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New South Wales worms, flies and lice update - May 2016

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides

Armidale: Rad Nielsen, Veterinary Health Research (

The north of the state continues to remain very dry. Worm development will have ceased over the majority of the New England region since the last meaningful rainfall event in early April. Worm monitoring activity too has slowed over this period, combined with a trend towards somewhat lower mean worm egg counts (WECs). Nonetheless, high worm burdens in individual mobs continue to be identified (and often within 4–6 weeks of last drench). This apparent high rate of re-infection simply reflects the significant degree of pasture contamination (which largely took place over summer), to which they have been exposed.

One property in the Walcha district recorded some exceptionally good WEC results in the past week, demonstrating that thoughtful grazing management can have a huge effect on worm burdens in sheep. Merino weaners drenched with a short-acting broad-spectrum anthelmintic on 1st February had a mean WEC of 104 epg in mid-May; ewe mobs also treated in the same week had mean WECs of 56 and 324 epg. The key to this result was the adoption of large mob size rotational grazing over this period.



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

You just weaned and drenched young cattle—did the drench work?

About this time of the year many cattle are being weaned in south-east Australia, including NSW. This will include weaners getting a drench, certainly in higher rainfall areas, for example, the eastern third of NSW. This drench will likely be a broad-spectrum drench, and in some cases, a fluke drench as well.

In many, perhaps most, cases the broad-spectrum drench will not be highly effective. And, more often than not, the producer will be unaware of this. How can I say this? Well, recent surveys have shown that resistance of cattle worms to drenches is quite common in Australia. Furthermore, relatively few cattle producers have checked the efficacy of the drenches they use.

"Isn't drench resistance mainly a problem for sheep producers?"

In one recent survey of around 30 cattle properties, most of them in NSW and Victoria, at least two-thirds of the farms tested had resistance to at least one of the macrocyclic lactone ('mectin', ML) actives in cattle drenches on the market in Australia. But, it's not just about the mectins.  All the important cattle worms (OstertagiaCooperiaHaemonchus) have developed resistance and all the broad-spectrum drench groups on the market are affected to a greater or lesser degree. It varies farm by farm.

For more information, see here:

If you are a cattle producer:

1. Assume you have resistance to at least one of the broad-spectrum drench groups.

2. Assume it is economically important.

3. Find out what drenches work on your property.

'DrenchCheck' is an easy way to begin. This means doing a worm egg count on or just before drenching a mob or group of cattle. Re-test the cattle 14 days later (as opposed to 10–14 days in sheep). Ideally, get a worm-type (larval culture) done as well as an egg count. If checking efficacy of fluke drenches, do a fluke egg count on the day of drenching and again 21–28 days later.

The ultimate is to do a drench resistance test (DrenchTest; worm egg count reduction test) on a number of different drench actives in one go. Check the information on WormBoss on DrenchTests - the general principles apply to cattle also, and get good advice. Continue doing DrenchChecks from time to time, so you build up a picture of your property's resistance profile, and how it changes over time. That way you are 'keeping ahead of the game'. If you don't measure it, you can't manage it."



Central West LLS

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

We have seen only a few WormTest results over the previous months. The recent widespread rain with follow-up rain, has changed the landscape from grey to green. Temperatures have remained mild. Although not a lot of larvae would have survived in the paddocks over the last few months due to the previous dry conditions, any worms (including barber’s pole) surviving in sheep will be depositing eggs on pasture and contributing to worm burdens carried by sheep grazing those pastures.

Producers therefore need to be thinking about:

Coonamble: Jillian Kelly, DV (

The Coonamble area has experienced wide spread decent rainfalls over the past two weeks. This is the first substantial fall of rain that was followed up by another consecutive fall in recent years for some producers. Very few worm tests have been sent in by producers in this area, but the limited data we have suggests that worm burdens are low. The recent rain has coincided with a drop in temperatures, which should suppress barbers pole activity.

Looking forward to another cracking bloat season now!!

Riverina LLS

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

Worm counts received by our office have identified moderate burdens amongst the mobs tested.

  • Nematodirus is still showing average counts of between 100–150 epg in weaned lamb mobs tested. 
  • Lambing ewe mobs have shown counts of between 60 epg to 580 epg.

One producer in the area experienced losses from barber's pole worm due to a lapse in his drenching regimen. Prompt drenching with an appropriate product immediately quelled the losses. 

Producers are reminded that the recent rain activity coupled with warm daytime temperatures (above average for the month of May) will encourage development of infective larvae and possibly cause issues to those who haven't remembered to factor worms into their management practices.

With more rain predicted for next week, and daytime temperatures to remain warm till the end of the month, worm egg count testing is advocated. 


North West LLS

Moree: Justine McNally, DV (

Class of stock (number)

Average Worm Egg Count (epg)

Range (epg)

% Black Scour

% Brown Scour

% Barber's Pole


Ewes (800)






Wether weaners (1100)






Ewe weaners (800)







Weaners (1200)







Ewes (800)






Lightning Ridge

Ewes (900)







It has been very dry for the past month. There were scattered falls of rain over the district, but nothing of great significance in the west. With the weather still relatively warm during the day and no frosts to date, the potential for worm issues to develop is a real possibility, especially if sheep are chasing short green pick.

Nyngan: Erica Kennedy, DV (

The Nyngan area has finally received some notable rain in the last two weeks (the first since the end of January); two main falls about a week apart with totals between 20–110mm for this period. The very dry preceding period meant that most producers were not doing worm egg counts and those that did had negligible numbers of parasites. With residual warmth and moisture in the ground and in conjunction with stock grazing low to the plant base it is possible that worm numbers could rise over the next few weeks before the temperatures drop further and their activity is suppressed. 

Murray LLS

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

Deniliquin: Linda Searle, DV (

Limited wormtest data was available for the western part of the district this month as only 3 samples were tested.

The three tests were performed in very different groups of sheep for different purposes.

No Nematodirus were found in any of the samples and the average epg of Strongyle varied from 0-400.

One group which had no eggs in the sample was a new mob of sheep with an unknown drenching history which had been brought in so the sample was used for a baseline test to find out what worms were present.

A group of pregnant merinos were checked and an average of 40 epg Strongyle were found, they had last been treated with a macrocyclic lactone in March 2015.

A group of hoggets which had been drenched in December 2015 with an older style combination drench (macrocyclic lactone, levamisole (clear), albendazole (white) ) were tested and had an average of 400 epg Strongyle.

There was very little worm testing in the east of the region during April, reflecting a dry month and late autumn break. Of the 3 samples sent to EMAI in the last month, each returned a moderate FEC between 200-500 eggs per gram. Larval differentiation showed a mixture of species, with barber’s pole and black scour worm the most dominant. With widespread rain in recent weeks creating short green feed, we can expect more producers to be monitoring worm burdens through May.

South East LLS

Goulburn: Bill Johnson, DV (

Several weeks of dry windy weather, interrupted briefly by widespread falls of about 40 mm and only one decent frost, did little to change the pattern of worm infection. Barber's pole worms still dominate egg counts on about half our properties with averages of several thousand common, regardless of sheep age. Some properties remain free of barber's pole worms, and have little worm activity of any sort at present.

Producers are trying to decide on their best strategy for ewes pre-lambing, knowing that feed conditions are far from ideal. You will need a few bits of essential information:

  • a current worm egg count and culture for worm type to know how many and what type of worms are present; and
  • the grazing history of the proposed lambing paddock, from as far back as when it rained around Australia Day. Much of our barber's pole hassle arose from eggs hatching after that rain event, and larvae were allowed to build up because producers then thought it became "too dry" for worms.

It is now not unusual to see the protection period from drenches containing closantel reduced as a result of developing resistance. Many closantel products had sustained activity against susceptible barber's pole worms, controlling re-infection and pasture contamination for up to six weeks after drenching. This was useful where sheep were returned to contaminated pastures after drenching. Loss of this protection period is often the first indication that the worms in your sheep are becoming resistant to closantel. Continuing to use the same drench will result in adult worms surviving drenching as well. One local property recorded a worm egg count of 5,800 eggs per gram (epg) in ewes twenty-five days after closantel, and 1000 epg after 18 days in wethers. The worms in both mobs were 100% barber's pole worms.

Editor’s Note: that is scary!

Liver fluke are showing up more frequently in tests of both sheep and cattle. A blood test on cattle grazing fluke-prone paddocks containing creeks or springs may be a useful way to monitor for fluke on your property if you run sheep and cattle.

Some producers are taking full advantage of their vet’s visit by collecting blood samples from cows during pregnancy testing.

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