Lecture 68 - Intestinal and GU Protozoa

Question 1

Intestinal protozoa: what are the species of interest?

What is the GU protozoa of interest ?

Answer 1

Entamoeba histolytica 0-9%
Giardia lamblia 1-24%

Coccidian Parasites: Cryptosporidium parvum 2-7% & Cyclospora

GU: • Trichomonas Vaginalis

Question 2

What forms do these protozoa exist in and when?

Answer 2

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

Question 3

Entamoebe Histolytica
epidemiology:
Transmission

Answer 3

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

Question 4

Pathogenesis: Amebiasis –

Answer 4

E. hystolitica
Invasiveness of trophozoites -- 
Adhere to lectin 
Amebapores -- form pores in targetted cells 
Phagocytosis of killed cells

Question 5

Amebiasis – disease manifestations

Answer 5

E. Histolytica

• Intestinal disease –
  Asymptomatic colonization
  Mild colitis; mega colon
  Diarrhea, Dysenterry, hematochezia

-Outside of Intestine – distribute through the blood stream
amebic liver abscess

Question 6

Diagnosis of Amebiasis:

Answer 6

• Intestinal disease: microscopy, fecal antigen detection, PCR,
• serology (may represent prior exposures )
• Liver Abscess: US, CT, MR imaging
§ Needle aspirate

Question 7

• Treatment: of Amebiasis

Answer 7

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

Question 8

• Giardiasis (Giardia Lamblia)

- where is it found geographically? when is it more commonly contracted ? by whom?

Answer 8

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–

Question 9

Giardia infection and transmission

cyst vs trophozoite

Answer 9

• 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

Question 10

Clinical manifestations of Giardiasis

Answer 10

• Watery Diarrhea, fatigue, cramps, malodorous stool
  * No blood in the stool
  * Can last several weeks

Question 11

Dx of Giardiasis

Answer 11

• Diagnosis:
• Microscopy of the stool
• Tests for stool antigen
trophozoite = “cross eyed faces”

Question 12

Treatment of Giardiasis

Answer 12

• Short course of – Tinidazole, metronidazole

Question 13

What are the two Coccidian Intestinal Parasites:

what is a differentiating test?

Answer 13

Cryptosporidia & Cyclospora

Cryptosporidia – does not fluoresce under UV light
Cyclospora – auto-fluroescence under UV light

Question 14

Cryptosporidia
- life cycle and pathogenesis

Symptoms

Answer 14

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

Question 15

Cryptosporidia
epi
where is it found? when?
what is unique about the cysts

Answer 15

• 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

Question 16

Cryptosporidia
dx
Treatment – immunocompetent vs immunocompromised
prevention

Answer 16

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

Question 17

• Coccidian intestinal parasites: Cyclospora

Lifecycle –
Transmission
Epi – where and when

Answer 17

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

Question 18

Cyclospora

clinical manifestations

Answer 18

• Sudden onset
  * Fever, Abd pain, cramping
  * Frequent watery diarrhea
  * Weeks long if untreated

Question 19

Cyclospora
Dx
Treatment
Prevention

Answer 19

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

Question 20

• Trichomonas Vaginalis

morphology
whats unique about its forms?
Transmission

Answer 20

• Morphology: pear shaped, flagella protozoan
Only trophic form – no cystic form

Transmission – venereal;
The most common non-viral STD
Most efficienctly transmitted men –> women

Question 21

• Trichomonas Vaginalis

Sx in Females

Answer 21

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

Question 22

Dx of Trichomonas vag

Treamtnet

Answer 22

• Diagnosis
  * Wet mount microscopy; Giemsa stain
  * PCR
  * Culture
  
  • Treatment
    
    • Tinidazole or metronidazole
      
      • Single dose