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

Trophozoites of Balamuthia mandrillaris are pleomorphic and measure approximately 15-60 µm.  They often produce long, slender pseudopodia. Trophozoites contain a large nucleus with a large, centrally-located karyosome but no peripheral chromatin.  There is no flagellated trophozoite stage as in Naegleria spp.

A	B

A: Several trophozoites of B. mandrillaris in brain tissue, stained with hematoxylin and eosin (H&E).
B: A single trophozoite (green arrow) of B. mandrillaris in brain tissue, stained with H&E.

C

C: A single trophozoite (black arrow) of B. mandrillaris in brain tissue, stained with H&E.