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==''Entamoeba histolytica''=====epidemiology===
*worldwide
*40-50 mil. symptomatic cases per year*number of asymptomatic cases unknown
*40,000-50,000 per year
*sexual transmission in developed countries
===life cycle and pathophysiology===
*feco-oral infection of cyst
*hutch in small intestine into trophozoite
*reside in large intestine
*propagate by binary fission
*some penetrate large intestine wall
**bloody diarrea
**trophozoites phagocityze RBC
**only RBC phagocitizing trophozoite means infection
**non-RBC-phagocitizing trophozoite means colonization
*some invade into portal vein through liver
**liver abscess
*some encyst in large intestine
*cysts are excreted from anus
===morphology===
*trophozoite 20-50 μm
*cyst has 4 nuclei, each nucleus has a nucleolus
==''Entamoeba dispar==
*formerly named as ''E. histolytica'' in 1903
*non-pathogenic type of old ''E. histolytica'' was distinguished as ''E. dispar'' in 1925
===distribution===
*''E. disper'' vs ''E. histolytica''
**3:1 in developing countries
**10:1 in developed countries
