you thought bad resistance (to BPW) was only in the New England?? (a report from Gulgong, central NSW)

Today is your lucky day: three WormMails in one day.

District Vets (LHPAs) from time to time share interesting cases with me.

For example, the ewe in the Forbes district full of lung worm (Dictyocaulus) and scour worms (Worm egg count (WEC) = 2920 eggs per gram faeces (EPG); no Haemonchus seen in the abomasum on necropsy. (Nik Cronin, Forbes).

More alarming is this case from Gulgong, in the Central North LHPA.  

(If you are not familiar with New South Wales, consult this map.  (You may need to zoom in). Gulgong is near Mudgee, northwest of Sydney, and on the southern boundary of the ‘WormKill’ zone).

Dr David Gardiner, District Veterinarian for the Central North LHPA located at Mudgee, has been investigating worm problems on a sheep property near Gulgong.

WormTesting indicates the problem worms are barber’s pole worm (BPW; Haemonchus contortus), black scour worm (Trichostrongylus) and small brown stomach worm (Ostertagia (Teladorsagia) circumcincta). At various times there are high BPW counts and clinical signs of haemonchosis.

A DrenchTest (faecal worm egg count reduction test) in February gave these results (% reduction in egg counts):

Ivermectin (IVM): 33%

Closantel: 68%

Benzimidazole (BZ) / Levamisole (LEV): 100%

Moxidectin: 90%

IVM/BZ/LEV:  100%

LEV (double dose): 100%

Untreated controls: mean WEC =  6384 (100% BPW).

The 100% results for BZ/LEV and for IVM/BZ/LEV might be largely due to the LEV component. Closantel at one third of the dose used here (the recommended dose) should be ~ 100% effective against BPW. Moxidectin, the most potent of the MLs available for sheep in AUS, only managed a 90% FECR.

Larval culture results raised the suspicion of Trichostronglyus and/or Ostertagia resistance to LEV and BZ as well.

One might not be surprised any more by this result in the New England region (northern NSW) or north coast, but it is somewhat more alarming in the Gulgong-Mudgee district further to the south.

SL

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Regional launch meetings (Australia) – Zolvix (monepantel)

(TO: WormMail, QAAH-L, DV, Sheep lists.  Recip. undisclosed. Apologies for list overlap)

Further to my recent mail, a high powered executive in Novartis has just given me permission to pass this on to you.

The first new anthelmintic in ~ 25 years: it should be interesting. A long time between drinks: perhaps we should sip rather than gulp.

Regards

SL

( I have converted this to the older ‘.xls’ format, for those of you who don’t have the file converter or, like me, don’t have the latest version of MS Office)

Zolvix to be launched next week

(TO: District Vets and Sheepos + QAAH-L + WormMail lists)  (Apologies if you get this twice due to overlapping mailing lists)

Greetings All,

It’s no longer a secret that Zolvix (monepantel; Novartis)) is being launched next week in Sydney.

Monepantel represents a brand new drench group (the AADs). It’s world launch was in NZ in autumn 2009. It has since been released in Europe and S/America.

Novartis will be running meetings for farmers and others around Australia during September, with speakers from the company as well as ‘independent experts’ (at least at some meetings).

The ‘independent experts’ see this as a golden opportunity to push some important worm control messages while they talk about how Zolvix fits.

I will pass on details of meetings when I can.

The other new kid on the block is ‘Startect’, released in NZ in July. We may get it in 12-18 months.

Startect (Pfizer) contains derquantel (new; different group from monepantel) and abamectin (not so new).

But you have heard all this in various issues of WormMail / Turning the Worm ……

Obviously it’s important we take care of these new chemicals. Novartis has commissioned studies (computer modelling by Dobson and others) on how best to use monepantel. Papers on this should be published soon-ish.

Regards

Steve

WormFax NSW – July 2010 now on-line; Drenches – what is effective?

To WormMail list (recipients undisclosed).  WormMail 201008181000

WormFax NSW – July 2010 now on-line

http://www.dpi.nsw.gov.au/aboutus/resources/periodicals/newsletters/wormfax

WormFax is a summary of WormTest results (in sheep) from around New South Wales (NSW).

Drenches – what is ‘effective’ ?

Hosking (2010) sums it up:

"..there are differences in efficacy standards applied between countries, for example, VICH (which most countries adopt) requires greater than or equal to 90% for a control claim whereas the APVMA in Australia requires greater than 95% for control and greater than 99% for persistent activity claims".

VICH (International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products ), officially launched in April 1996,  is a trilateral (EU-Japan-USA) programme aimed at harmonising technical requirements for veterinary product registration

Hosking BC (2010). Recent experiences in developing an efficacy dossier for a new sheep anthelmintic. ICOPA, Melbourne August 2010.

Regards

SL

Two new kids on the block in NZ (novel anthelmintics’ – ‘Zolvix’ and ‘Startect’)

WormMail list (recip. undisclosed).  WormMail 201008131400

WormMail readers will be aware that there are two new sheep drenches in the pipeline:

* ‘Zolvix’ (Novartis), which has monepantel as its active ingredient, and is a member of the new class of anthelmintics, the AADs (amino-acetonitrile derivatives), and

* ‘Startect’ (Pfizer), which contains the novel anthelmintic derquantel, in combination with existing anthelmintic, abamectin, which is a macrocyclic lactone (ML). Derquantel belongs to the new class, the spiroindoles.

Zolvix was released in New Zealand in autumn 2009, and Startect was launched in NZ just a few weeks ago.

It is thought that Zolvix could be launched in Australia in the next month or so, and one might guess that Startect could come on line in this country 12-18 months later.

There was about 25 years between the launch of the MLs and the recent releases of the AADs and spiroindoles. With this in mind, it would be overly optimistic to expect a continuing trickle of new drenches over the next decade or so.

So, the pressure is on to take good care of these new drugs, and to use them smartly so as to extend the life of older drenches as well.

(But, what’s in a  drench name?. Zolvix reminds me of that hard, grey, gritty soap you use to clean grease, stubborn stains and epithelium off your hands (Solvol). And Startect perhaps is something astral travellers use to get rid of Klingons…  ?)

Regards

SL

Sheep worm counts and drench decision aids

To: WormMail list (recip. undisclosed) WormMail.201008051430

When to treat sheep for worms is a common question.

Various decision aids have been used over the years. For example,a traditional approach has been to simply combine drenching with other management events, including joining (tupping or mating in other countries), off-shears, pre-lambing, at lamb marking, and at weaning.

In the pastoral areas such as the western division of NSW, where sheep are less frequently mustered, sheep may be drenched when they are mustered for other reasons.

In the Haemonchus – endemic areas of northern NSW and SE Qld (higher rainfall areas, eg > 700 mm, with summer rainfall dominance), drenching of young sheep in summer was largely a monthly affair prior to the 1982 release of the long-acting anthelmintic, closantel.

As well as considering the calendar (for management events and the seasonality of different types of worms), producers and advisers consider indications of worm burdens (typically worm egg counts (WECs)), the condition of sheep, the age and class of sheep, and their nutritional status.

As an aid in making decisions, skilled producers and advisers have always considered a number of factors, as outlined above. Drench decision aids merely facilitate this process and can take the form of charts, graphs and tables, or interactive computer programs or websites.

Following is a bird’s eye view of various decision aids.

The Brain

The brain has been a popular decision aid among hominins over the 2 million years or so of its development. However, despite their name, Homo sapiens have sometimes been less than wise in the use of this decision aid.

Seriously though, as intimated above, skilled operators use a combination of logic and intuition, weighing up various factors when deciding whether to drench or not. In essence, this is what all decision aids do. While superficially decision aids may look quite different, they are fundamentally similar, being built on similar foundations.

Image credit: Simpsons Trivia.

WormKill – 1980s

The original WormKill (1984 to early 1990s) was a simple, prescriptive strategic program. The WormKill table in effect was a decision aid.

Here is an example of the WormKill table from July 1986:

There are two further things to note.

Firstly, promotion of grazing management as part of worm control is not new.

Secondly, although WormKill (1980s versions) was a prescriptive program, regular worm egg count (WEC) monitoring was done on a number of properties. A WEC of 500 strongyle eggs per gram of faeces (epg) was used as a benchmark, with drenching considered advisable when WECs significantly exceeded this level.

WormTest for livestock and guide to egg counts – Primefact, I&I NSW

This Primefact (2003 and 2007 editions) discusses various factors in interpreting WECs. Two tables provide guidance:

Source: Primefact 480. http://www.dpi.nsw.gov.au/agriculture/livestock/sheep/health/internal/wormtest-eggcounts

The following table has been prepared for the revised editions of Primefact 480, and also ‘WormKill – the basics’ (in preparation).

The Rendell Matrix

David Rendell is a sheep veterinary consultant in western Victoria. He developed this matrix some years ago: the version below is from 2002. He has tested it in the field among his clientele.

Source: The Weekly Times 18.9.2002.

Remember that decision aids are applicable only for the areas for which they have been developed. The WECs (aka FECs) in the table above come mainly from black scour worm and brown stomach worm, with little from barber’s pole worm, apart from farms close to the Victorian coast.

And the make up of ‘scour worms’ can vary from one area to another. In the NSW northern tablelands Trichostronglyus colubriformis tends to be more common than another type of black scour worm, Trichonstronglyus vitrinus, which tends to be more pathogenic and produces fewer eggs. Also, the further one goes north in summer rainfall areas, small brown stomach worm (Ostertagia (Teladorsagia) circumcincta) – a relatively poor egg layer – becomes less common, to the point of being uncommon in Queensland. As one moves south into the non-seasonal and especially the winter rainfall areas of south eastern Australia, T. vitrinus and Ostertagia become more important.

Vet Lab Manual – Industry & Investment NSW (formerly Dept. Primary Industries)

Here is a guide to worm egg counts in sheep from the I&I NSW Vet Lab Manual. http://www.dpi.nsw.gov.au/agriculture/vetmanual/specimens-by-discipline/parasitology/egg_counts

These WEC benchmarks may seem alarmingly high: that’s because this table is not really a drench decision aid, but rather a guide to WECs that may be associated with clinical disease.

By the time parasitism is clinically obvious, productivity and economic returns have already taken a substantial hit, hence the lower benchmarks used in most drench decision aids.

In round figures, internal parasites cost the Australian sheep industry $400 million a year, and about 80% of this is from production losses, most of which is not obvious. This is why objective measurement (usually by way of worm egg count monitoring) is an important part of worm control.

Ask the Boss

Ask the Boss is the decision aid in WormBoss. http://www.wool.com/Grow_WormBoss_Ask-the-Boss.htm

The user interacts with Ask the Boss, and a worm egg count result is assumed.

The user is then presented with recommendations.

Decision Aid – IPM-S project (summer rainfall)

This is one of the more recent drench decision aids. It was developed by Lewis Kahn and others (UNE / Sheep CRC) as part of the AWI Integrated Parasite Management-Sheep (IPM-S) Project.

The aid was developed for and tested on several IPM-S project properties in the summer rainfall zone of north eastern NSW and south-eastern Queensland.

The aid’s ‘interface’ can be computer-based (interactive Excel spreadsheet) or hard copy (a table / matrix). Like other aids it aims to take into account a number of factors including WEC, condition of sheep and nutrition.

Below are snapshots (computer-based and hard copy versions):

More information on IPM-S: http://www.wool.com/Grow_Animal-Health_Integrated-Parasite-Management_Integrated-Parasite-Management-sheep.htm