The disease has been particularly active in the last few years, moving through countries in Asia, South America and Europe. It has also been detected in the Middle East and Africa. And as countries in these areas have learned, no place -- with even the best regulatory systems -- is immune. Foot-and-mouth disease showed up in Japan last year, even though it hadn't been present since 1908, and also in Korea, where it hadn't been seen for almost as long. The 1997 outbreak in Taiwan dealt a crippling blow to that country's meat industry, destroying its pig population and causing billions in estimated damages. Taiwain's meat industry still hasn't fully recovered.

But veterinarians say the United States may be less at risk because of bans already in place on all imported ruminants from the European Union. The U.S. banned ruminant imports from the United Kingdom in 1989 and the E.U. in 1997, following outbreaks of mad cow disease.

"We're monitoring the situation in the E.U. and basically we have very strict regulations in place to protect us from foot-and-mouth disease," says Kim Smith, spokeswoman for the United States Department of Agriculture's Animal and Plant Health Inspection Service (APHIS). "While it's a concern, it's not an extraordinary concern because our safeguarding measures are excellent," she says.

In light of the British outbreak, the Department of Agriculture is asking ranchers to continue surveillance of animals to make sure that there are no signs of FMD in their herds. In Texas, on Wednesday, government officials urged livestock producers to step up observation procedures and to take extra precautionary hygienic measures, which include wiping off shoes with disinfectant and making sure that wastefood fed to swine is properly cooked. The state's chief veterinarian also issued a warning to farmers: "If your livestock become lame or develop blisters or sores, call us ... Our emergency response within the first 24 hours after the first signs of disease will affect our outcome over the next six months."

Veterinarians and animal health officials believe that the growing international livestock trade is partly to blame for FMD's resurgence. The outbreak of diseases like FMD can also highlight the dangers of free-trade and open-border agreements like those found in the European Union. "For the time being, [E.U.] commerce has gotten ahead of public health," says Cliver. "This stuff moves around much more quickly than it used to, and some of it is stuff that has infectious disease agents in it."

Although a vaccine exists, it's difficult to immunize animals against the virus since seven sero-types of FMD exist, along with dozens of subtypes. Many times an animal will be given a vaccine that doesn't protect it from other strains. Also, since it's difficult to tell if an animal has the disease or is only vaccinated, many countries like the U.S. don't import meat from places where vaccines are administered.

In the United States, there is only one place where the highly infectious foreign disease is researched. And that's Plum Island, off the northeastern tip of Long Island, N.Y., where researchers are standing by in case infectious agents not present in the U.S. somehow make their way in. Of the 15 highly contagious diseases listed by the Office International Des Epizooties (World Organization for Animal Health), only three are present in the United States: bluetongue (a sheep and cattle virus disease), vesicular stomatitis (in cattle and horses) and New Castle disease (a viral poultry disease).

Marvin Grubman, a virologist who works with FMD, explains all the precautions he and the other researchers take just in order to work with the virus. They commute out every morning to the island, change into protective gear, and then shower before leaving. Since U.S. regulations prohibit the manufacture of the vaccine, the entire U.S. supply is imported. (Outbreaks in Europe have occurred in the past because the virus escaped out of the high-containment facilities where the vaccines were being manufactured.)

Grubman and his colleagues are working on developing a new vaccine that would be safer to produce and would produce immunity more quickly in animals. "We find that it can protect animals after they are vaccinated once; and when they are exposed, we can protect them from developing clinical signs of the disease," says Grubman. "It seems to be working on a small scale." The new vaccine also allows them to tell whether an animal is infected with the virus or has merely has been vaccinated. But still, Grubman says, any new and improved vaccine that could be used in case an outbreak occurs in the United States is probably several years away. If foot-and-mouth disease did make its way here, the United States would probably adopt the same disease eradication approach currently being used in the United Kingdom: the mass slaughter of animals, infected and uninfected.

Salon Politics: Unflinching daily political news, analysis and commentary.