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Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt > Protozoal infections - Coccidia, Toxoplasma, Giardia, Amoeba > Flashcards

Protozoal infections - Coccidia, Toxoplasma, Giardia, Amoeba Flashcards

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1
Q

What is giardia? Appearance? Lifecycle

A
  • Flagellate protozoan
  • Pear shaped 15um long
  • Attaches to small intestine with sucker but does not invade -> not bloody diarrhoea
  • Produces a small 4 nucleus cyst (expelled in stool)
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2
Q

Giardia incubation? Who has high risk?

A

7-10 days (occasionally months)

Children
MSM

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3
Q

Giardia Rx completed and test negative but ongoing diarrhoea probably due to?

A

Lactose intolerance

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4
Q

Giardia dx?

A
  • Stool microscopy for Characteristic small 4 nuclei cyst (may require 3 samples)
  • Also now ELISA / EIA and point of care tests
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5
Q

String test is used for? How does jt work

A

Giardia / stronglyotides
- Patient shallows some string which is attached to cheek with gelatin on end. Left overnight and then examined for trophozoites

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6
Q

Giardia small bowel biopsy?

A

Villlous flattening, crypt deepening and inflam infiltrate in lamina propria

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7
Q

Giardia rx? 2nd line (especially in HIV)

A

tinidazole
[Metronidazole / albendazole ]

Nitazoxanide

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8
Q

Prevention giardia

A

Boil water, sedimentation, flocculation

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9
Q

Prevention giardia

A

Boil or filter water, chlorination, flocculation, sedimentation

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10
Q

Main protective factor against giardia

A

IgA

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11
Q

Amoeba most common presentation? Geography

A
  • Dysentery
  • Then liver abscess
    [Only 4-10% of infected with E histolytica develop sx]

Found throughout tropics

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11
Q

Entamoeba which one causes issues? Which is much more common but doesn’t cause significant disease?

A
  • E Histolytica
  • E dispar - more common
  • Issue is that both cysts look the same on microscopy but no need to treat dispar
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12
Q

Confirm dx of amoebic dysentery? Stain? Differentiate from dispar?

A
  • Amoebic trophozoites containing ingested RBCs in a fresh Stool sample
  • Should be within 15 minutes of sample
    -iron haematoxylin / trichrome stain

Non-virulent Eg E Dispar would not have ingested RBCs

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13
Q

E histolytica life cycle

A
  • Four-nucleated cyst ingested following consumption of contaminated food / water
  • -> digested by gut releasing 8 trophozoites which continue to replicate through fission
  • Produce cysts which are excreted in stool and can survive weeks in water
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14
Q

Incubation of amoeba?

A

Few days to several years

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15
Q

Most common location amoebic abscess? What’s often seen on CXR? LFTs

A
  • Single one in right lobe of liver in 70%
  • Raised right hemidiaphragm or effusion (communication with abscess)
  • LFTs often unremarkable bar raised ALP
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16
Q

Stool microscopy makes mainstay of dx for Amoeba in resource poor settings - what about in richer? GOld standard?

A

[Egg microscopy]

  • ELISA Stool antigen testing - most common
  • PCR - gold standard
    -Serum IgG - does not differentiate from past infection
  • Enzyme immunoassay (EIA)
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17
Q

What does amoebic colitis look like on endoscopy?

A
  • Mimicks IBD with ulcers
  • Can take biopsies of these if other tests inconclusive
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18
Q

Amoeba rx?

A

Metronidazole for 5-10 days or single dose tinidazole (2g)

Followed by a course of luminal amoebicides to eradicate cysts
- Eg diloxanide furoate, paromomycin, iodoquinol

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19
Q

Prevention amobea

A
  • Improved hygiene/ sanitation and clean drinking water
  • Boil / peel / cook food and water
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20
Q

amoebic cysts resistant to?

A

Chlorination
Sensitive to iodine

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21
Q

How many people infected with amoeba develop the disease when infected?

A

4-10% in first year

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22
Q

Describe entamoeba

A

Non-flagellate protozoan

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23
Q

2 Main parts of life cycle entamoeba

A

Noninvasive, infective cysts
Invasive trophozoite

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24
Which receptor allows amoeba to attach to the intestinal mucosa
Galactose lectin [Can test for this]
25
amoebic colitis usual incubation? sx? risk of progression to?
sx after 1-2 weeks and lasts 4-6 weeks The pain is usually the worst LLQ Bloody diarrhoea Risk of fulminant colitis/NEC/Megacolon in risk groups (Immunosupressed, malnourished, pregnant)
26
Mass in caecum in amoeba is?
Ameoboma- inflammatory reaction in cecum
27
Ameoboma differentials
Intestinal TB, typhoid fever, appendiceal mass and colonic cancer
28
72 yo with AML Hx of chronic diarrhea develops bloody diarrhea on day 12 of chemotherapy multiple ulcers plus a 4cm mass in the ascending colon =
Ameboma
29
Which LFT most derranged in amebic liver abcess
ALP
30
Women or men more likely to have an amebic liver abscess
Men make up 90%
31
25 yo male from Lima Hx: 3 week history of fever, weight loss, RUQ pain no diarrhea PE: T 39C, pulse 120 chronically ill, pale no jaundice, tenderness over RUQ Labs: mild anemia, leukocytosis elevated alkaline phosphatase
Amebic liver abscess
32
2 complications of amebic liver abscess spread
Pericarditis Empyema
33
Where do you get cutaneous amoeba histolytica lesions? Due to? What does it look like?
ano-genital, perianal region ▪ direct inoculation from cysts in the stools ▪ well-demarcated, round-oval ulcer with heaped-up borders
34
Only way to diagnose ameoboma
Colonoscopy + biopsy
35
Ix gold standard for amebic liver abscess
PCR + imaging (US fine)
36
Positive amoeba but no dystentery or liver abscess Rx
Luminal agent - paromomycin, [ diloxanide furoate, iodoquinol]
37
Appearance of aspirate from amoebic abscess
Yellow-brown' 'anchovy paste'
38
Name 3 situations you would perform diagnostic tap amebic abscess
-Left lobe - risk of pericardial spread ->10cm -Not responding to medical therapy -Unclear diagnosis ?pyogenic
39
▪ 18 yo female from rural Trujillo ▪ 3 week history of diarrhea ▪ admitted with acute abdomen and sepsis ▪ multiple colonic perforations? What is it? Usual host? Dx? RX?
Balantidiasis -Balantidium coli is the largest intestinal protozoan of humans and the only ciliate [Massive oval with fluffy edge kidney-shaped nuclei] -Pigs usual hosts (humans accidental) -trophozoites in a fresh stool sample or in scrapings from a colonic ulcer Tetracycline or Metronidazole
40
TROPHOZOITE OF ENTAMOEBA HISTOLYTICA
41
CYST OF ENTAMOEBA HISTOLYTICA -one to four nuclei identical to that of trophozoites
42
Abscess in right lobe of liver + dysentery and now this on colonoscopy
Amoebic colitis multiple flask-shaped ulcers; extensive areas of hemorrhage and necrosis
43
Cryptosporidium which type for humans? Animals and humans? Life cycle.
- C hominis - C parvum Feacal oral - oocyst releases 4 sporozoites which invades epithelium - Can either produce thin-walled oocysts which auto-infect same host. Or thick walled which are excreted
44
Cryptosporidiosis dx? Stain that can be used?
Acid fast oocysts in faeces/ luminal aspirate using kinyoun acid fast stain [I was fucKinyoun when I had it] Most have PCR assays now
45
Unusual finding of eosinophilia in which protozoan infection? Rx?
cystoisospora infection Co-trimoxazole [CystoEYEsospora - egg looks like eye and has Eosinopholia]
46
Cryptosporidiosis rx?
- Usually self limiting - Nitazoxide
47
Cyclospora rx?
Co-trimox [or cipro]
48
2 main stages of protazoa? Which are infective? which are feeding?
Trophozoite : feeding/vegetative stage. May cause damage Cyst: non replicative, resistance stage. Spherical shape. Infective stage
49
Compare nucleus of histolytica vs dispar vs E coli
50
Compare Chromatid bars of histolytica vs dispar vs E coli
Histolytica and dispar - the blunt bois
51
Entamoeba histolytica Life cycle Infective vs diagnostic stage
Infective stage : mature cyst. Diagnostic stage : cysts, trophozoites.
52
Dispar / histolytica
53
Histolytica trophozoite
54
Hitolytica / dispar trophozoite even peripheral chromatin , central karyosome
55
ingested RBCs - E. histolytica nucleus (1), even peripheral chromatin , central karyosome
56
Ingested RBCs - E. histolytica nucleus (1), even peripheral chromatin , central karyosome
57
Ingested RBCs - E. histolytica nucleus (1), even peripheral chromatin , central karyosome
58
ingested RBCs - E. histolytica nucleus (1), even peripheral chromatin , central karyosome
59
E. histolytica / E. dispar - Pre cyst nucleus (1), even peripheral chromatin , central karyosome, chromatid bars ( blunt ends
60
E. histolytica / E. dispar - Pre cyst nucleus (1), even peripheral chromatin , central karyosome, chromatid bars ( blunt ends
61
E. histolytica / E. dispar - Pre cyst nucleus (1), even peripheral chromatin , central karyosome, chromatid bars ( blunt ends
62
E. histolytica / E. dispar - Premature cyst nuclei (2-3), even peripheral chromatin , central karyosome , chromatoidal bars ( blunt ends)
63
E. histolytica / E. dispar - Premature cyst nuclei (2-3), even peripheral chromatin , central karyosome , chromatoidal bars ( blunt ends)
64
E. histolytica / E. dispar - Premature cyst nuclei - 4, even peripheral chromatin , central karyosome , chromatoidal bars ( blunt ends
65
Entamoeba coli - Trophozoite nucleus (1), uneven peripheral chromatin ,
66
Entamoeba coli - Trophozoite nucleus (1), uneven peripheral chromatin ,
67
Entamoeba coli - Trophozoite nucleus (1), uneven peripheral chromatin ,
68
Entamoeba coli - Imature cyst central vacuole , nuclei (1-7, usually~2 )
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Entamoeba coli - Imature cyst central vacuole , nuclei (1 7, usually~2 )
70
Entamoeba coli - Mature cyst nuclei 8 , rarely 16, uneven peripheral chromatin chromatoidal bars ( sharp ends)
71
Entamoeba coli - Mature cyst nuclei 8 , rarely 16, uneven peripheral chromatin chromatoidal bars ( sharp ends)
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Entamoeba coli - Mature cyst nuclei 8 , rarely 16, uneven peripheral chromatin chromatoidal bars ( sharp ends)
73
Entamoeba coli - Trophozoite vs immature vs Mature cyst number of nuclei
Trop - 1 Immature - 2 (1-7) Mature 8 (or 16)
74
Giardia Trophozoite
75
Giardia Cyst
76
Giardia cyst
77
Giardia cyst
78
Endolimax nana [Looks like a little di]
79
Iodamoeba butschlii [Od shape]
80
Iodamoeba butschlii [Od shape]
81
Chilomastix mesnili [Chilled to the max 'dont make a mess' lemonade]
82
Chilomastix mesnili [Chilled lemonade]
83
Blastocystis hominis - Central vacuole - peripheral nuclei (nuclei blasted to edge)
84
Blastocystis hominis- Central vacuole - peripheral nuclei (nuclei blasted to edge)
85
Balantidium coli Trophozoite kidney shaped micronucleus, Cilia - fast moving
86
Balantioides coli Trophozoite kidney shaped micronucleus, Cilia - fast moving
87
Balantioides coli cyst kidney shaped nucleus
88
What are the 3 free-living amoeba that can cause meningitis in humans
naegleria fowleri Acanthamoeba Balamuthia mandrillaris
89
Which amoeba causes acute Haemorrhagic Meningitis? How does it get to brain?
naegleria fowleri - via olfactory nerve
90
Which ameoba sometimes produces cutaneous granulomatous lesions but may involve CNS with chronic granulomatous encephalitis (similar to chronic meningitis)? Spread to CNS
Acanthamoeba Haematogenous (from lungs)
91
2 ameba which cause granulomatous amebic encephalitis
Acanthamoeba spp. Balamuthia mandrillaris
92
cause of severe keratitis among contact lens wearers? Rx?
Acanthamoeba Pentamidine  + Fluconazole  + Miltefosine 
93
Cause of acute, and usually lethal, central nervous system (CNS) disease called primary amebic meningoencephalitis (PAM).
Naegleria fowleri -penetrating the nasal mucosa, usually during swimming and travels up olfactory nerves
94
5 days after swimming -> severe CNS dysfunction with rapid degeneration caused by hemorrhagic-necrotizing meningoencephalitis.
Naegleria fowleri:
95
Naegleria fowleri - trophozoite large single nucleus with large and densekaryosome, no peripheral chromatin, granular cytoplasm with many vacuoles
96
Naegleria fowleri - trophozoite [nae good, fowl bug] large single nucleus with large and densekaryosome, no peripheral chromatin, granular cytoplasm with many vacuoles
97
Granulomatous amebic encephalitis (GAE) / Keratitis =? Infective vs diagnostic stage?
Acanthamoeba spp. Infective stage: trophozoites Diagnostic stage: trophozoites, cysts.
98
Acanthamoeba spp. - Trophozoite spine-like pseudopodia, single nucleus with large karyosome, vacuoles
99
Acanthamoeba spp. - Trophozoite spine-like pseudopodia, single nucleus with large karyosome, vacuoles
100
Acanthamoeba - cyst double wall (exocyst and endocyst), single nucleus
101
Acanthamoeba - cyst double wall (exocyst and endocyst), single nucleus
102
Acanthamoeba - cyst double wall (exocyst and endocyst), single nucleus
103
Cause of Granulomatous amebic encephalitis (GAE) + lesions on nose? Infective vs diagnostic stage?
Balamuthia mandrillaris Infective stage: trophozoites Diagnostic stage: trophozoites, cysts
104
Balamuthia mandrillaris - trophozoite pleomorphic, long/slender pseudopodia (broader than Acanthamoeba), large single nucleus.
105
Balamuthia mandrillaris - trophozoite pleomorphic, long/slender pseudopodia (broader than Acanthamoeba), large single nucleus.
106
Balamuthia mandrillaris - cyst 3 layered wall , single nucleus
107
Balamuthia mandrillaris - cyst 3 layered wall, single nucleus
108
a 2-week medical mission trip to a village in Honduras. One week after returning, she developed bloating, epigastric discomfort, and diarrhea. The diarrhea consisted of watery and soft stools that are foul smelling. Name 4 protozoa that it might be and their Rx
Giardia lamblia – metronidazole Cryptosporidium – Nitazoxanide Cystoisospora belli - co-trimoxazole Cyclospora cayetanensis – Co-trimoxazole
109
Metronidazole side effects
-GI upset, metallic taste -Avoid alcohol -chronic use -> peripheral neuropathy
110
Name 3 uses of Nitazoxanide
cryptosporidium, giardia, backup for Fasciola herpetica
111
Pt had amoeba histolytica - treated with single dose of 1 drug - what was it? Why did they relapse
tinidazole Need to treat with luminal agent as well eg . paromomycin
112
Cystoisospora belli 1 oval oocyst with 1 or 2 sporoblasts (no sporozoites inside).
113
Cystoisospora belli 1 oval oocyst with 1 or 2 sporoblasts (no sporozoites inside).
114
Cystoispora belli infective vs diagnostic stage
Infective stage: mature oocysts with sporozoites. Diagnostic stage: immature oocysts in feces.
115
What is this? which stain?
Cystoisospora belli Ziehl-Neelsen / Kinyoun
116
Cyclospora cayetanensis infective vs diagnostic
Infective stage: mature oocysts with sporozoites. Diagnostic stage: immature oocysts in feces.
117
Cyclospora cayetanensis key implicated food
Raspberries [basil / cilantro]
118
Cyclospora cayetanensis 1 round oocyst (no sporozoites inside), thick wall, dark granules.
119
What protozoa has acid fast variability
Cyclospora cayetanensis kinyoun stain used
120
Cryptosporidium infective vs diagnostic
Both are mature oocysts with sporozoites Its the only one that does autoinfection
121
Cryptosporidium trophozoite - on outside of gut vili
122
2 types of cryptosporidium oocyst
Thick-walled mature oocysts (80%) -Survive in outside Thin-walled mature oocysts (20%) Internal autoinfection (not recovered from stools).
123
cryptosporidium 1 round oocyst with 4 sporozoites, dark granules. Ziehl-Neelsen / Kinyoun
124
cryptosporidium
125
Cryptosporidium vs Cyclospora vs Cystoisospora Size? Which one has a mature cyst as diagnostic stage? rX? Which can auto-reinfect? Which common cause of travellers diarrhoea? Which causes eosinophilia?
Cystoisospora - Eye shaped + E for eosinophilia
126
2 key species of Cryptosporidium
Cryptosporidium hominis Cryptosporidium parvum
127
Cryptosporidium survives in domestic water in low income countries why?
Resistant to chlorination
128
Long term impact of childhood diarrhoea
Early childhood diarrhea with: -decreased fitness (aged 6-9) and -Cognitive impairment (ages 6-10) Effects likely primarily due to stunting
129
Cryptosporidium Dx?
Routine stool exam AFB stains IFA Ag detection PCR Multiplex molecular
130
Name 3 things Nitazoxanide works for
Cryptosporidium, Entamoeba , Giardia helminths (also bacteria)
131
27 yo F with 4 wks of watery diarrhea, >5x per day. No mucus, blood Also, fatigue, nausea, anorexia, cramps, bloating sensation Travelling around Nepal for 4 mo Antibiotics, metronidazole no response -Eggs 9um dx? Rx? Key countries
Cyclospora cayetanensis co-trimoxazole Highly endemic in Peru, Haiti, Nepal
132
Cyclospora cayetanensis showing acid-fast variability
133
Chronic watery diarrhoea, mild eosinophilia ? rx?
Cystoisospora belli co-trimoxazole
134
Rx A/b/c
Cryptosporidium - Rx nitazoxanide Cyclospora - co-trimox Cystoisospora - co-trimox
135
Name 1 microsporidia species
Enterocytozoon bieneusi - diarrhoea + biliary in AIDs Encephalitozoon intestinalis - Diarrhoea in AIDs E. hellem -Systemic infection E Tachypleistophora - Myositis E Nosema Keratoconjunctivitis
136
AIDs with Diarrhoea, wasting, keratoconjunctivitis and myositis
microsporidia
137
Toxoplasma full name? Infective vs diagnostic stage?
Toxoplasma gondii Infective stage: bradyzoites, mature oocysts with sporozoites, tachyzoites. Diagnostic stage: tissue cysts with bradyzoites (biopsy), tachyzoites
138
Toxoplasma life cycle? Name 3 methods of infection and the form
Undercooked meat Tissue cysts with bradyzoites Organ transplantation (tissue cysts with bradyzoites) Contaminated food/water with cat feces (Mature oocysts) Blood transfusion (Tachyzoites) Transplacentary (Tachyzoites)
139
Toxoplasma gondii (Tachyzoite Crescent shaped with a prominent nucleus
140
Toxoplasma gondii (Bradyzoite) Spherical in brain (may be elongated in muscle)
141
Name the parts of toxoplasma here
A - tachyzoite B - pseudocyst c- tissue cyst D/E - sporulated oocyst
142
2 most common presentations of toxoplasma gondii
*Lymphadenopathy and “Mononucleosis like" *Chorioretinitis
143
Toxoplasma gondii
144
Toxoplasma gondii
145
AIDs. Most likely?
Toxoplasma gondii
146
Key side effects of Pyrimethamine + Sulfadiazine? How to reduce?
Anaemia (35%) Leukopenia (15%) Thrombocytopenia (5%) Add folic acid
147
Toxoplasma Ix?
Serology - IgM
148
Prevention of fetal toxoplasmosis when mum is positive Eg IgM?
Spiramycin
149
Diagnosis and Treatment of confirmed congenital toxoplasma
Amniotic fluid PCR -US aslso used pyrimethamine/sulfadiazine
150
Diagnosis and Treatment of confirmed congenital toxoplasma
Amniotic fluid PCR -US also used pyrimethamine/sulfadiazine

Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt (26 decks)

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