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New South Wales worm, flies and lice update - April 2014

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

Good widespread rain over the New England/North West region in late March has stimulated worm activity. Some sheep producers are now dealing with a late surge in Haemonchus levels, seen not only by high and rapidly rising worm egg counts, but also clinical symptoms and some reports of deaths. Not everyone is experiencing this immediate challenge, however. Some VHR monitor clients who have been able to establish low worm paddocks over the spring/summer period and who typically employ some form of grazing management are seeing the continued benefit of such practices, with worm egg counts remaining in the low to moderate range and no post-rain drench required to date.

April has once again proven to be a dry period for the majority of the north of the state. This will have limited the ‘window’ for Haemonchus development. Heading into May and with frosts imminent, there is little time left for this species to multiply. However, infective larvae will continue to persist on pasture, so continued monitoring is required.

In the Central Tablelands of NSW, worm egg count results have typically been low to moderate (i.e. less than 300 epg mean) over the past month. Three properties, however, were found to have significant (approx. 2000 epg mean) worm burdens in the Gunning/Goulburn district, all of which were Haemonchus dominant.

Liver fluke infections in both sheep and cattle are more prevalent in the New England region this autumn. Stock have been forced to graze in the normally wet areas of paddocks, ingesting liver fluke in the process. Treatment for this parasite is advised over April/May (if not already given) on those properties with known positive fluke status. If uncertain or seeking confirmation, fluke egg counts on faeces or blood antibody analysis are the common laboratory tests utilised to establish liver fluke status of livestock.

 

Armidale: Stephen Love, Veterinarian, Parasitologist, NSW Department of Primary Industries (stephen.love@dpi.nsw.gov.au)

April-May is prime time for a strategic fluke drench on flukey farms in south-eastern Australia. And this is the time to bring out the big guns, i.e. the most effective flukicides, which means triclabendazole-based drenches in sheep, goats, alpaca and cattle. In cattle, Nitromec(R) is another highly effective option for killing liver fluke (Fasciola hepatica).

Some properties may also need a fluke drench in August (if in doubt, test), and those with a severe fluke problem may even require a third drench, in summer.

Consider rotating between unrelated flukicides. Also consider management options to reduce exposure of stock to wet, flukey areas on farm.

Not sure if you have fluke? Check by getting a liver fluke egg count done on dung samples, or getting blood samples checked for antibodies to liver fluke (Liver Fluke ELISA).

Consider checking the efficacy of the fluke drench afterwards (fluke resistance does occur): get a fluke egg count done 28 days after drenching for liver fluke.

If you have fluke, make sure your vaccination program covers your stock for ‘black disease’ (Clostridium novyi).

On the human health side of things, if you live in a flukey area you might want to think twice about using water cress from local creeks in your salads.

More information:
http://www.wormboss.com.au/worms/flukes/liver-fluke.php
http://www.dpi.nsw.gov.au/agriculture/livestock/sheep/health/liverfluke-disease-sheep-cattle
http://www.dpi.nsw.gov.au/agriculture/vetmanual/specimens-by-discipline/parasitology/fasciola

Prepare for spring lambing
A critical element of best practice sheep worm control is preparing low worm-risk paddocks for lambing ewes and for weaners.

For those who lamb in spring, preparing the lambing paddock needs to begin by joining time or even a month earlier in 'cool' areas like tablelands districts of NSW. In these areas infective larvae on pasture die off more slowly due to cool to cold conditions over winter. Yes, the larvae can survive frosts in most areas.

The details and the preparation time needed varies with time of lambing and location, so it is critical that you check what is right for your region by consulting 'Your Program' in WormBoss. The information therein is 'state of the art', but a whole lot easier to read and apply than you may think. And the payback is considerable. An ounce of prevention ...
More information: http://www.wormboss.com.au/programs.php

 

LOCAL LAND SERVICES DISTRICT REPORTS

Riverina LLS

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

While few counts were spectacular with the recent uptake of larvae since the wonderful autumn break, egg counts may not reflect the total burden (immatures do not lay eggs). We have also been seeing some counts with a very high proportion (>95%) of the larvae identified as small brown stomach worms; a species that often has low egg counts despite significant worms numbers in the sheep. Not surprisingly, clinically there have been some reports of good responses to drench when counts were less than would normally trigger action.

Small brown stomach worms are the most common worm to be resistant in this area, so where they are present as a high proportion of the count, the question arises: has this come from the seasonal conditions or is it reflecting resistance?

A post-drenching sample 10–14 days after drenching with a request for the larval identification can be very helpful in determining if the drench used was fully effective.

There is plenty of research that shows drenching at lamb marking is a waste of time and money (except in the most exceptional circumstances). There are also drenches with specific advice not to drench lambs less than 6 weeks of age due to toxicity concerns. Drenching lambs at marking with a triple with that warning advice on the label resulted in the death of three of the 140 lambs treated.

South East LL

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

The turn-around in pastures and water supplies on the southern tablelands is extraordinary, described as the best autumn in more than three decades. Feed quality is high, reflected in the improved condition of sheep. Once again, the pattern of worm infection varies greatly from property to property, and even paddock to paddock, depending on the presence of barber's pole worms (Haemonchus).

It was hot enough and dry enough for long enough to give good effect to a first summer drench, with egg counts on many properties showing no need for a second summer drench. If there is no barber's pole worm, those egg counts are still pretty low. But worm egg counts are now climbing rapidly on properties and in mobs that had only a small amount of barber's pole worms a few weeks ago. Some sheep have shown typical symptoms of barber's pole infection; they flop down with anaemia when mustered, some have bottle jaw, while others die suddenly in good condition with no scouring. In most cases, though, infection has been identified through worm egg counts and treated early.

It is now too cold for new Haemonchus larvae to develop from eggs. But any larvae already on pastures will remain viable through winter, even though these will be diluted by the sheer volume of feed now available. Many producers took the opportunity to confine big mobs of ewes to ‘sacrifice paddocks’ while giving the rest of the property time to respond to autumn rain. These paddocks should be treated with caution over the next few months, with more frequent worm egg counts to monitor sheep running in them during winter.

Beware that liver fluke causes the same symptoms as barber's pole worms, and the dry spring and summer forced sheep to graze into creeks and swampy areas where liver fluke are found. A liver fluke blood test would be the most reliable way to identify liver fluke at this time of year.

Nematodirus (thin-necked intestinal worm) is still contributing to scouring in a few mobs of weaners. Because these worms are poor egg layers, worm egg counts often look relatively low, and the scouring is wrongly attributed to ‘the green pick’.

The combination of warmth and moisture saw an expected jump in flystrike reports in sheep. The seasonal conditions provided an all too rare test of long-term breeding and selection, with some properties experiencing a high proportion of body strike associated with fleece rot, while neighbouring properties were unaffected. Breech strike was typically associated with scouring and dags.

Central West LLS

Dubbo: Evelyn Walker, DV (evelyn.walker@lls.nsw.gov.au)
Worm egg counts from the Dubbo and surrounding areas have varied from nil to medium (averaging 500 epg.) Unfortunately, the barber's pole worm is still hanging around in our area. The worm population overall consists of about 82% barber's pole worm and the remaining a mix of black scour and brown stomach worms. One property had a spike of worm levels just 7 to 8 weeks after drenching lambs. Increased rainfall and inadequate pasture spelling time likely contributed to an outbreak in this case. However, no deaths have been reported this month due to worms. Recent sheep deaths in the area have been due to red gut, grain poisoning, and clostridial disease. 

Murray LLS

Deniliquin: Dan Salmon, DV (dan.salmon@lls.nsw.gov.au)

There have been very few wormtests in the Murray region. Most are from people with good parasite control and the counts have reflected that.

Even in the east, counts in flocks that had a drench early in the summer are very low.

In the west, some flocks have low egg counts despite several years without treatment.

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

Most worm tests in the area have come up with low numbers, but after the recent rain one property had a count of 3804 av. Strongyle (highest 10,240 ) 100% Haemonchus, plus 56 Nematodirus.