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

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

Worm counts in sheep across NSW are highly variable, probably reflecting the variability of seasonal conditions, even within districts.

On top of this is the issue of anthelmintic resistance. Possibly 5% of sheep producers across Australia, on average, do regular (more than once or twice a year!) worm egg counting (WEC), including periodic checking of drench efficacy: a WEC on the day of drenching and 14 days later (DrenchCheck). WormBoss of course gives good guidance on all this. Start by checking out 'Your Program' (Ed: see links at the top of this page) at WormBoss.

What is the one thing that sheep and goat producers could do that would most improve their worm control?  I have thought about this over the decades: I reckon regular WECs, e.g., every 4–6 weeks when conditions are good for worms, and out to say 6–8 weeks when things are not so good (sustained cold and/or dry). And, in the Rangelands, a WEC several weeks after good rain(s) producing a green pick.

'What about everything else?' you might say. Grazing management, genetics, nutrition etc!? All important—of course!—but, if I had to pick one thing I would still say WECing!  Once you start regular WECing, this will lead on to everything else. Think about it. (Of course, bedtime reading of WormBoss or other good, digestible information on worms is important as well).

So, we are now in autumn and careering towards early winter. This brings to mind two things: liver fluke, and weaning of calves.

Weaning calves? In many areas, calves are being weaned around now or a bit later. In say the eastern third of NSW, weaners will probably require a weaning drench, for roundworms at least, and maybe liver fluke as well (if on a flukey farm).

What broad-spectrum drench should you use? One of the ones that works on your place. The reality is that most people will be making a more or less educated guess on this. Remember that resistance of worms to drenches is now common in cattle. It's not just a sheep and goat thing.

If you don't know for sure, your best bet will be a combination of unrelated broad-spectrum actives. Even if you do know what works on your place, such a combination is arguably a good idea (if it works!), given that current resistance theory says it is probably a good idea. Whatever you do, consider doing a DrenchCheck: a WEC at day zero and day 14. What will it cost you in time and money? How valuable will the information be? I think it is a very good investment.

The problem with worms and drench resistance is invisibility. If you don't measure it, you can't manage it (as Arthur Le Feuvre would sagely say).

Now to liver fluke. For various reasons, the late autumn–early winter (April/May) fluke drench is considered the most important strategic treatment on 'flukey' farms. And this is the time you should use the most effective fluke drenches, i.e., not just the ones that kill late immature and adult fluke. For sheep, goats and cattle, this means a triclabendazole (TZ)-based drench. An added option in cattle is two injectable products based on the unrelated flukicides, nitroxynil and clorsulon. As always, check labels regarding withholding periods and so on.

Resistance to flukicides? Well, some of the first cases of flukicide resistance were found in Australia. (A dubious honour). The first case in the world of resistance to TZ, a very important drench that has been used since the 1980s, was found in Victoria in 1995, by Overend and friends. Boray and others found resistance to other flukicides in Australia back in the 1980s, but as late as the 1990s experts were saying resistance to fluke drenches wasn't yet a major problem. About 15 years ago, Dr Joan Lloyd (then with NSW DPI) and I, together with NSW District Veterinarians (with assistance from Novartis), embarked on a 'reconnaissance survey', aiming to check for resistance to TZ and closantel on 20 sheep farms across the state. We only got results on 8 properties. On one of these, we found TZ-resistance.

It's all changed since then. Various experts across the world are saying flukicide resistance is becoming a common and important problem. Nearer to home field and published reports of resistance seem to be more common as well.

What to do? The first thing is to check the efficacy of fluke drenches when you use them. Do a fluke WEC (different from the WEC for roundworms) on the day of treatment (day zero) and again 21 days later. (Not 14 days, as that is too early for fluke). An alternative test is the 'new' test, the 'faecal fluke antigen ELISA' (also called the 'coproantigen test'), currently available at the CSU Wagga and NSW DPI veterinary laboratories. Check with your advisor or the labs regarding availability and cost.


Central West LLS

Coonabarabran: Alix Ferguson, DV (

Our region has been devastated by the recent Sir Ivan Fire in which some producers lost sheep and goats. On a positive note, we have experienced some showers and storms recently and the new green growth is starting to poke its head out of the burnt ground. Worm Egg Counts (WEC) in the area have ranged from 128 to 3280 eggs per gram (epg), barber’s pole has been the predominant worm on cultures performed. One producer had losses and clinical signs resulting from a Haemonchus burden in just one particular mob. This highlights the need to do worm tests with a culture at 60 and 90 days after a long-acting treatment. Primer and exit drenches can be utilised in this situation to slow drench resistance.

Coonamble: Jillian Kelly, DV (

Very few worm tests from the Coonamble area have been submitted to EMAI, so I have seen very few results since Christmas. I expect that the long duration of extremely hot weather that we experienced in February cleaned larvae from pasture nicely. There have been no clinical cases of worms, and a small number of in-house faecal flotations have revealed few eggs. In recent days, the district has experienced 65 mm of rain. Producers are encouraged to WormTest ewes in the lead up to lambing and drench if necessary.

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

Conditions have been so dry and hot over the last few months in the Forbes area that it is unlikely many eggs/larvae would be surviving in the paddocks. The only worms surviving are those residing in the sheep. It is therefore particularly important that producers giving a second summer drench or a prelambing drench (if a WormTest indicates it is needed) ensure they use an effective multi-combination drench to minimise the chance of selecting resistant worms to individual drench groups.


Riverina LLS

Young: Elizabeth Braddon, DV ( and Rahul Shankar, DV (

On the worm front, counts received to date have shown egg counts averages of 0–200 eggs per gram (epg). Production losses that have been reported have declined for the past few weeks, but cases that have been investigated, have been skewed towards weaner lambs that were under-nourished and, as such, were immunologically challenged.  

We have just experienced nearly an inch (250 mm) of rain in the last 2 days, with more rain expected over the coming days. Temperatures are hovering in the low 20s (°C) and humidity is between 40–75%—still a good environment for flies

Crutching/shearing of animals and appropriate implementation of flystrike preventative chemical should be applied to any animals that may be susceptible to fly strike. 

With the recent rain activity and lower temperatures, regular worm egg counts should be conducted on any mobs you suspect are carrying worm burdens. Particular attention should be paid towards weaner lambs and pregnant ewes (especially during the last 6 weeks prior to the start of lambing). 

The 'Bulla Creek-Thuddungra' Lice group here in Young met for an update on how the group was progressing. Producers were reminded of the dos and don’ts of lice, biosecurity and general management strategies to keep lice off their property. The 'Bulla Creek-Thuddungra' lice group is a producer-driven initiative, made up of 50 producers.  The initiative has seen producers communicate more with one another on boundary fences, stray sheep, organising dipping contractors etc., and has seen over a 60% participation rate by producers in the group (either by chemically treating all their stock, receiving timely advice on how to manage lice infestations or by having their stock inspected regularly should they suspect lice). More about the group and its progress shall be mentioned in a not too distant feature article. 

On a side note, the last month has been comprised primarily of feet, feet and more feet! Throughout the district (and parts of the state) District Vets and animal health staff have been investigating cases of lameness, undertaking tracings and diagnosing virulent footrot in some mobs of sheep.

Virulent footrot is a notifiable disease in NSW and any producer or contractor that suspects footrot in sheep is obligated to contact Local Land Services immediately. 

More information of footrot can be found here:


Northern Tablelands LLS

Inverell: Andrew Biddle, DV (

There have been reports of severely affected mobs with significant mortalities in the past week. Recent rainfall events right across the Northern Tablelands have raised the barber’s pole worm threat.

Continued monitoring in the autumn will be needed to avoid significant production loss and mortalities. 


North West LLS

Northern Slopes: Ted Irwin, DV (

I saw a case this morning near Bingara; death was due to haemonchosis. Some good storm rain is around and the mild conditions should mean barber’s pole worm will be on the rise. However, overall sheep numbers are down in the slopes region so I don’t expect too many issues. Management is the main issue with small landholders set-stocking a handful of sheep on backyard-style paddocks. Larger farms may run into trouble with overstocking ewe and lamb mobs on paddocks that have not been spelled for long enough. We will see in the coming weeks though.

Moree: Justine McNally, DV (

Not as many worm tests were done in the past month, but those that were are still a mixed bag.   Black scour worm is still lurking about in areas. Barber’s pole worm is on the increase and I am sure there will be more about as the conditions have improved and we now have green pick under a lot of dry feed and moist cooler conditions. The two larval culture percentages for March were 97 and 100% barber’s pole worm, but when the conditions were drier in February the count was only 19% and the significant parasite was Ostertagia, now called Teladorsagia.

Date Tested



Drench Date

Mean (epg)

Range (epg)

Black Scour %

Brown Stomach


Barber’s pole



ewes and weaners

Rametin + Duocare








weaner ewes










Avomec Dual








weaner ewes









5-6 year ewes









mixed aged ewes

Q drench








2 year ewes

Q drench








wether lambs









5-6year ewes









7 month lambs

Ivomec dual








The past couple of weeks have been humid so I expect barber’s pole will be on the rise and producers will need to be watchful, especially in the younger sheep. From the few results the younger sheep are being hit more with worm numbers.  I think the take home message I have learnt over the past few months is "assume nothing"—it is imperative worm tests and cultures are done as no one result ever seems to quite fit the pattern and we have had black scour worm creeping about all summer, and barber’s pole numbers up and down, but not as significant as I thought they would be. 

To reiterate, a WormTest and culture is a must before instigating any management practice.

Narrabri / Walgett: Megan Davies, DV ( and Judy Ellem, DV (

There has been huge variability in worm test results across the north west this summer, and a large amount of testing, with over 100 results coming our way since Christmas. 

To the east towards the Northern Tablelands, and north towards the Queensland border, Haemonchus is the dominant species, making up 98% or more of counts in most cases. Relatively high counts have been seen, with 1000–6000 eggs per gram (epg) in many cases. 

To the west around Burren Junction, Walgett, Come-by-chance and Carinda, the counts and species have been more variable. In cultured samples, black scour worm (Trichostrongylus) made up between 1­–60% of worms, followed by Haemonchus ranging between 20–50%. Brown stomach worm (Ostertagia now called Teladorsagia) was also seen, ranging between 11–70%, and multiple properties also had large bowel worm (Oesophagostomum) making up between 3–12%. Some properties have tested multiple mobs and found significant variation in both numbers and species between mobs. 

South towards Boggabri and Tamworth, fewer samples were received, and those that were cultured were predominantly Haemonchus

With warm conditions continuing and a large amount of rainfall across many areas of the north west, producers will need to continue to monitor worm numbers over the coming months. Also, the variability in culture results shows the importance of getting cultures done in addition to worm egg counts—make sure you are using drenches that are effective against the species present in your stock. Also, test mobs separately, particularly on larger properties, as the results can vary substantially, affecting your management decisions. 


Murray LLS

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

Deniliquin: Linda Searle, DV (

While we didn’t have any clinical cases of worms that we were called in to investigate, we did have some WormTest results come in.

  • Around Wakool there was 1276 eggs per gram (epg) strongyle and 36 epg Nematodirus worm egg count in ram lambs that were last drenched in September 2016.
  • Around Deniliquin we had 16 epg strongyle and 28 epg Nematodirus worm egg count in ewes drenched in February.
  • Over at Jerilderie a 316 epg strongyle and 20 epg Nematodirus was identified on one farm (with a culture of 46% barber’s pole worm, 20% black scour worm, 33% brown stomach worm and 1% large intestinal worm) and on another, a 72 epg strongyle and 0 Nematodirus in ewes that had been drenched with a macrocyclic lactone in January 2016.
  • Over at Holbrook we saw a large difference in species in different samples having:

Barber’s pole worm

Black scour worm

Brown stomach worm

















  • As well, there was one farmer who had drenched on 3/2/17 and had scouring sheep but no worms.


South East LLS

Goulburn: Bill Johnson, DV (

Recent rainfall across the district can best be described as patchy. Most properties west of the Divide have received very little in the way of useful rain, while some areas to the east already have a fantastic start to autumn. Worms have tended to follow the pattern: some weaner mobs to the west are affected by malnutrition, Ostertagia (now called Teladorsagia) and Nematodirus, while some adult and weaner mobs to the east are affected by Haemonchus. With so much variation, monitoring with worm egg counts and culture for worm type would seem like the way to go. But beware a couple of issues.

One mob of weaners being supplemented with barley on a fresh green pick were not doing as well as they should; some were scouring, many were weak, and a few had died. The problem started about two weeks after rain. An autopsy showed a high burden of Nematodirus (thin-necked intestinal worms), many of which were immature and would not yet be laying eggs. A worm egg count may not identify this problem. Nematodirus are often first off the blocks when rain ends a dry spell, and as in this case, they can knock weaners about within a fortnight or so of rain.

A second mob of weaners had a moderate egg count (average 480 eggs per gram), which was no great cause for concern, despite a history of Haemonchus on this property. But worm egg counts only indicate the adult worm burden in the sheep almost three weeks previously. In this case, recent substantial rainfall had transformed the paddocks, now lush with green pasture. Worm eggs also hatched under the same conditions. An autopsy from this mob showed a mass of immature Haemonchus had been picked up since the rain. Finding this level of immature worms was a reminder of the need to do more frequent monitoring when seasonal conditions change rapidly.

With Haemonchus now showing up on at least half of the properties in this district, many producers rely on long-acting drenches to help with control. Resistance has reportedly rendered these products useless against Haemonchus on many properties in summer rainfall areas of NSW. Some producers in our area are now seeing the protection period offered by these long-acting drenches reduced against Haemonchus. No longer can we assume we'll get the 21, 28 or 90 or more days protection from re-infection it says on the label. It's essential to check the efficiency of the drench on your property with one or more worm egg counts during this nominal protection period.

There is always a temptation when green feed grows after a dry spell to move sheep, particularly weaners, from paddock to paddock, to give them as much of it as possible. Remember though that many of the worm crashes we've seen in lambing ewes over the years have occurred because weaners have grazed in autumn, those paddocks which we later use for lambing. It may seem a long way off, but before you shift those weaners around now, spare a thought for where you intend to lamb your ewes.


Western LLS

Bourke: Charlotte Cavanagh, DV (

Several worm tests were submitted by producers over February/March from Brewarrina in the north to the Hay region in the south.

Results have been varied with some averages as high as 2560 eggs per gram (epg). The cultures have also been of varied composition with from 1 to 88% Haemonchus recorded.

Most producers have carried out these tests as sheep, particularly weaners, have been reported as "not doing as well as expected". Drenches used were generally the macrocyclic lactones (MLs), this choice made because that is what is stocked locally. One producer used a short-acting levamisole drench and carried out a post drench check as advised, with a resulting reduction from 1156 epg to 140 epg.

Where counts have been significant there was generally a history of holding sheep in a paddock for several months and some storm activity, as the mainly very hot and dry conditions we have been experiencing would not favour larval survival.

The weather is cooling down, some sheep are down in condition due to declining feed quality so producers are advised to monitor their susceptible sheep groups closely, particularly if recent storm activity continues.

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