During February 1975, a tremorgenic neurotoxicosis decimated a herd of cattle in the northern
Transvaal. This hitherto unidentified disease was characterized by hypersensitivity, incoordination,
a peculiar stiff-legged gait of the hind legs, severe generalized tremors of the skeletal muscles, progressive
paresis, paralysis and constipation.
The most notable gross pathological lesions were degenerative and necrotic changes in certain
skeletal muscles, haemorrhages on the serosal surfaces, especially on the dorsal aspect of the rumen,
and gastro-intestinal stasis. Microscopical examination of the central nervous system revealed
cytopathological changes consisting of degeneration and necrosis of the large motor cells in the
ventral horns of the spinal cord and bigger neurones in numerous nuclei of the medulla oblongata,
midbrain and thalamus.
By feeding the suspect ration and its component parts to cattle and sheep, it was possible to
identify mouldy sorghum beer residue as the toxic component in the ration. A. clavatus. the dominant
fungus on the toxic residue, was readily isolated in pure culture. The entire syndrome was then
reproduced in a yearling Friesland steer dosed with pure cultures of the A. clavatus isolate grown on
autoclaved non-toxic sorghum beer residue. The toxic principle is not known, but it does not appear
to be patulin, tryptoquivalone, tryptoquivaline, or any other known tremorgen.