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New South Wales worms, flies and lice update - September 2019

NSW WormBoss Worm Control Programs

NSW WormBoss Drench Decision Guides






Central West LLS

Forbes: Nik Cronin, DV (

No significant rain has been received in the Forbes area and there is little district evidence for worm issues. Producers are advised to worm test sheep prior to administering a drench. Drenching animals unnecessarily increases the risk of drench resistance on your property.

Editors note: This is especially so during drought, when there may be no or few larvae on the paddocks and then only resistant worms remain in drenched sheep.

Riverina LLS

Young: Eliz Braddon, DV ( and Evie Duggan, DV (

There have been very few worm egg counts (WECs) in the Young region over the past month, and no clinical cases have been confirmed. Producers are currently in the midst of lamb marking and weaning. At marking, keep in mind that the decision to drench lambs should be based on the WEC results of the ewes. At weaning, lambs should always be drenched with an effective broad-spectrum drench and weaned onto a clean paddock. Lambs are highly susceptible to worm burdens, and this susceptibility is further increased by the stress of weaning. Drenching is required not only to ensure that the value of the feed is utilised and to increase survival rates, but also to allow for optimal growth rates to be achieved. Worm burdens have been shown to have a significant impact on daily growth rate and therefore, the time taken to finish a lamb. As many producers consider weaning into confinement feeding, it is a reminder that a comprehensive induction program (that includes a drench) is key to the lamb’s success. A WEC should be carried out to make an informed decision if the ewes require a drench at weaning while they are in the yards.  

As always, feel free to call your local district veterinarian to discuss any queries in relation to your own property. 

Murray LLS

Deniliquin (West): Scott Ison, DV ( and Linda Searle, DV (

Albury: Mark Corrigan, DV ( and Eve Hall, DV (

Small, frequent rains have seen the growth of pasture and crops throughout most of the area this winter. However, the rain now has eased, and a lack of subsoil moisture and increasing temperatures are likely to cause much of the feed on the ground to start to hay off. There has been some scouring in sheep in the district with causes identified as including worms, coccidia, dietary scours, and other conditions such as Johne’s disease.

Worm egg counts from a number of properties have shown variable results, and while the majority reported have been low, the range of counts indicates that it is worth checking. A  mob of ewes with lambs-at-foot in the Walla Walla area had an average worm egg count of 148 eggs per gram (epg) of strongyle-type eggs and 4 epg nematodirus-type eggs. These ewes had been treated with a drench-vaccine combo containing moxidectin, pre-lambing.

A few WormTests were done on a property in the Urana area. This property had an unknown drenching history. In one mob, an average of 132 epg strongyle- and 32 epg nematodirus-type eggs were found and on culture were 95% black scour worm and 5% brown stomach worm. Another mob on the property had an average of 120 epg strongyle-type and 38 epg Nematodirus-type eggs which cultured to be 4% barber’s pole worm, 71% black scour worm, 21% brown stomach worm and 4% Oesophagostomum. A group of maiden ewes had an average worm egg count of 32 epg strongyle-type and 28 epg Nematodirus-type. A group of 2.5 year old Dohnes had 60 epg strongyle- and 88 epg Nematodirus type eggs.

Merino lambs from the Moama area that had not received any treatment had an average worm egg count of 12 epg strongyle- and 4 epg nematodirus-type.

A farm in the Jerilderie area had an average worm egg count of 268 epg strongyle- and 120 epg Nematodirus-type eggs. Interestingly these results came from a mix of 5 year old ewes and 6 month old crossbred lambs. The ewes had been drenched with a combination of albendazole (white drench) and levamisole (clear drench) in July, and had a worm egg count range of 0–40 epg strongyle-type. The lambs had been drenched with a straight moxidectin on the same day and had a range of 0–1280 epg strongyle-type eggs.

A property near Swan Hill had treated ewes with moxidectin in February and had a count of 0 epg.

There were low to moderate numbers of coccidia present in most of the samples submitted.

South East LLS

Braidwood: Lou Baskind, DV (

In Braidwood, the dry and the frost seem to have kept worms under wraps for a couple of months. We received 41 mm of desperately needed rain on 16 and 17 September with the welcome addition of snow! Most animals here are currently grazing the lowest 10 cm of pasture-plant height. It is expected that the moisture from the rain, plus the warm temperatures of spring, will result in mass hatching of worm eggs into larvae. With animals being disadvantaged in terms of nutrition, which reduces their immunity to worms, illness is the likely result. Sheep should have a worm egg count test 4–6 weeks after this rain event. Young cattle and bulls will be due for a drench in December, but producers are recommended to monitor closely for weight loss, poor growth, ill-thrift or poor coat condition, and consider drenching earlier if necessary.

Yass: Alexandra Stephens, DV (

Many of the worm egg counts (WECs) in the Yass/Boorowa region are done through private laboratories, and as such, I have only seen a few local results from the government laboratory. Some higher counts are from the broader south-east region due to a high proportion of barber's pole worm in the counts.  

Seasonal conditions have been warmer and drier than average this year, with pasture heights low, but still mostly green. Effective drenching and pasture rotation have been very important this year in minimising larval pick up during the winter.  Recent rainfall activity may generate some good egg hatching conditions and a peak in larval availability.  I recommend WEC testing particularly in hoggets, and in ewes prior to weaning, to know if the first summer drench needs to be brought forward. It will also help to detect any emerging barber's pole problem that could be managed with an early sustained-action drench or a short-acting effective drench and move to clean pastures. 

I have also increased my recommendation for a post mortem on any stock losses.  As drought conditions have continued, we are finding more OJD cases even in vaccinated young sheep, and also higher coccidial counts. Cases of scours may not be best fixed by drenching. It is also very beneficial to rule out barber’s pole worm as the cause of sudden death. When we get rainfall after a sustained dry, we also need to be on the lookout for the effects of Nematodirus. The immatures of this worm can cause scouring and deaths in weaners and hoggets, and in the early stages, the infection is not detectable with a WEC. 

Berry: Evelyn Walker, DV ( and Amanda Britton, Sr Agricultural Advisor (

Worm activity and monitoring have been pretty quiet around the Berry, Illawarra and Shoalhaven areas.  The recent rainfall has been nice with some producers reporting 40 and up to 52 mm! The showers have been beautiful and hoping for more to come. A gentle word of caution, however, the recent rains and now warm conditions create an environment conducive for rapid grass growth and increased worm activity, especially the barber’s pole worm in sheep.

With rapid grass growth, especially following dry times, minerals such as magnesium, available in the animal, soil and plant, may become imbalanced and potentially trigger low blood magnesium (often referred to grass tetany or grass staggers in cattle and sheep). Low magnesium can potentially cause difficult calving and lambing.

Furthermore, with some pastures in our area being overgrazed by stock, there is a risk of livestock seeking out these actively growing plants and also coming in closer contact with worm larvae on the pasture. The majority of worm larvae are concentrated in the first 5 cm off the ground and move randomly on plant stems and leaves in films of moisture. For grazing and livestock management after recent rainfall, the following are suggested:

  • If practical, wait until the pasture is at least 12 cm before grazing to reduce the risk of grass tetany. This also has the added bonus of fewer worm larvae on the grass at this height.
  • Aim to have pastures at least a 3-leaf stage when grazing ryegrass and a 4-leaf stage for Kikuyu.
  • Check various at-risk mobs, at a minimum including young, pregnant and lactating animals with a WormTest 6 weeks after rain to see where their egg counts are at and whether a drench is required.

Central Tablelands LLS

Orange: Nigel Gillan, DV (

Parts of the Central Tablelands are faring better than the rest of the state, but conditions remain far drier than average. In drought conditions, it's important to avoid unnecessary drenching, which can not only waste money, but also speed up the development of drench resistance. For properties that are seeing some pasture growth with warmer temperatures and some rainfall, pick-up of infective worm larvae may be on the rise. For those yet to mark lambs, performing a worm egg count (WEC) on the ewes around a week beforehand will indicate whether drenching the ewes and lambs is warranted.

With supplementary feeding still common in the district, producers should remain aware of the usual risks, such as grain poisoning, or nitrate/nitrite poisoning from hay. Local Land Services can assist with feed testing—contact your nearest office for more information.

Greater Sydney: Aziz Chowdhury, DV (

Due to cold and dry conditions over the last few months, fewer worm egg counts have been conducted in this last month. However, a couple of sheep mobs (5–50 sheep/mob) appeared high in strongyle-type egg counts and 90–98% of them were Haemonchus (barber’s pole). At least one goat mob has come in with high Haemonchus and Oesophagostomum spp (large bowel worm) counts. Most of the high worm egg count farms are in north-west Sydney and the Central Coast where pasture conditions and moisture levels of the soil were slightly better than the other parts of Sydney.

There has been good rainfall recorded over the last week (mid-September). Maximum rainfalls in western Sydney were recorded up to 50 mm and in Central Coast up to 150 mm. Resulting from this, there is an expectation of good pasture growth in the farming area, which may encourage the small farmers to restock.

Also, because of that high rainfall, and the weather warming up at the same time, it is expected that the worm burdens will increase in the region. So, it is best to do the worm egg counts and larval cultures again to help decide how to manage worm problems in your farm. 

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