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Parasitebiology

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This PowerPoint presentation, "Parasites and their biology" is the first from a four-part webinar series on worms. The author is Susan Schoenian, University of Maryland Extension Sheep & Goat …

This PowerPoint presentation, "Parasites and their biology" is the first from a four-part webinar series on worms. The author is Susan Schoenian, University of Maryland Extension Sheep & Goat Specialist.

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  • 1. I. Parasites and their biology
    species, life cycles, pathogenicity, interactions
  • 2. Barber pole worms in abomasumImage source: ScienceWatch.com
    What is a parasite?
    A (generally undesirable) living organism that exists by stealing the resources produced or collected by another living organism.
  • 3. There are two kinds of parasites.
    Internal (endo) – a parasite that lives inside another organism.
    External (ecto) – a parasite that lives on the blood of the host or lays eggs on their hide or in their nose.
    External parasite: sheep ked (tick)Image from Colorado State University
  • 4. There are two general kinds of internal parasites.
    Helminthsmulti-cellular
    Nematodes
    Cestodes
    Trematodes
    Protozoasingle cell
    Coccidia
    Giardia
    Cryptosporidium
    Haemonchus contortus (barber pole worm)
    Image from University of Georgia
  • 5. 1. Helminths (parasitic worms)
    NematodesRoundworms
    CestodesTapeworms
    TrematodesFlukes
    Barber pole wormImage source: MicrobiologyBytes
  • 6. A. Nematodes (roundworms)Phylum Nematoda
    Approximately 1 million
    Over 28,000 described
    Over 16,000 parasitic
    Round
    Elongated
    Worm-like
    Have digestive systems
    Reproduce sexually
    Mostly host-specific
    Not all are pathogenic
    Most significant kind of internal parasites that affect sheep and goats.
  • 7. ClassNematoda -> SuperfamilyStrongyloidea -> FamilyStrongylidae-> Genera StrongylePrimary parasites affecting sheep and goats: Strongyles
  • 8. Haemonchus contortusBarber pole worm
    Most common in warm, moist climates with summer rainfalls.
    Adapting to cooler climates.
    Most deadly worm.
    Blood sucker.
    Prolific egg layer.
  • 9. Western Maryland Pasture-Based Meat Goat Performance Test (2009)
  • 10. Strongyle- type worms
    Direct life cycles
    Weather dependent
    14 to 21 days
    Eggs cannot be differentiated in fecal analyses.
    75 – 95 µ m
    Mixed infections common.
    Have developed varying levels of resistance to anthelmintics.
    L4, adult suck blood
    L3
    L1
    L2
  • 11. Environmental-parasite interactions
    Optimal conditions for development of Haemonchus larvae are 82⁰F and humidity above 70%.
    Teladorsagia is better adapted to cooler, temperate climates. They fair poorly in very hot, dry summers.
    Trichostrongylus spp. are more resistant to cold and desiccation than Haemonchus.
  • 12. Hypobiosisinhibited or arrested larval development
    Period of delayed development whereby 4th stage larvae stop development and remain in the mucosa for 3 to 4 months.
    Occurs when there is insufficient moisture or temperatures that are too cold for larval development.
    Occurs in winter or summer, depending upon parasite and geographic location.
    Probably involves some immune and environmental cues.
    Survival mechanism
    No host response
  • 13. Strongyles that cause occasional problems
    BunostomumHookworm
    Cooperiaspp.Small intestinal worm
    Nematodirusthreadneck worm
    OesophagastomumNodule worm
    StrongyloidesCommon threadworm
    TrichurisovisWhipworm
    MuelleriuscapillarisDictyocaulusfilaria Lungworms
    Paralaphostrongylus tenius Meningeal worm(brain, deer worm)
  • 14. Lungworms
    Muelleriuscapillaris
    Dictyocaulusfilaria
    Direct or indirect life cycle
    Prefer cool conditions
    Diagnosis is difficult
    Clinical signsPersistent coughing, respiratory distress, reduced weight gains
    Recovery of 1st stage larvae from feces
    Identify at post-mortem
    Image source: UPENN Vet School
  • 15. Meningeal worm
    White-tailed deer are the normal host.
    Infection typically causes no clinical disease in deer.
    Severe neurological disease occurs when infected snails or slugs are ingested by other cervids or ungulates.
    Gastropods serve as intermediate host.
    Parasite migrates to spinal cord and brain.
    10 to 14 days after ingestion of infected snail or slug
  • 16. TREAMENT
    CLINICAL SIGNS
    Variable
    Mimic other neurologic disease
    Weakness
    Lameness
    Circling
    Blindness
    Head tilt
    Abnormal behavior
    Paralysis
    Death
    High doses of anthelmintics
    Ivermectin for five days
    Fenbendazole for five days
    Anti-inflammatory drugs
    No controlled studies have confirmed or refuted the efficacy of various treatment recommendations.
  • 17. Prevention
    Limit deer access to pasture.
    Eliminate deer via lethal means.
    Deer-proof fencing for small operations.
    Make pastures less appealing to deer.
    Feed in enclosed areas.
    Reduce exposure to infected snails and slugs.
    Do not allow access to pastures that contain thick vegetation or moist shaded areas that are favorable snail and slug habits.
    • Prophylactic treatment with anthelmintics (every 10-14 d).
  • B. Cestodes (tapeworms)
    Flat
    Segmented
    Hermaphrodites
    Indirect life cycle
    Some cause symptoms in intermediate host
  • 18. Tapeworms affecting sheep and goatsGenus Moniezia
    Indirect life cycle
    Pasture mites serve as an intermediate host.
    6 weeks
    Segments visible in feces.Only worm visible in feces
    Generally thought to be non-pathogenic and of little consequence.
    Usually no benefit to treatment
    Treat with albendazole (Valbazen®), fenbendazole (Safe-Guard®), or praziquantel.
  • 19. Sheep measles (Ovine cysticercosis)
    Sheep tapeworm of dogs
    Transmitted to sheep eating forages contaminated with tapeworm eggs shed by canines.
    Sheep and goats host larval stage of parasite
    No clinical signs in sheep or goats.
    Causes development of cysts in skeletal and heart muscle.
    Cause of carcass condemnation.
    • Control point: dogs
    Image source: Optimal Livestock Services, LLC
  • 20. C. Trematodes (flukes)
    Flat
    Oval shape
    Indirect life cycle
    Hermaphrodites
    Image source: http://www.flickr.com/photos/peteredin/3386220058/
  • 21. Liver flukes
    Fasciola hepatica(common liver fluke)
    Gastropods serve as intermediate host.
    In U.S., found mainly in Gulf states, California, and Pacific Northwest.
    Symptoms include pale mucous membranes, bottle jaw, and weight loss.
    Treat with albendazole (Valbazen®).
    Image source: Agricultural Research Council in South Africa
  • 22. 2. Protozoan parasites
    Eimeria spp.Coccidia
    Giardia
    Cryptosporidium sp.
    Toxoplasmagondii
    Image source: FAO United Nations
  • 23. Eimeria spp. - Coccidia
    Single cell
    Life cycle
    Complicated
    Many stages
    Oocytes -> sporulation (hatching)
    Sexual and asexual reproduction
    21 days
    10 species known to infect sheep and goats
    Host specific
    Not all are pathogenic
    Damage cells of small intestines
    Subclinical
    Clinical (diarrhea)
  • 24. Internal parasites of sheep and goats
    Barber pole worm
    Teladorsagia (Ostertagia)Trichostronyglus spp.
    Roundworms
    Tapeworms
    Helminths
    Other strongylesLungworms
    Meningeal worm
    Liver flukes
    Coccidia
    Protozoa
  • 25.
  • 26. Small Ruminant Program
    Thank you for your attention.
    Any questions?
    SUSAN SCHOENIANsschoen@umd.eduwww.sheepandgoat.com
    Next webinar: Integrated parasite management (May 12)