Stringent Steps Taken To
Keep Mad Cow Out Of US
By Sandra Blakeslee - NY Times


As panic over the spread of mad cow disease grips Western Europe, American health officials say they have been taking stringent steps to prevent the disease from taking hold in the United States.
The brains of sick cattle are routinely tested for the disease. Imports of beef and certain beef products are banned. No one who lived in Britain since the late 1980's, when the epidemic became known, is allowed to donate blood.
"We are doing our best to not be complacent," said Dr. Linda Detiler, a veterinarian with the Animal and Plant Health Inspection Service at the United States Department of Agriculture. Pointing out that some European countries were sure they had no risk, but now find themselves caught up in the epidemic, she said, "We have tried to learn from their mistakes."
So far, they appear to succeeded. Mad cow disease and its human analogue, the new variant Creutzfeldt-Jakob disease, have not been found to have killed any cattle or been identified in people on this side of the Atlantic. Given the small number of human cases in Europe and that mad cow disease has never been proved to exist in American cattle, most experts agree that the risk for most Americans remains extremely low.
Yet experts on mad cow disease say that there is cause for concern. Despite a decade-long ban on British imports of meat and bone meal - a form of animal feed rendered from cows that is blamed for spreading the epidemic in Europe - the United States still imports tons of bovine byproducts and manufactured goods containing bovine materials from Britain and other European nations.
The disease formally called bovine spongiform encephalopathy because of the spongelike holes that appear in the brain and other nervous tissue, can also develop spontaneously. Although mad cow has not been detected in cattle in the United States, a related malady called chronic wasting disease is spreading rapidly among deer and elk herds, captive and wild, in six Western states and in Canada. In laboratory dish experiments, chronic wasting disease has been shown to infect human cells; in principle hunters who ate infected deer or elk meat could have the disease and, if they donate blood, could pass it on.
At 11 Midwestern farms, scores of captive mink developed a form of mad cow disease after being fed meat from "downer cows" - animals bred in America that died of unknown causes, possibly cases of mad cow disease that were never diagnosed. At various times, 45 states have had sheep that are infected with scrapie, another malady related to mad cow disease.
It is not known whether eating infected sheep, deer or elk causes any form of Creutzfeldt-Jakob disease in humans but the infectious agent, misfolded proteins called prions, has been shown to cross barriers between species.
Moreover, government officials acknowledge they are still finding and filling gaps in the wall designed to protect the American food supply from the disease. On Thursday, the Food and Drug Administration reported that hundreds of feed manufacturers and rendering companies were not complying with regulations intended to ensure the safety of domestically produced fee.
The United States' ban on risky British meat products, adopted in 1991 and extended to imports from other countries, contains many loopholes and exceptions that could leave the door open to infected products, says a report by a scientific advisory panel to the European Union on the risk of mad cow disease in America.
Missteps by European governments, too, have made the United States more vulnerable to the disease, said Dr. Maura Ricketts of the World Health Organization's animal-and food-related health risks unit.
Even though Britain and the United States banned the practice of feeding cows to cows in the early 1990's some British renderers continued to make and ship contaminated meat and bone meal around the world while some European farmers knowingly used such products until November because the products were cheap, Dr. Ricketts said. Public health officials suspect that infected meat was repackaged and resold as having come from countries presumed free of mad cow disease.
"The murky movement of live cattle and rendered animals around the world," Dr. Ricketts said, means mad cow disease has gone global.
A few weeks ago, the United Nations estimated that at the height of the mad cow epidemic in Britain at least 500,000 tons of untrackable bovine byproducts were exported from Britain to Western Europe and other nations around the world, including the United States.
British export statistics show that 20 tons of "meals of meat or offal" that were "unfit for human consumption" and probably intended for animals were sent to the United States in 1989. And 37 tons were exported to the United States in 1997, well after the government-banned imports of such risky meat. No one has tried to trace this meat or to determine whether it was allowed into the United States. In an exception to the import ban, many health supplements contain glandular material from animals whose health status cannot be determined. While acknowledging that the risk is very small, experts on mad cow disease note that glandular material is more likely to be infected with prions, the disease's infectious agent, than most other tissue. Products must have labels listing ingredients like bovine pituitaries and adrenals, but manufacturers are not required to list the country of origin.
Other beef byproducts that are still allowed in the country include milk, blood, fat, gelatin, tallow, bone mineral extracts, collagen, semen, amniotic fluid, serum albumin and other parts of European cattle that are widely used in American products, including vaccines and medicines. The federal Agriculture Department states that these tissues are not believed to contain dangerous levels of prions, but acknowledges that not all have been tested to prove that they pose no risk.
United States health officials are just now closing some of these regulatory gaps documents posted on their Web sites say, One year ago, the Agriculture Department told supplement manufacturers to avoid neural and glandular material from domestic and foreign sheep flocks infected with scrapie. Compliance is voluntary.
Although, cud-chewing animals, or ruminants, are the known carriers of mad cow disease, the Agriculture Department last month temporarily barred European feed supplements mad from nonruminant animals like chickens or pigs. This is because through November, many European farmers were still giving feed made from potentially infected cows to chickens and pigs and were then feeding chickens and pigs back to cows. This practice is now banned in Europe, and Agriculture Department officials are worried that European feed manufacturers will slash prices and try to dump their products on American farmers. In theory, prions could be spread in this feed.
On Dec. 23, the Food and Drug Administration told American drug manufacturers to stop using bovine serum from counties where mad cow disease has been found for making vaccines against flu, hepatitis A and diphtheria-pertussis-tetanus, but vaccines made from the materials are still being used. The agency maintains these vaccines are safe. An F.D.A. committee will meet this month to discuss extending restrictions on who can donate blood to include people who lived in Europe for six or more months in the 1990's. The committee is also expected to discuss whether to ban donations from deer and elk hunters.
As potential weaknesses have emerged, the American beef industry has become increasingly concerned, particularly about the safety of animal feed. On Jan. 9, the F.D.A.'s Center for Veterinary Medicine held a nationwide telephone conference with its field officers and 50 state agencies responsible for inspecting feed producers. The agency told the states that only about 2,700 of the estimated 9,500 feed manufacturers had been inspected for compliance, the center's director, Dr. Stephen Sundlof, said.
Among smaller companies that handle ruminant byproducts and wastes, nearly half did not have a system for putting labels on their products warning that they should not be fed to cattle or sheep, the F.D.A. said. More than a quarter of large rendering companies that handle risky material had no system to prevent the commingling of ruminent wastes with that of other animals like chickens and fish.
Dr. Gary Weber, executive director of regulatory affairs for the National Cattlemen's Beef Association said that enforcing the ban must be a priority for President-elect George W. Bush.
Compounding officials' concerns is the baffling nature of the infectious agent that is believed to cause these deadly diseases, collectively known as transmissible spongiform encephalopathies. For unknown reasons, a normal protein called a prion twists into an abnormal shape, usually in the brain. These misfolded prions accumulate into toxic clumps that eventually destroy normal brain tissue. Spongelike holes develop. Animals and people are driven mad and then die. Apparently, these diseases arise spontaneously in one out of every million humans, cows, sheep and many other mammals. Since 36 million cattle are slaughtered annually in the United States, about 36 cows spontaneously infected with mad cow disease could be entering the nations food chain each year.
These abnormal prions can pass from one species to another, including humans. Prions can survive outside the body for years and are not easily killed by freezing or cooking. No on knows the incubation period for humans. Nor does anyone know how much is required to transmit the disease, although evidence suggests that people can be infected from even a few bites of tainted beef.
Those infected share a genetic trait that appears to have made them susceptible to the disease. Eighty-eight people have died from or have been found to have the new variant, Creutzfeldt-Jakob disease, in Britain. Three people from France and one from Ireland have also died.
This variant has not surfaced in the United States. Dr. Pierluigi Gambetti, director of the National Prion Disease Pathology Surveillance Center at Case Western Reserve University in Cleveland, said he has examined tissues from 292 Americans known to have prion diseases but non have shown the hallmarks of this variant.
But at the same time, chronic wasting disease is a growing problem, said Hal Herring, a hunter and writer in Corvalis, Mont., who is tracking that disease. Thirteen captive herds in the United States have been infected and up to 18 percent of wild deer in parts of northern Colorado and southern Wyoming are infected, Mr. Herring said. In December, a federal agency in Canada slaughtered 1,700 domestic elk at six Saskatchewan farms to contain an outbreak. The disease was traced to a single animal, which never showed any signs of illness, exported to Canada form South Dakota. No one knows how deer and elk in the wild or in captivity pass the disease among themselves, Mr. Herring said.
An unknown number of American sheep are infected with scrapie, which, like mad cow disease, is a spongiform encephalopathy. It is not known if scrapie can harm humans who eat infected sheep tissue, but last autumn the fear of such transmission led the Agriculture Department to quarantine and order the destruction of a herd of sheep, exported to Vermont from Belgium. A few of the animals had been found to have developed a spongiform encephalopathy of unknown origin. The sheep's owners, who make cheese from the sheep mild, fought back. Lawyers continue to argue over the fate of the remaining animals, which show no sign of illness.
Dr. Tom Pringle, a biochemist in Eugene, Ore., and independent researcher on transmissible spongiform encephalopathies, says American officials have not done enough to battle the disease. He says the United States should set up a system to track bovine material coming into this country and increase testing. Out of 900 million cattle, the Agriculture Department tested fewer than 12,000 sick cows for mad cow disease in the last decade. None were found to have the disease. France, with 5.7 million cattle, is now testing 20,000 animals each week and identified 153 infected animals last year.
Dr. Pringle and other experts emphasize that Americans should not panic over events in Europe. While prion diseases are frightening, they say, the odds of coming into contact with them are extremely low for most Americans.

From Fred Houpt
Readers in Canada should ask whether it is wise of the Government of Ontario to advertise on the Ministry of Agriculture web site for farmers raising steer and cows to continue adding animal based protein supplements to their food?
This very same proceedure that has been linked to the spread of TSE in the U.K. The issue can be summarized as a problem of feeding herbivores to herbivores, regardless of whether TSE exists. What seems to be clear from the results of the New Guinea studies of kuru is that for mammals when we introduce cannibalism we end up, over time, with kuru which is what TSE seems to be. So, if this is the case, why is the Government of Ontario suggesting that farmers continue this ruinous course of action? Even more amazing is the fact that European farmers are now banned from doing so regardless of whether the food stocks have any TSE in the food. They European Union simply did not want to take any more chances and taking their lead from the U.K., they decided that the evidence was too strong to allow any more mammals being fed to cows. What is going on here in Ontario?
F. Houpt
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