Listed Disease

Foot and mouth disease

Foot and mouth disease (FMD) is a severe, highly contagious viral disease of livestock that has a significant economic impact. The disease affects cattle, swine, sheep, goats and other cloven-hoofed ruminants. It is a transboundary animal disease (TAD) that deeply affects the production of livestock and disrupts regional and international trade in animals and animal products. Members that are currently free of FMD without vaccination remain under constant threat of an incursion. FMD is caused by an Aphthovirus of the family Picornaviridae. There are seven viral serotypes (A, O, C, SAT1, SAT2, SAT3, and Asia1). FMDV serotype C has not been isolated by the network of WOAH/FAO Reference Laboratories for FMD since 2004, and no serotype C events have been reported to WOAH since then. The remaining serotypes are present in different countries and territories worldwide. Each serotype requires a specific vaccine to provide immunity to a vaccinated animal. The prevention of FMD is dependent on the presence of early detection and warning systems and the implementation of effective surveillance among other measures. FMD was the first disease for which WOAH established an official list of disease-free Members. They can be officially recognised as disease-free either in their entirety or in defined zones.

What is Foot and Mouth disease (FMD)?

Foot and mouth disease (FMD) is a severe, highly contagious viral disease of livestock that has a significant economic impact.
The disease affects cattle, swine, sheep, goats and other cloven-hoofed ruminants. 

Intensively reared animals are more susceptible to the disease than traditional breeds. The disease is rarely fatal in adult animals, but there is often high mortality in young animals due to myocarditis or, when the dam is infected by the disease, lack of milk. 

FMD is characterised by fever and blister-like sores on the tongue and lips, in the mouth, on the teats and between the hooves. The disease causes severe production losses, and while the majority of affected animals recover, the disease often leaves them weakened and debilitated. 

The organism which causes FMD is an aphthovirus of the family Picornaviridae. There are seven viral serotypes (A, O, C, SAT1, SAT2, SAT3, and Asia1).  FMDV serotype C has not been isolated by the network of WOAH/FAO Reference Laboratories for FMD since 2004, and no serotype C events have been reported to WOAH since then. The remaining serotypes are present in different countries and territories worldwide. Each strain requires a specific vaccine to provide immunity to a vaccinated animal. 

All seven of the serotypes have also been found in wildlife. African buffalo (Syncerus caffer) are important carriers for FMDV. Other species of wildlife do not seem to be able to maintain FMD viruses. 

FMD is a WOAH-listed disease and must be reported to the Organisation, as indicated in the Terrestrial Animal Health Code.   

It was the first disease for which the WOAH established official status recognition. Members can apply for official endorsement of their national control programmes. 


Transmission and spread

FMDV is found in all excretions and secretions from infected animals. Notably, these animals breathe out a large amount of aerosolised virus, which can infect other animals via the respiratory or oral routes. 

The virus may be present in milk and semen for up to 4 days before the animal shows clinical signs of disease. 

The severity of an FMD outbreak is related to the ease with which the virus can spread through any or all of the following: 

  • infected animals newly introduced into a herd (carrying virus in their saliva, milk, semen, etc.); 
  • contaminated pens/buildings or contaminated animal transport vehicles; 
  • contaminated materials such as hay, feed, water, milk or biologics; 
  • contaminated clothing, footwear, or equipment; 
  • virus-infected meat or other contaminated animal products (if fed to animals when raw or improperly cooked); 
  • infected aerosols (spread of virus from an infected property via air currents). 

Animals that have recovered from an infection can sometimes carry the virus and cause new outbreaks of the disease. 


Public health risk

FMD is not readily transmissible to humans and is not a public health risk. 


Clinical signs

The severity of clinical signs will depend on the serotype of the virus, the exposure dose, the age and species of the animal and the host immunity. Morbidity can reach 100% in susceptible populations. Mortality is generally low in adult animals (1–5%), but higher in young calves, lambs and piglets (20% or higher). The incubation period is 2–14 days. 

Clinical signs can range from mild or inapparent to severe: they are more severe in cattle and intensively reared pigs than in sheep and goats. 

The typical clinical sign is the occurrence of blisters (or vesicles) on the nose, tongue or lips, inside the oral cavity, between the toes, above the hooves, on the teats and at pressure points on the skin. Ruptured blisters can result in extreme lameness and reluctance to move or eat. Usually, blisters heal within 7 days (sometimes longer), but complications, such as secondary bacterial infection of open blisters, can also occur. 

Other frequent symptoms are fever, depression, hypersalivation, loss of appetite, weight loss, growth retardation and a drop in milk production, which can persist even after recovery. Chronically affected animals are reported to have an overall reduction of 80% in milk yield. The health of young calves, lambs, and piglets may be compromised by lack of milk if dams are infected. 

Death can occur before development of blisters due to a multifocal myocarditis. Myositis may also occur in other sites. 

More information on the disease can be found in the WOAH Technical Disease Card.   


Diagnostic

The disease may be suspected based on clinical signs. However, FMD cannot be differentiated clinically from other vesicular diseases, such as swine vesicular disease, vesicular stomatitis and vesicular exanthema. 

Confirmation of any suspected FMD case through laboratory tests is therefore a matter of urgency. Relevant tests are described in the Terrestrial Manual  


Prevention and control

The initial measures described in the Global FMD control strategy are the presence of early detection and warning systems and the implementation of effective surveillance in accordance with the guidelines detailed in the Terrestrial Code  . They help monitor the occurrence and prevalence of the disease and allow characterisation of FMD viruses. 

The implementation of the FMD control strategy varies from country to country and depends on the epidemiological situation of the disease.

In general, it is essential for livestock owners and producers to maintain strong biosecurity practices to prevent the introduction and spread of the virus. 

Measures that are recommended at the farm level include: 

  • control over people’s access to livestock and equipment; 
  • controlled introduction of new animals into existing herds; 
  • regular cleaning and disinfection of livestock pens, buildings, vehicles and equipment; 
  • monitoring and reporting of illness; and 
  • appropriate disposal of manure and dead carcasses. 

Contingency planning for potential outbreaks will identify the elements included in a response effort to eradicate the disease, such as: 

  • humane destruction of all infected, recovered and FMD-susceptible contact animals; 
  • appropriate disposal of carcasses and all animal products; 
  • surveillance and tracing of potentially infected or exposed livestock; 
  • strict quarantine and controls on movement of livestock, equipment, vehicles; and 
  • thorough disinfection of premises and all infected materials (implements, cars, clothes, etc.). 

Use of vaccination 

Depending on the FMD situation, vaccination strategies can be designed to achieve mass coverage or be targeted to specific animal sub-populations or zones. Vaccination programmes carried out in a target population should meet several critical criteria, mainly: 

  • coverage should be at least 80%; 
  • campaigns should be completed in the shortest possible time; 
  • vaccination should be scheduled to allow for interference from maternal immunity; and 
  • vaccines should be administered in the correct dose and by the correct route. 

The vaccines used should meet WOAH standards of potency and safety, and the strain or strains in the vaccine must antigenically match those circulating in the field. 

It is important to use inactivated virus vaccines, as inactivated virus does not have the ability to multiply in vaccinated animals.
The use of live virus vaccines is not acceptable due to the danger of reversion to virulence.

Vaccination can play a role in an effective control strategy for FMD, but the decision on whether or not to use vaccination lies with national authorities. 


Geographical distribution

Consult WOAH World Animal Health Information System (WAHIS).   


Global and regional activities

Global
Africa
Americas
Asia and the Pacific 
Europe
Middle East

References