Whether outbreaks of the disease have anything to do with scrapie or cattle feed is uncertain. What is known is that these and other diseased animals can be recycled back into the food chain through the rendering process. If TSE in elk or minks is capable of jumping the species barrier, it is being given every opportunity to do so in the rendering vat. And although the FDA's recent feed ban will limit the amount of rendered beef and lamb that is fed to cattle and sheep, it is almost certainly increasing the amount of rendered beef that is fed to other domestic and farm animals, notably poultry and pigs. But if the FDA is right, this can only make the feed more attractive to farmers of other animals.
Pigs are a particular worry.
Although they do not seem to get a TSE spontaneously, a recent study in England showed that one of ten pigs inoculated with BSE came down with an analogous disease. Several consumer groups have voiced concern that TSE in pigs may have appeared in this country. The brains of seventy of the pigs were examined, and one was found to have evidence of the spongelike formations and lesions associated with scrapie and transmissible mink encephalopathy. The study was shelved until 1996, when the USDA, alarmed by the British mad-cow outbreak, sent a single slide of the pig's brain to William Hadlow. Hadlow examined the slide but could find nothing conclusive.