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

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides


Armidale: Rad Nielsen, Veterinary Health Research (

Some welcome rain was received in early April across most of the New England region, enabling worm eggs to hatch and develop, but unfortunately, provided little pasture growth due to the underlying soil moisture deficit.

Worm egg counts at the VHR Laboratory continue to be on the high side, however, as is always the case, large variability exists between properties (and paddocks). This variability was highlighted recently on a Gurley sheep property, where eight mobs of ewes/weaners were worm tested. Three mobs required genuine treatment (mean WECs in excess of 1000 epg), whilst the other mobs had low WECs and did not require drenching. The benefit to be gained from worm monitoring is multifactorial in this example. The grazier is now aware of the infectivity status of the various paddocks (is set-stocked) and may make future management decisions based on this knowledge; he only needs to drench some of the mobs, saving both time and money; and in those paddocks where the sheep remain undrenched there is no selection for drench resistance within the worm population.

The 2015/16 Haemonchus “season” has once again highlighted the significant (and alarming) degree of drench resistance present in the New England region and the apparent lack of awareness of this fact by a large proportion of sheep producers. I would strongly urge graziers to take some time in planning how they can best establish the effectiveness of the drench compounds they use, whether that be in the form of a Faecal Egg Count Reduction Test (FECRT) or post drench tests.



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

April? Think 'liver fluke'

For those who have liver fluke on their properties, April/May (when cold weather/frosts begin) is the single most important time to drench for liver fluke. And at this time, use the most effective fluke drenches. This means (assuming no resistance) triclabendazole-based drenches, with the additional option in cattle of drenches containing nitroxynil+clorsulon (i.e., 'Nitrofluke'), and 'Nitromec' (= Nitrofluke+ivermectin).

If you need to drench for fluke again in August, rotate to a flukicide based on an unrelated active. For more information on drenches, go to WormBoss.

To check the efficacy of a fluke drench, do a fluke egg count on or just before the day of treatment and again 21-28 days later.

More information:



Central West LLS

Coonabarabran: Cecily Moore, DV (

Worm counts in the Coonabarabran region have been variable over the past month, with strongyle worm egg counts ranging from 0 to 3720 eggs per gram. A larval differentiation on one property showed a fairly even spread of worm types; 33% barber’s pole worm, 47% black scour worm and 20% brown stomach worm. This unexpected result shows the importance of requesting a larval differentiation when submitting samples for a WormTest. Differentiations should be performed if worm counts are high or a drench has been seen not to have worked as not all drenches are active against all worm types. 

Increasing numbers of producers in the area are feedlotting lambs and increases in parasitic infections of lambs confined in the feed lots has highlighted the need for good induction protocols. If the sheep are new to the property and some may go onto pastures, you should prevent introduction of someone else’s drench-resistant worms to your property. Give the new arrivals a "quarantine drench" and hold them with feed and water in yards that won’t be grazed for at least 6 months—these may be the feedlot pens providing they have no grass in them. If you are feedlotting your own lambs, simply ensure they receive a drench known to be effective on your property as they enter the feedlot.

Producers should now be preparing a low worm-risk paddock for lambing in September/October. This means that from now the lambing paddock should only be spelled, grazed only with cattle, or grazed only by sheep within 21 days of an effective short acting drench or 21 days after the end of the protection period of a long acting effective drench. 

Coonamble: Jillian Kelly, DV (

Coonamble is experiencing continuing dry conditions and there have been no clinical cases of worms infecting sheep or cattle in the district. Worm egg counts are low in the mobs tested.

Buffalo fly has once again appeared in the north-western part of the district, around Quambone and the Macquarie Marshes. This irritating fly that favours black cattle has migrated down from the north-east. Producers have decided not to treat affected cattle as it is expected the onset of colder weather in the next few weeks will halt its lifecycle and result in its disappearance from the area


Northern Tablelands LLS

Inverell: Andrew Biddle, DV (

Around the Inverell region the parasite situation is much the same as last month. There have been limited scattered showers and a few heavy storms on the west of the Northern Tablelands. Haemonchus levels have remained high most likely the result of heavy paddock contamination early in the summer.

Local sheep producers are expressing concern regarding the availability of Rametin as this drench is seen as critical for their effective drenching strategies.

Editor’s note: See April feature article regarding Rametin availability.


North West LLS

Northern Slopes: Ted Irwin, DV (

Some WormTests have shown moderate counts with the highest counts reflecting significant haemonchus burdens. With the recent storm activity it is possible that there may be another surge in haemonchosis cases, but overall, there haven’t been many reports of big losses in the region over the last summer.

Moree: Justine McNally, DV (

The table below shows that worms, particularly barber’s pole worm, are present in the region and often in numbers high enough to require drenching to avoid productivity losses. Producers are encouraged to conduct worm tests and larval differentiations to identify the types and numbers of worms present, and if drenching of all mobs or just some mobs is required.



Worm egg count

(eggs per gram (epg))

Larval culture

(% of the worm egg count)

Class of stock


Average count

Highest count

% black scour worm

% brown stomach worm

% barber's pole worm

Lightning Ridge











































Burren Junction

9 month weaner







ewe lambs






Figure 1. Results of worm egg counts and larval differentiations during March and April on three properties in the Moree LLS region.


Murray LLS

Deniliquin: Dan Salmon, DV ( and Linda Searle, DV (

In the west this month, there has been a great variation in the worm test results. Unusually for this region, barber’s pole worm was identified in the Jerilderie area; 85% of the worm egg count of 533 eggs per gram (epg) was due to barber’s pole. Across the other areas, worm egg counts showed a more normal mix of predominately black scour worm (100%, 95%) with much smaller numbers of brown stomach worm (2%) and large intestinal worm (3%).

Average numbers of strongyle type worm egg counts varied from 0-533 epg with the highest individual count of 1280 epg. The range of average nematodirus egg counts varied from 0-84 epg.

With a typically dry March (<25 mm across the region), there has been very little worm testing from the east of the region. Of the 3 samples sent to EMAI in the last month, each returned a moderate worm egg count of between 200-500 epg. Larval differentiations showed a mixture of species, with barber's pole and black scour worms the most dominant. 

South East LLS

Goulburn: Bill Johnson, DV (

“Warmer than normal and dry” sums up the weather. Despite this, worm egg counts on several properties have climbed steeply in the past few weeks, still predominantly barber's pole. Lambs in a mob drenched four weeks previously had egg counts nudging 30,000 eggs per gram, so either the triple combination drench did almost nothing, or not all lambs got the drench, or the paddock they returned to was already very heavily contaminated with worm larvae from wet weather early in summer (as larvae live for many months). To sort it out, the owner is conducting a drench check test, collecting dung samples 10-14 days after another drench.

Constant monitoring of barber's pole numbers with worm egg counting is important at this time of year. Once the promised autumn break comes, the eggs being deposited on pasture around that time will hatch, allowing larval numbers on pasture to increase and survive to cause problems through winter.

Several producers have asked about tapeworm treatments in lambs, having seen the white fleshy segments in faeces. Sheep tapeworms use a pasture mite to complete their life-cycle, so it is intriguing to see those mites apparently flourishing under such harsh pasture conditions. Treating sheep just for tapeworms is pretty much a waste of time, especially as most drenches that claim to aid in control, only do part of the job.

Editor’s note: WormBoss advises producers to ignore tapeworm. Treatment for tapeworm has not consistently demonstrated benefits. Take action about the worms you can’t see, rather than these obvious, but unimportant, tapeworms.

Weaner sheep are doing it tough, and those not being hand-fed are losing weight. This impairs their ability to cope with worms when the break comes. Supplementary feeding now to reverse weight loss could save lives in winter.

Positive liver fluke tests are coming in from all parts of the district, showing how widespread fluke and fluke snails are again becoming in our creeks, swamps and springs. One property hadn't seen liver fluke for fifteen years. Blood tests detect fluke more reliably in sheep and cattle at present, although several faecal tests have also been positive. Using a drench effective against immature liver fluke is recommended.

Lice are starting to show up in spring-shorn sheep. If you treated for lice at last shearing, finding lice now is a fair indication you didn't get rid of them, rather than blame a neighbour for re-infecting. You may not have to treat just yet, but it is a good time to begin planning, not only your long-wool treatment, but how you can best tackle the problem off-shears. Being able to shear and/or treat everything at once, including lambs, is key to eradication. The LiceBoss Treatment Guide is a great planning tool.


Central Tablelands LLS

Mudgee/Merriwa: Nigel Gillan, DV (

Worm egg count results have been mixed in the Mudgee region. Some producers conducting post-drench egg counts have found evidence of resistance—an important reminder for producers to continually monitor the effectiveness of drenches used on their properties. To check the efficacy of a drench, simply conduct a follow-up worm egg count 10-14 days after treatment. Also request a larval culture to determine which worm species are developing resistance.

For April 2016 state outlooks, please follow the links below:
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