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New South Wales worm update - January 2013

Rad Nielsen, Veterinary Health Research, Armidale (

There have been some big counts here over the last fortnight (3-4000 epg mean) after a prolonged period of relative stability, along with a report of ‘sudden’ worm induced deaths. The Christmas period rain in the NE has awakened Haemonchus! Close vigilance is now required.

Interestingly, some properties have significant Trich. infections (including one report of deaths). The weaners had recently been drenched with Lev + BZ on the assumption that Haemonchus was the worm of ‘interest’. This highlights the need to perform larval differentiation, particularly before selecting ‘narrow spectrum’ drench options.


Stephen Love, Veterinarian, State Coordinator-Internal Parasites, NSW Department of Primary Industries, Armidale (
With many District Veterinarians being involved in bushfire-related work, here is a quick overview in lieu of more detailed area-by-area reports.

Much of NSW has been very dry for a number of months. However there are localised exceptions, with some areas scoring good falls through storms for example, and being doubly lucky and getting some follow-up rain.

This is has been reflected in sheep WormTest results from various labs. Worm egg counts in general have declined over the last 2–3 months, but there are still some exceptions with gloriously high worm egg counts. The bottom line is that assuming your sheep are not wormy could make an ass out of you. Don't guess, WormTest. Stick to the program of worm egg count monitoring as outlined in the WormBoss program for your area.

If you do need to drench, consider doing a DrenchCheck to make sure the drench was effective. The most expensive drench is the one that doesn't work.’


Lachlan LHPA

Belinda Edmonstone and Nik Cronin, Forbes ( (

In the Forbes area of the Lachlan LHPA, 13 WormTests have been carried out, with the average count ranging from 0–2,176 epg, and the individual count ranging from 1–11,800 epg. The barber’s pole worm has been the predominant parasite in all of the tests with significant worm counts. The extremely hot and dry weather we have been seeing will certainly have cleaned up the on-ground worm populations by now. The only worms surviving this summer will be those inside the sheep, so this is an ideal season to clean things up with a strategic summer drench program. Use of an effective drench onto a clean paddock early in the season and follow with a WormTest in February to see if that second summer drench is required.

Kasia Hunter, Condobolin (

In the western area of the Lachlan LHPA, only a small number (4) of WormTests were conducted in December. The results were variable with average faecal egg counts ranging from 20–272, individual counts ranged from 0–880 epg. Haemonchus (barber’s pole worm) was the predominant species found on culture, followed by Trichostrongylus (black scour worm).

No reports of clinical disease have been noted. Conditions are dry and becoming very hot, thereby assisting to reduce worm pressure by reducing the survival of larvae on pastures. Most producers have completed their first summer drench, however are advised to monitor stock closely over the coming summer months. Retesting in February is advisable to determine whether a second summer drench may be required.

Eliz Braddon, Young (

The eastern end of the Lachlan LHPA has had limited worm activity for the past month. Most WormTests were done in ewe mobs with a few weaners as well. In general, the weaners were all requiring their first summer drench despite a weaning drench earlier in the year. For the ewes, most that had been drenched since October were in pretty good shape, but those not drenched since pre-lambing period required their first summer drench.

As mentioned above, the hot dry conditions are wreaking havoc on worm larvae so pastures are being cleaned up the natural way! Things to watch out for Haemonchus (barber’s pole) and/or Nematodirus (thin-necked intestinal worm) after a shower of rain in the summer months. These two worm species can build up quickly after a rainfall event especially while weather is warm. Haemonchus as we all know can kill all classes of stock quickly by sucking large amounts of blood out of the system. Nematodirus is usually only a problem in young stock (<12months) and can quickly sap strength and weight gains from these little fellows.

Tablelands LHPA

Jim McDonald, Yass (

Luckily in the Jugiong – Yass fire no homes were lost.

Lots of stock lost but many times more need feeding.

Fodder and agistment are the best way of assistance.


Amy Shergold, Wagga Wagga, ( and Tony Morton, Wagga Wagga (

The hot dry conditions of late spring and early summer saw a return to good conditions for worm control. Unfortunately while good for worm control, the hot, dry, windy weather was also associated with bushfires and loss of pasture quality.

A number of drench resistance trials were conducted across the Hume region last year. Qualitative results for eight properties near Wagga Wagga are shown below:

Property Moxidectin Ivermectin Lev/BZ Triple


1   R R    
2   R      
3   R R    
4   R      
5   R R R  
6 R R      
7   R R      
8   R    










R = resistance (<95% overall efficacy)
— drench not used in trial

Ivermectin resistance was found on all eight properties and overall efficacy ranged from 15 to 83%. The resistant worm species varied between farms but included Ostertagia (small brown stomach), Haemonchus (barber’s pole) and Trichostrongylus (black scour) worms. The emerging issue of ivermectin resistant Trichostrongylus species was seen on five of eight properties based on larval examination. This general trend was also consistently repeated in similar trials conducted from our other offices at Albury and Gundagai. On the whole moxidectin performed well; however, in light of the profound ivermectin resistance it should be used prudently. Resistance to white/clear combinations remains common as expected.

These results should help those individual producers concerned with their drench rotations. What happens when you combine a drench test, use of an effective product and good farm management? An example is a property where the six ewe mobs were drenched in early November as pasture hayed-off with a drench proven to be effective on that property; the highest count in six mobs monitored in early January was only 32 epg.

Central West LHPA

Evelyn Walker, LHPA DV, Dubbo (

Fewer sheep WormTests have been conducted this month compared to previous years. Of the WormTest results received, the majority of properties tested have worm eggs present but in low numbers. Average strongyle egg counts ranged from 0 to 292. However, one property did have medium to high levels of barber’s pole worm burdens (average strongyle egg counts ranging from 276 to 1848) in different mobs of sheep. These sheep were drenched 5–6 months ago. To date, there have been no reports of sheep deaths in the Central West region attributed to barber’s pole worm this month.

South East LHPA

Petrea Wait, LHPA, Cooma (

Things have been very busy here as a result of the bush fires. Regarding the situation from fires in our district, the majority of the stock losses have occurred on a single property and are estimated at around 400 sheep burnt or destroyed, 1 calf burnt, but several cattle missing and numerous sheep unaccounted for. There has been a large amount of feed donated to those affected. There is also about 100km of fencing lost.

Tablelands LHPA

Bill Johnson, Goulburn, (

The same weather conditions that have had everyone on high alert for fires have also given sheep some respite from worms. In most cases, the rate at which drenched sheep are becoming wormy again has slowed, with heat and dry destroying worm larvae on pasture. There are some exceptions, however, especially where sheep still have access to green feed in gullies. The message is not to become complacent, but to continue worm egg counts on select mobs through the summer. Early indications are that most breeder mobs will need a second summer drench, so WormTest before deciding no worms could have survived summer on your place.

The immediate problem for most young sheep is the dramatic deterioration in feed quality. Protein in the diet (green feed) plays a big part in establishing and maintaining immunity to worms. We’ve also seen the first cases of Nematodirus (thin-necked intestinal worm) affecting lambs. They scour, dehydrate and die quickly, often before worm egg counts rise. Outbreaks are common a couple of weeks after summer storms, especially in paddocks used annually for lambs.

Don’t forget to check your rams. You’d be surprised how often people find their rams poor or weak from worms, or flyblown, when they get them in the day before joining!

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