Foot and Mouth disease (FMD) is a viral disease of livestock that affects swine, cattle, sheep, goats and other cloven-hoofed ruminants. The FMD virus is highly contagious, and outbreaks of the disease can have severe economic consequences.
FMD is an endemic disease in several countries worldwide. It is caused by an aphthovirus of the family Picornaviridae and there are seven different serotypes (A, O, C, SAT1, SAT2, SAT3 and Asia1). Each serotype requires a specific vaccine to provide immunity, which may not be effective against all of the strains within each serotype.
FMD is endemic in most African countries and the Middle East, in several parts of Asia and in very limited areas of South America. Countries currently free of FMD are under constant threat of an incursion due to the transboundary condition of the disease, outbreaks in which can occur sporadically.
FMD is recognised by the World Organization for Animal Health (OIE) as a transmissible disease that is potentially serious and rapidly spread. Foot and Mouth disease has severe socio-economic consequences as livestock productivity is seriously affected. This viral infection costs Africa approximately US$2.3bn per year in economic losses, and both regional and international trade of animals and animal products are compromised and disrupted.
The clinical signs depend on many different factors such as the strain of the virus, the age and species of the animal, and the exposure dose.
Typically, the animal affected presents ulcers and wounds in the mouth and feet, causing hypersalivation and lameness. Specifically blisters can appear on the nose, lips, tongue, inside the mouth, between the toes, above the hooves, on the teats and at pressure points on the skin. Other frequent symptoms are fever, depression, loss of appetite and weight, growth retardation and heavy losses in milk production. In young animals sudden death can be seen.
FMD morbidity levels are very high, reaching 100% in susceptible populations. Mortality is generally low in adult animals.
FMD is estimated to circulate in 77% of the global livestock population, according to the OIE.
The virus is found in secretions and excretions of infected animals and can be present in milk and semen for up to four days before the animal shows symptoms. An infection may occur via the respiratory, or oral routes, or through contact with contaminated infrastructure and equipment.
Animals recovered from the disease may still carry the virus and are considered as potential sources of infection for new outbreaks.
The FMD virus is highly contagious and outbreaks of disease must be reported, movement restricted and control measures employed to avoid spread. Warning systems, early detection and effective surveillance are essential.
Best practice for livestock owners and producers in case of an FMD outbreak is to carry out regular cleaning and disinfection of equipment, buildings and vehicles. Maintaining safe biosecurity practices and monitoring and reporting possible illness is fundamental to the early diagnosis and control of FMD.