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[Acanthamoeba spp.] [Balamuthia mandrillaris] [Naegleria fowleri] [Sappinia spp.]

Trophozoites of Acanthamoeba spp. are pleomorphic and measure approximately 15-45 µm.  They often produce many spine-like processes called acanthapodia.  Trophozoites contain a large nucleus with a large, centrally-located karyosome but no peripheral chromatin.  There is no flagellated trophozoite stage in Acanthamoeba spp.

A	B

A: Trophozoite of Acanthamoeba sp. in tissue, stained with hematoxylin and eosin (H&E).
B: Trophozoites of Acanthamoeba sp. in a corneal scraping, stained with H&E.