Page 87 - VHSA - Onderstepoort 100 Years - Part 3

Gifblaar
(Dichapetalum cymosum
), containing monofluoroacetate, is deadly for ruminants
(
(
m
ONDERSTEPOORT 100
because it involves maize, a staple food of both humans and animals. The fact that it can also affect the unborn (a rarity for a mycotoxicosis) is very worrying.
Marasas and his co-workers had implicated F. verticililoides in the aetiology of oesophageal cancer of humans in the Eastern Cape Province, and because F. verticililoides was one of the most prevalent moulds on harvested maize in the world.
Our involvement in equine leukoencephalomalacia (LEM) began in the early 1970s when J.G. Pienaar
of the Pathology Section asked our opinion
on the brain of a horse showing erosions
of the white matter. After consulting with
Marasas, we decided that the horse probably
had LEM, a disease associated abroad with
the ingestion by horses of mouldy maize.
The diagnosis was made on the grounds
that the brains of horses affected by LEM
typically reveal (as in this case) large cavities
where the white matter had undergone
liquifactive necrosis. We immediately began
dosing trials with pure cultures of Fusarium
verticililoides, the dominant fungus on the
maize bran eaten by the horse, in order to
identify the responsible fungus.
Whilst we were busy with these trials
B.J. Wilson and R.R. Marinpot (1971) of the United States announced at an international congress in Pretoria that they had reproduced LEM by dosing cultures of F. verticililoides to a donkey. The next big step forward was the isolation by W.C.A. Gelderblom (a member of the Marasas team at the Medical Research Council) of a novel mycotoxin, fumonisin B1 from cultures of F. verticililoides. Fumonisin B1 immediately drew intense international interest, because, amongst other reasons,
Any mycotoxin in maize, a staple food of human and animals, is for obvious reasons, of signal importance to the international scientific community. The question now was, did fumonisin B1 also cause LEM? Marasas duly presented us with a minute amount of fumonisin B1 with which we were fortunately able to induce LEM in horses, effectively answering that question. Our research also had an interesting little sequel. A compara- tive study of the toxicity of F. verticililoides for various species of animals by N.P.J. Kriek, Kellerman and Marasas in 1981 revealed that the main target organ in pigs was the lung. In the early 1990s, large outbreaks of porcine lung oedema associated with LEM and the ingestion of mouldy rations in the
USA were positively diagnosed as fumonisin B1 poisoning. Thus, a relatively academic laboratory finding in South Africa, found practical application abroad.
Research on other poisonings
It might superficially appear as if comparatively little research has been done on major poisonings such as gifblaar poisoning, seneciosis, vermeersiekte and Lantana poisoning. This is not
177
“F. verticililoides was one of the most prevalent moulds on harvested maize in the world. Any mycotoxin in maize, a staple food
of human and animals, is for obvious reasons, of signal importance to the international scientific community.”
Toxicology
1908-2008
Years