MERIAL ANIMAL HEALTH AUCKLAND – NZ OCTOBER/2005 HELMINTHIC RESISTANCE TO DRUGS IN RUMINANTS E. L. BORDIN DVM, Pathologist

38.9 % 20.7 % 18.4 % 18.2 % 3.8 % MOST IMPORTANT PARASITES (VETERINARY PERCEPTION) TICKS INTERNAL PARASITES HORN FLY OTHER FLIES/MYIASIS LICE – MANGE

n NO n NO DATA n YES n NO n NO DATA n YES *FAO (papers and reports) REPORT ON HELMINTHIC RESISTANCE*

MORE THAN TWO SPECIES* n < 2 PARASITE SPECIES n > 2 PARASITE SPECIES n < 2 PARASITE SPECIES n > 2 PARASITE SPECIES *FAO

 Sheeps and Goats : Haemonchus contortus, Trichostrongylus colubriformis and Ostertagia circumcincta to BDZ, IVM, LEV/MOR., and MOX  Horses : Small strongyles to all groups but IVM/MOX. Ascarid to ivermectin ( lactones ?)  Cattle: Already described for Fasciola hepatica and Haemonchus spp to BDZ, Fasciola hepatica to closantel and to rafoxanide. Potential resistance to nitroxinil. Nematode resistance already described to macrociclic lactones Adapted from Prichard, R, (2002) HELMINTHS PARASITES RESISTANCE

Spreading* South America, Eurasia Cooperia spp.Cattle SpreadWorldwide Haemonchus contortus Sheeps and Goats ExtensionRegionNematodeAnimal Spreading*South America H. placei, T. colubriformis, Nematodirus spp Cattle Unknown *North America Parascaris equorum Horses RESISTANCE TO IVERMECTIN Adapted from Prichard, R, (2002) * Based on field evidences, on FEC and other experimental confirmations

* Cooperia oncophora, Cooperia spp, Trichostrongylus sp, Haemonchus spp A) Echevarria, et al. B) Vermunt, et al; Fiel, et al. C) Paiva, et al. D) Anziani, O.S; Suarez V. E) Costa, Alvimar. F) Lima, W; Malaco, M; Bordin, E.L. (not published) Brazil – E/F2004 FECRT / Larval CultureArgentina - D 2003 FECRT / Larval Culture / Necropsy FECRT / Larval MotilityBrazil - C2001 FECRT / NecropsyArgentina - B2000 FECRT / Larval CultureBrazil - A1999 FECRT / NecropsyNew Zealand1998 FECRTUnited Kingdom1996 DIAGNOSIS / METHODPLACEYEAR CHRONOLOGY OF SOME REPORTS OF NEMATODE RESISTANCE + TO MLs ON CATTLE

*Coprocultures ** Necropsies Anziani, O; Fiel, C. A. ProvinceDrugGenera*Species** Santa FeAvermectinsCooperiaC. pectinata Buenos Aires – West/Middle Avermectins BDZ Cooperia Haemonchus C. oncophora H. contortus Buenos Aires – North; Entre Rios, Corrientes AvermectinsCooperiaNot determinated La PampaAvermectinsCooperiaNot determinated Santa Fe – Middle Avermectins BDZ Haemunchos Cooperia H. placei, C. oncophora, C. pectinata CordobaAvermectins and BDZ Haemunchos Cooperia Ostertagia C. punctata, H. placei, O.ostertagi, C. oncophora, C. punctata CATTLE NEMATODE RESISTANCE TO ANTHELMINTHICS IN ARGENTINA APRIL 2000 – NOVEMBER 2003

FEC – Comparative – Field Study BRAZIL 40% reduction Ivermectin 3,5% 45% reduction Doramectin 1% 36% reduction Ivermectin 3,15% 7% reduction Control Comparative Results (0-29) Mean FEC Day “0” +29 Treatment Group

Number of Parasite Larvae (Days 0 – 29) 100% reduction020Oesophagostomun Increase of 33%3332Haemonchus Increase of 139%6748Cooperia Ivermectin 3,5% 100% reduction026Oesophagostomun Increase of 247%8936Haemonchus Reduction of 71%1138Cooperia Doramectin 1,0 % 100% reduction014Oesophagostomun Reduction of 62%1540Haemonchus Increase of 85%8546Cooperia Ivermectin 3,15%

Country Farms (n) Antihelminthics: % resistant parasites (farms) AlbenIverLevRfxClosB+LMean South Africa a Paraguay b ? Uruguay c Brazil d Argentina e a Van Wyk et al. (1999); b Maciel et al. (1996); c Nari et al. (1996); d Echevarria et al. (1996); e Eddi et al. (1996). Haemonchus spp RESISTANCE TO SEVERAL ANTIHELMINTHICS: COMPARISON BETWEEN THE SITUATION OF SOUTH AFRICA AND COUNTRIES OF SOUTH AMERICA (1999)

Herd Place A Place B LVZABZIVMLVZABZIVM Mean (Barreto, M. A et al, 2002) EFFICACY (%) OF SEVERAL FORMULATIONS BASED ON THE COMPARISON OF EGG COUNTS OF GI PARASITES IN GOATS (FECRT) - BRAZIL

Herd Place A Place B LVZABZIVMLVZABZIVM Mean (Barreto, M. A et al, 2002) EFFICACY (%) OF SEVERAL FORMULATIONS BASED ON THE COMPARISON OF EGG COUNTS OF GI PARASITES IN GOATS (FECRT) - BRAZIL

Insistence on treating all the animals in the herd Emphasis on the reiterated control that ignores the crucial role of refugia Fail on distinguishing maximum production X optimal “We have to admit that our previously efforts on the administration of resistance were useless at the best and contra-productive at worst” MAJOR PROBLEMS IN SHEEPS (BARGER, I., Australia)

Conclusions Sheep/Goats – Markets - Brazil Parasite Resistance has reached its maximum level. Producers start to adopt FEC for monitoring and FAMACHA ® /PCP just for sensible animals. Product combinations (Triton ® is strongly included in PCP). Producers are adopting a moving/treating management. When available a cattle/sheep combined pasturing has been recommended. It is necessary an urgent product registration harmonization. Sheep and goats markets are growing. Sheep and goat population: 40 MM Average meat consumption – 0,7 kg/year

Conclusions Cattle Market - Brazil Less expensive avermectin generics available (More than 60). Avermectin generics mostly used to control OPs and SPs resistant tick strain. Haemonchus spp. and Cooperia spp. more involved. Diagnostic of resistance based on FEC and larvae culture. Helminthic resistance is still incipient but potentially a short time threat. Market needs a combined formulation (LVS plus AVM?). PCPs for young animals has been claimed to avoid resistance. It is necessary an urgent product registration harmonization.

CONCLUSION The resistance tends to increase, for both parasites, internal and external, but can be mitigated through the use of drugs, or combinations of drugs, effectively used in oriented and monitored protocols