In Texas 1222 cattle were quarantined this past January after accidentally being fed the puréed carcasses of other cattle. In Vermont the United States Department of Agriculture seized 355 sheep imported from Belgium that were suspected of carrying prion disease. In Queens, New York, assemblywoman Margaret M. Markey is proposing seven bills designed to protect New Yorkers, including one that makes it a felony to feed cattle remains to other cattle.
How close is mad cow disease, or bovine spongiform encephalopathy (BSE), to the United States? Close enough to cause a wave of panic about all imported beef-based products -- including vaccines, medicines, herbal supplements, and cosmetics that may include animal organs or be gelatin-based. (And of course the current outbreak of foot and mouth disease, which doesn't hurt humans but is devastating to animals and is spreading like wildfire in Europe, only adds to the hype.) Close enough for the United States to risk a trade war with Brazil by banning Brazilian beef for a couple of weeks. So close that researchers like Dr. Stanley Prusiner have been saying since 1996 that BSE, and quite possibly the disease it causes in humans, varient-Creutzfeldt-Jakob disease (vCJD), is already here.
Should we buy it? Perhaps. Dr. Prusiner, after all, is the scientist who discovered the prion, the infectious agent of both BSE and vCJD. He won a Nobel Prize in medicine for his work. If he says we're in danger, then maybe we are.
Prion disease in general has been chronicled since the Fifties, when a cannibalistic tribe in Papua New Guinea was found to be harboring and passing kuru, a prion disease they got from eating one another's brains. In the United States prion diseases in mammals were noticed beginning in the Sixties. The New York Times correctly notes that, "At various times, 45 states have had sheep that are infected with scrapie, another malady related to mad cow disease." In the Midwest eleven farms have been found to be housing mad cow-contaminated mink, which were fed domestic "downer" cows -- cattle that died from unknown causes and were not tested before being ground up for mink chow. Scientists also are seeing a "slow" epidemic in wild deer and elk; animals in at least six Western states including Colorado, Wyoming, and Nebraska, have been diagnosed with a prion disease called Chronic Wasting Disorder (CWD). Recently a young hunter in Utah and another in Oklahoma, both of whom were believed to have eaten contaminated mad deer meat, died of a similar vCJD disorder. Meanwhile domestic deer-and-elk game farms have been found to be contaminated with CWD.
Those are the facts. Much of the rest is theory, because scientists simply don't know how much of an infectious dose needs to be consumed, what the incubation period is, and how many cattle or people may already have been infected. And they may not know for many, many years. Consider that kuru takes 40 years to incubate. Consider that kuru, which popular medicine says has been eradicated, still is thought to be alive and kicking, so to speak.
One of the theories put to rest is that there is a so-called species barrier that will prevent the spread of BSE from cattle to humans. Obviously wrong, though so far the numbers seem low: about 80 people infected from an original pool of 180,000 infected cattle. Perhaps, researchers are musing, genetic makeup presupposes some people to be more susceptible to BSE-infected tissues. (Immune systems have nothing to do with it, since the prions are not recognized as intruders or attacked by blood cells.) The Official Mad Cow Disease Website posts an article that proposes a scarier scenario: "If BSE crosses to vCJD only with great difficulty, then vCJD might spread quite easily through, say, blood transfusions or maternally -- so any “species barrier' quickly loses its comfort value."
Another theory is that the United States is safe because we have prohibited the import of British beef since the Eighties, and that Food and Drug Administration (FDA) regulations, officially adopted in 1997, have required companies to label meat-and-bone meal (MBM) products with "Do not feed to ruminants." Call us hypocrites. Although the United States officially has blasted Britain for delaying telling the world about its BSE epidemic, we have no more followed up on regulating feed manufacturers than they have. The FDA recently announced that out of 180 cattle-rendering companies, about 25 percent did not label properly or keep animal carcasses and remains separate and distinct. Out of 347 FDA-licensed feed mills, another quarter was found to be in the same violations. Of about 1600 smaller feed mills that are too miniscule for licensing, The New York Times says that a whopping 40 percent were failing to follow guidelines. The paper also estimates there are about 5000 more unlicensed feed mills that thus far have escaped inspection.
Hence the Texas feed lot quarantine. The MBM-contaminated feed, according to an FDA press release, was fed to cattle after "human error." Though the cattle, after testing, were found to be at very low risk -- the 600-pound animals each ate about a quarter-ounce of the feed, which itself is presumed to have been made from BSE-free carcasses -- we can only hope their carcasses don't wind up in our pets' food. Yes, there have been documented cases of house domestics dying from prion disease: 85 cats since 1990 and 19 dogs since 1992.