Lecture 68 - Intestinal and GU Protozoa Flashcards
Intestinal protozoa: what are the species of interest?
What is the GU protozoa of interest ?
Entamoeba histolytica 0-9%
Giardia lamblia 1-24%
Coccidian Parasites: Cryptosporidium parvum 2-7% & Cyclospora
GU: • Trichomonas Vaginalis
What forms do these protozoa exist in and when?
Trophic Forms (TROPHOZOITE) -- cause disease in the host; Feeding and replicating forms; locomotion via flagella or ameboid
Cystic Form: form the trophozoite exist in the environment do not replicate or feed; nonmotible resistant to environmental factors
Entamoebe Histolytica
epidemiology:
Transmission
50 million infected/yr –10% symptomatic
100,000 deaths per year
Highest incidence in the tropics
In the US – mostly in immigrant populations
Transmission: fecal-oral Direct person-to-person Contaminated food Contaminated water
Pathogenesis: Amebiasis –
E. hystolitica Invasiveness of trophozoites -- Adhere to lectin Amebapores -- form pores in targetted cells Phagocytosis of killed cells
Amebiasis – disease manifestations
E. Histolytica
- Intestinal disease –
Asymptomatic colonization
Mild colitis; mega colon
Diarrhea, Dysenterry, hematochezia
-Outside of Intestine – distribute through the blood stream
amebic liver abscess
Diagnosis of Amebiasis:
• Intestinal disease: microscopy, fecal antigen detection, PCR,
• serology (may represent prior exposures )
• Liver Abscess: US, CT, MR imaging
§ Needle aspirate
• Treatment: of Amebiasis
Asymptomatic cyst carrier: luminal agent — poorly absorbed
• Diloxanide furoate
• Paromomycin
• Iodoquinol
Invasive disease: tissue-active agent in combination with luminal agent to cover both intestinal and invasive disease
• Metronidazole (750 mg tid x 5-10D)
• Tinidazole
AND a luminal agent
• Giardiasis (Giardia Lamblia)
- where is it found geographically? when is it more commonly contracted ? by whom?
Found in Alaska and the the northern US
Mostly in clean running wter
Occurs in spring and summer; poeple who are outdoors a lot
associated with beavers
Cyst–
Giardia infection and transmission
cyst vs trophozoite
- Highly infective cysts – passed in feces of infected persons;
* The cysts are highly resistant can live in cold water and other extremes
* Flagellated Trophozoite – adheres to mucosa via ventral sucking disk leading to villi stunting and interfering with absorption tissues
Clinical manifestations of Giardiasis
- Watery Diarrhea, fatigue, cramps, malodorous stool
* No blood in the stool
* Can last several weeks
Dx of Giardiasis
• Diagnosis:
• Microscopy of the stool
• Tests for stool antigen
trophozoite = “cross eyed faces”
Treatment of Giardiasis
• Short course of – Tinidazole, metronidazole
What are the two Coccidian Intestinal Parasites:
what is a differentiating test?
Cryptosporidia & Cyclospora
Cryptosporidia – does not fluoresce under UV light
Cyclospora – auto-fluroescence under UV light
Cryptosporidia
- life cycle and pathogenesis
Symptoms
Thick Walled oocyst ingested by the host
excystation and infestation in the gut
Bug is an intracellular parasite – resides at the tip of the entereocyte
Immune defense is therefore T cell mediated
10-20 episodes of watery diarrhea per day
cramping, weight loss, vomiting
weeks to months – dehyration
Cryptosporidia
epi
where is it found? when?
what is unique about the cysts
- Peaks during summer months
* Transmission via treated recreational water (water parks, swimming pools)
* Not really from drinking water, or ponds, or lakes or rivers
* Cysts are resistance to chlorine
Cryptosporidia
dx
Treatment – immunocompetent vs immunocompromised
prevention
Dx: Fluorescent antibody test with fecal smear – no fluorescence under UV light; Acid fast
Treatment:
competent – supportive therapy; can use Nitzzoxanide
compromised – reverse the immune suppression
Prevention – don’t drink pool water
• Coccidian intestinal parasites: Cyclospora
Lifecycle –
Transmission
Epi – where and when
Fecal oral transmission
Host excretes unsporulated oocysts in stool
Can contaminate an food source –
sporulated oocysts ingested in contaminated food/water
epi – found all over the world
mostly occurs in the spring and summer
US outbreaks associated with produce
Cyclospora
clinical manifestations
- Sudden onset
* Fever, Abd pain, cramping
* Frequent watery diarrhea
* Weeks long if untreated
Cyclospora
Dx
Treatment
Prevention
Dx • Stool samples
• Acid fast staining or safranin stsaining
• PCR
• When viewed under UV light it auto-fluoresces
Treatment
• TMP/SMX; or no treatment for immunocompoenetn persons
Prevention
• Filtering water removes cysts
• Careful washing of fruits and vegetables from endemic areas
• Trichomonas Vaginalis
morphology
whats unique about its forms?
Transmission
• Morphology: pear shaped, flagella protozoan
Only trophic form – no cystic form
Transmission – venereal;
The most common non-viral STD
Most efficienctly transmitted men –> women
• Trichomonas Vaginalis
Sx in Females
Females- 25% asymptomatic
Vaginal dc, soreness, dysuria, urinary frequency
Increased risk to other STD/HIV
Men – asymptomatic or have mild urethral d/c
Complciations: prostatits, epididymits, urethral stricutre disease
Trich + HIV = 6x the viral load
Dx of Trichomonas vag
Treamtnet
- Diagnosis
* Wet mount microscopy; Giemsa stain
* PCR
* Culture- Treatment
- Tinidazole or metronidazole
- Single dose
- Tinidazole or metronidazole
- Treatment
