Track mad cow disease.

Byline: The Register-Guard

Agriculture Secretary Ann Veneman attempted to reassure the nation this week after early laboratory tests showed that a single cow in Washington state had mad cow disease. The facts that are known are on her side. The trouble is, other facts remain unknown. Until it's discovered how the first American case of mad cow disease occurred, speculation and extrapolation will fill the vacuum.

Mad cow disease - bovine spongiform encephalopathy, or BSE - first arose in Great Britain in 1986. The disease is poorly understood, but it's believed to be transmitted through the addition of animal protein to livestock feed. The bovine version of the disease resembles a disease called scappie that affects sheep. Sheep and beef byproducts added to cattle feed caused the fatal scrappie-like disease among cattle. People who ate beef from cattle affected by mad cow disease, in turn, were at risk of developing a variant of Creutzfeldt-Jacob disease, and 150 people have died of it.

Mad cow disease caused the most costly agricultural calamity in Great Britain's modern history. The problem was worsened by British officials' initial attempts to minimize the threat of the disease and discourage research linking it to human fatalities.

The Bush administration, along with state and local health and agriculture officials, must avoid making a similar mistake, and adopt a policy of total candor.

The British experience has already led the United States to take stringent precautions. Cattle that arrive at slaughterhouses unable to walk - a primary symptom of BSE - are immediately tested; that's how the Washington case was identified. The Food and Drug Administration banned the use of mammalian protein in livestock feed in 1997. Imports of bovine products from countries where BSE is present are banned. A single case of BSE reported in Canada last May led to a ban on Canadian beef, though limited imports have been resumed.

All of these are sensible and necessary steps, but they make the Washington case an even greater mystery. That cow should not have been given feed of the type that transmits mad cow disease - but if it was, it probably wasn't the only one. The source of the feed and any other animals affected must be located.

If another means of transmission is involved, the tracking job is even more urgent - the vector must be found, all other cases of livestock exposure identified. The beef from the single currently suspected case and any others must be traced and recalled.

Statistically, Americans have little to worry about. In Great Britain, an estimated 180,000 cattle were affected by BSE, leading to 150 cases of variant Creutzfeldt-Jacob disease in a population of 60 million. One case of mad down disease in a nation with a population approaching 300 million means that the likelihood of human fatalities is vanishingly small, even without a beef recall.

But statistics offer little comfort if there's a possibility that the single case of mad cow disease is only the first. Veneman, state officials and the cattle industry must move quickly to identify the route of transmission, find any other affected animals and recall all potentially affected beef. Americans' confidence in the safety of beef, and the survival of a major agricultural industry, hangs in the balance.