Foot and mouth disease (FMD) is a highly contagious viral illness that affects cattle, pigs, sheep, goats, and other cloven-hoofed animals. It does not affect humans in any meaningful way, and it is completely different from the childhood illness called hand, foot, and mouth disease. FMD is one of the most economically devastating animal diseases in the world, costing an estimated $6.5 to $21 billion globally each year in lost productivity and vaccination efforts.
What Causes It
FMD is caused by a virus in the family Picornaviridae, genus Aphthovirus. There are seven distinct serotypes of the virus (labeled O, A, C, Asia 1, SAT-1, SAT-2, and SAT-3) and roughly 65 known strains. Crucially, infection with one serotype provides no protection against the others, which makes both vaccination and outbreak control significantly more complicated.
Which Animals Get It
Any animal with cloven hooves (split hooves) is susceptible. That includes domesticated cattle, pigs, sheep, and goats, as well as wild species like deer, bison, and antelope. The most severe effects are seen in dairy cattle, where the disease causes dramatic drops in milk production, spontaneous abortions, and sometimes lasting infertility. Young animals are the most vulnerable to death, with mortality among calves and piglets typically running 2 to 3 percent.
Horses, dogs, and cats cannot catch FMD. Neither can humans. You may have seen alarming headlines that blur the line between FMD in livestock and hand, foot, and mouth disease in children. These are caused by entirely different viruses. You cannot catch foot and mouth disease from farm animals, and you cannot spread it to them.
Symptoms in Infected Animals
The hallmark sign is blisters, called vesicles, that form on the tongue, lips, inside the mouth, on the udder or teats, and around the hooves. These blisters eventually rupture and leave raw, red erosions that are extremely painful. Infected animals typically develop a fever first, followed within a day or two by the appearance of blisters.
Because of the pain, affected animals stop eating, drool excessively, become lame, and refuse to stand or walk. Dairy cows experience a sharp drop in milk yield, often as high as 80 percent in chronically affected herds. Even animals that survive and recover may never return to their previous level of productivity, which is a major reason the economic toll extends far beyond the immediate outbreak period.
How It Spreads
FMD is extraordinarily contagious. The virus can spread through direct nose-to-nose contact between animals, through the fluid inside blisters, through saliva, and through manure. It also travels in the air. Under the right weather conditions (cool, humid, low wind), airborne virus particles can drift dozens of miles from an infected farm to neighboring herds.
People, vehicles, and equipment can act as mechanical carriers. The virus survives on boots, clothing, truck tires, and feeding equipment, which is why biosecurity measures during an outbreak are so strict. Contaminated meat, milk, and animal products can also introduce the virus to new regions if imported from areas where the disease is circulating.
Why It Matters Economically
Few animal diseases carry the economic weight of FMD. The global cost from direct production losses and vaccination in countries where the disease is endemic runs between $6.5 and $21 billion per year, with an average around $11 billion. On top of that, outbreaks in previously disease-free countries add another $1.5 billion annually.
The damage comes from multiple directions. Milk production plummets. Animals lose weight and fertility. Young stock die. But the biggest financial blow often comes from trade restrictions. The moment a country confirms even a single case of FMD, its meat and dairy exports are effectively shut out of premium international markets. Countries that are FMD-free, like the United States, Japan, and EU members, typically have meat prices about 50 percent higher than countries where the disease circulates. Losing that access is catastrophic.
Real-world examples illustrate the scale. The 2001 outbreak in the United Kingdom cost the nation roughly one billion euros. South Korea’s 2010-2011 outbreak led to the destruction of 3.4 million livestock and $2.78 billion in costs. A 1997 outbreak in Taiwan, concentrated mainly in pigs, reduced the country’s total GDP by 0.28 percent. Modeling suggests a major outbreak could cost Australia between $4 and $6.5 billion, with export revenue dropping by 70 percent in the first year alone. Countries that experience an FMD outbreak typically lose between 0.2 and 0.6 percent of GDP.
How Outbreaks Are Controlled
Because FMD spreads so fast and the economic consequences are so severe, governments respond aggressively. The standard approach in disease-free countries is called “stamping out,” which means all clinically affected animals and those in direct contact with them are culled and disposed of. This sounds extreme, but it is the fastest way to eliminate the virus and regain disease-free trade status.
Movement restrictions are imposed immediately. Protection zones and control areas are drawn around infected farms, and no livestock, vehicles, or animal products move in or out without authorization. Surveillance intensifies across the broader region to catch any additional cases early.
Emergency vaccination is sometimes used alongside culling, particularly when the outbreak is large or spreading quickly. However, vaccination strategy is complicated by the seven serotypes. A vaccine effective against one serotype provides no protection against the others, and even within a serotype, protection varies depending on how closely the vaccine strain matches the circulating virus. About 2.35 billion doses of FMD vaccine are administered worldwide each year, at a cost of roughly $0.40 to $3 per dose (occasionally up to $9) including delivery. In some response plans, vaccinated animals are eventually slaughtered rather than kept, because their antibodies make it difficult to distinguish them from animals that were actually infected, complicating ongoing surveillance.
Where FMD Exists Today
FMD is endemic across large parts of Africa, the Middle East, and South and Southeast Asia. It circulates persistently in these regions despite ongoing vaccination programs. North America, Western Europe, Australia, New Zealand, and Japan are currently recognized as free from the disease without vaccination. Several South American countries, including Brazil and Bolivia, have achieved disease-free status in recent years after decades of control efforts, though their free zones vary by region.
The World Organisation for Animal Health (WOAH) maintains official lists of FMD-free countries and zones. Maintaining that status requires constant vigilance: strict import controls, robust surveillance systems, and rapid response plans. For countries on the border between free and endemic zones, the cost of reducing FMD control efforts is steep. Research from Zimbabwe found that every dollar saved by cutting back on control programs resulted in five dollars lost to the national economy.