parasitology lab notes


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parasitology lab notes

  1. 1. Lab 6: Protozoans & Equine Nematodes
  2. 2. Intestinal Coccidians - Isospora <ul><li>Isospora spp. – intestinal parasites of cats & dogs </li></ul><ul><li>One of the most common protozoan diseases of kittens & puppies </li></ul><ul><li>Rarely cause issues in mature animals </li></ul><ul><li>Oocysts can be found on fecal floatation, are unsporulated in fresh feces & are very small </li></ul><ul><li>Prepatent period usually 7-10 days </li></ul>Isospora canis
  3. 3. Isospora spp. – Life Cycle <ul><li>Unsporulated oocyst in feces, sporulates in environment – infective stage contains 2 sporozoites </li></ul><ul><li>Ingestion – invades intestinal epithelial cells, becomes meront </li></ul><ul><li>Undergoes asexual reproductionto become merozoites , which then become microgametocytes or macrogametes which then undergo sexual reproduction to produce oocysts which are shed in feces </li></ul>
  4. 4. Isospora spp. – Signs & Predisposing factors <ul><li>Clinical signs associated with heavy infections only </li></ul><ul><li>Chronic diarrhea, straining – especially in puppies & kittens </li></ul><ul><li>Some animals may become asymptomatic carriers </li></ul><ul><li>Predisposing factors include humid summer months, exercise pens, indoor boarding kennels/vet hospitals, stress </li></ul>
  5. 5. Intestinal Coccidians – Eimeria spp. <ul><li>Intestinal coccidian of ruminants & horses, rabbits, rats, mice & guinea pigs </li></ul><ul><li>Have cap on one end & up to 4 nucleii depending on species </li></ul><ul><li>Life cycle, clinical signs & predisposing factors similar to Isospora </li></ul><ul><li>Avians can have both Isospora and/or Eimeria </li></ul>
  6. 6. Intestinal Coccidians – Toxoplasma gondii <ul><li>Toxoplasma gondii – intestinal coccidian of cats </li></ul><ul><li>Usually diagnosed on standard fecal flotation, unsporulated in fresh feces </li></ul><ul><li>Immunodiagnostic tests also available using whole blood or serum </li></ul><ul><li>Prepated period varies depending on infection route (5-24 days) </li></ul><ul><li>Very important zoonotic parasite! Can cause severe damage/death to developing fetus in pregnant women </li></ul>
  7. 7. Intestinal Flagellates – Giardia spp. <ul><li>Several different species infects people, domestic animals & birds </li></ul><ul><li>Intermediate hosts are beavers, cows & dogs </li></ul><ul><li>To diagnose: will see oocysts in formed stool (using zinc sulfate only) or will see trophozoites in direct smear (using iodine to highlight internal structures) </li></ul><ul><li>Trophozoites are very fragile, stomach acid will kill </li></ul>Giardia trophozoite
  8. 8. Intestinal Flagellates – Giardia spp. <ul><li>Clinical signs can range from asymptomatic carriers to severe watery diarrhea </li></ul><ul><li>If severe can see severe dehydration, poor hair coat, weight loss, emaciation </li></ul><ul><li>Zoonotic potential!!! Drinking or swimming in contaminated water </li></ul>Giardia oocysts: stained
  9. 9. Equine Nematodes – Parascaris equorum <ul><li>Largest nematode (roundworm) of horses </li></ul><ul><li>Affects foals <6 months most – can get from contaminated food sources (plus foals LICK everything!!!!) </li></ul><ul><li>Can cause stasis, intestinal rupture due to size of worms & large burden – can cause death by impaction </li></ul>Parascaris ova
  10. 10. Parascaris equorum: Life cycle & predisposing factors <ul><li>Undergoes hepatotracheal migration </li></ul><ul><li>Prediliction site – small intestine </li></ul><ul><li>Clinical signs: unthriftiness, depression, pot-bellied, anorexia, colic & cough w/ nasal discharge </li></ul><ul><li>Predisposing factors: contaminated food/water troughs, contaminated pastures, very environmentally resistant </li></ul><ul><li>Control – worming & rotating pastures especially where foals & weanlings graze </li></ul>
  11. 11. Equine Nematodes: Strongyles <ul><li>Divided into large & small strongyles – eggs are virtually identical </li></ul><ul><li>Large strongyles more pathogenic </li></ul><ul><li>Eggs found on fecal flotation – identification of species through fecal culture (allows identification of larvae) </li></ul><ul><li>Eggs contain 8-16 cell morula </li></ul>3 common types of strongyles
  12. 12. Strongyles: Life cycle & clinical signs <ul><li>Clinical signs: colic, weight loss, lethargy, fever & poor appetite </li></ul><ul><li>Prevention: worming, pasture rotation & routine fecal exams </li></ul>
  13. 13. Strongylus westeri : Intestinal Threadworm <ul><li>Unique equine nematode – only females are parasites (parasitic males do not exist) </li></ul><ul><li>Produces larvated eggs </li></ul><ul><li>Mare can transmit to foal through colostrum </li></ul><ul><li>Prepatent period 5-7 days </li></ul><ul><li>Signs: diarrhea, weight loss, anemia & poor appetite </li></ul><ul><li>Good worming for mare & foal needed to prevent infection </li></ul>
  14. 14. Equine Nematodes: Oxyuris equi - Pinworm <ul><li>Adult worms found in cecum, colon & rectum </li></ul><ul><li>Adult females attach eggs to exterior anus with a gelatinous, sticky material that produces anal pruritis </li></ul><ul><li>Eggs may be larvated, have an operculum, are smooth & thick shelled, very tapered on one end </li></ul><ul><li>Common in foals, not zoonotic </li></ul><ul><li>Diagnosed by scotch-tape test! </li></ul><ul><li>Can see eggs on fecal flotation, occasionally see adults in stool </li></ul>
  15. 15. Oxyuris equi: Life cycle <ul><li>Gravid female migrates to rectum/anal area – lays eggs on perianal area (sticky!) – eggs hatch, horse rubs against food/water troughs, eggs/larvae fall into trough – eggs ingested by host – adults develop in cecum, colon & rectum </li></ul>