Necrotic encephalitis as a manifestation of acute sarcocystosis in cattle.

Extensive brain pathology attributed to Sarcocystis is described in a heifer and a 2- to 4-month-old calf. These appear to be the first recorded cases of naturally occurring acute sarcocystosis in cattle in sub-Saharan Africa. The heifer became recumbent and had convulsions before dying, while clinical signs in the calf included loss of body mass, diarrhoea, nervousness and opisthotonus. Disseminated haemorrhages were noted in the brains of both animals at necropsy. Microscopically, the grey and white matter contained multiple areas of necrosis associated with haemorrhage, fibrinoid vasculitis, perivascular cuffing and gliosis. A multifocal meningitis was also present. First-generation Sarcocystis schizonts were evident in, or adjacent to endothelial cells of several arterioles and small arteries. The association of first- (as opposed to second-) generation schizogony with overt and fatal bovine sarcocystosis, has not previously been reported.