Luminal Protozoa Flashcards
Clinical of E. histolytica infection?
-Majority asymptomatic and clear infection
-Small proportion develop invasive intestinal disease (abdo pain and bloody diarrhea)
-Can become fulminant
-Can be chronic with intermittent but long-lasting symptoms
Trophozoites with ingested RBCs?
Entamoeba histolytica
What is the pathologic sign of invasive intestinal amoebiasis?
Flask-shaped ulcer
Diagnostic methods for amoebiasis?
-Wet-film microscopy on fixed and stained samples (cannot distinguish histolytic/dispar)
-Serology
-Tissue biopsies
-Antigen detection
-NAAT
When is serology useful for amoebiasis?
ALA - almost always positive
How to diagnose ALA?
-Clinical signs and symptoms
-Serology (usually strongly positive)
-Imaging (CT, U/S)
-PCR detection of circulating E. histolytica DNA
Tx for E histolytica - invasive disease?
Metronidazole followed by luminal amoebicide (paromomycin)
Primary symptoms of Giardiasis?
- Diarrhea
- Malaise
- Flatulence
- Foul-smelling faeces
- Weight loss
- Extraintestinal symptoms - eyes, skin, joints and urinary
Impact of giardiasis in children?
-Malnutrition
-Growth impairment
-Cognitive deficits
-Alteration of gut microbiome
How to diagnose giardiasis?
-Wet film microscopy of fecal samples (high specificity, low sensitivity)
-DFA staining of cysts
-Antigen detection (ELISA/card, less sensitive than DFA)
-PCR
Giardia cysts?
-Oval
-8-12 um
-4 nuclei at one end
-Line (axoneme) length of cyst
-One or more curved median bodies
How is giardia transmitted?
Ingestion of cysts ->
Food
Water (most outbreaks)
Person-person
What makes giardia easy to acuire?
-Small infectious dose
-Cysts resistant to chlorine
-Limited efficacy of conventional wastewater treatment plants at cyst removal
-Cysts remain viable for weeks in cold water
-Animal reservoirs for some genotypes
