In January 1929, a California farmer named Frank B. Haas noticed that some of his hogs were lame. He saw little reason to worry. The animals ate garbage that sometimes contained bone, tacks or pieces of glass that pierced the animals' hoofs.
But the number of sick hogs rose. After Haas called a county livestock inspection agent, officials found foot-and-mouth disease on his ranch. The source? Some of the garbage fed to the hogs had come from a steamship that carried meat scraps from South America contaminated with the foot-and-mouth virus.
His herd of 3,271 animals was destroyed.
That was the last outbreak of foot-and-mouth disease in the United States - but not the last threat from it.
In Great Britain, nearly a half-million animals have been slaughtered since an outbreak of foot-and-mouth disease was detected last month. The outbreak, also believed to have started from contaminated hog swill, has spread to France and the Netherlands.
The United States has been free of foot-and-mouth disease for 72 years, but that doesn't mean the country's livestock is impervious.
"We're scared," says Gary Wilson, an Angus cattle breeder near New Concord, Ohio. Wilson's family has operated a farm since 1926 but, like most U.S. farmers, has no firsthand experience with the virus. "Once you learn about it you know you sure don't want it," he said.
Foot-and-mouth infects only animals, not humans. It's rarely fatal. But the virus is so contagious that Jerry Redding, a spokesman for the U.S. Agriculture Department, likens an outbreak of foot-and-mouth to the onset of a war.
"If foot-and-mouth were established here, it would be here forever," said Redding, who explained that the wild deer population's susceptibility to the virus would make the disease impossible to eradicate. "We would never again export another hamburger or pork chop."
Foot-and-mouth is so contagious that possession of the live virus on the U.S. mainland was made illegal in 1958. The only stock of the live virus in the United States is at the Agriculture Department's Plum Island animal Disease Center near Orient Point, N.Y. - two miles offshore.
Corrie Brown, a University of Georgia veterinarian who spent 10 years as the head of the pathology unit at the Plum Island research center, can testify to the infectiousness of the virus. "Humans can't be infected by the virus," Brown said, "but you could be around an infected animal, go to another place and sneeze and start a new outbreak."
As an employee of Plum Island, Brown had to sign an agreement stating she would not have any contact with farm animals within seven days of leaving the island. She had to shower every time she left an animal room or lab to avoid spreading the disease.
"My record was 11 showers in one day," Brown said.
U.S. officials and others credit aggressive bans on imports of animal products from countries with foot-and-mouth outbreaks - a ban against the European Union went into effect March 13 - as well as increased vigilance at airports where travelers might be transporting foreign meat, for their success at keeping the disease out of the country.
`Disease of economics'
The United States does not allow food imports from a country that is vaccinating animals against the virus until that country discontinues the vaccinations and is free of the disease for at least a year.
"It's a disease of economics," said Brown, who estimates that the U.S. livestock producers could lose as much as $20 billion if an outbreak were to occur here. There are more than 98 million cows, 59 million pigs and 7 million sheep in the United States, according to the USDA.
Foot-and-mouth also affects sheep, goats, deer and other cloven hooved animals, including wild ones. Resident in the mucus and feces of infected animals, the virus can live for up to three weeks. Once it gets into the body, the virus settles on the tongue, feet and teats and causes blisters.
"The virus makes the animals sore," Brown said. "They don't want to move, eat, or nurse their young. They lose a lot of weight but recover in about three weeks." Even though infected livestock can recover, letting the disease run its course isn't an option because of the economic implications.
Vaccines, though available for seven serotypes of the disease, aren't widely used internationally for the same reason: An animal vaccinated against foot-and-mouth tests positively for the disease and therefore can't be exported.
The disease could also establish itself in a population of vaccinated animals and go undetected, said microbiologist Peter Mason, leader of the foot-and-mouth research unit at Plum Island.
"This disease is a very difficult nut to crack," Mason said, because the virus changes quickly, making it difficult to study. The most promising research Mason and his team have made is in the development of a new vaccine that is made using a synthetic form of the foot-and-mouth virus. He is "optimistic" the new vaccine will be available within five years.