A disease that destroys brain cells in horses, equine leukoencephalomalacia
(ELEM), is currently a death sentence. But promising new research findings
may someday improve the odds.
ELEM is caused by corn contaminated with the fumonisin-producing fungus,
Fusarium moniliforme. The toxin is insidious--only a small amount makes
horses sick. While the animals appear healthy, they suffer irreversible
damage.
Scientists at USDA's Agricultural Research Service and Animal and Plant
Health Inspection Service, in collaboration with Emory University, found
that the fungi's toxin interrupts the way a horse's liver, kidney and lungs
make a special kind of fat known as sphingolipid. The toxin also causes an
inappropriate fat intermediate (sphinganine) to accumulate and other
necessary fats to be depleted.
The ARS researchers are based at the agency's Richard B. Russell
Agricultural Research Center in Athens, Ga. They found that another fungus,
Isaria sinclairii, produces a compound called ISP-I or myriocin that
temporarily reduced the sphinganine accumulation in mice with no ill
effects. If confirmed by other studies, the myriocin discovery might lead to
treatments.
Animals exhibiting neurological effects of fumonisin poisoning can't be
saved. But for other members of the herd exposed to contaminated food, the
downward spiral of sphinganine overproduction could be stopped. The results
of the preliminary studies in mice are being published in Environmental
Toxicology and Pharmacology.
ARS and Emory scientists have received a patent on a technique to detect
fumonisin poisoning in an animal's tissue, serum and urine. It's based on
changes in sphinganine.
Fumonisin poisoning is not common in the United States, but it does happen.
In 1995, 38 horses in Kentucky and Virginia died from it. The Food and Drug
Administration is considering setting guidance amounts to protect both
humans and livestock, following long-term exposure studies.
ARS is the chief research agency of the U.S. Department of Agriculture.