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Worm diagnostics


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This presentation is the third in a four part webinar series on internal parasites in sheep and goats. This presentation focuses on the diagnostic tools available to producers to help them control parasites in the flocks and herds. The presentation is by Susan Schoenian, University of Maryland Extension Sheep & Goat Specialist.

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Worm diagnostics

  1. 1. III. Diagnostic tools for worm control<br />FAMACHA© system, Five Point Check©, lab tests<br />
  2. 2. How do I tell if my sheep or goats are infected with parasites?<br />
  3. 3. They all are. <br />Almost all sheep and goats have parasites, probably of different kinds.<br />“Positive” egg or oocyst counts are “normal.” Negative tests are rare (during the periods of risk).<br />Some level of parasite infection is required for immunity.<br />
  4. 4. They all are. Accept it!<br />Clinical disease occurs at a certain level of infection that can vary by animal.<br />Not all parasites are pathogenic or highly pathogenic.<br />Not all straingsof parasites are pathogenic.<br />
  5. 5. The more important question to ask is:How do I tell if my sheep or goat is clinically parasitized (suffering negative effects) and requires anthelmintic treatment?<br />
  6. 6. Diagnostic tools<br />On-farm<br />Animal<br />Fecal<br />Laboratory<br />Blood<br />Fecal<br />Larvae<br />
  7. 7. Diagnostic tools<br />ON FARM<br />LABORATORY<br />Animal<br />FAMACHA©<br />Five Point Check® NEW!<br />Fecal<br />Simple flotation<br />Fecal egg counts<br />Fecal egg count reduction test (FECRT)<br />Dipstick<br />Carla® saliva test<br />Blood<br />Packed cell volume<br />Fecal<br />Simple flotation<br />Fecal egg counts<br />FECRT<br />Lectin staining test NEW!<br />Larvae<br />Larvae culture<br />Larval development assay[DrenchRite®]<br />Pasture<br />
  8. 8. The FAMACHA© System<br />Develop for small-scale sheep producers in South Africa in response to the widespread development of anthelmintic-resistant worms. <br />A practical system for assessing barber pole worm infection in sheep and goats and determining the need for deworming individual animals.<br />Named for its originator:Dr. Francois “FAffa” MAlanCHArt<br />
  9. 9. FAMACHA©<br />General treatment recommendationsDeworm adults at scores 4 and 5*Treat lambs and kids at categories 3, 4, and 5<br />*The South Africans recommend goats be treated at categories 3, 4, and 5<br />
  10. 10. Using FAMACHA© <br />Must take training to get card.<br />Use card<br />Replace card periodically(colors fade)<br />Do not use in a vacuum; consider other factors.<br />Frequency of checking varies by risk.<br />Should incorporate FAMACHA© into an integrated parasite management program.<br />
  11. 11. Benefits of FAMACHA©<br />Reduces number of anthelmintic treatments. <br />Reduces dollars spent on anthelmintics.<br />Identifies susceptible and resilient animals.<br />Increases refugia <br />Prolongs effectiveness of anthelmintics<br />
  12. 12. 6<br />5<br />4<br />1.2%<br />1.2%<br />3<br />4.8%<br />2<br />7.1%<br />16.7%<br />1<br />41.7%<br />0<br />26.2%<br />Using the FAMACHA© system to control internal parasites in grazing lambs<br />% Lambs/No. times treated<br />
  13. 13. Limitations of FAMACHA©<br />Doesn’t save time.<br />LESS deworming<br />MORE monitoring<br />Only useful where (when) barber pole worm is the primary parasite.<br />Must know which anthelmintics are effective.<br />
  14. 14. The Five Point Check © (5.©)<br />Expands the FAMACHA© system to include evaluation criteria for other internal parasites.<br />Check five places on animal’s body<br />FAMACHA© score<br />Bottle jaw<br />Body condition score<br />Dag score<br />Nasal discharge<br />
  15. 15. Backbody condition (and coat condition)<br />2<br />Tailsoiling , dags(scours)<br />EyeanemiaFAMACHA© score<br />1<br />3<br />5<br />4<br />Nosenasal discharge(nose bots)<br />Jawswelling, edema “bottle jaw”<br />Five Point Check© (5.©)For targeted selective treatment of internal parasites in small ruminantsG.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  16. 16. Five Point check©<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  17. 17. FAMACHA© eye anemia score<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  18. 18. Bottle jawSub-mandibular edema<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  19. 19. Body condition score (BCS)<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  20. 20. Dag Scoresbritch soiling, evidence of scouring (diarrhea)<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  21. 21. Nasal discharge<br />Source: G.F. Bath and J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria, South Africa<br />
  22. 22. Packed cell volume (PCV)<br />Portion of whole blood occupied by red blood cells.<br />A measure of anemia <br />Primary symptom of Haemonchosis(or barber pole worms).<br />A measure of resilience.<br />
  23. 23. Uses of fecal testing<br />Identify worm eggs and determine existence and levelof infection<br />Simple fecal flotation<br />Fecal egg counting<br />Determine parasite species <br />Larvae culture<br />Lectin staining test<br />Determine effectiveness of anthelmintic treatment<br />Fecal egg count reduction test (FECRT)<br />Larval development assay (LDA) or DrenchRite® test<br />
  24. 24. Fecal testing<br />QuantitativeFecal egg count (FEC)<br />QualitativeSimple fecal flotation<br />Use McMaster egg counting slide<br />Weigh feces and measure flotation solution<br />Determine general egg typesStrongyle vs. coccidia vs. tape<br />Determine level of infection<br />Eggs per gram of feces<br />Use simple slide and cover slip<br />Determine general egg typesStrongyle vs. coccidia vs. tape <br />Determine existence and general level of infection<br />Eggs per field of viewe.g. Eggs Plus system<br />
  25. 25. What you need to do your own fecal egg counts<br />Microscope40x objective x 10x eye piece = 400Only need 100xMechanical stage recommended<br />Flotation solutionSaturated salt or sugar solutionSpecific gravity of 1.2Can also purchase<br />McMaster egg counting slide<br />Miscellaneous suppliesscale, beaker, pipettes, vials, craft sticks, cheese cloth or strainer<br />
  26. 26. Fecal egg countseggs per gram of feces<br />Indicate “potential” parasite burden in animal.<br />Indicate potential parasite burden on pasture..<br />Use to determine level of drug efficacy.<br />Use to determine genetic differences in parasite resistance.<br />
  27. 27. Fecal egg counts are not definitive.<br />Fecal egg counts are not always well-correlated with clinical disease.<br />Presence of eggs or does not mean that the animal is clinically parasitized and needs treatment.<br />Absence of eggs or oocytes (coccidia) or a low count does not mean that the animal is parasite-free and not needing treatment.<br />
  28. 28. Limitations to fecal egg counts<br />Some parasite eggs look the same and cannot be identified at the egg stage).<br />There is a fairly regular fluctuation in fecal egg output.<br />Egg output varies by season of the year.<br />Eggs are not always evenly distributed in the feces.<br />Parasite species vary in their egg producing capacity.<br />Some parasites are prolific egg producers (e.g. Haemonchus)<br />Some parasites do not produce very many eggs. (e.g. Nematodirus)<br />Some parasites produce eggs intermittently<br />Some parasites can produce asexually<br />Immature worms (L4’s) do not lay eggs<br />Inhibited larvae do not lay eggs<br />Not all parasites are pathogenic (disease-causing)<br />Total egg counts may include a mixture of species with different levels of fecundity and pathogenicity.<br />Diarrhea increases fecal moisture and may dilute the number of eggs.<br />Human error.<br />
  29. 29. Clinical significance of fecal egg counts<br />
  30. 30. Fecal egg count reduction test (FECRT)<br />First and most widely used method to access efficacy of anthelmintics.<br />Before and after fecal egg counts.<br />d 0 and d 7-14 post treatment<br />With or without untreated controls <br />Minimum of 10 animals.<br />
  31. 31. DrenchRite® Larval Development Assay (LDA)<br />In vitro test for the detection of anthelmintic resistance.<br />Evaluates resistance to all major anthelmintics from a single pooled fecal sample.<br />Requires pooled fecal sample from 10 or more animals <br />Mean FEC of > 350 epg minimum<br />Mean FEC of > 500 epg preferred.<br />Select feces from animals scored as FAMACHA© 3, 4, or 5.<br />Available through University of Georgia (<br />
  32. 32. Larvae culture and differentiation<br />It is difficult to differentiate the eggs of many common species of worms during a worm egg count. <br />Culture of the feces for the purpose of hatching parasite eggs and obtaining larvae for morphological identification.<br />Image source: Dr. Woodgate, Western Australia Department of Agriculture<br />
  33. 33. Western Maryland Pasture-Based Meat Goat Performance Test (2009)<br />
  34. 34. Lectin staining test<br />Fast, easy, less-expensive way to test for the presence and quantity of barber pole worms.<br />Lectin-staining test based on peanut agglutin that binds to egg of barber pole worm.<br />Only requires a small amount of feces.<br />Results available in as little as two days.<br />Available through Oregon State University and University of Georgia.<br />Image source: University of Georgia College of Veterinary Medicine.<br />
  35. 35. New tests (not available in U.S.)<br />CARLA® SALIVA TEST<br />HAEMONCHUS DIPSTICK TEST<br />Measures antibodies against worm larvae.<br />Use to select animals which suffer less from parasites and pass fewer eggs onto pasture.<br />Detects blood in feces to determine presence of barber pole worm and level of infection.<br />
  36. 36. Small Ruminant Program<br />Thank you for your attention.<br />Any questions?<br />SUSAN<br />Next webinar (last) : Using anthelmintics effectively - May 26<br />