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

DPI NSW

Armidale: Stephen Love, Veterinarian/Research Officer (Parasitology) (stephen.love@dpi.nsw.gov.au)

Although the northeast of NSW had above average rain in October, the tap seems to have been turned off for most of the time into November, and the rest of the state continued dry overall. http://bit.ly/2AVOsWr

But, there have been some WormTests that have returned high worm egg count results. Even in drought years this happens: from time to time worm problems still occur because people have not been expecting them (and don't keep up with monitoring), and because of localised conditions, for example, catching a few storms, and also management factors, one being the unwitting use of ineffective drenches.

The best thing to do?   Follow the WormBoss 'Your Program' for your area. It covers all the bases, and very nicely too.

Turning now to cattle: if you have yearling cattle (now about 14 months old, assuming a spring calving), and plan to retain them (e.g. as replacement heifers), you might think about whether they need a drench. 

Ostertagia is the most important roundworm of cattle in temperate regions of the world, and most of the pickup of these worms by young cattle in NSW is in late winter through to late spring, depending on the area. Some of these larvae could well become inhibited, so worm egg counts (WECs)  may not give you a true picture of the actual worm burden, even apart from the fact that WECs in cattle are not always a great guide to worm burdens (unlike in small ruminants) once cattle get much past weaning.

If you are targeting Ostertagia, and especially inhibited Ostertagia, macrocyclic lactone (ML) drenches, or a combination drench containing an ML, is your best bet. Keep in mind that resistance is happening in cattle worms as well - not just in sheep/goat worms. Consider doing a DrenchCheck, just like in sheep: a WEC on the day of drenching, and again 14 days later.

Speaking of cattle worms, NSW DPI has just published a revised/expanded PrimeFact 419, November 2017 on the subject. See here: https://www.dpi.nsw.gov.au/animals-and-livestock/beef-cattle/health-and-disease/parasitic-and-protozoal-diseases/cattle-worm-control or http://bit.ly/2jAeE4J

And, more good news! Cattle worms are coming to WormBoss in 2019, with the team —including experts from across the country—currently gathering all the current content. Cattle will also be included in FlyBoss (Buffalo fly), LiceBoss and a new TickBoss.

Editor's note: Steve is off on an extended period of long service leave shortly. His wise contributions will be sorely missed. We hope to see Steve back later in 2018.

NSW LOCAL LAND SERVICES

Central West LLS

Coonamble: Jillian Kelly, DV (jillian.kelly@lls.nsw.gov.au)

Only a few WormTests were sent to the DPI laboratory from the Coonamble district in the last few weeks. Those that were sent showed an increase in worm burdens in most flocks with counts typically ranging from 600-1500 eggs per gram (epg). This is to be expected due to the small but frequent rainfall over the last month.  In the worm tests performed, there was a mix of worm species present, with a moderate percentage of black scour worms around Gulargambone, and a larger percentage of barber’s pole worm throughout the rest of the district.  There were no clinical cases of worms in sheep. 

Flies continue to be an emerging problem for sheep, with most producers in agreement that we are in for a bad fly summer.  Heavy reliance on chemicals for prevention can be problematic for the development of resistance, and we are encouraging producers to submit maggots to the DPI research program that is currently running. Contact your local LLS if you are interested to be involved.

Editor’s note: When to drench? See the Worm egg count thresholds in the table at Question 7 in the Drench Decision Guide. 

Forbes: Nik Cronin, DV (nik.cronin@lls.nsw.gov.au) and Belinda Edmonstone, DV (belinda.edmonstone@lls.nsw.gov.au)

Very few WormTests were submitted in the Forbes area this month, probably indicating that with the dry conditions over winter, worm issues have been few and far between. However, young sheep not yet drenched could be suffering production loss due to subclinical infestations. Also, sporadic rainfall over the last few weeks means barber's pole could become an issue in the next few weeks. 

With harvest well underway across the area there is the opportunity to give an effective first summer drench onto clean paddocks. It is recommended to worm test prior to drenching and to base drenching decisions on the results. It is likely that young/more susceptible classes of sheep will require a drench, but mobs in flocks with good nutrition and worm control may not. Where testing shows very low worm egg counts, a drench is not recommended as it increases selection for drench resistance (refugia). 

 

Northern Tablelands LLS

Inverell: Andrew Biddle, DV (andrew.biddle@lls.nsw.gov.au)

Seasonal conditions in the western New England are now very much in favour of barber’s pole worm.

Regular rainfall has ensured every possible worm egg in the past 2 months has hatched -  so many paddocks are now loaded up with hungry larvae!

It is important to consider the likely levels of paddock contamination by reviewing the mob susceptibility and egg counts of previous paddock residents to determine ongoing management, making regular WormTests an important management tool.

A couple of worm egg counts I did today had averages around 5000 eggs per gram (epg) with a range of 400 to 18500 epg.

 

North West LLS

Northern Slopes: Ted Irwin, DV (ted.irwin@lls.nsw.gov.au)

Not much to report since last time. One case of dead dorpers was diagnosed as acidosis but the faecal worm egg count (WormTest) was 3000 eggs per gram (epg) indicating that worms were also part of the issue. Other than that it has been quiet on the slopes front.

 

Murray LLS

Albury: Scott Ison, DV (scott.ison@lls.nsw.gov.au) and Mark Corrigan, DV (mark.corrigan@lls.nsw.gov.au) and

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

Eastern region:

Sporadic late-season rain throughout the region will likely see worm numbers on the rise, and the need for a first summer drench either in November or early December is certainly indicated. Worm egg counts (WormTest) will further help to clarify this. A limited number of recent submissions from this area have indeed reflected the need for a first summer drench; three flocks of non-clinical mixed-aged lactating ewes had average strongyle counts of 220 eggs per gram (epg), 300 epg, and 180 epg respectively, and a mob of non-clinical wether lambs averaged 360 epg. Should occasional summer rain continue, producers are advised to monitor mobs with worm egg counts to determine the need for a second summer drench.

Given recent weather conditions, flies will be out in full force and producers are reminded to implement their management and treatment strategies for flystrike, being mindful of Export Slaughter Intervals (ESI) and Sheep Rehandling Intervals (SRI). 

Western region:

Very few worm test results have been received this month. Two tests were collected from 5-6 month old lambs. One lot was from ram lambs that had been treated with an abamectin/ praziquantel mix when they were weaned in August. These lambs were in good condition and not losing weight or scouring. While the average result was 836 epg (strongyle type eggs) the range was from 0 to 2200 epg. A larval differentiation showed that the species present were 65% black scour worm, 12% brown stomach worm and 23% large bowel worm. The other result was from ewe lambs that were in good condition and not scouring or losing weight, and had not previously received any drench. They had an average result of 220 epg strongyle type eggs and 20 epg nematodirus type eggs. The same species of worms were found to be present although in slightly different percentages, 79% black scour worm, 16% brown stomach worm and 5% large bowel worm.

Editor’s note: When to drench? See the Worm egg count thresholds in the table at Question 6 in the Drench Decision Guide.

 

South East LLS

Braidwood: Kate Sawford, DV (kate.sawford@lls.nsw.gov.au)

There have been a number of reports of liver fluke across the district over the past couple of months. Producers have become aware of high burdens of this parasite due to reports from the abattoir, results from WormTests, as well as illness and death in stock.

As with all parasites, the key to control is ‘know thy enemy’.

Adult liver fluke can live in the liver of a number of host species, including sheep, cattle, horses, goats, and alpacas. Adult liver fluke lay eggs that pass through the bile duct, travel through the intestinal tract, and end up in the faeces. Under optimal conditions, the eggs hatch in wet areas. The first larval stage invades the intermediate host, the lymnaeid snail, where they develop and multiply. The final larval stage leaves the snail and swims until it encysts on vegetation, and is the infective stage for grazing livestock. This stage can survive for many weeks at temperatures below 20°C – higher temperatures and desiccation will destroy this infective stage in a short time. If ingested, immature fluke are released in the small intestine from which they enter the abdominal cavity and migrate through the liver tissue. Their final destination is the liver bile ducts where they become adult liver fluke for the life cycle to begin again. The time between ingestion and commencement of egg laying in the bile ducts is around 8-10 weeks.

Editor’s note: WormTest reports on the number of eggs in a known sample of dung. For liver fluke, eggs take about 8-10 weeks after infection to be shed into the faeces so a WormTest then can only detect an infection older than 8-10 weeks. 

There are three things required for liver fluke infection at the property level: 1) A suitable snail species (the intermediate host); 2) An environment that suits the fluke eggs, snails, and larval fluke, namely springs, slow-moving streams with marshy banks, irrigation channels, and seepages; and 3) Adult liver fluke in a host species i.e. sheep that have access to the suitable environment containing the snail species.

Fluke eggs hatch when mean temperatures increase to above 10°C. In summer it takes approximately 21 days for eggs to develop into the first larval stage, while in spring and autumn this part of the life cycle can take up to 90 days. 

The intermediate snail host increases its numbers from spring to late autumn. Snails containing intermediate parasite stages can also survive submerged in dry mud for a long time, and tolerate low temperatures.

So why issues with liver fluke in the Braidwood district during a dry spring? My theory is that during the warm wet summer and autumn of last year, snail numbers increased dramatically due to an increase in suitable habitat, and therefore so did fluke numbers. For producers that missed the most important fluke drench, triclabendazole (effective against all stages of fluke) given in April/May (after the first frosts), adult fluke numbers had ample opportunity to accumulate in grazing livestock. And now the current dry spring in the district is creating nutritional stress and encouraging stock to graze in previously marshy areas where there was green pick that also had the potential to be heavily contaminated with the final infective larval fluke, and you pretty much have a perfect storm.

Disease due to liver fluke can present in a number of ways. In acute infection animals may show signs of abdominal pain and become jaundiced prior to death from blood loss. In sheep, these losses can present very similarly to those from acute barber’s pole worm infection. If infection is less acute, animals may present with jaundice, poor body condition, or pale mucous membranes. Death usually occurs in 8-10 weeks due to severe anaemia and liver failure.

Most commonly, liver fluke infection is quite chronic. The adult liver fluke in the bile ducts consume blood, causing anaemia and chronic liver inflammation. Clinical signs develop slowly, with animals becoming increasingly anaemic, pale, and reluctant to travel. Some may have a decreased appetite and develop ‘bottle jaw’, or fluid under the jaw.   

Concerned yet? If there is a history of liver fluke on your property you probably should be. In sheep, consider a WormTest and make sure you tick the box to include testing for liver fluke, as it requires a different testing process. In cattle, you may be better off looking for antibody to liver fluke in blood samples as looking for liver fluke eggs is generally considered to be less reliable in cattle compared to sheep. Discuss options for testing with your local veterinarian.

Editor’s note: A blood test (antibody [ELISA] test) is available from various laboratories, for example, the NSW Department of Primary Industries State Veterinary Laboratory at Menangle. The faecal antigen test for fluke is available through Charles Sturt University’s Veterinary Diagnostic Laboratory

If you have liver fluke on your property, consider drenching all stock with a drench that is effective against all stages of the fluke (triclabendazole) as well as a regular liver fluke control program. And remember that liver fluke control is more than just about reliance on drenching – consider improved drainage, fencing, and grazing management.

For more details on liver fluke and its control refer to the NSW DPI’s excellent PrimeFact, March 2017, 446 fourth edition, titled “Liver fluke disease in sheep and cattle”. Be sure to discuss your strategy with your local veterinarian.

 

Western LLS

Bourke: Charlotte Cavanagh, DV (charlotte.cavanagh@lls.nsw.gov.au)

Broken Hill: Hannah Williams, DV (hannah.williams@lls.nsw.gov.au)

There weren’t any worm tests submitted from the Western LLS region in the last month.

We did receive some sporadic rainfall and some follow up rain. Temperatures continue to be favourable for larval survival, and we may see some worm burdens develop in sheep that are ‘down on condition’ due to the dry weather conditions.

 

Greater Sydney LLS

Nigel Gillan, DV (nigel.gillan@ils.nsw.gov.au)

Warm weather and recent rainfall have combined to create conditions that favour Haemonchus (barber's pole worm) survival on pasture. Barber's pole is a significant internal parasite of both sheep and goats. It causes anaemia by attaching to the wall of the 4th stomach (abomasum) and sucking blood - signs to look out for include sudden deaths, weakness/lethargy, bottle jaw (sewelling under the jaw) and pale skin around the eyes or gums.

All sheep and goat producers in the Greater Sydney region should be aware of barber's pole worm and should take steps to prevent it becoming an issue. Preventative measures include managing grazing to minimise pasture contamination (e.g. avoiding overstocking, spelling paddocks), and appropriate use of drenches (chemical worm treatments). If you're unsure if worms are an issue in your flock, regular WormTests (worm egg count) are the best way to catch a worm problem before it gets out of hand.  Barber's pole can become a problem very quickly in warm/wet seasons, so it's important to regularly monitor your animals.

Conditions that favour barber's pole also increase the susceptibility of sheep to fly strike.  Producers can manage the risk by shearing/crutching, or strategic use of chemical treatments.