Trophozoites of Naegleria fowleri

In a Wright's stain of cerebrospinal fluid from the patient drawn at the time of hospital admission (A, bar = 100 microns), an ameba is visible in the center of the field, indicated by the arrow, and abundant polymorphonuclear cells are present. Brain tissue stained with hematoxylin and eosin (B, bar = 10 microns and C, bar = 100 microns) demonstrates perivascular amebic infiltrates and an amebic micro-abscess with surrounding tissue necrosis. Examples of amebae are indicated by the arrows. Naegleria fowleri–specific immunofluorescent antibody staining (D, bar = 10 microns) highlights amebic infiltrates.