Ban on Canadian beef imports prompts concern of overreaction by ranchers and others in industry.
It's just one cow. But the ripple effects of a confirmed case of mad-cow disease in western Canada this week are myriad - falling stock prices of fast-food chains, the closing of US borders to Canadian beef imports, even perhaps a dip in economic growth rates.
They highlight, as did the SARS outbreak, how fear of disease in today's interconnected world can travel at fiber-optic speed - and can roil markets and wreak havoc on global trade and national economies.
Yet as serious as the threat is, experts insist there are strong reasons to counterbalance the concerns. Knowing how quickly plagues can spread, for instance, officials in many countries have erected barriers to mad-cow and other diseases.
Once news about a scourge gets out, countries can mobilize vast resources to stop their spread. When SARS hit, for instance, researchers in several countries scrambled to understand and halt it.
"When something new shows up and you don't know a lot about it, you're really scared," says George Gray, acting director of the Harvard Center for Risk Analysis, who led a 2001 study of US susceptibility to mad-cow disease. "But as we learn more, it tends to lessen our fears."
Dr. Gray notes that mad-cow disease is much harder to spread than many believe. It's also becoming clear that the human version of the plague is much less harmful than was thought. And both the US and Canada have strict measures in place to keep the disease from spreading.
Since 1997, it's been illegal in both countries to feed rendered bits of protein - cow parts, essentially - to animals. Eating tainted bits of brain or spinal cord seems to be the main way the disease spreads to other cows. It's not always clear how closely such laws are followed, of course. But even assuming some degree of noncompliance, the Harvard study found that in a hypothetical scenario in which 10 infected cows were imported, only about three new cases of BSE (short for bovine spongiform encephalopathy, the scientific term for mad cow disease) would occur.
"There were hundreds of thousands of cases in the UK, and we managed to keep it out - or at an extremely low level - in North America," says Gray.