Page 86 - VHSA - Onderstepoort 100 Years - Part 3

OND
ERSTEPOORT 100
Research on mycotoxicoses
Another major thrust of our research in the latter half of the last century was the investigation of mycotoxicoses that cause stock losses in South Africa. Amongst the mycotoxicoses investigated were lupinosis, diplodiosis
him, this finding, his most telling contribution to science, passed him by, as neither he nor anyone else understood the implications of what he had done! The word mycotoxicosis then did not even exist.
(rated one of the six most important poisonings of stock in the Republic) and equine leukoencephalomalacia.
In the late 1980s Kellerman and co-workers, notably Schultz, C.J. Rabie (mycologist), G.C.A. van der Westhuisen (mycologist) and Prozesky (pathologist), re-opened investigations into diplodiosis, because, as stated above, it is the most important mycotoxicosis of livestock in southern Africa. The disease, caused by the ingestion of maize infected by the common cob-rot fungus, Stenocarpella maydis, is characterized by ataxia, paresis and paralysis. Amongst their most notable findings was that the fungus also causes stillbirths and neonatal losses in the off- spring of ewes and cows exposed to diplodiosis during the second and third trimesters of pregnancy. Even the offspring of dams that had never shown overt signs of diplodiosis can be affected. To date, despite the dedicated efforts of Snyman, the active principle responsible for diplodiosis has not been isolated. Diplodiosis is very important from a medical and veterinary perspective,
In the middle 19th century lupines
played an important part in the nutrition of
sheep in central Europe. This happy state of
affairs came to an end with the appearance
of a destructive liver condition known as
lupinosis. Professor J. Kühn of Düsseldorf
(1880), in an inspired moment, suggested
that lupinosis might be a mycotoxicosis.
Unfortunately for him he could not re-
produce the disease with cultures of fungi
from toxic fields. Interest in lupinosis then
shifted to Australia where lupines are grown
on a large scale. Australian researchers
soon established that the condition, which
affects both cattle and sheep, was indeed
a mycotoxicosis, but the causative fungus
was not identified. This was the position in
1969, when K.T. van Warmelo undertook
a mycological investigation on a field of
the Hermon district of the Western Cape Province where 530 ewes had died of the disease. Examination of the field revealed that the sheep had grazed almost entirely on pods, many of them moulded. Fortuitously, the pods were infected
176 almost exclusively by a fungus, Phomopsis leptostromiformis. Equally fortuitously, P. leptostromiformis from the mouldy pods, cultured on sterile lupine seeds, caused typical signs of the disease in sheep dosed at Onderstepoort. This was the first experimental induction of lupinosis by dosing pure cultures of a fungus to animals. Australian researchers have since established that the principal mycotoxin responsible for lupinosis is a linear heptapeptide, phomopsin A.
The next person to imagine that an ordinary mould (as opposed to, say, a mushroom or ergot) can poison animals was D.T. Mitchell. Asked what Mitchell was like, Douw Steyn replied that he suffered from a squint and that he was a ‘befoeterde’ (crusty) man. Appointed by Theiler, Mitchell floa- ted, as work demanded, between Onderstepoort, Allerton Laboratory in Natal and Armoedsvlakte. Be it as it may, this crusty man in collaboration with P.F. van der Bijl (mycologist) in 1918 succeeded in reproducing diplodiosis, a nervous dis- order of ruminants, with pure cultures of Stenocarpella maydis (= Diplodia maydis, Diplodia zeae). As far as we can tell this is the first time that a mycotoxicosis had been reproduced by feeding a pure culture of a fungus to the target animal. If we are correct, this would make Mitchell no less than the ‘father’ of modern medical and veterinary mycotoxicology. Sadly for
“Asked what Mitchell was like, Douw Steyn replied that he suffered from a squint and that he was a ‘befoeterde’ (crusty) man. Be it as it may, this crusty man in collaboration with P.F. van der Bijl in 1918 succeeded in reproducing diplodiosis, a nervous disorder of ruminants, with pure cultures of Stenocarpella maydis (= Diplodia maydis, Diplodia zeae).”
white lupines in
Geigeria aspera has been responsible for large outbreaks of vermeersiekte in small stock
PART 3
History of Individual Disciplines
1908-2008
Years