Mad Cow: It Can Happen Here

As infections go, mad cow disease and foot-and-mouth disease don't have much in common. Mad cow disease is hard to transmit, takes years to incubate in an infected animal and is almost impossible to detect until symptoms emerge late in the course of the infection. Foot-and-mouth, by comparison, is one of the most contagious animal diseases known. Unlike mad cow disease, which is hard to spread but always fatal, foot-and-mouth disease spreads quickly but rarely even kills animals and is considered harmless to human beings.

The fact that both diseases have emerged in the United Kingdom is mostly a matter of British bad luck. But both have something to teach us about the virtues of precaution. Diseases of livestock and people lurk in hidden crevices of the world, and the very technologies that we celebrate as emblems of modern progress can also serve as vehicles for transforming those diseases into epidemics. Just as AIDS spread throughout the world thanks in part to the speed and ease of modern travel, other diseases are cropping up with increasing frequency as a result of factors including increasing urbanization of wildlife habitats and intensive livestock farming practices.

Origins of an Epidemic

The recent British outbreak of foot-and-mouth disease began in early February on a farm in Northumberland, England's most northerly county. By February 25, most of the country had been declared a contaminated area. Its spread was assisted on February 13 when 40 sheep were purchased in Northumberland and shipped to Devon, a county on England's southwest peninsula. By the time the outbreak was identified as foot-and-mouth disease, consignments of sheep and pigs had already been shipped from infected areas throughout the country and to other parts of Europe. By March 1, the number of detected cases had reached 30, with new outbreaks occurring in Ireland and Scotland. Europe started slaughtering animals imported from Britain as soon as the epidemic became apparent, but by then, antibodies to foot-and-mouth were already being found in Germany. By March 21, nearly 400 cases had been detected, and the army had been called in to help with the disposal of carcasses as thousands of animals were slaughtered in an effort to eradicate the disease.

Europe will spend billions of dollars bringing this particular outbreak under control. But outbreaks of foot-and-mouth have risen throughout the world, due to activities that spread the disease, such as illegal smuggling of animals, international tourism and the globalization of trade. "The last two years have been among the worst on record, with more than 60 countries experiencing outbreaks, including many which have not had one in generations," reports the Guardian of London. Examples include Taiwan, Korea, Brazil and South Africa, as well as an outbreak last year in Japan that was traced back to diseased straw imported from China via Russia.

Unlike foot-and-mouth disease, which has vexed farmers for centuries, mad cow disease is a recent phenomenon created by technical innovations in agricultural production itself. The innovation that caused it was actually quite simple. In order to dispose of slaughtered animal parts that have no commercial value, the meat industry put them through a "rendering" process that consisted of grinding them up and cooking them in large vats to produce a product called "meat and bone meal" that was then fed back to other animals. This created what was essentially a cannibalistic feeding loop, as cows consumed the remains of other cows, sheep were fed to sheep, pigs to pigs, chickens to chickens and so forth.

Common sense might dictate that this practice is a bad idea, but the scientists and farmers who used this material genuinely believed it would be safe. What they didn't realize was that this feeding loop was also an amplification loop through which mad cow disease -- something that had never even been detected prior to the 1980s -- would become a devastating epidemic that has so far killed more than 170,000 cattle and began to kill human beings in 1996. To date, nearly 100 people have died, presumably from eating infected beef, and scientific projections for the eventual death toll in Europe range from a few hundred to 100,000.