Amoebic Diseases

Question 1

Description of Protozoa parasites

Answer 1

Characteristics:

• cell membrane
• unicellular
• use mitosis to reproduce
• are motile (cillia, flagella, pseudopods)

Question 2

Types of protozoans based on locomotion

Answer 2

Amoeboids = pseudopodia

Ciliates = cilia

Non-motile = sporozoa

Flagella = flagellates

Question 3

Specific high-yield geographic information about Protozoa

Answer 3

Giardia lamblia:

• ubiquitous campers, ski resorts, wild animals, beaver exposure
• infects small intestines

Entamoeba Histolytica:

• fecal continuation worldwide
• infects colon and liver

Cryptosporidium:

• cattle-raising/farmers
• infects small intestine and respiratory tract

Cyclosporia:

• tropical/subtropical regions
• infects small intestines

Question 4

What’s the easiest way to differentiate amoebas?

Answer 4

The size of the cysts

Question 5

Entamoeba histolytica cyst information

Answer 5

10-20 micrometers

• Quadranucleated cysts are present when matured*
• if not mature, will binulceated with chromatoid body

Question 6

Pathogenesis of entamoeba histolytica

Answer 6

Trophozoities invade interstinal epithelium
- produces a flask-shaped ulcer and lytic necrosis

produces symptoms that mimics Crohn’s disease “amebiasis colitis”

• *key difference is there is a known start date for amoeba Crohn’s, where as true Crohn’s has no identifiable start date
• also produces a giant granuloma-like mass (ameboma)

in rare cases, will spread to the liver and cause invasive amebiasis (abscess of amebias in liver)

Treatment = paromomycin and metronidazole

Question 7

Naegleri Fowleri pathogenesis

Answer 7

Exceptionally rare amoeba that travels from freshwater, sediment warm water to the brain/spinal cord of the infective organism

Mimics meningitis via severe Purulent hemorrhagic inflammatory reaction in the brain

• meningoencephaltiis
• rapid onset severe bifrontal headache with seizures and inability to smell and taste

**difference is it is extremely fatal compared to normal meningitis (>98% fatality)

** cyst is usually mononucleated

Treatment = amphotericin B (almost always dies though)

Question 8

How does naegleri fowleri travel to brain?

Answer 8

Uses the olfactory nerve to retrograde travel across the cribiform plate

Question 9

Acanthamoeba

Answer 9

Opportunistic amoeba that is higher chances of infection in immunocompromised patients

Symptoms:

• **keratitis of the eye
• granulomatous amoebic encephalitis (GAE)

Reproduces via binary fission and most cysts have survived in vitro for 20 years

Question 10

Giardia duodenalis specifics

Answer 10

Amoeba is binucleated and is a multiple flagellate amoeba

Often causes acute watery diarrhea and flatulence

• is exceptionally foul smelling and greasy
• does this by attacking the duodenal and jejunal mucosa

Question 11

Cryptosporidium

Answer 11

Sporozoa that is immobile

Self-limiting in healthy, severe and sometimes fatal in immunocompromised people

Oocyte are 4-5 micrometers

Uses a multitude of virulence factors

Treatment = nitazoxanide for immunosupression

Question 12

Cyclospora cayetanensis

Answer 12

Sporozoa

Oocysts are 8-10 micrometers and take a while the become infections (only transmitted via water or food)

Causes shortening of intestinal villi and produces

• diarrhea, anorexia, fatigue, weight loss
• usually selflimiting however often relapses

Treatment = TMX-SMX