GI protozoa

Question 1

What causes amebiasis?

Answer 1

Entamoeba histolytica

Question 2

What is the transmissible form of entamoeba histolytica?

Answer 2

Cyst form

Question 3

What is the pathogenesis of entamoeba histolytica?

Answer 3

1. Cyst form breaks out and invades wall of colon 2. Can remain in lumen to replicate or penetrate intestinal wall to go to brain, liver, etc

Question 4

Which pathogen causes characteristic flask shaped lesions?

Answer 4

Entamoeba histolytica

Question 5

Who is more infectious in an entamoeba histolytica infection - symptomatic or asymptomatic person?

Answer 5

Asymptomatic - more cysts in stool

Question 6

What are the symptoms of symptomatic entamoeba histolytica infection?

Answer 6

Bloody, mucousy diarrhea (fever is rare)

Question 7

What is the route of transmission for entamoeba histolytica?

Answer 7

Fecal-oral, ingestion of cysts

Question 8

What are the properties of invasive amebiasis?

Answer 8

1. Penetration of intestinal wall by trophozoites 2. Flask shaped lesion 3. Spread via blood stream - liver abscess, abdominal pain, fever, increased WC

Question 9

In amebiasis infection, solid stool contains more cysts or trophozoites?

Answer 9

Cysts

Question 10

What is the cause of giardiasis?

Answer 10

Giardia lamblia

Question 11

What is the infective stage in giardia lamblia?

Answer 11

Cyst

Question 12

What is the lifecycle of giardia lamblia?

Answer 12

1. Excysts in duodenum 2. Multiples by longitudinal binary fission 3. Trophozoites on mucosa of duodenum 4. Trophozoites and cysts shed in stool 5. Trophozoites disintegrate, cysts reinfect

Question 13

What are the stool characteristics for giardiasis infection?

Answer 13

1. Greasy, foul smelling floating stools 2. No blood 3. No fever

Question 14

What are the properties of symptomatic vs asymptomatic individuals with giardiasis infection?

Answer 14

1. Symptomatic - frank abdominal distress, likely passing trophozoites in stool 2. Asymptomatic - tend to pass cyst form

Question 15

What causes balantidiasis?

Answer 15

Balantidium coli

Question 16

What are the properties of balantidium coli?

Answer 16

1. Only ciliated organism that infects humans 2. Disease is very similar to entamoeba histolytica 3. Can stay in lumen or invade for dysentery like symptoms 4. Frequently associated with pigs

Question 17

What is the life cycle for balantidium coli?

Answer 17

1. Ingestion of infective cyst 2. Trophozoite remains in colon lumen to multiply, or invades wall of colon to multiply 3. Trophozoite detected in stool and shed

Question 18

What causes cryptosporidiosis?

Answer 18

Cryptosporidium parvum

Question 19

What is the transmission for cryptosporidium parvum?

Answer 19

Ingestion of fecal oocysts

Question 20

What are the symptoms of intestinal cryptosporidiosis?

Answer 20

1. Profuse watery diarrhea accompanied by cramping, fatigue, and weight loss. 2. No blood

Question 21

What is the life cycle for cryptosporidium parvum?

Answer 21

1. Ingest oocyte 2. Sporozoites attach to surface of intestinal epithelium and mature 3. Sexual forms develop and produce fertilized oocyst 4. Mature oocyst detected in stool 5. Cows are known reservoirs

Question 22

What stain is used to detect mature oocysts in cryptosporidiosis?

Answer 22

Acid fast stain

Question 23

What is unique about cryptosporidium parvum pathogenesis?

Answer 23

Sexual and asexual reproduction occur in host

Question 24

What is the life cycle for isospora belli?

Answer 24

1. Ingestion of immature oocyst with sporocyst 2. Sporozoites divide and mature in cells of intestinal mucosa 3. Sexual forms develop and produce fertilized oocyst

Question 25

What are the properties of isospora belli?

Answer 25

1. Often seen in immunocompromised patients 2. Fever, diarrhea, weight loss

Question 26

What are the features of cyclospora?

Answer 26

1. Profuse, watery diarrhea 2. Cramping, fatigue, weight loss 3. Prolonged symptoms (weeks) 4. Similar to cryptosporidiosis

Question 27

What is the diagnosis for cyclospora?

Answer 27

Oocysts fluoresce under UV light

Question 28

What causes microsporidiosis?

Answer 28

Microsporidia

Question 29

What are the properties of microsporidia?

Answer 29

1. Obligate intracellular parasites 2. Primitive eukaryotes 3. Infection via ingestion of spores 4. Intestinal disease or disseminated disease

Question 30

What are the extraintestinal signs of microsporidiosis?

Answer 30

1. Keratoconjunctivitis - early dissemination 2. Dependent on organ system involved