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.
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.