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Protozoa - Coggle Diagram
Protozoa
Phylum Apicomplexa
Oocyst – the thick-walled, resistant stage of the life cycle of cocciditial parasites. It contains a zygote (sporoblast) and under appropriate conditions sporulates to become a mature infective oocyst. It may also remain infective for long periods in dry conditions.
sporoblast divides in two Sporocysts, sporocysts divide twice to produce four Sporozoites each
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Toxoplasmagondii (cats)
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stages
Oocysts – resistant stages for environmental transmission shed in cat feces; only produced by cats definitive hosts
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Bradyzoites – slowly dividing, encysted tissue stages found in all warm-blooded vertebrate hosts
Zoonotic –Congenital (prenatal) infection of fetuses can occur, with a risk of abortion, stillbirth and neonatal disease in the offspring.
Cryptosporidium
many animals; most common in calves in Ontario (Cryptosporidium parvum), also in pigs and humans
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Diagnosis
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Acid-fast stain of direct smear of feces; Oocysts measure about 4 to 5 µm in diameter (most common method used in clinical practice)
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Neospora caninum
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Congenital infection (vertical transmission) occurs in both dogs and intermediate hosts when tachyzoites cross the placenta.
Puppies infected in utero often have hind limb paralysis, cervical weakness and dysphagia -> death
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Phylum Sarcomastigophora
Giardia spp.
Trophozoite state (motile feeding stage)
Pear-shaped, dorsoventrally flattened, contains four pairs of flagella
Cyst stage (resistance)
Mature cyst = Oval, refractile wall and four nuclei
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Ingestion of cysts in contaminated water or feces
Cyst releases trophozoite in small intestine
Trophozoite attaches to wall of small intestine
Trophozoites divide by binary fission
Some encyst and are passed in feces
Cysts can survive for extended periods of time in environment
Primary clinical signs = diarrhea +/- mucous or fat. Range in acute profuse, watery, explosive to subtle soft stool.
Zoonotic risk = both ways!!
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Flagellates – use long, whiplike Flagella
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Sporozoans – “Spore-forming protozoa”, don’t really move, they glide, twist and bend to move.
