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Sheep drench resistance in Australia – how common? Stephen Love Veterinarian/State coordinator-internal parasites NSW Department of Primary Industries.

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Presentation on theme: "Sheep drench resistance in Australia – how common? Stephen Love Veterinarian/State coordinator-internal parasites NSW Department of Primary Industries."— Presentation transcript:

1 Sheep drench resistance in Australia – how common? Stephen Love Veterinarian/State coordinator-internal parasites NSW Department of Primary Industries Australian Sheep Veterinarians Conference, South Australia, 2011

2 Drench resistance – who cares?  Important because worms are important  Even with good IPM, drenches are important  Worms are important because –Economic cost –Animal welfare –Farmer satisfaction (when sheep are healthy) Stephen Love, 2011

3 Cost of sheep worms in Australia Sackett and others, Stephen Love, 2011 About 80% of worm cost is production losses…. i.e. ~ invisible

4 Cost of worms – northern NSW (Kelly) Gareth Kelly. Studies over 2 years on sheep on farms in northern tablelands, NSW. Cited in Australian Farm Journal, Sept (See also Kelly, Kahn, Walkden- Brown An Prod Sci ) Stephen Love, 2011

5 Saucy details  Sources: Colleagues around Australia  Their sources Older large surveys in AU (1970s-1990s) On-going WECRTs on farm Observations  What we are saying: –Just best-guess estimates of prevalence –‘Resistance’ generally means <95 WECR%  More details in paper than presented here Stephen Love, 2011

6 Collaborators in crime M Lyndal-Murphy, R Nielsen, J Bailey, A Biddle, S Eastwood S Slattery, L Reid, D Lunau, T Irwin RB Besier, J Lyon, R Woodgate D Lehmann Many thanks! P Nilon D Gardiner, M Rogers, B Edmonstone, J McDonald, W Johnson, R Templeton, B Watt. D Star D Salmon, H Suddes D Hucker C Haylock C Trengove, S Ellis Stephen Love, 2011

7 Resistance – how fast? Sheep drenches (AUSTRALIA)Released1 st report resistance Years Thibenzole ® [BZ] Rametin ® [OP] 1960s1981~20? Levamisole [LEV] Closantel Ivomec® [ML] Cydectin® [ML] Combinations - triples and 4-way [Resistance? Yes!] Modified from Love, 2011-Primefact-Drench Resistance. BZ=benzimidazoles, OP=organophosphates, LEV=levamisole, ML=macrocyclic lactone; combinations include ML+BZ+LEV+/-Closantel (CLOS) Stephen Love, 2011

8 Broad overview of prevalence (AU) Above graph. Australia-wide thumbnail sketch. (Excl pastoral/arid zones) Exceptions e.g. lower prevalence of LEV resistance in Haem. All products on market affected except ‘Zolvix’ (and ‘Startect’ –not here yet) Even 3- and 4-way combinations in some areas Modified from Love, 2011-Primefact-Drench Resistance. Zolvix®=monepantel, Startect®=derquantel+abamectin Stephen Love, 2011

9 summer rainfall zone (~700mm + pa) Stephen Love, 2011 New England region of NE NSW + SE Qld Queensland New South Wales Western Australia South Australia

10 Summer rainfall zone (Haemonchus-endemic)… * Date on graph: indicative only *Prevalence ML resist. Haem: Mox >30% farms (+50%? emerging), IVM: ~ 80+%. * Resist to combos * NAP – reports of resist : Haem (Green, Trich (Le Jambre) + cases with reduced efficacy *CLOS and TCBZ-fluke * ML (mox) resist Trich (sheep) confirmed Qld (Knox et al). BZ:benzimidazole, LEV:levamisole, ML:macrocyclic lactone, CLOS:closantel, Haem: Haemonchus contort., Trich:Trichostrongylus sp; Tel: Teladorsagia circum. NAP:naphthalophos; MOX:moxidectin; IVM:ivermectin Stephen Love 2011

11 NSW North West Slopes ( mm rain pa) similar resistance patterns to higher rainfall summer rain fall zone (New England to the east, but lower prevalence (about half) ML resistance not yet detected Pastoral zones of NSW/Qld (western plains) (<400 mm) Resistance status unknown, but consider status of the NSW Riverina (also low rainfall) Stephen Love, 2011

12 NSW Central and Southern Tablelands/Slopes *some cases suspect ML-resist. Trich. * BZ resist. Nematodirus common * cases with reduced MOX protective period seen with Tel. * some cases MOX resist Haem *NAP+BZ or LEV commonly % WECR WECR: worm egg count reduction. Date in graph indicative only; see paper for details Stephen Love, 2011 Mostly uniform rainfall: ~ mm pa

13 NSW South West slopes (Cootamundra-Gundagai area) * D Star, Novartis. * OK, histogram slightly ridiculous as n=5 (n is from 1-5 for the different results. See paper) * A+B+L=ABA+BZ+LEV * ‘Resistance’ <95% WECR (may not be resistance with NAP); Suspect R: <95% WECR but control WEC for genus was <150. * Suspect ML resist Trich Stephen Love, 2011

14 Western Victoria (1) Stephen Love, 2011 * D Hucker (Para Tech Services). * WECRTs 2008, 2010, 2011 (n ranges from 8 to 99). * Strong =strongyle, usually Tel+.Trich * B=BZ, L=LEV, N=naphthalophos, P=pyraclofos

15 Western Victoria (2) Stephen Love, 2011 * D Hucker (Para Tech Services). * See notes previous slide, and paper. * I=IVM=ivermectin. A=ABA=abamectin. MOX=moxidectin. B=BZ. L=LEV. * Most IVM resist in past in Tel. Some of MOX resist may be in Trich.

16 Tasmania (P. Nilon, 2010)  Tas. About 10 years behind mainland (wrt resistance)  Tel still the genus with most resistance  Most farms: WECR 99% for MLs.  Trich often resist to BZ, rarely BZs  Combinations work on most.  OP use still uncommon  Cases of suspect ML-resistant Trich Stephen Love, 2011

17 South Australia C Trengove (s-east); S Ellis (mid north). Strong=strongyle, mostly Tel + Trich. Haem rarely an issue; Fasciola rare. B=BZ, L=LEV. IVM usually 97-98% WECR (Trich), 85-95% (Tel). One case (WECR for IVM): Trich 80%, Tel 60% Stephen Love, 2011

18 South Australia – Kangaroo Island (1) % WECRTS with <95% WECR (mostly Trich/Tel) (n=44) (n=19) (n=21) BZ98 LEV89 BZ+LEV3776 (BZ+LEV)x2538 IVM7593 ABA38 MOX38 IVM+BZ+LEV2550 ABA+BZ+LEV20 PYR+BZ25 NAP+BZ+LEV1146 Stephen Love, 2011 Source: D Lehmann

19 South Australia – Kangaroo Island (2) Debra Lehmann. (Not in conf. proceedings, but in amended paper ) Haemonchus is rare and liver fluke is absent. PYR=pyraclofos. NAP=naphthalophos Resistance emerging to MOX(idectin) LA injection. BZ, LEV, BZ+LEV resistance: prevalence is similar in both Trich and Tel. ML resistance seen in Tel; no evidence of resistance in Trich. Evidence of reduced efficacy of OPs against Tel and Trich.

20 Concluding comments  MLs –Rapid increase prevalence last 10 years, notably Haem (summer), Tel (uniform/winter) –All MLs (avermectins, milbemycins) now affected –ML-resist Trich emerging  How long will long acting products provide a safey net?  OPs – evidence of declining efficacy, many regions

21 Thank you for your attention


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