Foot and Mouth Disease Virus (FMDV)

FMDV is a member of the family Picornaviridae, genus Aphthovirus. Seven immunologically distinct serotypes have been identified: A, O, C, SAT1, SAT2, SAT3, and Asia1. Infection with one serotype does not confer immunity against another. Virions appear smooth and round in outline, are non-enveloped, 27 nm in diameter, and have icosahedral symmetry. The genome is a single linear molecule of ssRNA and is about 7.2-8.4 kb in size. Virus replication is restricted to the cytoplasm of the cell. Genomic RNA is infectious.

Species of the family Bovidae, as well as sheep, goats, swine, all wild ruminants and Suidae are natural hosts of FMDV. Species of family Camelidae have low susceptibility.

Foot and Mouth Disease (FMD) is one of the most contagious animal diseases, with important economic losses. FMD cannot be differentiated clinically from other vesicular diseases, including Swine Vesicular Disease (SVD), Vesicular Stomatitis (VS), and Vesicular Exanthema (VE). Laboratory diagnosis of any suspected FMD case is therefore a matter of urgency. Typical cases of FMD are characterised by a vesicular condition of the feet, buccal mucosa and, in females, the mammary glands. Clinical signs can vary from mild to severe and fatalities may occur, especially in young animals. Incubation period of FMDV is 2-14 days. FMDV occurs in most parts of the world, often causing extensive epidemic in domestic cattle and swine.
The virus can cause persistent infection of the pharynx in cattle, sheep, goats, and the other ruminants, and more than 70 species of wild mammals belonging to more than 20 families are susceptible to infection. The mechanism of persistence is unknown and its epidemiological significance has been difficult to assess.

Mortality is low among adult animals, but there is often high mortality in young due to myocarditis. Morbidity is high. Convalescence and virus shedding from affected animals may be protracted and it is these features that make foot and mouth disease so important, especially when the virus is introduced into countries previously free of disease.

FMDV is endemic in parts of Asia, Africa, the Middle East and South America (sporadic outbreaks in free areas). According to the List of Foot and Mouth Disease free countries many countries or zones within national territories are free from FMDV. Among them are Australia, Europe, the United States etc.

FMD is classified as an OIE List A disease.