Amebiasis

Question 1

Describe the lifecycle of Amebiasis parasite

Answer 1

• ingests cysts
• trophs have tropism for and invade liver, lung, large intestine, etc.
• Cysts and trophs shed in feces. Cysts can survive.

Question 2

For which organs to Amebiasis trophs have a tropism?

Answer 2

liver, lung, large intestine

Question 3

Clinical: What are the asymptomatic concerns with amebiasis? (3)

Answer 3

• Stools will have cysts but no evidence of tissue invasion
• Negative serum Ab, normal colonoscopy
• generally found by accident

Question 4

Clinical: What are the clinical manifestations of amebiasis via diarrhea?

Answer 4

Amebic colitis (diarrhea) or amebic dysentery

• onset over several days, mucoid diarrhea, gross or occult blood
• abdominal discomfort +/- fever
• *almost always Occult blood**

Question 5

Clinical: What are the clinical manifestations of amebiasis via liver abcess?

Answer 5

Liver abcess (most common extraintenstinal disease)

• fever, RUQ pain, tenderness over liver
• Remote history of diarrhea but not generally during this stage
• patient will report travel history and iarrhea, fever, malaise, RUQ discomfort weeks to months go
• CT reveals liver abcess

Question 6

Approximately how many deaths occur from Amebiasis annually?

Answer 6

70,000-100,000 deaths annually

3rd leading cause of parasitic death globally

Question 7

In which countries is amebiasis most common?

Answer 7

Central or South America, Africa, Asia

In US mainly due to traveler’s

Question 8

In which populations does amebiasis most often present?

Answer 8

Generally see it in travelers. Prevalence is low

• institutionalize patients (poor hygiene)
• men having sex with men
• recent immigrants
• migrant works from endemic areas

Question 9

Amebiasis is the only parasite that causes _____ disease?

Answer 9

microvascular disease

Question 10

How do you diagnose Ambiasis?

Answer 10

Diagnosis is very problematic because:

• stool exams for cysts generally negative – may need multiple samples
• non-pathgenetic cysts look the same, including E. coli
• Extra-intestinal disease (hepatic abscess)
  
  • not many will have cysts in stool
  • CT may reveal an abscess but hard to tell
  • Index of suspicion with travel hx and general hx
• Serum Ab tests are important
  
  • indirect hemagglutination previously
  • now ELISA
• Microscopic stool exam in lab
  
  • RBC within cytoplasm of trophs this is suggestive of E. histolytica
  • Fecal WBC = active amebic colitis with bowel inflammation Probably not overwhelming amounts b/c they use lyse neutrophils
• EIS on stool – fresh or frozen

Question 11

Which diagnostic tests are most important with Ambiasis? (6)

Answer 11

• CT to reveal abscess + hx
• Serum Ab tests
• ELISA
• Microscopic stool exam (RBC within cytoplasm of trophs is suggestive of E. histolytica
• Fecal WBC = active amebic colitis with bowl inflammation (but probably not a lot)
• EIA on stool, fresh or frozen
• Basic Stool exam often negative 3 amebas look the same & cysts are not usually present!

Question 12

How do you treat Ambiasis?

Answer 12

• Look up!

- Treat asymptomatic to decrease risk for invasive

Question 13

How do you prevent Ambiasis? (4)

Answer 13

• proper waste disposal and water purification
• boil contaminated water - iodine/chlorine WON’T kill!
• Assume fruits and veggies to be contaminated
• avoid fecal/oral contact