protozoan infections Flashcards
(53 cards)
unicellular eukaryote with ability to form cyst
protozoa
different protozoa classified by movement
amoebas
flagellates
ciliates
sporozoas
protozoa stage which is dormant and highly resistant to environmental stress
cyst stage
stage that is active, reproductive, and feeding. form that typically causes disease.
trophozoite
- caused by entamoeba
- tropical/subtropical regions
- transmitted by ingestion of cysts
- fecal oral contaminated food and water
–> person to person
–> flies
–> human excrement as fertilizer - penetrates intestinal wall, possible resulting in dysentery or extra intestinal disease
- extra intestinal disease = liver abscess
amebiasis
3 species of amebiasis
E histolytica
E dispar
E moshkovskii
most symptomatic disease of amebiasis caused by
E histolytica
- infection from ingestion of amebic cysts from fecally contaminated food/water
- cysts remain viable in environment for weeks to months
- cysts pass through stomach to small intestine, where they turn into trophozoites
- trophozoites invade and penetrate the mucous barrier of colon causing tissue destruction and increased intestinal secretion and leads to bloody diarrhea
entamoeba: amebiasis
how does entamoeba histolytic cause intestinal destruction
- secretes proteinases that destroy proteins
- amebapore formation which are pores in the lipid bilayer of intestine that leads to cellular destruction
- disrupts tight junction proteins resulting in increased intestinal permeability
entamoeba: amebiasis symptoms
- most frequently asymptomatic
- bloody diarrhea
- abd pain
- colitis
- fever
- intestinal perforation
-mucosal sloughing
severe complication of entamoeba: amebiasis
- abscesses due to hematologic spread
- liver MC
- hepatomegaly
-RUQ pain - weight loss
how to diagnose intestinal amebiasis
- stool microscopy
- stool antigen testing
- stool PCR (preferred)
how to diagnose hepatic abscess
-Ultrasound, CT, or MRI
- anti amebic antibodies in serum
- elevated liver enzymes
entamoeba: amebiasis treatment
metronidazole or tinidazole + luminal agent
luminal agents:
- diloxanide
- iodoquinol
- paromomycin
and fluid replacement
entamoeba: amebiasis treatment alternative
tetracycline + chloroquine
- free living ameba
- flagellate form
- thermophilic organism found in soil, fresh and polluted warm lake water, domestic water supplies, swimming pools, thermal water, sewers
naegleria fowleri
- fulminant CNS infection caused by N fowleri
- aspiration of contaminated water or soil
- recent swimming in lakes or heated swimming pools
- tap water exposure through neti pots
- rapidly fatal
primary amebic meningoencephalitis (PAM)
PAM symptoms
early: HA, fever, stiff neck, lethargy
1-2 days later: photophobia, palsies of 3,4,and 6 cranial nerves, N/V, behavioral abnormalities, seizures, AMS
7-10 days: coma, death
how to diagnose PAM
- elevated intracranial pressure
- CSF: high WBC, elevated protein, low glucose
- purulent meningitis
- relevant history
how to diagnose naegleri fowleri
detection of motile trophozoites in CSF
–> centrifuged CSF wet mount prep immediately after getting sample
MRI: extensive edema and necrosis of the front lobes
treatment of PAM due to N. fowleri
(uncertain)
combination of:
amphoterecin B
rifampin
fluconazole
miltefosine
azithromycin
steroids
- protozoal infection of the upper small intestine caused by Giardia lamblia
- flagellated
- most common protozoan parasite infection in the US
- poor sanitation areas (households, daycare, contaminated water, food, fecal oral route)
giardia
how does Giardia infection occur
- ingestion of cyst
- bind to small intestines and excitation releases trophozoites. causes symptoms.
- trophozoites then multiply and pass to large intestine where they produce cysts
- infectious cysts passed in stool
high risk groups for Giardia
- travelers to endemic areas
- those drinking from contaminated water during recreational wilderness travel
- partners performing anal intercourse
- impaired immunity
