protozoan infections Flashcards
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
giardia symptoms acute phase
- profuse and watery diarrhea
- usually self limited
- lasts days or weeks
- monitor for dehydration
guardia symptoms chronic disease symptoms
- abd cramping
- bloating
- flatus
- malaise
- anorexia
- stools greasy, frothy, foul smelling*
how to diagnose Giardia
PCR stool assays
giardia treatment
metronidazole
giardia treatment if pregnant
paromycin
-infection caused by plasmodium species
- single cell parasite spread via mosquito
- P falciparum
- endemic to most to the tropics, south and central America, Middle East, India, Southeast Asia, Africa
malaria
human phase of malaria
asexual phase
mosquito phase of malaria
sexual phase
infected RBC stages of malaria
- early trophozoite: ring form
- late trophozoite: growing ring form
- further trophozoites growth digestion of HGB and leave behind hemozoin (schizont) (replicative phase)
- rupture
hallmark of malaria
history of travel to endemic area
uncomplicated malaria symptoms
anemia
jaundice
hepatomegaly
splenomegaly
- generates a sticky protein that coats the surface of the RBC
- organ dysfunction
- neurologic disease
- severe anemia
- hypotension/shock
severe complicated malaria
how to diagnose malaria
- Giemsa stained blood smears
- rapid antigen test for plasmodium is alternative but can have false negative for P. falciparum
treatment for P malariae
chloroquine
treatment for P vivax or P ovale
chloroquine + primaquine (check G6PD)
uncomplicated P falciparum malaria treatment
artemether lumefantrin
severe malaria treatment
IV/IM artesunate
- caused by protozoal species toxoplasmosis gondii
- found worldwide in humans, mammals, and birds
- cats definitive host
- mild fever, fatigue, non tender lymphadenopathy
toxoplasmosis
4 clinical syndromes of T gondii
- primary infection in immunocompetent person: asymptomatic may be mild febrile illness
- congenital infection: maternal infection during pregnancy
- retinochoroiditis: symptoms present weeks to years after congenital infection
- disease in immunocompromised person
1st stage of toxoplasmosis
primary infection in immunocompetent person
2nd stage of toxoplasmosis
congenital
Hallmarks:
- the congenital triad: chorioretinitis, hydrocephalus, intracranial calcifications**
- blueberry muffin rash: thrombotic thrombocytopenia purpura
3rd stage of toxoplasmosis
retinochoroiditis (ocular toxoplasmosis)
- inflammatory condition affecting the retina and choroid in the eye
4th stage of toxoplasmosis
disease in the immunocompromised person
- reactivation in AIDS, cancer, and immunosuppressive drugs pts
how to diagnose toxoplasmosis
serologic testing
- presence of IgM and/or IgG
- confirm IgG antibodies in 2 weeks
histopathologic examination
- tissue, blood, sputum, etc stained with standard histologic dyes looking for tachyzoites and or cysts
toxoplasmosis treatment
immunocompetent: tx not neccessary
severe: pyrimethamine plus sulfadiazine with folinic acid
what should pregnant women not do to prevent toxoplasmosis
don’t change cat litter box
- STD caused by protozoal trichomonas vaginalis
- Male: nongonoccal urethritis, minimal discharge
- female: vaginitis with copious discharge, malodorous, frothy, and yellow/green color
trichomoniasis
how to diagnose trichomoniasis
- wet mount= motile organism
- point of care antigen and nucleic acid amplification assays
trichomoniasis treatment
metronidazole
tinidazole
