Foot-and-mouth disease (FMD) or hoof-and-mouth disease (HMD) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids. The virus causes a high fever lasting two to six days, followed by blisters inside the mouth and near the hoof that may rupture and cause lameness. FMD has very severe implications for animal farming, since it is highly infectious and can be spread by infected animals comparatively easily through contact with contaminated farming equipment, vehicles, clothing, and feed, and by domestic and wild predators. Its containment demands considerable efforts in vaccination, strict monitoring, trade restrictions, quarantines, and the culling of both infected and healthy (uninfected) animals. Susceptible animals include cattle, water buffalo, sheep, goats, pigs, antelope, deer, and bison. It has also been known to infect hedgehogs and elephants; llamas and alpacas may develop mild symptoms, but are resistant to the disease and do not pass it on to others of the same species. In laboratory experiments, mice, rats, and chickens have been artificially infected, but they are not believed to contract the disease under natural conditions. Cattle, Asian and African buffalo, sheep, and goats can become carriers following an acute infection, meaning they are still infected with a small amount of virus but appear healthy. Animals can be carriers for up to 1–2 years and are considered very unlikely to infect other animals, although laboratory evidence suggests that transmission from carriers is possible. Humans are only extremely rarely infected by foot-and-mouth disease virus (FMDV). (Humans, particularly young children, can be affected by hand, foot, and mouth disease (HFMDV), which is often confused for FMDV. Similarly, HFMDV is a viral infection belonging to the Picornaviridae family, but it is distinct from FMDV. HFMDV also affects cattle, sheep, and swine.) The virus responsible for FMD is an aphthovirus, foot-and-mouth disease virus. Infection occurs when the virus particle is taken into a cell of the host. The cell is then forced to manufacture thousands of copies of the virus, and eventually bursts, releasing the new particles in the blood. The virus is genetically highly variable, which limits the effectiveness of vaccination. The disease was first documented in 1870.
