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Integrating Anthelmintics, FAMACHA and Other Alternative Measures for Controlling Nematodes in Small Ruminants

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PowerPoint presentation for FAMACHA workshops
by Jim Miller, retired Louisiana State University

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Integrating Anthelmintics, FAMACHA and Other Alternative Measures for Controlling Nematodes in Small Ruminants

  1. 1. Integrating Anthelmintics, FAMACHA and Other Alternative Measures for Controlling Nematodes in Small Ruminants American Consortium for Small Ruminant Parasite Control
  2. 2. Overview • Biology of Haemonchus contortus • Understanding drug resistance • Diagnosis of drug resistance • Concept of “Smart Drenching” • FAMACHA – concepts and practice • Non-chemical approaches
  3. 3. Background To The Problem • Abomasal and intestinal worms are the most important (??) pathogens of sheep and goats • Worm control has relied almost exclusively on the frequent use of anthelmintics – Resistance is now common • American Consortium for Small Ruminant • Parasite Control Group Formed in 2001
  4. 4. Gastrointestinal Nematodes (Worms) of Small Ruminants • Abomasum • Haemonchus contortus* (southeast US) – Barberpole worm • Teladorsagia circumcincta – Brown stomach worm • Trichostrongylus axei • Small intestine • Trichostrongylus colubriformis – Bankrupt worm • Cooperia • Nematodirus • Coccidia (protozoa, not worm) • Large intestine • Oesophagostomum – Nodular worm • Trichuris - Whipworm
  5. 5. Haemonchus contortus (Barberpole Worm) • Sheep, goats, deer, exotic ruminants • Blood-sucking worm • Highly pathogenic • Anemia • Hypoproteinemia -- “bottle jaw” • Most important worm parasite in sheep/goats raised in warm/wet environments • Southeastern US, but becoming more of an issue in northern cooler areas with warm wet summers
  6. 6. Life Cycle of H. contortus http://www.ext.vt.edu /pubs/sheep/410- 027/figure1.html
  7. 7. Why is H. contortus such a problem? • Evolved in tropics • Thrives in warm/wet climates • Very fecund ~ 5,000 eggs per day • 30 goats/sheep • 300 worms/animal • 1.5 million eggs per day per animal • Over 1 billion eggs per month • Long transmission season - southeastern US • Short life cycle – 4/5 weeks during summer • Immunity to worms is slow to develop • Can take up to 6-8 months of age • Immunity wanes around the time of parturition
  8. 8. Background to the Problem • Age of modern anthelmintics • Parasitologists recommended strategies that maximized benefits of deworming • Ignored resistance issues • Over-reliance on anthelmintics • Over-use of anthelmintics • Prophylactic vs. therapeutic • Loss of common sense management- based approaches
  9. 9. We Created Our Own Problems • This strategy has turned out to be shortsighted and unsustainable • The prevalence of multi-drug resistant H. contortus is extremely high • We are at risk of having no effective anthelmintics to use in the near future • “We have what we have” • > $200 million to develop new drug • New ones coming (hopefully, when is ??)
  10. 10. Anthelmintic Resistance • The ability of worms to survive dewormings that are generally effective at the recommended dose rate • Considered a major threat to the current and future control of worm parasites of small ruminants and horses • Becoming an issue in cattle • Development of resistance • Deworming eliminates worms whose genotype renders them susceptible • Worms that are resistant survive and pass on their “resistant” genes • Resistant worms accumulate and finally deworming is ineffective • Clinical definition = <95% reduction in fecal egg count
  11. 11. Parents Selection for Resistance Resistant Next Generation Resistant Deworming
  12. 12. Where Did We Go Wrong - What Actually Causes Resistance? • Deworming at frequent intervals • Many farms > 6 dewormings per year • Dewormiing all animals at same time • No refugia • Deworming and moving to clean pasture • No dilution • Under dosing • Worms with low-level resistance survive
  13. 13. Refugia • The proportion of the population that is not selected by deworming • “In Refuge” from drug effect • Provides a pool of susceptible genes • Dilutes resistant genes in that population • Until recently, overlooked as the most important component of anthelmintic resistance selection
  14. 14. Resistance is Inevitable • Natural biological consequence of deworming • What Can We Do ??? • Rate of selection for resistance can be greatly reduced • ‘Smart Drenching’ • FAMACHA • Preserve dewormer efficacy for as long as possible
  15. 15. Anthelmintics (Dewormers) • Benzimidazoles • Albendazole (Valbazen) • Fenbendazole (Safegard, Panacur) • Oxifendazole (Synanthic) • Imidazothiazoles • Levamisole (Prohibit, Tramisol, Levasol, Rumatel) • Macrocyclic Lactones • Ivermectin (Ivomec) • Doramectin (Dectomax) • Moxidectin (Cydectin) • Eprinomectin (Eprinex, LongRange) • Amino-acetonitrile derivatives (AAD) – Canada, Not in US • Monepantel (Volvix) • Spiroindoles – Canada, Not in US • Derquantel with abamectin (Startect)
  16. 16. Prevalence of Resistance (H. contortus) • Common • Benzimidazoles (Valbazen, Panacur, Safeguard), Ivermectin (Ivomec) and Doramectin (Dectomax) • Lowest level of resistance • Levamisole (Prohibit) • Becoming widespread rapidly • Moxidectin (Cydectin)
  17. 17. Is It Really as Bad as it Sounds? • Resistance is relative • Not all worms on farm are resistant • Killing some worms may relieve disease symptoms • Clinically it appears that the deworming was effective • Animals require deworming again very soon • Eventually most worms become resistant and deworming fails – animals may die
  18. 18. Scatter Plot of Anthelmintic Efficacy on 18 Goat Farms
  19. 19. What Does All This Mean For The Small Ruminant Industry? • Anthelmintics can no longer be thought of as a management tool to be used exclusively to improve animal productivity • Reality = effective long-term control of worms (especially Haemonchus) will only be possible if anthelmintics are used intelligently with prevention of resistance (not disease per se) as a goal
  20. 20. When to Suspect Resistance • When fecal egg count remains high or clinical signs persist following deworming • One must also rule out other possibilities with similar clinical signs • Other infectious disease • Nutritional deficiency • Knowledge of prevalence of resistance in the local area
  21. 21. Causes of Dewormer Failure Other Than Resistance • An inadequate dose was administered • Underestimated weight • Spilled/spit-out • Errors of calculation • Suspensions not thoroughly mixed before use • Invalid extrapolation of dose from other hosts • Activity is reduced • Beyond its expiration date • Stored improperly • Errors in methods used for fecal egg count • An improper or non-quantitative egg counting technique was used • Fecal egg count was rechecked too late after deworming to detect an effect of a short acting dewormer (reinfection has occurred) • Fecal egg count was rechecked too soon for long acting dewormer to have worked
  22. 22. McMaster Fecal Egg Count • Quick, easy to perform • Should be part of routine services offered • Slides available from: • Chalex Corp (vetslides.com) • chalexLLC@gmail.com – Quickest response • P.O. Box 981956 • Park City, UT 84098 USA • FAX: (503) 914-0379 • Green grid
  23. 23. Diagnosis of Resistance • Producer/Veterinarian in the field -- simple on-farm anthelmintic trial • Fecal egg count reduction test • Fecal egg count at deworming and again 7- 14 days later • Laboratory – DrenchRite • Dr. Ray Kaplan’s lab (UGA) - $$$ • Only one test needed per farm • One pooled fecal sample from 10 animals • All 3 major dewormer classes tested in assay
  24. 24. “Smart Drenching” • An approach whereby we use the current state of knowledge regarding: • Host physiology • Anthelmintic pharmacokinetics • Parasite biology • Dynamics of selection for resistance • Resistance status of worms on the farm • To develop strategies that maximize the effectiveness of dewormings while also decreasing the selection of resistance
  25. 25. Proper Dose/Drenching Technique • Ensure proper dose is delivered • Proper technique when drenching ruminants is very important • Critical that the full dose lodges in the rumen • If drench is delivered to the buccal cavity, rather than into the pharynx/esophagus • Can stimulate closure of the esophageal groove with much of the drench bypassing the rumen • Faster drug absorption • Shorter duration • Efficacy is reduced
  26. 26. Host Physiology - Maximize Efficacy • Restrict feed intake for 24 hours prior to deworming • Once in the rumen, the duration of the dewormer effect is largely dependent on the flow-rate of the digesta • Decreasing digesta transit leads to an increase in dewromer contact with worms and increased efficacy
  27. 27. Proper Dewormer Dosage and Administration • Goats metabolize dewormers much more rapidly than other livestock • Rule of thumb -- goats should be given a dose 1.5 to 2 times higher than for sheep or cattle • Levamisole 1.5 X • All others 2X • Administer all dewormers orally • Pour-ons are absorbed poorly • Injectibles have long residual - resistance • Combinations • Combination (2-4 anthelmintics) products currently used in Australia/NZ are being pursued for FDA approval in US • Administering 2 or more dewormers (different classes) is now being promoted to slow development of resistance
  28. 28. Do Not Buy Resistant Worms • All new additions should be quarantined and aggressively dewormed upon arrival • Deworm with at least 2 dewormers with different mechanisms of action (different class) • Valbazen and Prohibit, for example, upon arrival • Should remain in quarantine for 10 - 14 days • Perform fecal egg count to confirm that minimal eggs are shed • If quarantine is not possible: • Deworm with at least 2 dewormers and confine to pens for a minimum of 48 hours following deworming
  29. 29. Selective Deworming FAMACHA
  30. 30. Concept Behind Selective Deworming • Worms are not equally distributed in groups of animals • 20-30 % of animals harbor most of worms • responsible for most of egg output
  31. 31. 0 4000 8000 12000 16000 20000 FEC 0 1000 2000 3000 4000 Individual Goats FEC 33% of Goats 80% of Eggs Distribution of FEC/Infection Deworm high 33% Greatly Reduces Daily Pasture Contamination With Eggs Over 1 Month: Pasture Contamination Reduced By: 5.7 Billion Eggs 230 M 33% 46 Million 66%
  32. 32. Impact of Selective Deworming on Refugia • The more of the population that is in refugia, the slower the rate with which resistance develops • Selective deworming significantly increases the percent of the population in refugia
  33. 33. How to Achieve Selective Deworming  ID Poor doing animals  Fecal egg count (FEC)  Includes all worms – can’t distinguish  The FAMACHA© system  Technique for the assessment of Haemonchus infection Indirectly evaluate worm burden by level of anemia  Selective deworming leads to a substantial reduction in dewormer usage
  34. 34. 5-Point Check
  35. 35. The FAMACHA© System • Named for its originator • Dr Francois “Faffa” Malan • FAffa MAlan CHArt • Drs. Jan van Wyk, Gareth Bath, Adriano Vatta, Tami Krecek and Jørgen Hansen
  36. 36. The FAMACHA© System • Eye color chart with five color categories • Compare chart with color of mucous membranes of sheep or goat • Classification into one of five color categories: • 1 – not anemic • 5 -- severely anemic
  37. 37. • Examine in sunlight • Open as shown - for a short time only • Look at color inside lower eyelid
  38. 38. Always Use Card !!! Compare eye color to chart
  39. 39. Other Recommendations for Proper Use • Check both eyes • Score animal based on lowest eye score • No ½ scores • Assign lower whole number score if unsure • Do not hold eye open more than few seconds • Wait and retry in other eye • Keep records !!!! • Record numbers of animals in each category on the block histogram sheet provided • An easy visual record of situation in herd/flock
  40. 40. FAMACHA© • Use as guide to determine which animals to deworm • Significantly reduces number of dewormings given when compared with conventional deworming practices • Should significantly decrease the rate of development of resistance • Only useful where H. contortus is the primary worm species
  41. 41. Integrating the FAMACHA© System • Start examining at two week intervals in the spring • Treat categories 4 and 5 • Go to one week intervals as necessary during Haemonchus “season” • In cooler times of year every 4 to 6 weeks may be sufficient • If >10% of flock/herd in categories 4 and 5, start deworming 3s as well • Change pastures if possible • Do not deworm all animals before move • Examine especially animals which lag behind the flock/herd • Check for animals with “bottle jaw” and deworm these, regardless of whether they look anemic or not
  42. 42. Precautions • Paleness or reddening of the eyes may have other causes • Other causes of anemia: • Other parasites • Nutritional deficiencies • Other diseases • Other causes of redness: • Environmental conditions • Other diseases • Infectious eye diseases
  43. 43. Precautions • Only properly trained persons should apply the FAMACHA© system • The card is an AID in the control of Haemonchus only • Replace card after 12 months’ use • Maintain management-based worm control measures • The system is best used by producers where back-up assistance is available from a veterinarian
  44. 44. Other Advantage of Selective Deworming (FAMACHA) • Identify animals that need deworming most often • These are the ones contaminating the pasture for others in the herd/flock • Cull these and improve genetics of resistance of the herd/flock • You now have a measure for determining start and severity of worm transmission • Will change from year to year depending upon weather
  45. 45. Where Do I Get FAMACHA Cards? • By request of Professor Bath in South Africa, only properly trained lay individuals can purchase the cards • Sanctioned Training Workshop • Online training (wormx.info) • Through a veterinarian • Vets expected to train themselves before training others • Information at famacha@uga.edu
  46. 46. Alternative Methods for Worm Control
  47. 47. Breeding for Resistance • Select resistant individuals (FEC/FAMACHA) and cull susceptible animals – Estimated Breeding Values • National Sheep Improvement Program • Katahdin, Polypay, etc. • Goats can participate • Use resistant breeds for crossbreeding (Commercial) • Long term process, but will be rewarding
  48. 48. Copper-oxide Wire Particles • Haemonchus only • Marketed for use in cattle/small ruminants (Copasure/UltraCruz) for copper deficiency but also kills abomasal worms • Appears to work better in sheep but potentially toxic • Works synergistically with dewormers • Selective deworming for individuals • FEC/FAMACHA • Copper sulfate added to feed or as a drench does not work as well
  49. 49. Condensed Tannin Containing Plants  Sericea lespedeza  Forage that grows relatively well in SE US Establishment as pasture may fit some operations Hay, meal, pellets, etc. may be suited for other operations Sims Bros. (simsbrothers.com)  Has effect on Haemonchus – Female worms lay fewer eggs • Reduced pasture contamination – Kills some worms
  50. 50. Worm-trapping Fungi • Duddingtonia flagrans – Affects all worm larvae in feces – Mix with supplement for daily administration or with loose minerals for extended administration periods – Primary objective is to clean up pasture • Long term results (?, maybe 2-3 years) – Available (BioWorma and Livamol/BioWorma) through Premier One and veterinarians • Cost is relatively high, but should come down as market dictates
  51. 51. Vaccine • Promising for Haemonchus – Barbervax - works well in sheep, not so in goats – Drawback is that vaccination has to be done frequently (4-5 times each year) because protection is not complete – Originally expensive to produce • Refined product has been developed – Cost is now acceptable in Australia, but will not be marketed in the US (??) • Other vaccines for multiple worms have been investigated, but protection is variable
  52. 52. Herbals/Diatomaceous Earth • Many promoted as effective for controlling worms • Scientific studies to evaluate some of these indicated there is limited or no effect – Maybe they make the animal feel and look better in spite of being infected • impression that worms are gone or fewer in number • Using these products should be done with caution, especially in areas where heavy infections occur
  53. 53. Integrated Strategy • Use FAMACHA/FEC for monitoring infection level • Cull high infection individuals – resistance selection • Deworm individuals as necessary • Effective drug – smart drenching • Copper oxide wire particles • Sericea lespedeza • Worm-trapping fungus • Management • Stocking rate, mixed species grazing, dry lot, pasture spelling, etc. • Future – New drugs, vaccine (??)
  54. 54. Seasonal Control Considerations • Spring – Immature and mature Haemonchus contortus – Immature Fasciola hepatica (liver fluke) • Summer – Immature and mature Haemonchus contortus* – Immature and mature Fasciola hepatica* – Flies*/Ticks – Coccidia*
  55. 55. Seasonal Control Considerations • Fall – Mature Haemonchus contortus – Mature Fasciola hepatica* – Dictyocaulus filarial (lungworm) – Lice/Mites • Winter – Mature Fasciola hepatica* – Dictyocaulus filaria* – Melophagus ovinus* (Sheep ked – wingless fly) – Lice*/Mites*
  56. 56. Healthy Harmony
  57. 57. American Consortium for Small Ruminant Parasite Control (Wormx.info)
  58. 58. Questions?

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