Fear of foot-and-mouth disease has friendly Midwestern farmers pulling up their welcome mats. Zoos and theme parks around the country are posting warning signs. Some universities are canceling overseas exchange programs and even quarantining foreign students.
Around the nation, Americans are closely examining their own cows, hogs even giraffes while also watching for anybody or anything that could carry into the United States the highly contagious disease ravaging Britain's livestock.
And just in case foot-and-mouth strikes this country for the first time in more than 70 years, officials are drawing up worst-case scenarios, from destroying entire herds of cattle to mobilizing the National Guard.
"I wake up nights thinking about it," said Gene Eskew, a veterinarian for the Oklahoma Department of Agriculture. "This particular virus is the most contagious in the world."
Foot-and-mouth is dreaded because it can be transmitted so easily by dirt on vehicle tires, clothes, shoes, even in the air.
The virus is harmless to humans but destroys animals' hooves and causes mouth blisters that ruin their appetite. The United States has not had a confirmed case since 1929.
In Britain, more than a million animals have been condemned to slaughter in an attempt to contain the outbreak, and restrictions have been imposed on tourism events and the movement of animals.
The United States has already banned imports of livestock and raw meat from Europe. Now, many of the precautions are aimed at international travelers.
Zoos from New York City to Chicago are posting signs asking visitors who have been overseas recently to avoid petting zoos or other areas where they can come in close contact with animals.
At the Busch Gardens theme park in Tampa, Fla., visitors step into a disinfectant shoe bath before boarding buses for tours where they can feed giraffes and get close to other exotic animals.
Many farm states are canceling agricultural tours that bring in visitors from out of town or overseas.
Leading agriculture universities across the Midwest are isolating students who have been abroad until the risk of contamination is over and restricting access to school farms. Seventeen foreign students who came to the University of Minnesota began their training on farms this week after cooling their heels for eight days at a suburban St. Paul hotel.