"The economic impact of this is going to be horrendous," says Dean Cliver, professor of food safety at the University of California at Davis and a member of the FDA's transmissible spongiform encephalopathies advisory committee. "Especially superimposed on the problems they had to face in the aftermath of the mad cow thing, this is going to be a big, big blow to the economy in England." Already, 37,000 animals are being killed, and that number could rise to 67,000. But so far only 40 animals have been documented as actually having the disease.

Indeed, the main fear with foot-and-mouth disease (FMD), besides the welfare of the animals, is financial. British farmers, barely recovering from the mad cow epidemic, may lose up to $73 million just on this weeklong ban of livestock, and even more if it continues. And animal health officials in the United States say if it ever reached this continent, it could significantly damage the $4.2 billion-a-year meat industry. Many countries halt importation of meat from countries where even a single case of FMD has been reported for at least a year.

Foot-and-mouth disease is among the most contagious of animal viruses. All cases in the U.K. can reportedly be linked to an outbreak at a single farm in Northumberland, England. Fortunately, unlike mad cow disease, FMD does not pose a risk for humans. But it is extremely virulent, and can be spread by almost anything -- from cars, clothing, shoes and even, possibly, the wind. That's why it can move through a continent like Europe and cause an infectious domino effect on countries there; it's also why France and Ireland are particularly concerned about the disease's possible infiltration and are taking extra precautions to keep it out. One farm in Ireland was quarantined because it was merely suspected that the animals had been in contact with sick animals at a farm in Northern Ireland.

Although it is rarely fatal to an adult animal, veterinarians say FMD is extremely painful and it can cause blisters on the tongue, muzzle, teats or feet of cloven-hooved animals like deer, pigs, cattle, goats and sheep, as well as spiking a fever. As the disease progresses, the skin of the tongue or feet can peel right off, making it excruciatingly painful for infected animals to eat, swallow or walk. FMD has a short incubation period -- symptoms usually show up within a few days -- so if an animal is quarantined for a week, and there are no telltale signs, chances are the disease is not present. Diseased animals rarely produce as much milk as they did before coming down with the condition. Though the cloven-hooved can eventually recover from the virus, the only way health officials believe they can control the disease is through eradication. And that has set the stage for mass slayings of cattle and other livestock across Britain. Many of the animals have not even been infected; they were merely exposed to foot-and-mouth.

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