A

A: Naegleria fowleri trophozoites, cultured from cerebrospinal fluid.  These cells have characteristically large nuclei with a large, dark staining karyosome.  The amebae are very active and extend and retract pseudopods.  Trichrome stain.  From a patient who died from primary amebic meningoencephalitis in Virginia.

B

B: Naegleria fowleri trophozoite in spinal fluid.  Trichrome stain.  Note the typically large karyosome and the monopodial locomotion.  Image contributed by Texas State Health Department.

C	D	E

F	G	H

C, D, E, F, G, H: Naegleria fowleri in brain tissue, trichrome stain.

I	J

Acanthamoeba sp. keratitis.  I: Corneal biopsy showing a trophozoite;  J: Cyst with the characteristic stellate shape, in corneal scraping.

K

K: Acanthamoeba polyphaga trophozoite in tissue culture, trichrome stain.

L

L: Balamuthia mandrillaris trophozoites in brain tissue.