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New South Wales worms, flies and lice update - August 2017

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Armidale: Stephen Love, Veterinarian/Research Officer (Parasitology) (

WormFax is now up on the NSW DPI website:  WormFax is a monthly summary of sheep worm egg counts for NSW from the DPI (Menangle) and Invetus (Armidale) laboratories. Many thanks to both these laboratories.

Worm egg counts (WormTests) have generally trended down as winter has progressed, but still there were some WormTests with average egg counts up to 2000 eggs per gram (epg) or so. (And, as a rule of thumb, there will be individual sheep in every mob with counts up to 2–4 times the mean worm egg count for the WormTest).

You can never take your eye off the ball: you have to keep getting the basics right. Two of these are regular worm egg counts, and checking that the drenches you use are effective. An all-encompassing 'basic': read and follow Your Program



Central West LLS

Coonabarabran: Alix Ferguson, DV (

The worm tests submitted across our area have indicated generally a low burden, and some properties reported counts of 0 eggs per gram (epg) i.e. no worm eggs seen. Nutrition has tightened up for most people leading into lambing, and some producers are supplementary feeding. Lambing combined with sub-optimal nutrition could cause ewes to have a decreased immunity to worms. A worm test to assess the worm burden prior to lambing is advised in our area, and also a drench check to identify a suitable pre-lambing drench if required. 

Coonamble: Jillian Kelly, DV (

The dry weather has continued and worm burdens have remained low as a result. Many crops have not survived and almost everyone is supplementary feeding.  Our spring and summer feed outlook appears grim unless it rains significantly.   A recently conducted faecal worm egg count reduction trial (Drench Test) showed barber’s pole worm resistance to moxidectin and abamectin, which is the type of resistance often seen on farms in our district. This is a good reminder that this type of trial provides really useful information and should be done on every farm, at least every 3 years. 

If you are about to wean lambs and they have a faecal worm egg count that is worthy of a trial i.e. meets the required minimum levels for a DrenchTest, then farmers should take the opportunity to do so. Speak to your local district veterinarian for more information. 

(Editor’s note: a mob WormTest result of 200 epg each for black scour worm and brown stomach worm, and 500 epg for barber's pole worm are considered the minimum levels required before conducting a DrenchTest.)

Dubbo: Evelyn Walker, DV (

Forbes: Nik Cronin, DV ( and Belinda Edmonstone, DV (

In the Forbes area, although the season has been better than in the north, we have seen very little worm activity. There was one case of scour worm in weaner lambs about 1 month after drenching as these lambs were put back out onto the same paddock and were reinfected. This is a reminder that you need to prepare 'low worm-risk' paddocks for susceptible stock such as weaners.


Riverina LLS

Wagga Wagga: Timothy Biffin, DV ( and Lauren Kelly (CSU veterinary student) and Emily Stearman, DV (

Isn’t it nice to finally see some decent moisture falling from the sky! Unfortunately, green pasture and full dams aren’t the only things that arrive in full force with warmer, wetter weather. Gastrointestinal worm burdens will start to become more significant going into spring, so it’s time to start thinking about your on-farm management. Whether you’re going to use chemical or pasture management methods, ideally both, a good starting point is to conduct a worm egg count of mobs on farm, and lamb marking is the perfect time to collect samples from the ewes. Black scour and brown stomach worm are of biggest concern currently, so keep on the lookout for poor-doing young stock with scours. It is important to note that even without clinical signs, worm burdens can cause large production losses. As a rule of thumb, if you are starting to see clinically affected animals you have left things far too late. NSW farmers may contact their local district veterinarian if help is needed in developing a worm control program or for other general worm problems. 


Murray LLS

Albury: Scott Ison, DV ( and Mark Corrigan, DV ( and

Deniliquin: Linda Searle, DV (

Since our last report we have seen the season turn from dry winter to wet underfoot in many places in our region.

The eastern part of the region has seen a few worm egg counts with larval differentiations showing that barber’s pole worm is still the most prevalent type of worm in the area.

WormTest results are as follows:

Eastern Region

Class of sheep / drench history

WormTest result eggs per gram (epg)

Strongyle type

Nematodirus type

Pregnant maiden merino ewes



Mature wethers



Pregnant stud ewes (2–7 years)



Pregnant ewes (3–6 years)



Wether lambs (scouring)



Lambing ewes

abamectin/ albendazole/ closantel/levamisole  

(January 2017)


84% barber’s pole

4% black Scour

12% brown scour


Ewe weaners                        

abamectin (November 2016)



Pregnant poll Dorsets




And there was a larval differentiation which was 100% barber’s pole worm.

As per usual in the West our most common worm is the black scour worm.

We had the following results in sheep:

Western Region

Class of sheep / drench history

WormTest result eggs per gram (epg)

Strongyle type

Nematodirus type

Poor doing males/ moxidectin (May 2017)



Merino ewes/ cross bred lambs at foot


66% black scour 

29% brown stomach

5% large intestinal


Ewes (5 years) cross bred lambs at foot






Ewes ( 5 years)




We also had the results from one mob of goats. The goats were feral, but had been taken to a property to grow to an acceptable size prior to sending to the abattoir. There had been a large number of deaths in the group with some known to be scouring and in poor condition. A WEC revealed 2608 epg strongyle type eggs and 48 epg Nematodirus type eggs. There was also varying amounts of coccidia present with most having low numbers, but one of the samples which was towards the lower end of the scale WEC-wise was found to have a large number of coccidia present. 

South East LLS

Goulburn: Bill Johnson, DV (

Rainfall across the district is still well below par for this time of year, which is, so far, having a beneficial effect on worm populations in sheep. The majority of mobs tested for worms in recent weeks have not needed drenching, and there are fewer scouring weaner mobs to be seen when driving around. But just because worms are having limited effects at present, it doesn't mean you should ignore them. Barber's pole worms account for the highest percentage of worm eggs on many properties. While it is still too cold for barber's pole eggs to hatch, warmer spring temperatures and rain will soon re-start the process. It would pay to do a worm test and worm type before then, to possibly give yourself a bit of advance warning.

Treating for liver fluke is recommended now, before fluke snails warm up and get going. Check on the need for a fluke drench with dung or blood tests, targeting mobs that grazed paddocks with swampy areas or creeks in the autumn.

The majority of sheep in this area will be shorn over the next four months, which means many producers are now seeing the effects of lice in their long-woolled sheep. We get frequent requests to recommend "the best" lice treatment, and most people leave annoyed when we ask more questions before we give answers. The reality is that even the best and most expensive lice product will not work unless it is applied correctly. Simple as it sounds, the most common reason for failure of lice eradication programs is failure to treat all sheep, properly. It is easy to make excuses. Maybe a few ewes lambed before the treatment had time to work, or there were lambs at foot a couple of weeks older than can be treated without shearing, or stragglers turn up that were missed at shearing muster. Too often, decisions about lice control are made in haste, without considering all the possible complications. Neighbours usually cop the blame when lice are found. But if most sheep in a mob now have lice and you treated that same mob at shearing last year, it's a fair bet that what you did last time didn't work. You only have one opportunity a year to eradicate lice, so it is worth spending a bit of time planning your attack. LiceBoss has a stack of useful information, and your district vet can help you pull it all together.

Braidwood: Kate Sawford, DV (

Only a few WormTest results have been received over the past few weeks. On those properties that do regular WormTests the worm typing results have revealed a higher percentage of Trichostrongylus (black scour worm) compared to previous tests. This result was expected as black scour worm eggs can hatch at temperatures greater than 10°C compared to barber’s pole worm whose eggs require temperatures above 18°C to hatch. Knowing the primary worm species you’re dealing with helps you to decide if you need to drench and the combination of actives required, so don’t forget to ask for a worm type (larval differentiation or culture) at most times of the year.

There have been two confirmed reports of resistance to long-acting drenches in the district over the past three months. While the long-acting drench may not have caused this resistance (it may have come about by historic use of its short-acting counterpart), these cases serve as a reminder that you can assume nothing when it comes to worm control.

In the first instance the producer had given the long-acting combination drench to a mob of ten-month-old lambs. Around fifty days later lambs started dying and the producer decided it was time for a WormTest. The WormTest showed individual worm egg counts (WEC) ranging from zero to 21000 eggs per gram (epg) with an average WEC of around 5000 epg. In the second instance the producer gave a long acting containing a single active to two separate mobs of ewes that had been formed following scanning and dividing the previously larger mob into single- and twin-bearing ewes. The producer decided to do a DrenchCheck around two weeks after giving the long acting and found that both mobs still had WECs and the drench had been less than 90% effective in each of the two mobs.

The currently available long-acting treatments contain a macrocyclic lactone (an “ML”), a benzimidazole (a “white drench), or a combination of the two. Effective long-acting products can work very well in cases of high larval challenge or during high risk periods (e.g. lambing ewes). However, they select for resistant worms because of those larvae that are ingested while the drench persists and only those susceptible to the drench will die, leaving the resistant larvae to develop into adults and lay eggs, contaminating the pasture with even more eggs and larvae from drench-resistant worms for a prolonged period. Yikes!

If you are going to use long-acting drenches follow best practice guidelines – always use primer and exit drenches with any long-acting drench, and an exit drench at a minimum for any mid-length drenches. Also, it is vital to check that the long-acting is still working as recommended under ‘Effective use of long-acting drenches’ on the WormBoss website.

  • Where your DrenchTest results indicate that the active/s are effective on your property (i.e. reduced worm egg count by at least 98%) then conduct a WormTest at 30, 60 and 90 days after treatment.
  • If you do not have current DrenchTest results you should do a WormTest at 14, 30, 60 and 90 days after treatment.
    In both cases, if it is shown to be ineffective at one of the earlier tests, then the later test/s will be of no value.)

By using these techniques, some properties have used long-acting drenches strategically for many years with continuing good results.

It pays to limit the use of mid-length or long-acting products to specific purposes (e.g. cleaning up contaminated paddocks) or high worm-risk times of year (e.g. pre-lambing and into lambing or when conditions are warm and wet leading eggs to hatch and larvae to develop). Better yet, use short-acting treatments and WormTests to determine the need for further drenching in combination with management tools to reduce paddock contamination with worm eggs and larvae. Long-acting drenches can cost up to ten times as much as a short-acting drench. But remember, the most expensive drench is the one that doesn’t work and further promotes drench resistance on your property.


Western LLS

Bourke: Charlotte Cavanagh, DV ( and

Broken Hill: Sophie Hemley, DV (

Yes, it’s too dry for worms!

There were only two worm tests submitted during August. One was for cattle and the other was for sheep with average worm egg counts (strongyle type) of 10 eggs per gram (epg) and 20 epg respectively. 

Conditions are very dry across the entire western region and some stock are down in condition and many producers are supplementary feeding. Although with the weather warming up (32°C degrees yesterday), intestinal parasites may become an issue if we get some much needed rain.

For August 2017 state outlooks, please follow the links below:
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