E3- GI Protozoans Flashcards
How does Giardia lamblia present clinically?
- Watery diarrhea (NO blood)
- Vitamin B12 deficiency
What type of pathogen is Giardia lamblia?
Zoonotic flagellate GI protozoan
What population does Giardia lamblia most commonly affect?
Children
What stage of Giardia lambli exists freely in the small intestine and feeds on mucosal secretions?
Trophozoite
What is the morphology of the trophozoite stage of Giardia lamblia?
Tear drop shaped with 2 nuclei
Does the trophozoite stage of Giardia lamblia invade or destroy RBCs?
No (no blood in diarrhea)
What is the infectious stage of Giardia lamblia?
Cysts
What form of Giardia lamblia is passed into the environment?
Cysts
What is the morphology of the cysts stage of Giardia lamblia?
4 nuclei (1 cysts produces 2 trophozoites)
How is Giardia lamblia acquired?
Ingestion of cysts (infectious stage) from contaminated food or water with feces
Once Giardia lamblia cysts have been ingested, what occurs next?
- Ecystation and then the trophozoites move to into the small intestine to divide
- Trophozoites encyst in neutral pH and bile salts
- Cysts are passed into the environment (immediately infectious)
Why is Giardia lamblia highly contagious?
Cysts are immediately infectious
Infective dose = 10-25 cysts
>25 cysts = 100% infection rate
When are Giardia lamblia infections most prevalent?
June-october
Where geographically are Giardia lamblia infections most prevalent in the US?
Western states (Rocky mountains)
How is Giardia lamblia dx?
- Stool sample
- ELISA to detect GSA-65
What type of pathogen is Entamoena histalytica?
Protozoan that can result in colitis and liver abcesses
What is the etiology of amoebiasis?
Entamoena histalytica
What stage of Entamoena histalytica (amoebiasis) is invasive and ingest RBCs?
Trophozoite (blood in stool)
What is the morphology of the trophozoite stage of Entamoena histalytica (amoebiasis)?
- 1 nucleus
- Non-flagellated
- Pseudopod forming
What is the infectious stage of Entamoena histalytica (amoebiasis)?
Cysts
What is the morphology of the cysts stage of Entamoena histalytica (amoebiasis)?
4 nuceli (1 cyst produces 4 trophozoites)
How is Entamoena histalytica (amoebiasis) transmitted?
Ingestion of cysts (infectious stage) from contaminated water or food with feces
Once Entamoena histalytica cysts have been ingested, what occurs next?
- Excystation, which forms highly motile trophozoites that colonize the mucosa
- The trophozoites may encysts and be passed in feces OR
- The trophozoites may invade the intentional mucosa/bloodstream
Which GI protozoan infection is a reportable disease?
Entamoena histalytica (amoebiasis)
Which GI protozoan infection can cause disseminated disease?
Entamoena histalytica (amoebiasis)
What is the clinical presentation of Entamoena histalytica (amoebiasis)?
- Bloody stools
- Intestinal ulcers
- Fever
- R. upper quadrant pain
What are the virulence factors of Entamoena histalytica (amoebiasis)? (4)
- Lectin
- Phospholipases
- Ameobapore
- Cystein proteases
How is Entamoena histalytica (amoebiasis) dx?
- Stool sample
- ELISA (can differentiate from other Entamoena spp)
Are Entamoena histalytica (amoebiasis) cysts resistant to chlorine?
Yes
What population does Cryptospordiosis hominis most commonly affect?
Children
What is the presentation of Cryptospordiosis hominis in healthy individuals?
Self-limiting watery diarrheal illness that lasts ~2 weeks (NO blood)
What population can Cryptospordiosis hominis cause severe illness in?
Immunocompromised
What is the infectious stage of Cryptospordiosis hominis?
Oocysts
What is the morphology of Cryptospordiosis hominis’s oocysts?
Contain 4 sporozoites
Can Cryptospordiosis hominis multiply outside of the hosts?
No
How is Cryptospordiosis hominis transmitted?
Ingestion of oocyst (infectious stage)
Once Cryptospordiosis hominis oocysts have been ingestion, what occurs next?
- The oocysts is activated to release its 4 sporozoites
- Sporozoites bind to receptors on intestinal epithelial cells and are ingested into parasitophorous vacules
- Parasite undergoes sexual and asexual reproduction
What protozoan is ingested into parasitophorous vacules?
Cryptospordiosis hominis
What type of replication does Cryptospordiosis hominis undergo?
Sexual and asexual
Through what type of reproduction are thin walled oocyst produced in C. hominis? What this their purpose?
- Asexual
- Reinfect the host
Through what type of reproduction are thick walled oocyst produced in C. hominis? What is their purpose?
- Sexual
- Shed into the environment (immediately infectious)
How are endemic cases of Cryptospordiosis hominis usually transmitted?
Person-to-person
How are sporadic cases of Cryptospordiosis hominis usually transmitted?
Contaminated water or food
Is Cryptospordiosis hominis resistant to chlorine?
Yes
How is Cryptospordiosis hominis dx?
- ID of round acid fast oocyst in stool sample
- ELISA
What type of pathogen is Cyclosporiasis cayetanesis?
Diarrheagenic Protozoan
What geographic location is Cyclosporiasis cayetanesis linked to?
Latin America
How can you differentiate the oocyst from Cryptospordiosis hominis from the oocyst from Cyclosporiasis cayetanesis?
The oocyst from Cyclosporiasis cayetanesis is much larger and is autofluorescent
How is Cyclosporiasis cayetanesis transmitted?
Ingestion of oocysts from contaminated water or imported foods (fruits and vegetables)
What is different about the oocysts infectability in Cyclosporiasis cayetanesis?
- Oocyst shed in feces must sporulate in the environment
- NOT immediately infectious
What is the clinical presentation of Cyclosporiasis cayetanesis?
Explosive watery diarrhea (NO blood)
How is Cyclosporiasis cayetanesis dx?
- ID large oocysts in stool samples
- ID acid fast autofluorescent oocyst
What GI protozoan has a large central vacuole and multiple nuclei distributed around the rim of the cytoplasm?
Blastocytis hominis
What GI protozoan is zoonotic (pigs), contains a macronucleus, has cilia on the trophozoite stage, and can cause gut perforation?
Balantidium coli
