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New South Wales worms, flies and lice update - March 2015

Armidale: Rad Nielsen, Veterinary Health Research (rnielsen@vhr.com.au)

Over the past month the VHR Laboratory has received an increased number of submissions with high to extreme worm egg counts, typically associated with Haemonchus dominant infections. Reports of sheep deaths and clinical symptoms have also been noted. The good January rain over the New England region, in particular, was the trigger for this ‘set-up’, and although a large area has experienced dry conditions over February/March, the worm risk will remain high for some time for those properties currently dealing with high worm challenge. Conversely, graziers who have maintained good worm control to now should find it easy to maintain this status until at least next spring.

Barbervax vaccine: Encouraging results have been seen in respect to the Barbervax vaccine, launched in the New England region in October 2014. A number of properties have recorded surprisingly low mean worm egg counts in lambs receiving the vaccination program, particularly when combined with some beneficial grazing management. What has been highlighted with worm monitoring results is the need for close adherence to the vaccination timing schedule, i.e. not exceeding the 4–6 week gap between vaccination administration. Regular worm monitoring should also be a key component of the program, not only to establish if a drench is in fact required, but also to identify the nature of the infection. Scour worms have been demonstrated to be present at significant levels in a number of submissions, necessitating genuine broad spectrum treatment. Of particular interest has been the apparent partial (and greater) therapeutic effect of the vaccine against Haemonchus when administered on the fourth (and likely subsequent) occasion(s). Worm egg counts have been shown to decline by a significant percentage in the two weeks following V4 administration (without drenching) on a few properties, removing the need for anthelmintic support to this time.

Barbervax is expected to be more widely available for the 2015/16 Haemonchus season and to be registered for sheep of all ages.

LOCAL LAND SERVICES DISTRICT REPORTS

Riverina LLS

Amy Shergold, DV (amy.shergold@lls.nsw.gov.au) and Tony Morton, DV (tony.morton@lls.nsw.gov.au)

Significant worm burdens have been seen in the Gundagai region over the past month. There have been light losses due to barber's pole worm in weaners and ewes, diagnosed on post-mortem. Worm egg counts are mostly revealing mixed burdens of scour worms and barber's pole worm. The highest counts averaged 1200 epg, while other tests came back with minimal numbers that did not warrant drenching. The larger burdens have mostly been in weaners, while adult sheep have had lower counts.

Keep in mind that barber's pole worm is still active and choose your drench carefully. There is resistance to 'mectin' drenches in some populations of barber's pole worm, including moxidectin (Cydectin). There was a case recently where sheep became infested with barber's pole worm after receiving a long acting moxidectin drench. This suggests potential resistance and subsequent shortening of the pay-out period. Abamectin triples and Q drench, monepantel (Zolvix), naphthalophos combinations (Rametin combination and Napfix) and derquantel combination (Startect) have been performing well against barber's pole worm locally.

Wagga Wagga: Timothy Biffin (timothy.biffin@lls.nsw.gov.au)

There has been reduced egg count data received in the LLS Wagga Wagga office over the last month. I hope this is because the majority of producers have already completed their second summer WormTest, as a guide prior to committing to a second summer drench. However, from the information that has been received egg counts appear to be reducing. This may be a reflection of the effective parasite management and current climatic conditions. 

Egg counts have been ranging from 40 epg to <300 epg (mob averages) with mixed cultures: Haemonchus sp. (barber's pole worm), and Ostertagia sp. (brown stomach worm).

Having said all this, there has been some recent deaths (within the month) in sheep in the Wagga region caused by barber's pole worm. This has been predominantly been on properties with a poor drenching program and which rarely submit WormTests for assessment.

Young: Rahul Shankar, DV (rahul.shankar@lls.nsw.gov.au) and Eliz Braddon, DV (eliz.braddon@lls.nsw.gov.au)

WormTests from the Young area have come back at varied counts and types. These have ranged from individual animals having counts of up to 1200 epg and averages of 480 epg being detected in some of the mobs tested.

Barber’s pole worm (BPW) has been found as incidental findings during disease investigations, but the primary burden for those that have chosen to undertake larval differentiation have been Ostertagia and Trichostrongylus.

One producer has seen production losses from what was presumed to be BPW, with wether lambs that were anaemic, with bottle jaws and an obvious tail to the mob. Drenching with a suitable product appears to have quelled the situation and no further losses were reported. Interesting to note that the paddock the lambs were grazing was one where no stock had been on for 2 months prior, and the stock that was previously on was only dry stock, with the worm burdens being kept in check with worm counts from a test conducted at the time.

Producers have been asked to be mindful of worm burdens that may creep up with the rain that is supposedly forecast for the coming weeks. Drench rotations have been advocated for those producers undertaking their first drench of the year, with some producers opting to use derquantel and closantel to ensure they maintain the longevity of their drenches in regards to resistance. 

South East LL

Goulburn: Bill Johnson, DV (bill.johnson@lls.nsw.gov.au

With little rain during February and the district drying off rapidly, several producers delayed routine worm monitoring—after all, the sheep looked good, and conditions were unkind to worms. It has come as a surprise for some to now find worm egg counts of several thousands, dominated by Haemonchus (barber's pole worms). On some properties, the Haemonchus problem is evident in all mobs; for others, the problem is confined to just one or two mobs. Barber's pole worm eggs will hatch where there have been patchy thunderstorms, and these larvae will now survive into the winter. It is worthwhile knowing if Haemonchus is present, if only to identify those paddocks that may cause problems later.

Haemonchus has also been responsible for low-level losses in some mobs and the following investigations reinforce the value of monitoring using worm egg counts and including larval differentiation.

The losses were seen as sudden deaths in otherwise fat, 'healthy' sheep, such as in one mob of spring-drop cross-bred lambs. This mob of 200 lambs passed ‘the Honda test’ (showed no fatigue during a weekly 400 m sprint across the paddock), yet one lamb died suddenly each week for three weeks from Haemonchus. More typically, barber's pole was the cause of the sudden death of six fat Merino rams over a three-day period, six weeks after an effective ‘triple’ drench. These rams lived in ankle-deep green grass in a small paddock near the woolshed, with three collapsing during yarding for treatment­—only one got up.

At the same time, there are still a large number of properties that have next-to-no worms of any sort at present. In some cases, their most recent adult worm drench was pre-lambing, more than six months ago.

Sheep are now chasing green feed into low-lying parts of paddocks, increasing the risk of picking up liver fluke. It takes two to three months before these liver fluke will show up in faecal egg tests, so it is worth tracking mobs that have been in creek and swamp paddocks during autumn for later monitoring for liver fluke, either by faecal or blood tests.

(Editor’s note: The paddock used by the rams in the investigation described above was likely a continuous ‘ram paddock’, so every decent shower of rain through spring and summer allowed barber’s pole worm larvae to hatch. When rams must be confined to a single high-security paddock for most of the year to prevent out of season joining, and conditions for barber’s pole worms are likely to be favourable, it may be prudent to give a long-acting (3-month) product and a primer (with both effective against barber's pole worm). These set-stocked ram paddocks present a high risk to a valuable and susceptible group of sheep and warrant occasional WECs to determine when such a treatment should occur. With increased drenching to safeguard these valuable stock, these paddocks are also likely to harbor worms that are more drench-resistant than the general population of worms on the property. Therefore, when rams leave the paddock for joining, ‘quarantine drench’ them with no less than 4 unrelated actives (click here for more details on quarantine drenches).

Murray LLS

Deniliquin: Linda Searle, DV (linda.searle@lls.nsw.gov.au)

We have a lot of WormTest data in the west this autumn due to the increase in people sending away samples. Hopefully our Making More from Sheep workshops have helped spread the message of the importance of WormTest!

There were variable results in the west, about half our flocks did not need to drench at all, but worms were still around and with species not common in our area. Barber’s pole worm has made an appearance east of the Cobb Highway, due to summer storms, in numbers great enough to be causing anaemia and bottle jaw in some flocks. Black scour worms have also shown an unusual increase in numbers west of the Newell Highway, where it is not commonly a problem. All clinical cases seem to be responding well to drenching.

The east has also had problems with barber’s pole, as well as small brown stomach worm, with one producer losing 5-month old wether lambs to barber’s pole; drenching stopped further deaths. Wet conditions in January/February led to ideal conditions for worm numbers to build up, although the season has now started to dry off.

To avoid developing drench resistant worms we encourage all our producers to check if drenching is necessary. By using drenches only when needed and rotating drench types when used producers can decrease the rate of resistant worms occurring and save the cost of unnecessary drench.

Central Tablelands LLS

Alan Taylor, DV (alan.taylor@lls.nsw.gov.au)

We have had scattered showers and warm weather, so are getting some interesting worm counts come through.

The usual ones over 1000 epg are 100% Haemonchus, but the following result showed the benefit of larval differentiation.

The actual worm count was 7280 epg, and I expected this to be Haemonchus, but the differential showed only 23% Haemonchus, 37% Trichs, and 40% Ostertagia. A Barber's Pole only drench would not have done his sheep much good.

Bourke: Charlotte Cavanagh, DPI, (charlotte.cavanagh@dpi.nsw.gov.au)

Not too much to report out this way as the conditions continue to be mostly dry. 

A worm egg count from scouring sheep produced a neglible result.

I submitted samples from a mixed mob of Dorpers after the owner had reported deaths and bottle jaw. The average WEC came back at 1240 epg. All the sheep had been purchased and I think brought their worms with them—hence the importance of the quarantine drench. Lack of adequate nutrition was definitely a problem here and perhaps the worms were having a bigger effect than usual on these sheep.