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

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






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

For the 3 months up to the 30 April, most of NSW, apart from the north-western corner, had average to very much above average rain.

The standout month was March, at least for the north-eastern corner of the state. One locality on the north coast had the equivalent of Armidale's average annual rainfall (~780 mm) in one day. Armidale itself had its previous rain record for the month of March blown away.

But there was above average rain elsewhere in March. The central west and southern tablelands, for example, got very good rain after a dry start to autumn and are at higher than usual risk for worm problems in sheep.

For barber's pole worm and the scour worms, March was like all their Christmases coming at once: plenty of moisture and mild to warm temperatures. You can assume there are plenty of infective larvae on the ground, and these are somewhat less bothered than worm eggs by cool to cold temperatures. In fact, cool and moist conditions keeps them alive for longer.

If, during autumn, you had sheep or goats on what will be your spring lambing paddocks, then you have a higher risk of worm problems in lambing ewes and their progeny. “Your Program” in WormBoss describes how you can prepare low worm risk lambing paddocks next year.

Getting the basics right will make all the difference: regular Worm Testing, and when you do drench, using a highly effective drench. And don't forget 'DrenchCheck': a worm egg count on the day of drenching and again 14 days later. Think of these tests as an investment, not a cost.



Central West LLS

Coonabarabran: Alix Ferguson, DV (

The rainfall on the weekend was welcome, especially for those sowing winter crops. Worm Egg Counts (WEC or WormTest) carried out in the Coonabarabran region had means ranging from 192 to 4996 eggs per gram of faeces (epg).

Barber’s pole worm was the main culprit in these tests, and in some cases a poor efficacy of the drench used has been the issue. If you are concerned that your drench program is not working, a DrenchTest is recommended (or at least a DrenchCheck). A Worm Egg Count Reduction Test (WECRT) is the procedure, and it is the most accurate way to test for drench resistance.  

Some producers in our region have also DrenchChecked weaner cattle to make sure that their weaning drench was successful. This process requires a test prior to drenching, then another sample taken 14 days later. This can give a lot of information about the type of worms present, and the efficacy of the drench product used in your cattle.

Coonamble: Jillian Kelly, DV (

I have not seen one single WormTest performed through EMAI for the month of May from our area so I have little grasp on worm burdens in the Coonamble district. There have been huge variations in scanning results reported in flocks, with many producers blaming the heat during joining for poor results. It is hard to definitely pinpoint a cause and it seems that each case needs to be considered individually. Heliotrope poisoning has been diagnosed recently in sheep grazing stubble paddocks. Fly burdens are low.


Riverina LLS

Young: Elizabeth Braddon, DV (

Tim's comments (see Tim Biffin, Wagga Wagga, below) about the Wagga region also reflect what is happening in the Young portion (north east section) of the Riverina LLS.

Autumn lambers are in full swing with either lambs just being dropped, or some already on the ground. Worm burdens have varied from farm to farm depending on the varying worm control measures in place. Sound advice in this instance is to do the WormTest 6–8 weeks out with a larval differential to make sound decisions on drench type and requirement for durations of action. For example, if a Haemonchus (barber’s pole worm) burden is high on a particular pasture, then a product with a longer duration of action may be prudent to get through lambing without having a breakdown in the ewe mob. 

This advice is now aimed at the spring lambing groups as they are in the window of opportunity, or fast approaching it, to get these management practices in place.  

Young: Rahul Shankar, DV (

Autumn is upon us, but barring today's 20–40mm of predicted rainfall (which is still ongoing as I type this - 20th May), the last few weeks have been dry and daytime temperatures have hovered between 20–25°C, so a warm autumn!

On the parasite front: 

Worms: routine worm egg counts from producers in the district have shown low to moderate egg counts (0–400 eggs per gram of faeces (epg) on average). Most of these have been in pre-lambing ewe mobs, with some checks being conducted for weaner lambs as well. Main worm species identified have been black scour worm and the brown stomach worm.  

A few cases of liver fluke were diagnosed in April, in both cattle and sheep. Producers were reminded about preventative and treatment options as per recommendations on ParaBoss:

Flies: still very much active. Fly strike preventative measures should still be maintained on farms as sheep are still susceptible to fly strike.

Lice: Reports of breakdowns and infested flocks are starting to come through.  Producers are reminded about implementing appropriate biosecurity measures on their individual farms in addition to choosing a suitable chemical application method (complete immersion of the sheep is always recommended as the gold standard for treatment) should a problem be detected. In all cases, on-farm management is essential to ensure that the treatment has worked and that re-infestation is unlikely to occur and include: checking boundary fences regularly, communicating to neighbours regularly, quarantining stray stock immediately, quarantining new stock that arrive on your property and ensuring complete musters are occurring where a treatment method has been implemented. 

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

At this time of year, and as always, internal parasite management is dependent upon the farming enterprise. With many ewe mobs lambing at present across the Riverina it is not practical or appropriate for drenching to occur in these mobs, emphasizing the importance of prior planning. For example, if you were hoping to withhold a pre-lambing drench, a Worm Egg Count (WEC) 6–8 weeks prior to lambing should be used as a tool to help gauge the current worm burden within the mob. Having said this, there have been many farmers surprised at having identified significant parasite burdens in pre-lambing ewes. Mild weather and some rainfall over the last few weeks has provided favourable conditions for round worm development.

With the significant rainfall seen mid-2016 in the Riverina, an early autumn break (while temperatures were still quite warm) could have caused a much bigger regional issue with barber's pole worm (BPW) than was observed. Considering the current climate though, scour worm is expected to be a much bigger issue in weaned lambs over the next few months. 


Northern Tablelands LLS


Inverell: Andrew Biddle, DV (

It is often said that sheep spend their lives looking for a way to die. If this is the case merino weaners are specialists.

We have recently seen a spike of investigations of weaner age sheep (mostly merinos) suffering increased mortalities, poor growth and a growing "tail" in the mob.

The factors contributing to this problem vary, but include:

Nutritional. Sheep battling through long grass or overgrazing small areas of short feed in large paddocks.
Worms. It has been a good year for barber’s pole worm (BPW) and these affected mobs often get their first set back from BPW so keep monitoring. This current mild moist autumn will maintain the threat of worms.
Liver Fluke. Technically a worm too, but if you are in an area with fluke or have purchased weaners from such an area get a Worm Test specifically for fluke done.
Mycoplasma ovis (Eperythrozoonosis or “Epi”). This is a blood parasite of sheep that causes anaemia and signs can look a lot like barber’s pole. The sheep’s immune system fights it, but stressed weaners can be severely affected.
Blindness (Pink eye). This is different to pink eye in cattle and is usually caused by Chlamydia. Sheep normally get over it without treatment and yarding animals to treat it increases spread. Valuable individuals may require antibiotic eye ointment. Blind weaners move with their mob and cope well.
Scouring and breech strike. With a warm autumn, flies are still about.
Coccidiosis. Causes scouring, which may contain blood.

Target weights. You should aim to have weaners around 23 kg or more. Lighter lambs will have lower muscle and fat reserves going into winter and struggle to fight off common health problems. Lighter weaners need supplementation with a high protein product.
Nutrition. A spelled low worm, high quality pasture paddock gives weaners the best opportunity going into winter.
Monitor for worms. Whether it be barber’s pole or black scour worm monitoring worm burdens gives you an insight into potential threats before they become a crisis. 
Investigate health problems. If you are getting deaths or other health problems have it investigated early and take action before large numbers are affected.


North West LLS


Northern Slopes: Ted Irwin, DV (

There haven’t been any reported cases of haemonchosis since my last report. Worm numbers would still be quite high in the Gwydir Shire area, but I do not have any reports of deaths. Temperatures have cooled significantly, but not enough to stop worm larval development. I suspect the paucity of reports are due to producer knowledge of common causes of sheep deaths at this time of year and familiarity with clinical signs of high worm burdens, also availability of new drench groups leading to more successful drench campaigns.

I suspect worms could be an issue until mid-June when temperatures become too cold for larval development.


Murray LLS

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

Deniliquin: Linda Searle, DV (

All of the WormTest results this month came from the eastern part of the region.

We have had faecal worm egg counts ranging from 4 eggs per gram of faeces (epg) up to 520 epg strongyle type (meaning the combination of all roundworm types), and from 0 to 40 epg nematodirus type.

The majority of sheep tested were drenched in November last year with either a triple combination drench containing abamection, oxfendazole and levamisole or a naphthalophos based drench.

Many of the tested animals were pregnant ewes, which were in good condition without any signs of scouring, deaths or weight loss.

There have been no clinical cases reported this month, or observed, as part of a disease investigation.


South East LLS

Goulburn: Bill Johnson, DV (

Would you be prepared to not drench a mob of ewes with an egg count of 1000 eggs per gram (epg)? Several producers have been weighing up that decision in the past week. Normally you'd have the drench gun charged the moment you got that result. Their sheep look fantastic though, not scouring and travel without fatigue. But you need more information than that.

The laboratory has confirmed that close to 100% of the worm eggs in these sheep are barber's pole worms. So why no drench yet? Unlike with scour worms, a mob average of 1000 epg barber’s pole worm causes negligible productivity loss because anaemia needs to be at a severe level before it stops the sheep getting about slowly and eating, and then death is imminent.

Also, further pasture contamination is of little concern because any barber's pole worm eggs passed by sheep now are doomed; it is too cold for them to hatch once daily maximums are below 18°C. However, sheep can be picking up barber's pole worm larvae already on pasture following the autumn break, which had very favourable conditions for egg hatching.

In the NSW Northern Tablelands summer rainfall region, the recommended drenching thresholds are up to 1200 epg (when both sheep and pastures are in good condition). Individuals at this level are unlikely to be affected, but this average threshold takes into account that some individuals in the mob could have much higher counts—possibly 3,000–5,000 epg or higher—and would be at a higher risk of death.

So, if you have barber’s pole worm counts higher than the levels at which you would normally drench scour worms, don’t immediately reach for the drench gun.

Keep a close watch on sheep, including with monthly worm egg counts and cultures (or a little sooner if counts are nearing 1000 epg) and they'll be right to leave a little longer, but be prepared to respond in case counts rise rapidly. You will need to remove these barber's pole worms prior to spring, before it warms up enough for barber's pole eggs to hatch. For some of these mobs, this will coincide with a drench pre-lambing or at lamb marking.

On other properties, it is shaping up as a good year for dags. While not all dags are due to worms, some mobs have high counts of black scour and/or brown stomach worms, and have dags to match. Both these worms hatch at lower temperatures than barber's pole eggs, so owners of these mobs will get plenty of crutching practice.

Enquiries about lice in sheep have increased, which has more to do with spring-shorn sheep now having enough wool for rubbing to show. Most producers are aware that treatment now in long wool will not eradicate lice, although one producer asking about plunge-dipping his ewes with eight months wool on the point of lambing was hoping to give it a red hot go. It was the wrong approach on so many levels—animal health and welfare, chemical residues in wool, cost and wool damage for starters. The aim with long-wool treatments is to restrict loss of wool value prior to shearing, when short-wool treatments should then achieve eradication. It's often hard for conscientious wool producers to get their heads around, but sometimes it is better not to treat in long wool at all, if only a small percentage of sheep are rubbing, and shearing is not too far away.

You can calculate the costs of treating your sheep or not using the Long Wool Lice Tool on the LiceBoss website. One thing that must be done now, though, is to have a word to all your neighbours. Let them know what is happening, to give them time to plan, and to lessen the chance you'll get lice back from them next year.

Braidwood: Kate Sawford, DV (

A number of WormTest results from sheep were received in May this year, though they came from only a handful of properties. Average Worm Egg Counts (WECs) for the mobs have ranged from 4 eggs per gram of faeces (epg) to 2852 epg, with individual animal counts ranging from 0 epg to 5240 epg. Results from two properties highlight the need to test each mob individually and not assume that the results from one mob can be applied across an entire property. For example, one property submitted samples from six separate mobs. Average WECs counts in the different mobs ranged from 4 to 2272 epg. Only two of the six WECs required a culture, with one yielding 99% barber’s pole worm and the other a mixture of worm types. Clearly there was money saved through WECs and selective drenching of the mobs that needed it. The counts also gave the producer valuable information about pasture contamination with worm larvae, which enabled him to better understand the paddocks that required a clean-up and the paddocks that could be utilized for lambing and weaning.

There have been a wide range in results from larval differentiations—some mobs have had very high burdens of Trichostrongylus (black scour worm), some have had very high burdens of Haemonchus (barber’s pole worm), while others have had mixed infections. Those with mixed infections have tended to have low WECs. This finding highlights the importance of requesting a ‘type’ when doing a WormTest.

Worm eggs require warmth (or more specifically brown stomach worm eggs require daily maximum temperatures >8°C, black scour worm eggs temperatures >12°C, and barber’s pole worm eggs  >18°C) and sufficient moisture (generally about 10–15 mm rain over a few days or so) to develop into larvae and therefore this part of the life cycle slows considerably as we move from autumn into winter. However, unlike worm eggs, the larvae are quite resistant to cold and therefore the cold nights we’ve been having do little to reduce pasture contamination with existing larvae, even if they are spelled for a short time. Grazing heavily contaminated paddocks with cattle, or sheep for 0–21 days after an effective drench, are your best options for cleaning up paddocks for spring weaning and lambing this time of year, unless you’re going to crop them. “Your Program” in WormBoss describes how you can prepare low worm risk lambing paddocks.

And speaking of effective drenches, reports of drench resistance are on the rise across the district. If it has been some time since your last DrenchTest there’s no time like the present. If you’ve done a DrenchTest recently and want to do a quick check of a drench you’re planning to use on your property plan on a DrenchCheck—do a WormTest up to 10 days before a mob is drenched with a short-acting drench and then a second WormTest 14 days after the drench.

On a final note, don’t forget about liver fluke this time of year. Remember that to have fluke three things are required: the habitat for the snail (the intermediate host), the correct snail species, and then the fluke. If you’re unsure if you have fluke on your property contact your veterinarian to discuss options for testing. If you know you have fluke, now (April/May) is the time to drench for the immature and mature stages of the parasite. If you don’t have fluke and you want to do all you can to keep it out make sure that you drench any newly introduced stock for fluke with a product that targets the immature and mature stages and quarantine the stock in a paddock with no creeks or springs or no suitable snail habitat for a couple of weeks before moving stock out onto your property. Remember that one of the ways that liver fluke moves to previously uninfected properties is through the moment of infected snails in water from neighbouring properties following storm events. If you’ve never had liver fluke but you have suitable snail habitat it’s worth doing routine monitoring every 2-3 years to make sure you haven’t had an introduction. Once again, contact your veterinarian to discuss testing options.


Central Tablelands LLS

Mudgee/Merriwa: Nigel Gillan, DV (

Many producers have been performing worm egg counts (WormTest), with a range of results.  Some high counts have been seen, often with Haemonchus (barber's pole) as the predominant worm species.  Often these high counts reflect grazing history, and illustrate the importance of preparing low risk paddocks for more susceptible sheep (particularly weaners at this time of year).  Some egg counts have indicated drench resistance, mostly where single active drenches have been used.


Western LLS

Bourke: Charlotte Cavanagh, DV (

Broken Hill: Sophie Hemley, DV (

Good rainfall across the majority of the western district over the past month has promoted good herbage growth for the winter season. Over the month of May results of two Worm Egg Counts (WEC or WormTest) were submitted to the Western LLS.

WECs from a mixed aged group of lambing ewes from the Euston district returned results of 240 and 6640 eggs per gram of faeces (epg), strongyle type. Interestingly, these ewes were from the same mob, in average body condition score and had no previous drenching history.

(Editor’s note: this highlights the considerable differences in natural immunity between individual sheep, which can be increased by breeding with more worm-resistant rams.)

A WEC from a cow in the Bourke region returned a count of 100 epg of strongyle type eggs.

With many producers in the southern area well into the lambing season and many producers to the north commencing shearing, it is a good time to think about the best treatment options for internal and external parasites for your livestock whilst they are yarded. For more information please call your local district veterinarian.

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