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Trop Med > Protozoans > Flashcards

Protozoans Flashcards

1
Q

What is the species?

A

E. histolytica trophozoite

pseudopods, vacuoles, cytoplasm, ingested RBCs (E. histolytica), nucleus even peripheral chromatin, central karyosome.

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2
Q

How do you Rx cystoisospora?

A

Co-trimoxazole

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3
Q

What is this?

A

Acid fast variability on staining
Cyclospora
Some stain in their entirety, some do not

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4
Q

What is the species?

A

E. histolytica / E. dispar trophozoite
Cyst
cytoplasm, nuclei (2-3), even peripheral chromatin, central karyosome,
chromatoidal bars (blunt ends).

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5
Q

What is the organism for cyclospora?

A

Cyclospora Cayetenesis

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6
Q

Transmission of cryptosporidium?

A

Person-to-person - main!
Drinking water
Recreational water
Swimming pools, water parks, lakes and streams
Contaminated food
Animals

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7
Q

What do you get from raspberries?

A

Cyclospora cayetensis
Requires environmental maturation

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8
Q

What is the smallest of the intestinal protozoans?

A

Cryptosporidium
4-5 microns

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9
Q

How may cryptosporidium present differently if CD4 <50?

A

Cholera like diarrhoea with volume depletion
Biliary tract infection - cholangitis
Chronic diarrhoea

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10
Q

What is the cryptosporidium that infects cattle?

A

C. parvum

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11
Q

What is the most common flagellated parasite to cause human disease?

A

Giardia lamblia

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12
Q

Name the species

A

Chilomastix mesnili (non pathogenic to humans)
Cyst
Flagellate

Lemon shaped
1 nucleus
Eccentric karyosome
Anterior hyaline protuberance

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13
Q

What blood test is useful for cystoisospora?

A

Eosinophilia - mild

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14
Q

What is the treatment of chagas disease?

A

benznidazole for 60 days or nifurimox for 90 days

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15
Q

How do you Rx microsporidia?

A

Albendazole E. intestinalis

Fumagillin E bieneusi

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16
Q

What is the route of transmission of chagas disease?

A

by vector-faeces into skin break or oral, also by blood transfusion, organ transplant, vertical transmission

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17
Q

What size are cyclospora?

A

8-10 microns

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18
Q

What is this organism?

A

Chagas (Trypanosoma cruzi)
amastigotes inside cardiomyocytes

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19
Q

What type of organisms are coccidia?

A

Intracellular with an apical complex

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20
Q

Name the species

A

Balantioides coli
Trophozoite

Ciliated
ovoid, macronucleus (kidney-shaped), micronucleus, contractile vacuole, cytostome.

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21
Q

What is an ameoboma?

A

Inflammatory reaction in the caecum
Palpable LIF mass (DD: intestinal TB, typhoid, appendix max, Ca, Crohns)
Histology: Marked granulation tissue

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22
Q

What is this organism?

A

Stool miscroscopy - Giardia
x3 fresh samples – identifies Giardia in 90%
Trophozoites: Saline wet mount - need to be fast
Cysts: Zinc sulfate flotation + iodine staining

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23
Q

Name the species

A

Cystoisospora belli

Immature oocysts with sporoblasts

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24
Q

What is unique about the way cryptosporidium infects the gut?

A

Apical complex forms complex with cell membrane of epithelial cells

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25
Q

What are the main classes of intestinal protozoans?

A

Pseudopods (use ecto and endoplasm to move)
Flagella
Cilia
Apical complex/intracellular

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26
Q

What is the clinical presentation of cystoisospora?

A

Diarrhea usually chronic
Frequent assoc biliary disease

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27
Q

How do you treat giardiasis?

A

Tinidazole one dose
Metronidazole (5-7 days)

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28
Q

Name the species

A

Giardia lamblia
Cyst

axostyle - long stick centrally

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29
Q

Are the immature oocysts that are shed in faeces immediately infective for cystoisospora?

A

No!
No auto infection

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30
Q

How do you treat E.Histolytica?

A

have to Rx cyst and trophozoite - treat trophozoite first!
Need non-absorbable luminal agents to kill the cysts (no systemic activity) - Iodoquinol, paramomycin
Metronidazole to kill trophozoite

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31
Q

What is the value of immunity from cryptosporidium?

A

Cannot be reinfected

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32
Q

Rx of cryptosporidiosis?

A

Most infections self limiting with fluids and electrolytes
Rx of choice - Nitazoxanide
Always start ARVs or optimise immunosuppression

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33
Q

What is the infective/diagnostic stage of cyclospora?

A

Mature oocysts - infective
Immature oocysts in stool - diagnostic

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34
Q

What is the infectious stage of the life cycle of ameobiasis (entamoeba histolytica)

A

Cysts
Amoebic cysts are resistant to chlorination, but sensitive to iodine solutions

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35
Q

Which patients with Chagas disease warrant treatment?

A

Indications for treatment
Acute Chagas
Reactivated Chagas (mostly those with HIV)
Congenital Chagas
All children with Chagas (acute or chronic)
Adult <50y old, without advanced cardiomyopathy

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36
Q

What is the vector/reservoir/infective stage of chagas disease?

A

Vector: triatomine insects 3 important genera: Triatoma, Panstrongylus, Rhodnius

Infectious stage: metacyclic trypomastigotes

Reservoir: domestic animals - dogs

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37
Q

What is this organism?

A

Trophozoite and cyst of E.Histolytica
Well demarcated single nucleus with central nucleolus, peripheral chromatin
Ingests erythrocytes - visible inside trophozoite

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38
Q

Symptoms of giardia?

A

Diarrhoea
Prolonged duration of diarrhoea >1wk
Bloating, flatulence
Steatorrhoea, foul smelling greasy
Weight loss
Malaise

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39
Q

What is pathogenesis of giardia?

A

Disrupts the brush border, mucosal invasion, secretion of enterotoxin, induces inflammatory reaction

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40
Q

Is foodborne/waterborne the only way of transmitting giardia?

A

No - sexual transmission - msm

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41
Q

What is the infective stage of giardiasis?

A

Cysts

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42
Q

Name the species

A

Giardia lamblia

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43
Q

How does cryptosporidium present?

A

Diarrhoea, watery.
Travellers diarrhoea in particular (endemic areas ppl have immunity)
Often prolonged or persistent
Causes malnutrition, may cause cognitive and developmental delay in children

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44
Q

What is the treatment for giardiasis?

A

Single-dose tinidazole (or metronidazole 5-7d)

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45
Q

Microsporidium - interesting points re: life cycle?

A

Live inside body within cells
Transmitted as spores
Coiled microtubular structure

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46
Q

∆ of cryptosporidium?

A

Microscopy
Also immunoassay antigen detection and PCR

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47
Q

Name the species

A

Iodamoeba butschlii (non pathogenic to humans)
Cyst

5-20um
1 nucleus
Big eccentric karyosome
Big glycogen vacuole

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48
Q

What is the species?

A

E. histolytica / trophozoite

pseudopods, vacuoles, cytoplasm, ingested RBCs (E. histolytica), nucleus even peripheral chromatin, central karyosome.

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49
Q

Name the species

A

Balantioides coli
Cyst

cyst wall, macronucleus (kidney-shaped), micronucleus, vacuole.

Cilia get taken up inside cyst wall

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50
Q

How do you treat cryptosporidium?

A

Nitazoxanide

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51
Q

What is the Rx for cyclospora?

A

Co-trimoxazole

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52
Q

What is the species?

A

Entamoeba coli (non pathogenic to humans)
Trophozoite

pseudopods, vacuoles, cytoplasm, nucleus (1), uneven peripheral chromatin,
eccentric karyosome.

53
Q

What are the predictors of mortality in chagas disease?

A

NYHA status 3 or 4
Cardiomegaly on CXR
Impaired LV function on echo
NSVT on holter

54
Q

What is this?

A

Cystoisospora Belli

55
Q

Name the species

A

Endolimax nana (non pathogenic to humans)
Cyst

5-10um
1-4 nuclei
Big central karyosome
No peripheral chromatin

Like 4 on dice

56
Q

What stages of intracellular protozoan may be found in stool culture?

A

Trophozoite or cyst
Trophozoite: long, 1 nucleus, has pseudopods
Cyst: circular, multinuclear

57
Q

What is the most common intestinal protozoa causing diarrhoea in resource poor settings?

A

Cryptosporidium hominis

58
Q

What organism causes chagas disease?

A

Trypanosoma cruzi

59
Q

What are the most common microsporidia?

A

Enterocytozoon bieneusi (1)
Encephalitozoon intestinalis (2)

60
Q

What is the name of organism for cryptosporidium?

A

Cryptosporidium hominus
(Most common protozoa in HIV)

61
Q

What is the transmission of Entamoeba histolytica?

A

faeco-oral, water, foodbourne

62
Q

What is this?

A

Cryptosporidium hominus

63
Q

How does cryptosporidium cause auto infection?

A

1 mature oocyst = 4 sporozoites

64
Q

Name the species

A

Blastocystis spp (hominus)
Vacuolar form

central vacuole, annular cytoplasm, peripheral nuclei (2-6).

65
Q

What stain do you need for the Coccidia species for ∆?

A

Acid fast (Ziehl Neelson) - some

66
Q

What is the best diagnostic test for Chagas disease?

A

serology for IgG (chronic), (blood smear / serum PCR for acute)

67
Q

What is the only protozoa to cause eosinophilia?

A

Cystiospora Belli

68
Q

How does microsporidia present?

A

Main 2 species - AIDS patients causing diarrhoea and biliary disease

Rarer subtypes cause myositis, keratoconjuncitivitis

69
Q

What are the key tests to diagnose ameobiasis?

A

Stool samples - identifying trophozoites and cysts
Need to examine quickly as trophozoites inactivate quickly. Fresh sample - 30mins, 3 samples to improve sensitivity

Antigen in stool and serum

ELISA against galactose-lectin antigen

PCR gold standard, often not available

70
Q

What is the mode of transmission for giardia?

A

Waterborne and foodborne - drink untreated surface water

71
Q

What size are cystoisospora on acid fast?

A

20-30 microns

72
Q

What proportion of people infected with entamoeba histolytica are symptomatic, and what is the main presentation of invasive disease?

A

Bloody diarrhoea: amoebic dysentery
Abdo pain - usually left lower quadrant

73
Q

How do you treat balantoides coli?

A

Tetracycline

Largest protozoan.
Only ciliated parasite that infects humans.
Dysentery, perforation.

74
Q

Name the species

A

Cyclospora cayetanensis
Acid fast variability

75
Q

Transmission of cyclospora?

A

Foodborne - berries, herbs
Waterborne

76
Q

What are the pathogenic ameobas?

A

Free-living amoebas
- Naegleria
- Acanthamoeba
- Ballamuthia

Entamoeba histolytica

77
Q

How do you do microscopy for microsporidia?

A

modified trichrome,
hot Gram, UV2 - not typical stains!

78
Q

What is this?

A

Cryptosporidium.
Some of the cells stain acid fast to different degrees - lots of heterogeneity

79
Q

What is the species?

A

Entamoeba coli (non pathogenic to humans)
Mature cyst

cytoplasm, nuclei (8, rarely 16), uneven peripheral chromatin, eccentric
karyosome, chromatoidal bars (sharp ends).

80
Q

Which is the most common amoeba to cause human disease?

A

Entamoeba histolytica

81
Q

Presentation of cyclospora?

A

Diarrhoea, abdo cramps, weight loss, nausea
For >2 weeks

82
Q

Why does auto infection not occur with cyclospora?

A

Sporogony
At least 1-2 weeks in environment

83
Q

How do you diagnose cyclospora?

A

Microscopy

84
Q

Where else in the body can be affected by ameoba?

A

Liver abscess, splenic abscess, lung abscess, GU infection, Pericarditis
Cutaneous amebiasis – very rare,

85
Q

What is the best diagnostic test for giardiasis?

A

Antigen test of stool – ELISA for cyst wall glycoprotein

86
Q

How do you treat cystoisospora and cyclospora?

A

Co-trimoxazole

87
Q

What is the classical presentation of chagas disease?

A

Acute disease - not common
Febrile disorder lasting 1-2 months (1wk incubation) with Romana’s sign - periorbital unilateral oedema

Chronic disease – determinate form 10-30y after exposure: Cardiomyopathy (CHD – Chagas heart disease), Heart failure, Conduction defects – heart block
Arrhythmia – NSVT, RBBB – frequent ECG finding

Also:
Mega-oesophagus
Dysphagia, oodynophagia, regurgitation
Mega-colon
Sigmoid colon
Constipation

88
Q

What are the names of the organisms for giardia?

A

Giardia lamblia, duodenalis, intestinalis

89
Q

What is the most common presentation of ameobiasis?

A

Self-limiting asymptomatic infection – 90%

90
Q

What is the species?

A

E. histolytica trophozoite
pseudopods, vacuoles, cytoplasm, ingested RBCs (E. histolytica), nucleus even peripheral chromatin, central karyosome.

91
Q

What Is the infective/diagnostic stage of cystoisospora/cyclospora?

A

Infective: mature oocysts with sporozoites
Diagnostic: immature oocysts

92
Q

What is the most common parasitic cause of diarrhoea?

A

Giardia

93
Q

What is the drug of choice for Rx of balantioides?

A

Tetracycline

94
Q

What is the largest protozoan?

A

Balantidium Coli

95
Q

Which protozoan commonly affects pigs? Causes dysentery and perforation.

A

Balantidium Coli

96
Q

What do you commonly see in aspirate from an entamoeba histolytica liver cyst?

A

No organisms

97
Q

What is infective stage of most intestinal protozoan?

A

Cyst
Trophozoite would be destroyed by stomach
(diagnostic stage - trophozoite or cyst)

98
Q

How many people are asymptomatic of E.Histolytica?

A

90%

99
Q

What non pathogenic Entamoebas may you see on stool sample?

A

Endolimax nana
Iodamoeba butschlii

100
Q

How would you differentiate E.histolytica and E.Dispar?

A

PCR, ELISA

101
Q

Who gets severe infections with E.histolytica?

A

Kids, pregnant, immunosuppressed

102
Q

Key features of amebiasis colitis?

A

Onset - 1-2 weeks, lasting for 6 weeks
Abdo pain- LEFT SIDE
Bloody diarrhoea
Wt loss
Can progress to fulminant colitis/toxic megacolon in 0.5%

103
Q

What are the GI complications of amebiasis?

A

Ameoboma - inflammatory reaction in the caecum
Colitis

104
Q

Non GI complications of amebiasis?

A

Liver abscess - 1-4 weeks
Fever, weight loss, abdo pain, hepatomegaly, jaundice occasionally
Also pleural and pericardiac spread

105
Q

What bloods would be suspicious of an ameobic liver abscess?

A

ALP rise, WCC rise, mild elevation of liver enzymes

106
Q

Presentation of amoebic abscess in children?

A

High mortality, multiple abscess, present with diarrhoea, HM common

107
Q

Imaging of amoebic liver abscess?

A

Raised hemidiaphragm on right CXR

108
Q

∆∆ of ameobic abscess

A

Pyogenic abscess - septic pt, purulent material
Hydatid cyst
Cancer

109
Q

Spread of ameoba to perianal region presents as?

A

Perianal abscess from direct inoculation

110
Q

Infective stage of amebiasis?

A

Cyst

111
Q

Diagnosis of ameobic liver cyst?

A

E.histolytica in the stool - wet mount cyst or trophozoite

112
Q

Other tests for amebiasis?

A

ELISA against galactose lectin antigen. Only + in first 7 days
Antibodies
PCR - gold standard!!!

113
Q

Non serology tests for E.Histolytica?

A

Endoscopy - multiple ulcers, exudate, in caecum and ascending colon

114
Q

When would you do an endoscopy for E.Histolytica?

A

If stool negative but high clinical suspicion
If suspicion of an ameboma

115
Q

What do you see on endoscopy for E.histolytica?

A

Multiple flask shaped ulcers

116
Q

What is this?

A

Flask shaped ulcer, E.Histolytica

117
Q

Where would you find trophozoites in a colonic ulcer?

A

At margin

118
Q

What tests can you do on the liver abscess?

A

sterile, odorless, brown fluid, trophozoites are hardly found, antigen positive. Anchovy paste fluid!
PCR of fluid

119
Q

Mx of liver abscess with ameoba?

A

Metronidazole plus paramomycin (luminal) same as colonic

120
Q

Which ameobic liver abscesses do you manage with drainage?

A

Not responding to med Rx, large, left lobe

121
Q

Presentation of balantidium coli?

A

Dysentery

122
Q

Definitive host for balantidium?

A

Pigs

123
Q

Giardia organism?

A

Giardia lamblia, duodenalis, intestinalis

124
Q

Infective stage of Giardia?

A

Cyst

125
Q

Difference between ameobiasis and giardiasis anatomically?

A

Giardia affects small bowel

126
Q

3 presenting syndromes of giardia?

A

Acute diarrhoea
Chronic diarrhoea
Malabsorption - can lead to vitamin deficiencies

127
Q

Key features in the hx for giardia?

A

Prolonged diarrhoea
Bloating and flatulence
Foul smelling greasy stools
Weight loss

128
Q

Test of choice for Giardia?

A

Antigen detection ELISA - detects a cell wall glycoprotein of giardia and cryptosporidium

Stool exam - 3 samples increases sensitivity

129
Q

Rx of giardiasis

A

Metronidazole 7/7

Trop Med (49 decks)

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