Foot and mouth disease (FMD) is one of the most devastating viral animal diseases affecting cloven-hoofed animals such as cattle and swine, and has occurred in most countries of the world at some point during the last century. Although the disease has no human-health implications, it can have enormous economic and social consequences, as recent outbreaks in the United Kingdom and Taiwan have demonstrated. These consequences occur because the international community values products from countries that are FMD-free and generally restricts international trade in FMD- susceptible products from countries affected by an outbreak. Most FMD- affected countries, therefore, take whatever measures necessary to regain their FMD-free status as quickly as possible. In the United States, the U.S. Department of Agriculture (USDA) has primary responsibility for protecting domestic livestock from animal diseases such as FMD. The U.S. Customs Service supports USDA in these efforts. FMD—a highly contagious viral disease affecting primarily cloven-hoofed animals, such as cattle, sheep, swine, and goats—has 7 types and over 80 subtypes. Immunity to, or vaccination for, one type of the virus does not protect animals against infection from the other types. FMD-infected animals usually develop blister-like lesions in the mouth, on the tongue and lips, on the teats, or between the hooves, which causes them to salivate excessively or become lame. Other symptoms include fever, reduced feed consumption, and abortions. Cattle and pigs are very sensitive to the virus and show symptoms of the disease after a short incubation period of 3 to 5 days. The incubation period in sheep is considerably longer, about 10 to 14 days, and the clinical signs of the disease are usually mild and may be masked by other conventional conditions, thereby allowing the disease to go unnoticed. The mortality rate for nonadult animals infected with FMD varies and depends on the species and strain of the virus; in contrast, adult animals usually recover once the disease has run its course. However, because the disease leaves them severely debilitated, meat-producing animals do not normally regain their lost weight for many months, and dairy cows seldom produce milk at their former rate. The disease therefore can cause severe losses in the production of meat and milk. The FMD virus is easily transmitted and spreads rapidly. Prior to and during the appearance of clinical signs, infected animals release the virus into the environment through respiration, milk, semen, blood, saliva, and feces. The virus may become airborne and spread quickly if pigs become infected because pigs prolifically produce and excrete large amounts of the virus into the air. Animals, people, or materials that are exposed to the virus can also spread FMD by bringing it into contact with susceptible animals. For example, the virus can spread when susceptible animals come in contact with contaminated animal products, such as meat, milk, hides, skins, and manure; transport vehicles and equipment; clothes or shoes worn by people; and hay, feedstuffs, or veterinary biologics. The FMD virus has a remarkable capability for remaining viable for long periods of time in a variety of animate and inanimate objects. For example, the virus can persist in the human nasal passages for up to 36 hours, manure for 1 to 24 weeks, fodder for 1 month, and on shoes for 9 to 14 weeks. The ability of the virus to persist in the environment and other products depends on the temperature and potential of hydrogen (pH) conditions. Generally, the virus can survive freezing but cannot survive at temperatures above 50° Celsius (122° Farenheit) and at pH levels of less than 6, or greater than 9. Table 1 shows the various lengths of time that the FMD virus can survive in some selected products. FMD can be confused with several similar but less harmful animal diseases that also produce blisters and cause animals to salivate, such as vesicular stomatitis, bovine viral diarrhea, and foot rot. Two foreign swine diseases are also clinically identical to FMD—swine vesicular disease and vesicular exanthema of swine. The only way to distinguish between FMD and these other diseases is through laboratory analyses of fluid or tissue samples. FMD is also sometimes confused with mad cow disease or bovine spongiform encephalopathy (BSE). BSE is a fatal, neuro-degenerative disease found in cattle in 23 countries around the world. Cattle contract the disease through animal feed that contains protein derived from the remains of diseased animals. Scientists generally believe that an equally fatal disease in humans—known as variant Creutzfeldt-Jacob Disease—is linked to eating beef from cattle with BSE. However, unlike mad cow disease, FMD has no known human health implications. FMD is present in about 60 percent of the countries in the world and endemic in many countries in Africa, the Middle East, Asia, and South America. The relatively few areas that are considered free of FMD include North and Central America, Australia, New Zealand, and the Caribbean. Figure 1 shows the presence of FMD worldwide for the period 1992 through 2002. In 2000 and 2001, over 40 countries reported outbreaks of FMD, and during the first 5 months of 2002, five countries reported outbreaks. The spread of certain strains of the virus also demonstrates how quickly it is spreading throughout the world. For example, the FMD virus serotype O, known as the Pan-Asia strain, was first identified in northern India in 1990 and was subsequently found in Nepal in 1993. It then spread westward into Saudi Arabia during 1994 and, subsequently, throughout the Near East and into Europe (Thrace region of Turkey, Bulgaria, and Greece) in 1996. The Pan- Asia strain was also found in Bangladesh in 1996 and in Bhutan in 1998. In 1999 it was reported in mainland China and then detected in Taiwan. By late 1999 and in 2000, it had reached most of Southeast Asia. Most recently, the Pan-Asia strain was found in the Republic of Korea, Japan, the Primorsky Territory of the Russian Federation, and Mongolia (areas free from FMD since 1934, 1908, 1964, and 1973, respectively). The Pan-Asia strain is also responsible for the 2001 outbreak of FMD in the United Kingdom that subsequently spread to France, Ireland, and the Netherlands. Figure 2 shows the incidence of four types of FMD virus worldwide, including the type O Pan-Asia strain. In North America, the last outbreaks of FMD for the United States, Canada, and Mexico occurred in 1929, 1952, and 1953, respectively. The United States has worked closely with both Canada and Mexico to eradicate FMD from North America. The Office International des Epizooties (OIE)—an intergovernmental organization created in January 1924 by an international agreement signed by 28 countries—was established to guarantee the transparency of information on the animal disease status of member countries. In addition, OIE collects and analyzes veterinary scientific information and disseminates it to member countries, provides expertise and promotes international solidarity for the control of animal diseases, and guarantees the sanitary safety of world trade by developing rules for international trade in animals and animal products. In May 2001, OIE had 158 member countries. OIE classifies member countries (or certain zones within these countries) as being FMD-free with or without vaccination if they meet certain criteria detailed in the OIE International Animal Health Code. For example, to obtain FMD-free status without vaccination, a member country should (1) have a record of prompt animal disease reporting; (2) send a declaration that it has been FMD-free and has not used vaccination for 1 year; (3) present evidence that it has an effective system of surveillance; (4) implement regulatory measures for the prevention and control of FMD; and (5) provide evidence that no vaccinated animals have been imported into the country, since such animals can become the source of future infections. Similarly, to obtain FMD-free-with-vaccination status, a country should (1) have a record for prompt animal disease reporting, (2) send a declaration that there have been no outbreaks of FMD for 2 years, (3) provide evidence that the country has effective surveillance systems and has implemented necessary regulatory measures to prevent and control FMD, (4) provide proof that routine vaccinations are carried out and that the vaccines comply with OIE standards, and (5) have an intensive and frequent system to detect any viral activity. When FMD occurs in an FMD-free country or zone where vaccination is not practiced, the affected country must reapply after the outbreak to regain its FMD-free-without-vaccination status from OIE. OIE standards require a country to wait until 3 months after the last reported case of FMD when a “stamping out approach” (immediate slaughter of diseased and exposed animals with no vaccination) is used to eradicate the disease before the country can apply for reinstatement of its FMD-free status. As part of this process, surveillance results of laboratory-screening tests (serological surveillance results) must be provided to OIE to prove that the disease has been eradicated. If vaccination was used to control the outbreak, then the country must wait until 3 months after the last vaccinated animal is slaughtered and serological surveillance results prove that the disease has been eradicated before reapplying for FMD-free status. The international community generally places a high value on products from countries that are FMD-free without vaccination. Such countries can export both live animals and animal products easily to other FMD-free countries. In contrast, countries that have an FMD-free-with-vaccination status are restricted to trading animal products that can be treated to ensure that the virus is inactivated. As a result, most countries that are FMD-free without vaccination resort to a stamping out process to eradicate the disease if an outbreak occurs.