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

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






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

I was talking to a friend in Armidale on the weekend. Naturally the conversation drifted to worms.

Like many parts of the state, Armidale and the New England had a stinking-hot summer (various new records set; not good for worms), followed by a very wet March (new rainfall record for the month), with mild conditions temperature-wise extending into early winter.

Anyway, based on worm egg count (WEC) results, this guy drenched a particular mob of sheep 6 weeks ago. Does he know the drench worked? Yep, because he does regular DrenchChecks. The WECs were zero 14 days after drenching.

ED: Excellent! This is what we are talking about!

For various reasons, these sheep had to go back into the same paddock after drenching. My friend has just done another WEC. Result: ~1200 eggs per gram, 6 weeks after an effective drench. Larval differentiation ('wormtype') to come. 

Given a good autumn for worms, and limitations regarding 'low worm-risk' paddock preparation, my friend has some worm challenges ahead, but he has two big advantages: he knows what drenches work on his place, and drenching is not based on guesswork.

I could have found out more, but a second friend, with no interest in worms (yeah, incredible I know), joined us and had the temerity to change the subject to something else. Some people have no social skills.


Central West LLS

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

There is very little to report on the worm side of things in the southern area of the Central West LLS. I have not seen any worm test results or any clinical cases involving internal parasites over the last month. Conditions are marginal with lack of rain and a series of frosty mornings that will prevent many worm eggs developing to infective larvae. But existing larvae will be surviving these frosts and will continue to infect sheep, so producers are reminded to continue to monitor their flocks with regular WormTests.

Riverina LLS

Wagga Wagga: Timothy Biffin, DV ( and Emily Stearman, DV (

The cold weather around Wagga at the moment is an effective retardant to internal parasite activity i.e. it’s often too cold for worm eggs to develop to infective larvae (but the existing larvae will still be there to infect sheep). This is a good thing considering that many producers are currently lambing or in the process of lamb marking and would not have had the potential to drench mobs if it were required. There have been some reports of moderate worm egg counts (WEC), e.g. mean ~400 eggs per gram (epg), especially in pregnant ewes that did not receive a pre-lambing drench. Moving forward with these mobs (ewes with lambs at foot), lambs with ewes, or lambs without ewes should be considered candidates for a weaning drench, and clean pastures should be available for these lambs post weaning. When determining the duration of grazing an individual weaner paddock consider factors that may favour internal parasite development, e.g. mild-warm temperatures, high rainfall, short pasture, high stocking density, drench efficacy (if applied). 

Worm egg counts are a cheap, easy and effective means of gauging the internal parasite burden of sheep. Considering lamb prices are currently quite strong, it is very easy to justify the $25-80 per test given the production gains achieved from a well-managed internal parasite program. 


North West LLS

Northern Slopes: Ted Irwin, DV (

We have continued to see moderate to high counts from WormTests, but there have not been any clinical cases since the last report. I have had a few cases of haemonchosis (ill-effects of barber’s pole worm) over the autumn but these cases seem to be confined to where management is less than ideal; poor paddock preparation, or no paddock preparation in combination with high stocking rates. Mostly I think producers seem to be on top of the worm issues at this time of year.

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

Only one worm test was conducted this month across the whole of the district - it showed light burdens of 100% Ostertagia (now named Teladorsagia) on a sheep property near Walgett.

It’s likely that producers aren't testing for worms at the moment due to early lambing, and also due to decreasing numbers of sheep across the north-west as producers continue to prefer cattle.

Ideally, producers should be conducting faecal worm egg counts (WECs) on lambing ewes 3-4 weeks prior to lambing, which is soon to begin. 

Murray LLS

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

Deniliquin: Linda Searle, DV (

This month there was a clinical case of barber’s pole worm in the eastern part of the region. The property has had barber’s pole issues in the past and in March this year they used a moxidectin drench that unfortunately failed to control these worms. This poor result matches with the known widespread resistance in barber’s pole worms to macrocyclic lactone group of drenches. Interestingly, this producer sent in WormTest samples from three mobs after this clinical diagnosis and found that one mob had a worm egg count of 4 eggs per gram (epg), another of 88 epg and the third had a count of 4696 epg,  99% of which were barber’s pole worm and 1% was brown stomach worm.

(Ed: this highlights the value of WormTests, as this was clearly not a “whole-property” issue).

Two other WormTests were submitted from this region this month.

  • A group of mixed aged sheep in good condition, and drenched with an abamectin and derquantel mixture in March had an average egg count of 336 epg strongyle type eggs, made up of a range of individual results from 0 epg up to 2120 epg.
  • A nine month old ewe lamb mob that was drenched in February with a triple combination drench containing abamectin, levamisole and oxfendazole had an average count of 100 epg strongyle type eggs and 20 epg nematodirus type eggs.

In the West of the region there were no clinical cases reported, and only two sets of WormTest results.

(Ed: such a result would have been the cause of or worsening their poor condition)

  • The second set of results was for a mob of one and a half year old Merino ewes with an unknown worming history. They were in medium condition and had an average score of 240 epg strongyle type eggs and 20 epg nematodirus type eggs.

South East LLS

Goulburn: Bill Johnson, DV (

The most common question at the moment is "what drench should I use pre-lambing?” It's more than a question of drench choice, and involves what type of worm(s) you are dealing with, and how worm-free your lambing paddocks are. You need some information specific to your property.

A worm egg count (WEC) on ewe mobs is the starting point. Recent results have varied widely. Some mobs have very low worm egg counts, several with an average well below 50 eggs per gram (epg), and therefore the pre-lamb drench was not required.

Most properties in the district now have barber's pole worms as part of their worm mix. Sheep are generally in good condition, despite no rain for a month west of the divide and some decent frosts. Properties to the east have scored a few wet days, but daytime temperatures across the district are too cold (less than 18°C) for barber's pole worm eggs to hatch. That isn't the end of the barber's pole story for this season, however. There are a lot of barber's pole larvae on pastures on some properties, left over from a warm, wet autumn. Some of them will still be there until September. Sheep on these paddocks develop pretty solid worm egg counts (average 800 eggs per gram in one case) within six weeks or so after drenching. Don't assume that just because these sheep still look good, are fit, and have no sign of scour that they don't have worms. You need to ask the laboratory to check worm type (larval differentiation) from the dung samples you submit. Paddocks like this are also a risk for lambing, especially as ewes lose some of their worm immunity at this time.

With the dry start to the year, many producers were left with carry-over lambs well into the autumn. These lambs often heavily contaminate paddocks with worm eggs that hatch in time for winter-lambing ewes to pick up. These paddocks are not a good choice for lambing, especially if pastures are short and green.

When it comes to drench choice, it is recommended to use a combination product—one that contains more than one drench type. If you have barber's pole worms in your sheep, recent tests have shown, for example, that most of the barber's pole worms in the district have some resistance to the popular chemical abamectin when used alone. You may also need this pre-lamb drench to remove liver fluke, if tests or experience have shown this to be a problem on your property.

(Ed: a drench resistance test done at a time of year when all worm species are prevalent will give very valuable information on which drenches to use on your property.)

Don't take your eye off your weaners this month. We often see them rapidly get shitty as a result of black scour and brown stomach worms during late winter. The problem is made worse by declining feed availability and body condition score, but we often miss that sign due to their wool length.

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