Page 84 - VHSA - Onderstepoort 100 Years - Part 3

OND
ERSTEPOORT 100
Erasmus duly extracted crude steroidal saponins from T.
To understand the research that follows, one must be aware that geeldikkop belongs to a world-wide group of ovine crystal-associated hepatogenous photosensitizations induced by a variety of plants. These photosensitizations are distinguished by the presence in the liver, and particularly the bile ducts, of crystalloid material. In 1934 C. Rimington and
terrestris which, when dosed to sheep, induced geeldikkop (1991). This finding, of course, did not constitute irrefutable proof that steroidal saponins were responsible for geeldikkop, because some unidentified causal toxin might unbeknowingly have lurked in the crude saponin extract.
The fifth most important plant poisoning in the 1996 study, gousiekte, is the most curious of all. Gousiekte is characterized by sudden heart failure of apparently healthy ruminants (affected stock literally drop dead at the slightest provocation) 6 to 8 weeks after ingesting certain members of the Rubiaceae (gardenia) family. Anecdotes of gousiekte abound. It is said that a number of affected cattle pastured alongside a railway line in Botswana dropped dead whenever a train to Bulawayo passed. Another has Theiler standing beside a flock of sheep, watching the owner and his dog approaching across the veld. When the barking dog suddenly rushed at the flock, a catastrophe happened – scores of sheep died! Apocryphal or not, these anecdotes illustrate the unusual course of the disease.
According to Theiler, J. Walker (1904-1906), the Government Veterinary Officer at Ermelo,
first reported the appearance of gousiekte, a serious new disease which caused the sudden death
of sheep. As a result of his investigations, Walker became convinced that the causative agent of gousiekte was a plant, but the matter was not pursued until a severe outbreak in 1915 again focused attention on the disease. In that outbreak, more than a thousand sheep died after trekking across a ‘toxic’ farm near Kaalfontein in the Pretoria district.
A series of experiments were quickly conducted on the suspect farm by Theiler and his co-workers (1916–1922), in which, according to L.E. Codd, despite numerous setbacks and conflicting results, it was established beyond doubt that Pachystigma pygmaeum was the cause of the disease. In the decades that followed, several other members of the Rubiaceae
have been incriminated by various workers in the aetiology of gousiekte, namely Pachystigma thamnus, and Pachystigma latifolium, Fadogia
homblei, Pavetta harborii and Pavetta schumanniana.
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PART 3
History of Individual Disciplines
1908-2008
Years