Entamoeba histolytica

Beth Wozney

Geographic Distribution

• Worldwide!

• Higher rates:• Tropical areas

Hosts

• Definitive• Humans

• Intermediate• None are necessary

• Reservoir• Dogs• Pigs• Monkeys• Humans (asymptomatic)

Causes Amebic Dysentery

• Symptoms:• Abdominal pain• Weight loss• Bloody, mucous diarrhea• Intestinal lesions• Can invade liver, lungs, and brain

• May cause death• 40,000-100,000 deaths per year

Entamoeba histolytica

• http://animal.discovery.com/videos/monsters-inside-me-entamoeba-histolytica.html

Life Cycle

Life Cycle Continued…

• Human ingests cysts from fecally contaminated food or water

• In the large intestine, trophozoites undergo binary fission and multiply.

• Cysts and trophozoites are passed in the feces.

Life Cycle…

Pathogenesis

• Vary from asymptomatic to severe

• Amoebic dysentery: trophozoites invade the intestinal wall, leading to amoebic ulcer formations.• Diarrhea with blood and mucus• Liver abcesses• Spread to lungs and brain• Death

Diagnosis

• Direct Fecal Smear and staining: ingested red blood cell with distinctive nucleus• Cysts: Cigar-shaped bodies, 4 nuclei,

chromatoid bodies

• Enzyme Immunoassay (EIA)

• Indirect Hemagglutination

• Antigen Detection

• PCR: for species identification

Treatment

• Metronidazole

• Tinidazole

• Best method: Prevention!• Filter drinking water in endemic areas• Wash fruits and vegetables• Wash your hands

E.Histolytica vs E.coli

Entamoeba coli

• Common

• Similar life cycle (Ingested cysts)

• Nonpathogenic

• Must be differentiated from E. histolytica

Some True/False…

1. Entamoeba histolytica is only found in Africa and South America.

2. Entamoeba histolytica is the only pathogenic species of all the amebae.

3. Trophozoites and cysts can both be found in the stools of infected patients.

4. An intermediate host is necessary for the transmission of Entamoeba histolytica.