More severe histopathologic lesions were apparent in the brains and gastrointestinal tracts of KFDV-infected mice than AHFV-infected mice.

<p>(A) Brain, hippocampus, KFDV-infected mouse, 6 dpi; acute necrosis and loss of hippocampal neurons (segment delineated by arrowheads), with adjacent, relatively unaffected neurons (arrow). (B) Brainstem, KFDV-infected mouse, 6 dpi; severe meningoencephalitis with perivascular cuffing (arrow) and widespread gliosis in the adjacent neuropil (asterisk). (C) Brainstem, AHFV-infected mouse, 7 dpi; mild meningoencephalitis characterized by perivascular cuffing (arrows). (D) Small intestine, mock-inoculated mouse; normal tissue section demonstrating anatomic location of submucosal (arrow) and myenteric (arrowhead) nerve plexi and normal intestinal villi; inset shows higher magnification of neuron cell bodies in plexus. (E) Small intestine, KFDV-infected mouse, 7 dpi; moderate, predominantly histiocytic, inflammatory infiltrate in submucosa and muscularis, involving and disrupting myenteric plexi (arrowheads). Inset shows higher magnification of infiltrate and cell debris in plexus. (F) Small intestine, KFDV-infected mouse, 7 dpi; intestinal crypts are dilated and filled with necrotic cells (asterisks), intestinal lumen contains abundant cellular debris (top of image), and villi are blunted and fused. All H&E images, original magnification 200x.