Naegleria fowleri
Naegleria fowleri, trophozoites, tissue
Shown are hematoxylin and eosin-stained tissue sections from a case of fatal primary meningoencephalitis due to Naegleria fowleri. Small trophozoites of N. fowleri are seen invading into brain tissue. The trophozoites have abundant cytoplasm and a small round-to-oval nucleus with a large blot-like karyosome (which is difficult to see in histologic sections).
Naegleria fowleri, trophozoites, cerebrospinal fluid
Shown are trophozoites of Naegleria fowleri in a Giemsa-stained cytospin preparation of cerebrospinal fluid. This is a critical result that should be reported to the clinical team immediately, since N. fowleri causes a rapidly-fatal meningoencephalitis. The trophozoites have abundant bubbly cytoplasm and a small round-to-oval nucleus with a large blot-like karyosome.