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Clinical Parasitology > Protozoans > Flashcards

Protozoans Flashcards

1
Q

Describe Giardia sp.

A
  • Direct lifecycle
  • Hosts: mammals, birds, amphibians
  • Giardia duodenalis- assemblages
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2
Q

What are these?

A

Left = cyst

Right - Trophozoite

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3
Q

How do cysts differ from trophozoites?

A
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4
Q

Describe the Giardia lifecycle

A
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5
Q

Describe the clinical signs and pathogenicity of Giardiasis

A
  • Usually no clinical signs
  • If any:
    • Attachment of trophs:
      • blunting of intestinal villi - malabsorption, diarrhea
      • damage enterocytes
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6
Q

How do you diagnose Giardia?

A
  • Fecal exam
  • ELISA - always back up!
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7
Q

How do you treat Giardia duodenalis?

A
  • None approved
  • Dogs: Febantel, pyrantel, praziquantel, Fenbendazole +/- metronidazole
  • if they are asymptomatic, treatment may not be necessary if you treat only once
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8
Q

How do you control Giardiasis?

A
  • Bathe animals
  • removal of feces
  • difficult - resistant cysts
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9
Q

Describe Tritrichomonas blagburni

A
  • Avg. 15 x 9 um (SUPER teeny)
  • Pseudocysts
  • Longitudinal binary fission
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10
Q

Describe feline trichomoniasis

A
  • Large bowel disease
    • chronic diarrhea (blood +/- mucus), tenesmus, flatulence, irritated anus, fecal incontinence
    • diarrhea can last weeks/months/YEARS
    • avg. Age of onset = 9 mo.
  • Transmission: fecal-oral route, survival outside of host
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11
Q

How do you diagnose feline trichomoniasis?

A
  • Direct fecal smear
  • Culture
  • PCR
  • Colonic biopsy
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12
Q

How do you treat and control Tritrichomonas?

A
  • No approved treatment
    • Ronidazole
    • Metronidazole or tinidazole
  • Keep infected cats away from other cats
  • Do not allow litter box sharing
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13
Q

What are each of these?

A
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14
Q

What are 2 non-pathogenic Trichomonads?

A
  • Pentatrichomonas hominis
    • cecum and colon of mammals (dogs)
  • Tritrichomonas canistomae: T. Felistomae
    • mouths of dogs and cats
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15
Q

Describe Trypanosoma cruzi

A
  • Parasites of vertebrates - blood and tissues
  • majority transmitted by blood feeding arthropods
  • most not pathogenic
  • vector = Reduviid bug
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16
Q

What are the hosts of T. Cruzi?

A
  • American Trypanosomiasis: dogs, cats, opossums, raccoons, armadillos
  • Chagas disease: humans
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17
Q

What are the two life stages of Trypanosoma cruzi?

A

Left - Trypomastigote (subterminal kinetoplast)

Right - Amastigote

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18
Q

Describe the life cycle of T. cruzi

A
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19
Q

What is this?

A

Amastigotes clustered in a pseudocyst

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20
Q

Describe the clinical presentation of American Trypanosomiasis in dogs

A
  • Acute stage: trypomastigotes in circulating blood
    • fever, anorexia, lethargy, diarrhea
  • Chronic stage: no longer circulating
    • CHF, DCM, arrhythmias, lethargy, resp difficulties, hepatomegaly, anemia
    • sudden death

Sporting/working dogs over-represented

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21
Q

How do you diagnose Trypanosoma cruzi?

A
  • Serological testing
    • TESA blot/Western blot (trypomastigote Ag)
    • ELISA
    • IFA
    • Cross smear
    • Xenodiagnosis
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22
Q

How do you treat Trypanosoma cruzi?

A

Most experimental

  • Low efficacy vs. chronic disease
  • Treat over 2-3 months
    • Benznidazole - acute dz
    • Ravuconazole - parasitemia suppressed; no cure
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23
Q

Cystoisospora and Eimeria are monoxenous…what does that mean?

A

parasitize one host (DH)

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24
Q

What is the difference between Cystoisospora and Eimeria?

A
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25
Q

What are the 4 species of Cystoisospora in dogs?

A
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26
Q

What are the 2 types of Cystoisospora in cats?

A

C. Felis and C. Rivolta

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27
Q

Describe the life cycle of Isospora sp.

A
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28
Q

What is the clinical presentation of a Cystoisospora infection?

A
  • Occasional diarrhea, death
  • enteritis, colitis, weight loss, dehydration
  • not zoonotic
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29
Q

How do you control Cystoisospora?

A
  • Kennel sanitation, prompt feces removal
  • disinfectants with high ammonia concentrations
  • steam/heat
  • treat all animals
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30
Q

How do you treat Cocciodiosis?

A
  • Sulfadimethoxine
  • Furazolidone
  • Ponazuril
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31
Q

True or False: Eimeria is not a true parasite of the dog or cat

A

True - it’s a spurious parasite acquired by dogs and cats via predation or coprophagy

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32
Q

Describe Cryptosporidium sp.

A
  • C. Canis - dogs
  • C. Felis - cats
    • both rarely zoonotic
  • Habitat = SI
33
Q

Describe the life cycle of Cryptosporidium

34
Q

How is Cryptosporidium transmitted?

A
  • Direct contact with infective oocyst (in feces)
  • Contaminated food or equipment, hands, shoes/boots/clothing
  • Water

​low infective dose

35
Q

What does physical disinfection of Cryptosporidium entail?

A
  • Extreme heat or freezing, UV irradiation
36
Q

What does chemical disinfection entail for Cryptosporidium?

A
  • Chlorine
  • hypochlorite (bleach)
  • hydrogen peroxide
  • iodine
37
Q

What is the clinical presentation of Crypto?

A
  • Most infections = subclinical
    • ​profuse, watery diarrhea
    • anorexia, dehydration, wt loss
    • villous atrophy, enteritis, fusion of villi (biopsy)
  • Healthy dogs/cats - infections usually self limiting
  • Persistent infection = underlying cause (e.g. CDV, immunosuppressed)
38
Q

How do you diagnose Cryptococcus?

A

fecal float, intestinal biopsy

39
Q

How do you treat Cryptosporidiosis?

A
  • Alinia (nitazoxanide)
  • Paromoycin
  • Tylosin
  • Azithromycin
40
Q

Describe Toxoplasma gondii

A
  • Obligate, intracellular parasite
  • Hosts:
    • IH - most mammals
    • DH: felids
  • Transmission:
    • Acquired - ingesting infective oocyst, consumption of raw/undercooked meats
    • Congenital - transplacental
41
Q

What’s the difference between tachyzoites and bradyzoites?

A
  • Tachyzoites - rapidly dividing, found in liver, lungs, spleen, lymph nodes
  • Bradyzoites- slowly dividing, found in brain, heart, skeletal mm, eye
42
Q

Describe the life cycle of Toxoplasma gondii

43
Q

Describe the clinical presentation of Toxoplasma gondii

A
  • No confirmed oocyst shedding in clinically ill cats
  • Seroconversion 2-3 wks PI; most sero+ cats already shed oocysts (shed once)
  • Dz often in immunocompromised cats
    • Fever, anorexia, jaundice, abdominal pain/discomfort, hepatitis, pancreatitis
44
Q

How do you diagnose Toxoplasma gondii?

A
  • fecal exam
  • Multiple IFA, ELISA
    • Most seropositive cats have completed oocyst shedding
  • PCR
  • Histo exam (biopsy)
45
Q

How do you treat Toxoplasma?

A
  • Sulfonamide
  • Clindamycin
  • TMS
46
Q

How do you control Toxoplasma?

A
  • Zoonotic
    • neuro dz, birth defects, stillbirth, ocular dz
  • cook meat thoroughly
  • change litter daiy
  • wear gloves while gardening
47
Q

Describe Neospora caninum

A
  • Hosts:
    • IH: cattle, sheep, goats, deer, many mammals, birds
    • DH: dogs, coyotes
  • Transmission:
    • Acquired: ingesting infective oocysts, consumption of raw, infected meat, aborted fetus, placenta
    • Congential: transplacental
48
Q

What are the 3 life stages of Neospora caninum

A
  • Bradyzoite: usually in CNS
    • can remain in viable tissue (dead animals) for 7-10d
  • Tachyzoite: any tissue
  • Oocyst: sporulates within 24h​
49
Q

Describe the life cycle of Neospora canis

50
Q

Describe the clinical presentation of Neospora caninum

A
  • Most severe in congenitally infected puppies
    • Limb paralysis - hind limb hyperextension
  • Generalized disease some pups, older dogs
    • CNS involvement, myocarditis, hepatitis, pneumonia
  • Death if untreated
51
Q

How do you diagnose Neospora?

A
  • Fecal exam
  • Multiple serological exams (IFA, ELISA)
  • Biopsy
  • PCR
52
Q

How do you treat Neospora?

A
  • Clinical improvement unlikely if rapidly ascending paralysis present
  • Adults/older puppies:
    • TMS
    • Clindamycin
  • Puppies 9-13 wks: Clindamycin

**nothing kills tissue cysts

53
Q

Describe Hammondia spp.

A
  • Morphologially similar to Neospora and Toxoplasma
  • Obligatory 2 host lifecycle
  • Transmission:
    • DH: ingest bradyzoites
    • IH: ingest oocysts
54
Q

Describe Hammondia hammondi

A
  • Hosts:
    • DH: cats
    • IH: rodents, pigs, dogs
  • Non-pathogenic
55
Q

Describe Hammondia heydorni

A
  • Hosts:
    • DH: dogs, coyotes
    • IH: cattle, water buffalo, camels, sheep, moose, goats, dogs
  • Possible diarrhea
56
Q

Describe the life cycle of Hammondia spp.

A
  • No congenital transmission
  • DH: ingest bradyzoites
    • no extraintestinal stages - no tachyzoites, no cysts
    • schizogony and gametogony in intestine
    • oocysts sporulate outside DH
  • IH: ingest oocysts
    • tachyzoite/bradyzoite cysts in sk mm, lungs, lymph nodes, brain
57
Q

How do you diagnose Hammondia?

A
  • Fecal float
    • cat - Toxoplasma or H. Hammondi
    • dog - Neospora or H. Heydorni
    • Hammondia spp. Are rare
  • Experimental PCR
  • Serology for Neospora and Toxoplasma
58
Q

True or False: Neospora, Toxoplasma, and Hammondia are morphologically identical

59
Q

Describe Sarcocystis spp.

A
  • Hosts:
    • Predator-Prey relationship
    • DH: carnivore
    • IH: herbivore
  • Transmission:
    • DH: consuming IH tissue containing sarcocysts
    • IH: ingesting food contaminated with sporocysts
60
Q

Describe the life cycle of Sarcocystis spp.

61
Q

What is this?

62
Q

How do you diagnose Sarcocystis spp.?

A
  • Fecal float - sporulated sporocyst (DH)
  • Biopsy/necropsy
  • Western blot - Ab in serum or CSF
  • PCR
  • History
63
Q

What two parasites are seen in this fecal float?

A

Top left = Sarcocystis oocyst (sporocyst)

Bottom right = Cystoisospora oocyst (unsporulated)

64
Q

Which species of Coccidia pass sporulated oocysts in the feces? How about unsporulated feces?

A
  • Sporulated:
    • Sarcocystis spp. - oocysts OR sporocysts
    • Crytosporidium spp. - oocysts WITHOUT sporocysts
  • Unsporulated:
    • Isospora (largest)
    • Hammondia spp
    • Neospora
    • Toxoplasma
65
Q

Describe Cytauxzoon felis

A
  • Piroplasms = invasive stage
  • Hosts:
    • DH: domestic cats
    • IH/vector: Dermacentor variabilis, Amblyomma americanum
    • Reservoir host: N. American bobcat
66
Q

Describe the life cycle of Cytauxzoan felis

67
Q

Describe the clinical presentation of Cytauxzoon felis

A
  • Fatal form:
    • fever (105*), depression, lethargy, anorexia, jaundice, death < 1 wk
  • Non-fatal form:
    • similar signs as ‘fatal’ form, can be asymptomatic, persistent parasitemia
68
Q

Describe the pathogenicity of Cytauxzoon felis

A
  • Schizogenous phase = most destructive
    • macrophages infected w/ schizonts block blood vessels —> multi-organ failure
  • C/S 6-10d PI
  • Postmortem - dark, enlarged spleen, lungs, l.n. Reddened and petechiated, pericardial sac may contain gelatinous icterus fluid
69
Q

How do you diagnose Cytauxzoon felis?

A
  • Giema stained blood smears
  • PCR (8-12 or 14d PI)
  • Biopsy/necropsy of visceral organs — histiocytes filled w/ granules
70
Q

How do you treat Cytauxzoon felis?

A
  • Supportive care
    • IV fluids, antimicrobials
  • Atovaquone and Azithromycin
  • Heparin PRN
71
Q

Describe Babesia spp.

A
  • Invasive stages = piroplasms
  • 2 main species in dogs (US)
    • B. Canis
    • B. Gibsoni
  • IH: tick
72
Q

Describe the Babesia life cycle

73
Q

How do the hosts of B. Canis and B. Gibsoni differ?

A

B. Canis

  • DH: dogs, wolves, jackals
  • IH: Ixodid ticks - Rhipicephalus sanguineus or Dermacentor spp.

B. Gibsoni

  • DH: canids
  • IH: suspect Rhicephalus sanguineus
74
Q

Which of these is which?

75
Q

Describe the epidemiology of B. Canis

A
  • Adults: usually carriers, mild/unapparent dz
  • Puppies: severe dz
  • ​Transmission: ticks = main vectors
76
Q

Describe the epidemiology of B. Gibsoni

A
  • Adults & puppies: same disease, any age
  • Transmission: fighting, ear cropping, tail docking, blood transfusions, transplacentally
77
Q

Describe the pathogenicity of Babesia sp.

A
  • Acute or chronic - erythrocyte destruction and anemia
  • C/S: anemia, pale MM, fever, amber/brown urine, splenomegaly
    • thrombocytopenia
      • B. Canis - mild to severe
      • B. Gibsoni - can be sever and persistent
78
Q

How do you diagnose Babesia spp.?

A
  • Blood film - piroplasms visible ONLY if clinically ill - not if carrier
  • IFA: titers >1:80 significant
  • PCR: will detect carriers, to differentiate spp.
79
Q

How do you treat. B. Canis vs. B. Gibsoni?

A

B. Canis

  • mild anemia - no tx required, can be reservoirs, relapse possible
  • imidocarb disproprionate (Imizol)

B. Gibsoni

  • Combo tx: Azithromycin and Atovaquone
  • Supportive care: blood, fluids
  • Relapse more likely
  • Does not respond as well to Imizol

Clinical Parasitology (7 decks)

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