Diagnostic Criteria

• FMD should be suspected whenever mouth lesions and/or  foot lesions/lameness develops in a number of animals of a susceptible species at any one time. The mouth and feet should then be examined for vesicles. (B47, B209)
• Provisional diagnosis is usually based on clinical evidence: a highly contagious disease with vesicular lesions on the tongue and feet of bovines, pigs, sheep, goats and/or other susceptible species  (B58).
• Disease in cattle "is usually acute and relatively unmistakable" (J3.102.w6)
• In sheep and pigs, the occurrence of a sudden-onset severe lameness in several animals at one time is suspicious (J3.102.w6).
• FMD should always be suspected in pigs with vesicular lesions (J3.102.w6)
• N.B. initial diagnosis may be difficult if strains produce anomalous disease pictures; this may occur with:
  • strains with a high species-tropism, e.g. the O Taiwan 1997 strain affected pigs and it was very difficult to infect cattle (J3.141.w2).
  • low virulence strains in which few typical vesicular lesions are produced (J63.14.w1).
  • exceptionally virulent strains causing unexpectedly high adult mortality (J63.14.w1).

"In the majority of cases a definitive diagnosis of FMD is based on the presence of FMD virus or antigen. Tests identify whether or not virus is present and also the specific serotype. When tissue samples cannot be obtained, diagnosis may be based on the demonstration of specific antibodies in serum samples." (J64.11.w2).

Definitive diagnosis of foot-and-mouth disease is usually based on detection of virus or virus antigens. Serological tests for antibody may be used to confirm diagnosis even in the absence of detectable virus, but antibodies are not detectable very early in the infection

• Differential diagnosis from other vesicular diseases affecting livestock (swine vesicular disease SVD, vesicular stomatitis VS, vesicular exanthema VE) depends on history including the species affected, clinical signs and laboratory tests. Only VS affects horses, cattle may be affected by both FMD and VS, while only pigs are affected by SVD and VE. If a vesicular disease is seen in pigs, all four diseases must be suspected until a definitive diagnosis is made (B47, D34).

Field diagnosis using large animals; inoculation with fresh vesicular fluid:

• Horse (intradermolingual inoculation) will develop vesicles with VS only (small local lesion may occur with VE). (B47, D34).
• Cattle (intradermolingual inoculation) will develop disease with FMD and VS, not with VE. (B47, D34).
• Cattle (intramuscular or intravenous inoculation) will develop disease with FMD only. (B47, D34).
• Guinea-pig (intradermal in footpad) will develop lesion with FMD or VS. (B47, D34)
• Inoculation of pigs is not helpful as lesions may develop with any of the four vesicular diseases. (B47, D34).
• N.B. Must be carried out under biosecure conditions (V.w23).

Detection of virus (virus isolation or detection of virus antigen) is generally carried out on epithelium from intact vesicles (blisters), fluid from vesicles, or the tags of epithelium from the edges of ruptured  vesicles (erosions). Blood may also be tested for the presence of virus (viraemia) and other tissues/secretions are also used sometimes. Cells and mucus from the pharynx, sampled using a probang cup, may be used for the detection of virus in subclinically infected animals and carriers (J3.77.w3, J42.118.w1, W18.Apl01.sib1).

• Virus typing by complement fixation (CF) test, enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction (PCR) may be carried out directly on material expected to contain large amounts of virus, such as fluid or epithelium from intact or recently ruptured vesicles. Samples which are negative must then be tested by growth in cell culture followed by virus typing of the cell culture supernatant. Samples which are less likely to contain large amounts of virus are tested by growing the virus from the sample in cell culture, followed by virus typing. (B58, B207, B210.89.w89, B216, B219).
• Direct serotyping using ELISA is able to produce a result within three hours from the time the test is set up (J64.15.w3).
• Repeated sampling of oesophageal/pharyngeal fluid and detection of virus in this fluid is required for the detection of carrier animals as an animal negative on one occasion may be positive at a later date. The sensitivity of testing is probably 50%; this can be improved by repeated sampling.(J3.77.w3, J42.118.w1).
• Recently, work has been carried out developing kits which, subject to satisfactory validation, could be used for rapid pen-side testing for FMD virus (J71.144.w1, P22.2000App18.w1)

Detection of antibody is carried out on serum samples.

• Traditional tests detect antibody to structural proteins of the FMD virus and the serum must be tested for each of the seven different types of virus. These tests can be used to determine which types of virus are/have been present in an area.
• More recently, tests have been developed which detect non-structural proteins. These tests detect infection with any type of FMD virus.
• The oldest of the tests for non-structural antibodies detect antibodies to "virus infection associated antigen" (D3). However, animals which have been vaccinated repeatedly with inactivated vaccines may be positive with this test (for example due to contamination of some impure vaccines with this non-structural protein and because the virus particle contains some of this protein in its capsid (V.w23)).
• In the last several years, tests have been developed, mostly based on ELISAs to various non-protein antigens, which are sensitive, specific and suitable for screening large numbers of serum samples. These tests are able to distinguish between animals which have been infected with foot-and-mouth disease virus (had virus replicating in them) and those which have not, whether or not the animals have been vaccinated.(J69.20S2.w1, J69.20S2.w2, J70.17.w2, J71.142.w1, J71.143.w1, J71.145.w1) However, these are not yet accepted by the OIE for the purposes of international trade.

• Literature Reports: Virus Identification Techniques (Goes to Virus Species Information page)

• Literature Reports: Clinical-Pathological Test Findings (including serology)

• Diseases producing vesicles which may affect the mouth and feet
  • Vesicular stomatitis VS (cattle, pigs, horses, sometimes sheep/goats) (B100, B211, B207)
  • Swine vesicular disease SVD(pigs only) (B58, B100, B207, B211,J3.102.w6)
  • Vesicular exanthema VE (pigs only) (B58, B100, B207, B211)
  • Sunlight-induced snout and sometimes foot vesicles in white-skinned pigs fed parsnips or celery (B207, B210.89.w89, B211)
  • Rarely, fungal lesions may produce confusing skin lesions (B207)
  • In humans, hand, foot and mouth disease (B47)

• Diseases which may produce lesions affecting the mouth and feet, but not vesicles
  • Mucosal disease BVD/MD(no vesicles, lesions begin as erosions) (B207, B210.89.w89, B211)
  • Bluetongue (sheep, goats, rarely cattle) (B58, B207, B210.89.w89, B211)
  • Orf (contagious pustular dermatitis) (B210.89.w89, B207)
  • Malignant catarrhal fever (foot lesions rare)(B58, B207, B210.89.w89)

• Diseases which may produce mouth lesions, but not vesicles and not foot lesions:
  • Rinderpest (no vesicles, lesions begin as erosions) (B58, B207, B210.89.w89, B211)
  • Bovine papular stomatitis (B210.89.w89, B207)
  • Epizootic haemorrhagic disease of deer (B58, B207)
  • Infectious bovine rhinotracheitis (B210.89.w89, B207)
  • Lumpy skin disease (Bovine herpesvirus 2: Allerton strain).(B209)
    • In African buffalo in East Africa. Well-defined ulcers on the tongue, palate and buccal mucosae (J64.7.w2).

• Diseases which may produce foot lesions, but not vesicles and not mouth lesions
  • Foot rot (B100, B211, B210.89.w89)
  • Interdigital dermatitis (scald) (B207)

• Diseases which may produce udder lesions
  • Pox infections of the udder (e.g. cowpox, pseudocowpox, orf) (B207, B211)
  • Bovine herpes mammilitis (B207)

• Disease producing skin lesions, in elephants
  • Elephantpox (B212)

• Disease producing neonatal mortality
  • Enterotoxaemia (B207).
  • Bluetongue (B207).
  • Encephalomyocarditis virus disease (B207).

N.B.

• Cattle fed grain treated with caustic soda may salivate profusely (B207).
• Ingestion of any caustic material may result in salivation and oral blisters (vesicles ) (B207)
• Trauma may cause lesions similar to those seen with FMD (W18.Apl01.sib1).
• Abscesses, e.g. at the coronary band, may appear similar to FMD vesicles (W18.Apl01.sib1).

Specific Medical Treatment (Antiserum, Antidote, Anti-(viral/bacterial/fungal) etc.)

(B47, B219, B214.3.18.w8, J3.148.w6, J79.11.w1, P5.40S.w1)

• Literature Reports: Specific Medical Treatment

General Nursing and Surgical Techniques

In areas of the world where slaughter of animals with clinical signs of foot-and-mouth disease is not mandatory, and in the case of infection in very important animals where an exception to an automatic slaughter policy might be given, nursing and supportive care are important for the welfare of the individual animal and to minimise the time for which it is clinically affected.

However, with severe disease and particularly if there are severe secondary infections and complications, culling may be preferable on the grounds of the welfare of the animal and also the prevention of additional losses to the farmer due to animals which are "poor doers".

(B207, B211, B214.3.7.w3, D34, J79.11.w1)

• Literature Reports: Nursing and Supportive Care

Not applicable.

• Literature Reports: Surgical Treatment - not applicable for this disease

Vaccination & Prophylactic Treatment

1)   VACCINATION REGIMES

Vaccination may be used to prevent major epidemics of disease. By providing vaccinated animals with protection, the number of susceptible animals is kept below the level required for disease transmission to be sustained.

In many areas of the world where foot-and-mouth disease is enzootic or there is a high risk of the disease, vaccination is used on a routine, prophylactic basis. Following initial vaccination, booster vaccinations are given at appropriate intervals for the area. Species other than cattle are not always included in these programmes.

In the face of an epidemic, whether or not in an endemic area, vaccination may be used alongside other measures to limit the spread of disease. In such a situation, it is advisable to vaccinate as many animals as possible of all susceptible species. It has been suggested that vaccination of at least 80-85% of the livestock in an area is required to provide "herd immunity" and effectively prevent disease spread.

The vaccine strain or stains to be used should be chosen carefully to ensure maximum protection is given against the virus type(s) circulating in the field.

The use of vaccines is often controlled at a national or regional level by the FMD control policy in force. 

(B207, B210.89.w89, B214.3.14.w6, B214.3.17.w7, B217.38.w38, B219, J3.102.w8, J16.8.w1, J16.22.w1, J18.49.w1, J18.116.w1, J19.100.w1, J19.116.w1, J21.9.w1, J21.12.w2, J21.12.w3, J21.40.w2, J21.41.w2, J35.141.w1, J35.151.w1, J35.158.w1, J64.11.w1, J64.11.w2, J70.9.w1, J70.11.w2, J70.12.w1, J70.16.w2, J70.17.w4, J71.57.w1, J78.3.w1, P5.40S.w1, P5.40S.w2, D38, V.w23, W18.Apl01.sib1, W32.Apl01.sib1)

2)  FOOT-AND-MOUTH DISEASE VACCINE DEVELOPMENT

Killed Vaccines

Killed vaccines against FMDV are produced by growing virus in cell culture, inactivating the virus and combining it with an adjuvant, a substance which enhances the immune response. Further processing may be carried out to concentrate the antigen to reduce the volume required for vaccination of each animal, and allow storage of antigen for prolonged periods without loss of efficacy. Testing during vaccine production ensures safety and efficacy of vaccines produced under standards of Good Manufacturing Practice.

The development and use of vaccines against foot-and-mouth disease virus (FMDV) has been complicated by the presence of seven different  immunologically distinct virus types, antigenic variation within virus types, the continuous emergence of new subtypes, the relatively short time for which FMD vaccines provide effective protection.

Considerable progress has been made in areas such as virus growth, inactivation, purification and the development of effective adjuvants to boost the immune response to the vaccine.

In recent years "vaccine banks" have been developed containing purified concentrated vaccine which may be used to produce high potency emergency vaccines at short notice.

The effectiveness of vaccination in practice depends not only on the standard of the vaccine but also on its being stored, transported and administered correctly.

(B47, B210.89.w89, D35.w1, J3.102.w8, J3.102.w9, J13.24.w1, J16.8.w1, J16.22.w1, J19.61.w1, J35.148.w1, J70.6.w1, J70.8.w1, J70.9.w1, J70.10.w1, J70.10.w2, J70.12.w1, J70.16.w2, J70.17.w3, W18.Apl01.sib1).

Live Vaccines

Live vaccines have been used historically. Their use ceased due to the problem and potential problem of reversion to virulence.

(J3.102.w8, J16.8.w1,  J35.148.w1, J70.9.w1).

Genetically Modified Vaccines

There has been considerable interest in the development of genetically modified vaccines which would, for example, not need to be kept refrigerated during storage. There are a yet no fully-developed genetically modified FMD vaccines.

(J13.51.w1, J20.278.w1, J35.148.w1, J70.6.w1, J70.10.w3, J70.11.w1, B210.89.w89)

• Literature Reports: Vaccination Regimes

• Literature Reports: Foot-and-Mouth Disease Virus Vaccine Development

Not applicable.

• Literature Reports: Prophylactic Treatment (other than vaccines)

Environmental and Population  Control Measures

• Thorough cleaning is required as the presence of organic matter/dirt may stop the applied disinfectant being effective.
• Disinfectants effective against FMD virus generally rely for their action on being acids or alkalis. These must NOT be mixed.
• Prolonged times may be required for the action of disinfectants on some substances (e.g. slurry).
• Small amounts of detergent (e.g. 1ml detergent per litre of disinfectant solution) may be added to disinfectants to increase effectiveness.
• It is important to use effective (approved) disinfectants and to use these at their effective (approved) concentrations.

(B214.2.4.3.w2, D37.Para138, J3.102.w7, W32.Apl01.sib1, W32.Apl01.sib16, W39.31May01.sib4, W39.31May01.sib5, W39.31May01.sib7)

• Literature Reports: General Environment Changes, Cleaning and Disinfection

• Literature Reports: Chemical Toxicities / Disinfectants
• Literature Reports on Physical Susceptibility (Inactivation)

The measures may include:

• Routine movement restrictions and quarantine for movement between areas, in countries with endemic FMD
• Fencing to prevent contact between domestic livestock and wildlife populations in which FMD is known to circulate.
• Import/export restrictions for between-country movement of animals.
• Rapid culling of infected animals and appropriate disposal of their carcasses, which is particularly important in non-endemic areas.
• Severe restrictions on movements of animals in an area during an outbreak of FMD.
• Restriction on movements of animals back onto premises which have been infected.

It is important that population control measures are enforceable and enforced. Consideration must be given to the problems associated with movement restrictions, including welfare problems of wildlife prevented from reaching water or other vital resources. It is also important to consider that where means of enforcement are poor and/or the importance of such control measures are not understood and appreciated, illegal movement of livestock is likely to undermine control efforts.

Culling operations should be designed to minimise the spread of disease while avoiding unnecessary slaughter.

• Because of the highly contagious nature of foot-and-mouth-disease virus (FMDV), and because animals are known to release large amounts of virus into the environment before starting to show clinical signs (up to five days before for cattle and sheep, as long as ten days for pigs), it is usual in FMD-free countries to cull not only those animals with clinical disease (lesions) but also all "dangerous contact animals"  such as:
  • All other animals on the same farm;
  • All other animals which have been in contact at e.g. a market;
  • Other animals considered likely to have been infected by indirect contact (e.g. transported in same lorry immediately after it has been used for infected animals, or tended by stockman immediately after tending infected animals).
• This is because there is a high chance that these animals will already be infected and may already be producing virus and releasing it into the environment. This policy, the slaughter and burial or burning of all affected and in-contact susceptible livestock (dangerous contact animals) on an affected premises is also known as "stamping out" (J3.131.w1).

Effective rapid disposal of carcasses following culling is recognised to be an essential part of effective FMD control.

(B209, B211, J3.96.w3, J3.131.w1, J3.140.w6, J3.148.w3, J18.49.w1, J19.68.w5, J19.124.w2, J21.33.w1, J21.69.w1, J35.134.w2, J35.127.w1, J42.84.w1, J42.85.w2, J42.118.w1, J64.7.w1, J68.B302.w1, J72.41.w1, W18.Apl01.sib1, W32.Apl01.sib1, W32.Apl01.sib6, W39.31May01.sib1, W39.31May01.sib3, D36.AppendixII, D37.Para216).

• Literature Reports: Population Control Measures

Quarantine of an individual animal or group of animals would frequently involve testing for disease (screening) to reduce any possible risk of introducing the virus to a previously unexposed population.

(B211, B214.3.14.w6, J3.102.w6, D37.Para85, W32.Apl01.sib1, W32.Apl01.sib2, W32.Apl01.sib4, W32.Apl01.sib5, W32.Apl01.sib16, W32.Apl01.sib17, W32.Apl01.sib19, W32.Apl01.sib21, W32.Apl01.sib22, W32.Apl01.sib23, W32.Apl01.sib24, W39.31May01.sib5)

• Literature Reports: Isolation and Quarantine