattle, adults often require little or no drenching - except where liver fluke is a problem.
Young animals, up to two years of age, are likely to need more frequent drenching

32. Physiological status
Late pregnancy or lactating animals have a temporary relaxation of immunity
it may be appropriate to consider drenching at lower egg counts than otherwise.

33. Host species
Host immunity will have a bearing on the interpretation of egg counts.
Well-grown cattle and sheep over two years of age develop some immunity to worms.
The immunity in cattle tends to be stronger than in sheep.
Goats do not appear to develop a great deal of immunity, even when they reach adulthood.

34. Nutritional status
Well-nourished animals quickly develop a strong immunity to worms
withstand a worm challenge better than poorer animals
moving animals onto a better pasture, or hand feeding can, in some cases, have the same effect as drenching

35. Forecasting
A decision to drench or not, based on a certain egg count, may be influenced by how wormy pastures are likely to get in the coming weeks and months.
plans for a move to cleaner, better pasture will impact on the decision to drench.

36. The worm mix
if barber’s pole worm is a common problem, egg counts are likely to be higher.
of the three major sheep worms, barber’s pole worm has the highest egg output (around 10,000 eggs/day), followed by black scour worm ( eggs/day) and then small brown stomach worm (50-100/day).

37. Guide to worm egg counts in sheep
The department has a Primefact that gives guidelines for result interpretation.
As a rough guide:
0-200 epg –low
epg – moderate
– high
Remember to
Check egg counts in 4-6 weeks after significant rain, or before a ‘management event’ e.g. summer drench, pre-lambing, prior to yarding, or when there are signs consistent with parasitism.
animals can get a heavy worm burden quickly before egg counts rise.

38. Control Options for Internal Parasites
When designing control program need to take into account
Available land
Range of animals involved
Limiting restraints eg pasture
Environmental conditions

39. Control Options for Internal Parasites
The 4 main components are:
Strategic drench management
Grazing management
Nutrition of the animal
Breeding for worm resistant animals (in sheep)

40. Strategic Drench Management
Drenches divided into classes based on main active component
There are broad and narrow spectrum drenches
Need to rotate between classes to minimise development of resistance

41. Strategic Drench Management cont…
Broad spectrum
Effective against wide range of parasite species & include:
Benzimidazole (BZ) or ‘white’
Levamisole (LEV) or “Clear”
Macrocyclic lactone (ML) includes the avermectin (ivermectin/abamectin) and milbemycin (moxidectin) sub-groups.
Naphthalophos (NAP) or OP (organophosphate), often used in combination with white and clear drenches
Narrow spectrum
Only effective against one or two parasite species
Closantel which has sustained activity against susceptible barber’s pole worm, and strains of liver fluke.
Triclabendazole which is highly effective against mature and immature stages of susceptible strains of liver fluke.

42. Strategic Drench Management cont…
Multi-combination drenches
Recent developments with 3 (eg TritonTM ) or 4 (Q-Drench TM) components.
May be used where resistant worms are known to be present.
New Drench on the Block
Zolvix is a short acting broad spectrum drench
Developed by Novartis
Belongs to a new drench group AADs (amino-acetonitrile derivatives)
First new drench family since 1988
Not yet available in Australia – may a few years before released here

43. Strategic Drench Management cont…
Get the most out of each drench by:
Choose the correct drench for the job
Get the dose right (to heaviest in mob)
Calibrate drenching equipment
Deliver the dose correctly
Fasting before drenching (do not do this with clear or rametin based drenches)

44. Strategic Drench Management cont…
Effective drench kills 95% or more of worms.
Important to know your drench resistance status
Can check by
Quick Drench Check
Drench Test

45. Strategic Drench Management cont…
Drench Resistance in Sheep in NSW
Drench
Prevalence of resistance (<95% drench efficacy)
Benzimidazole (BZ)
Approx. 90% of properties
Levamisole (LEV)
Combination (BZ/LEV)
Approx 60-80% of properties
Macrocyclic lactones (MLs, ‘mectins)
Up to 80% of properties
Closantel
Resistance in Haemonchus is common in northern NSW and QLD. Small number of resistant liver fluke in Australia.
Triclabendazole
Small number of resistant liver fluke in Australia.
Naphthalophos (Rametin®, Combat®)
One recorded case in Australia

46. Strategic Drench Management cont…
Sheep
Strategic worm programs designed for sheep producers in NSW
DrenchPlan
WormKill
WestWorm
FarWestWorm
aim to reduce the number of drenches and worm larvae on the paddocks and to minimise production loss.
Wormboss program
Australian Wool Innovation and the Sheep CRC
has information on all aspects of sheep internal parasites
has an interactive component “Ask the boss” to provide interactive advice.

47. Grazing Management Prepare “low worm-risk” paddocks
have relatively lower levels of infective larvae than other paddocks.
use for most vulnerable animals i.e. weaners, pregnant/birthing animals.
achieved by grazing with another animal species
most worms are host specific - ingestion by the non-preferred host results in the death of the larvae.
Exception is barber's pole worm and stomach hair worm (T axei) which can infect both sheep and young cattle. Therefore, the use of adult cattle for cross grazing is preferred.

48. Grazing Management cont…
The length of time needed to graze paddock to help clean off infective larvae will vary from region to region and also depend on seasonal conditions.
If running one type of animal - use older dry animals to graze the paddock (higher immunity).
If the sheep are treated with a fully effective short acting drench, they can be used to "clean" paddocks for weaners (smart grazing) for the day period without fear of recontamination of the paddock.

49. Grazing Management cont…
Spelling a paddock
may be viable in some situations.
the length of time needed will vary depending on
seasonal condition
length of pasture
type of worms present.
short-term spelling is of little use for worm control
studies have shown that spelling for more than 10 weeks in autumn/winter is needed to have a useful reduction in worm larvae numbers.

50. Grazing Management cont…
Cropped paddocks
summer crops, such as lucerne, provide high nutrition to help the animal fight off worm infections.
very good for young and susceptible stock
help to break the worm cycle as generally have very low worm larvae contamination levels.
But these paddocks can help to select for worm resistance.
If the animals are drenched when going onto the paddock, the only worms left in the animals will be those resistant to the drench used. If animals left on paddock for more than 30 days any eggs/larvae deposited on the paddock will be a resistant strain.
It is important to keep this in mind when making future management decisions involving the paddock.

51. Grazing Management cont…
Other strategies include:
harrowing to break up the manure
slashing when spelling pasture to expose larvae to sunlight
removing manure on a regular basis (useful in small paddocks)
putting animals in to graze when pasture length is longer (larvae usually only travel up the first 10 cm of the grass blade).

52. Nutrition
has an enormous impact on the immunity and ability to handle worms.
a well-nourished animal will have better immunity than a poorly nourished one.
strategic implementation has positive effect on immunity and worm control (particularly with protein supplements).
supplementary feeding of certain minerals may increase the resistance of animals to worms.
if using supplements remember to check toxicity levels of mixtures being used
also monitor with regular worm egg counts to ensure that worm levels are under control

53. Nutrition Research
Department of Agriculture & Food WA – Dr Brown Besier
When sheep fall below condition/fat score 2, live weights and wool production will suffer when they become infected with worms
At condition score 3, the bulk of sheep will handle parasites very well
At condition score 4, only a small percentage of sheep will suffer any production losses from a parasite infection
Once young sheep and pregnant ewes were on a rising plane of nutrition, the animals become far more resilient to worms
They are able to maintain relatively unchanged growth rates, wool growth and milk production despite having a worm infection

54. Nutrition Research continued..
South Australia Research & Development Institute
3 year study showed weaners that were supplementary fed in early summer to boost their nutritional level could have up to 50% lower faecal worm egg counts than unfed weaners
The high nutrition weaners produced 2-4kg more live weight & up to 250g more wool per head than unfed groups
This was estimated to be worth around $6/hd
Also found improving the condition score of ewes in late pregnancy can halve faecal egg counts which was important to reduce worm burdens for new born lambs and help reduce the worm drench resistance cycle.

55. Other interesting facts
Research in the New England region found that as a rule of thumb after a month of daily temperatures of 30oC or more, about half of the larvae in the paddock will die
If daily temperatures are around 15oC, it would take 2 months to kill the same number of larvae
Studies show that grazing paddocks with cattle six months prior to sheep grazing can reduce numbers of barber’s pole and black scour worms by as much as 98%, increase sheep annual weight gain by as much as 7kg, and lift greasy wool weight by around 0.7kg/head

56. Breeding Worm Resistant Sheep
Nemesis Program (CSIRO)
found that resistance against the effects of worms in sheep is a heritable trait
Animals that are resistant to worms have the ability to:
reduce the worm population by preventing development of infective larvae into adult worms
accelerate rejection of adult worms from the animal
reduce the egg-laying ability of female worms.
it can take up to 10 years of using resistant rams to have an overall effect on flock immunity.
A recent concept of developing resilience, i.e. the ability of an animal to be productive despite a sometimes heavy worm burden, is now being advocated by some parasite researchers