In 1985, the year the first BSE cases were diagnosed in England, Marsh heard of a TSE epidemic at a mink farm in Stetsonville, Wisconsin. He went to check things out, curious among other things whether sheep meat might be to blame--scrapie cases had been diagnosed not too far away. But the farm's coolers and freezers contained nothing but cow carcasses, and the farmer swore he'd fed nothing but downer cows. "At that point, a lightbulb went on in the heads of the investigators," says Doris Olander, who works on the TSE research with Marsh (who was unavailable for comment due to illness).

           Marsh decided to check. He injected some of the infected mink brain tissue into U.S. cattle; they died with spongy brains, though without the typical BSE symptoms. When he fed the brains of those cows back to healthy mink, they in turn developed a spongiform encephalopathy and died. The infection, whatever it was, seemed to work both ways; species-jumping at its best.

           A few years later, USDA researchers conducted a series of related experiments, injecting scrapie-infected sheep brains into the brains of healthy cows. Sure enough the heifers got sick, but they didn't act like Britain's mad cows. Instead they simply fell down and died--just like downer cows, and like the cows Marsh had inoculated with mink brains. "This evidence suggests," Marsh wrote in a dairy trade magazine, "that a BSE-like disease is present, but not recognized in the U.S."

           Marsh's research remains controversial; several University of Minnesota scientists contacted for this story said the evidence seems too thin to form a conclusion. Olander, for her part, is quick to caution that the UW team doesn't think all downer cows are victims of an American strain of BSE. But some, she says, may be, and to find out for sure would take more study. The team applied for research funding several times, but no one was interested.

           Downer cows, it appears, are not something either government or the industry cares to look into. The subject is so obscure no one even knows how many there are, though rough estimates run around 100,000 a year. University of Minnesota professor Victor Cox, who's widely acknowledged as having done more research on the subject than anyone else, says he was able to pretty well describe what killed "the vast majority" of the animals--injuries, and in particular nerve compression after calving--but adds that that leaves a lot of downers about which very little is known. Still, he goes on, "While there are many cases which are not diagnosed, I have no reason to suspect that their cause is any different from the large sample I have observed." He, too, has run out of funding and has taken to putting his personal money into studying treatments. "It comes down to a cost-benefit thing," he says: Even though the dead animals amount to a loss to the industry, it's cheaper and less hassle to replace them than to worry about the cause. And, adds Olander, ag specialists seem leery about attracting attention to the problem, period. "It's something of an Achilles' heel," she says, "something the animal-rights people might get ahold of."

           Which leaves the UW team, and a few other researchers, with one suspicion: If a new strain of BSE is active in American herds, and if it's not diagnosed because the symptoms don't fit the expected pattern, the animals affected are most likely being fed straight back to other animals--and humans? (Government regulations prohibit sick cattle from being slaughtered for food, though they can be rendered; animals not showing symptoms can be used for any purpose.)

           For years now, Marsh's team as well as consumer organizations like the Foundation on Economic Trends have been calling on the U.S. government to ban feeding ruminants--cud- chewing animals, such as cows and sheep--to other ruminants. That's what Britain has done since 1989, and what the World Health Organization recommends for all countries.

           So far, U.S. officials have resisted the idea, though not always comfortably. In 1991, the federal Animal and Plant Health Inspection Service (APHIS) produced an internal document on U.S. rendering policy that said staff members were split on the matter: Some believed that "a spongiform encephalopathy is present in the U.S. cattle population," and that ruminant-to-ruminant feeding should be outlawed. But those staff members, the document said, were a minority. Besides, such a measure would create a disposal nightmare and encounter "considerable industry opposition."

           Sure enough, the industry's main trade group, the National Cattlemen's Beef Association (NCBA), adamantly opposed a ban until very recently--though not necessarily for economic reasons. In 1993, association spokesman Gary Weber told the trade paper Food Chemical News that ranchers could probably get by without protein from rendered cows and sheep. But, he said, the NCBA didn't want to appear to be ruled by "activists."

           Three years later, Weber stood before a bank of microphones and announced that his group had changed its mind: They would voluntarily ban ruminant-to-ruminant feeding. The announcement may have been designed, in part, to steal the thunder from the Food and Drug Administration, which a few weeks later came out with its own feed ban proposal. But more than anything, it was a way, as Weber all but acknowledged, to slow down what seemed like a runaway public-relations train in the wake of the British announcement. "We cannot afford to have what is a $160 billion industry in the U.S. [including beef and allied trades like veterinary medicine and parts of the pharmaceutical industry] be played Russian roulette with," he said. "There is simply no margin of error here if we are wrong."

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