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Protozoan disease

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Protozoan disease

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Protozoan disease

  1. 1. WELCOME
  2. 2. Seminar on Protozoan Disease in Fishes Presented by Balwant Singh M.Sc. (AAS)
  3. 3. Protozoan Disease in Fishes • Protozoan disease in fishes are divided in to following categories- 1)Flagellated Protozoans 2)Ciliated Protozoans 3)Myxozoans
  4. 4. (1) Flagellated Protozoans • Flagellates are protozoans: simple, single-celled animals (over 50,000 recognized species) • Very small (15-30 µM), body elongate, leaf-like appearance, up to 975,000/mL of blood • Flagellum arises posteriorly and can be connected to other parts of body, pulls animal through the blood • Most famous are Trypanasoma, Trypanoplasma, Ichthyobodo necatur
  5. 5. Ichthyobodo necatur • A Mastigophoran, but a member of Class Diplomonadea • Also small, but flat and ovoid when swimming • It has 2-4 flagella arising from a basal body (kinetosome) at anterior end • Obligate parasite, poor swimmer, attaches to gills, but not good at attaching • Uses a sucking organelle to penetrate host • Tissue penetrated becomes necrotic
  6. 6. Icthyobodo necatur • Largely affects young, undernourished carp and trout • It can also parasitize frogs/tadpoles • Wild fish/frogs serve as reservoirs, found everywhere • Seasonality affect resulting from salmonid hatchery stocking seasons (April - May) • Affects smolts by attaching to gills and not allowing them to adapt to seawater
  7. 7. Ichthyobodo necatur • Pathogenicity: dull spots on body (blue slime), pale gills, hemorrhaging, fin necrosis, loss of appetite, flashing, moribund fish • Control: salmonids need prophylaxis with formalin (1:4000 for 1 hr); carp need 1% salt bath 30 minutes repeated 3-4 times
  8. 8. Ichthyobodo necatur
  9. 9. (2)Ciliates: Ichthyophthirius multifilis (ICH) • Another single-celled protozoan type • Adult is round in shape, up to 1 mm in diameter, known as “trophont” (rem? Same as Amylodinium) • Short cilia in rows over entire cell, obvious as free- living stages “tumble” through the water • Life Cycle: the trophont attaches to gills or skin, after 7-10 days, the trophont drops off and is called a “tomont” (same, also), tomont attaches to substrate and encysts, cyst ruptures releasing swarmers known as “theronts” • Throats are the parasites (have perferatorium), also use hyaluronidase, only for less than 20 hrs, displace normal tissue as they grow
  10. 10. Ichthyophthirius multifilis (ICH) • Signs: white pustules in advanced cases, sometimes called white spot disease; if found on gills, not found on body • Behavioral changes: fish scratch against bottom (flash), hide in corners, twitching fins • Death in 20-26 days, thought to be due to osmoregulatory failure in most cases • Host/parasite range: broad, mainly in catfish/salmonids
  11. 11. Ichthyophthirius multifilis (ICH) • Control: prevention (once in, difficult to treat) • Chemotherapy requires treating water, not the fish (cysts, stages in fish unaffected) • Formalin: around 250 ppm, goes up as temp goes up • Malachite green: 1.25 ppm daily for 30 min (Nox-Ich, Ich-out) • Remove fish, raise temp to 90o F
  12. 12. Ichthyophthirius multifilis (ICH) Cell embedded in tissue
  13. 13. Ichthyophthirius multifilis (ICH) Theronts (swarmers)
  14. 14. Ichthyophthirius multifilis (ICH)
  15. 15. Ichthyophthirius multifilis (ICH)
  16. 16. Cryptocaryon irritans • Similar to ICH • primarily marine • trophozoite similar to ICH • life cycle similar to ICH • primarily problem for mariculture facilities and marine aquaria
  17. 17. Epistylus sp. • Colonial, stalked ciliate • possess ciliary spiral around cytostome • usually on skin • causes flashing, which can lead to harm • really just a bother, little apparent harm
  18. 18. Trichodina sp. • Body shaped like hockey puck • also spiral cilia around cytostome • makes them fly through the water like a flying saucer • lives on gills, skin mainly • have rings of chitinous teeth
  19. 19. (3) Myxozoans: Myxobolus cerebralis • Rather odd, exclusively endoparasites • Cnidarians? (Phylum Cnidaria) • Multicellular during adult life • Cause: “whirling disease” (specifically: Salmonid Whirling Disease)
  20. 20. Salmonid Whirling Disease • Important characteristic: can produce spore that is highly resistant (15 yrs dessication), associated with dispersal • Life Cycle: infective stage (amoebula; “trophozoite”) penetrates skin, most visible stage is the spore, spore released to environment, oligochaete vector. • Fish eats oligochaete or encounters free spores
  21. 21. Salmonid Whirling Disease • Found in salmonids, not contagious. • Pathology: development in cartilage, usually young fish, carriers asymptomatic, fish exhibits whirling (tail chasing) when feeding or alarmed, whirling caused by destruction of inner ear by spores (loss of equilibrium) • Can cause “blacktail” by controlling production of chromatophores in spinal column, also “pugnose”, skeletal deformities
  22. 22. Salmonid Whirling Disease • Diagnosis: remove gill arch, grind and allow to settle, check supernatant for spores • other methods: cook head/plankton centri- fuge, pepsin-trypsin digestion/centrifuge • Fluorescent Antibody Test (FAT) w/rabbit • Transmission: direct during first year, indirect via annelid, contamination (cyst) • Hosts: trout, salmon, char, grayling
  23. 23. Salmonid Whirling Disease • How did it get here? Came from Europe via Danish frozen trout in the 50’s • Control: Non-treatable, avoidance critical, UV of water, filtration to less than 10 µM • Accomodation: incubate eggs and rear fry separately in UV trt’d water, check new ponds with sentinels (poor fish)
  24. 24. Salmonid Whirling Disease sporoblast mature spores
  25. 25. Salmonid Whirling Disease
  26. 26. Thank You

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