1. Background

• humans are the only reservoir of entamoeba histolytica
• E. histolytica are water-bourne protozoan parasites
• the infection is spread by cysts in the stools which contaminate food and water (cockroaches and flies can also spread cysts)
• Trophozoites penetrate the mucosa of the bowel in regions of relative stasis such as the cecum, appendix, and colon. A small abscess forms and may ulcerate. They may then enter the portal vein and lodge in the liver, lungs, pleura, heart, skin, and brain months to years later.
• diarrhea is thought to be secondary to a cytopathic effect of the ameoba of the colonic epithelium

1. Diarrhea

• loose stools may be intermittent or associated with explosive defecation and mucousy/bloody diarrhea (amoebic dysentery)
• associated symptoms include headache, fever, chills, cramping, right upper quadrant (RUQ) pain with tender liver

2. Complications

1. Stool

• O&P (hemophagocytic and multinucleated protozoa)

2. Biopsy

• colonic ulcerations are discrete (1-20 inches in diameter) with an overlying whitish or yellowish exudate; the intervening mucosa is normal

3. Serum

• isonatremic dehydration
• serological test with indirect hemagglutination test (IHA) is positive (1:128) in 90% of those with amoebic colitis (i.e., invasive)

4. Imaging Studies

• liver CT shows abscesses and percutaneous needle drainage will retrieve an "anchovy paste"

1. Supportive

• oral rehydration fluid (ORF) or intravenous rehydration

2. Medications

• Metronidazole