Bovis ISSN 2398-2993

Foot and mouth disease

Synonym(s): FMD

Contributor(s): Veronica Fowler , Adam Dunstan-Martin

Introduction

  • Cause: foot-and-mouth disease (FMD) is a highly contagious, transboundary viral disease of cloven-hooved mammals caused by FMD virus (FMDV).
  • Signs:
    • General clinical signs include: short-lived pyrexia which precedes the development of gross clinical signs such as excessive salivation/nasal discharge, and the formation of vesicles on the oral mucosa (tongue, dental pad, gums), nostrils, teats, the inter-digital spaces and coronary bands of the feet.
    • However, the severity of clinical signs varies with the strain of the virus, exposure dose, age and breed of animal, host species, and level of host immunity.
  • Diagnosis:
    • FMD can be suspected on appearance of clinical signs, however, definitive diagnosis cannot confirmed without further laboratory tests.
    • Diseases, such as vesicular stomatitis (VS) present with the same clinical signs in cattle.  
  • Treatment:
    • Vaccines do exist for FMD and are used prophylactically in some areas of the world.
    • Vaccines will be ineffective if the animal is already infected.
    • There is no commercially available treatment which can specifically target FMDV once an animal is infected but supportive care including painkillers and antibacterials can be used for severe infection and secondary bacterial infection respectively.
    • Animals usually recover from clinical signs after clearance of the virus within about two weeks. Return to previous milk production can have a lag phase depending on breed.
  • Prognosis: high morbidity (up to 100%), low mortality in adult animals (1-5%) but is observed in young animals due to myocarditis.
Print off the farmer factsheet on Foot and mouth disease to give to your clients.

Pathogenesis

Etiology

  • The disease is caused by FMDV Foot and mouth disease virus which belongs to the genus Aphthovirus within the family Picornaviridae.
  • The FMDV genome is a single-stranded positive sense RNA virus approximately 8400 nucleotides (nt) in length.
  • There are seven immunologically distinct serotypes: A, O, C, SAT 1, SAT 2, SAT 3, and Asia 1, and these do not confer cross immunity.
  • New FMDV variants are frequently generated due to the mutation from error-prone RNA replication, recombination, and host selection.

Transmission pathways

  • Susceptible animals may become infected if they:
    • Have direct contact with infected animals.
    • Have direct contact with contaminated inanimate objects (hands, footwear, clothing, vehicles, etc).
    • Inhale infectious aerosols (FMD can be airborne, especially in temperate zones (up to 60 km overland and 300 km by sea)).
    • Consume untreated contaminated meat products (swill feeding) (primarily pigs).
    • Ingest contaminated milk (calves).
    • Are artificially inseminated with contaminated semen.
    • Vaccination using poor vaccines which have not been sufficiently inactivated (risk only within endemic regions).

Pathophysiology

  • The primary site of infection is believed to be the dorsal soft palate/tonsils (except where virus entry is via abrasions to the skin or mucosa).
  • After initial replication, virus enters the bloodstream through regional lymph nodes.
  • Further subsequent viral replication occurs within the epithelia of the skin and mouth, leading to the development of vesicular lesions on the tongue, dental pad, gums, nasal mucous membranes, coronary bands, teats, udder, and interdigital spaces.

Timecourse

  • The incubation period of FMD is typically between 2 – 14 days, but can be highly variable, depending on factors such as the species, husbandry conditions, and route of transmission, strain and dose of the virus.
  • Clearance of the virus typically occurs within two weeks of infection, however some animals may become ‘carriers’ (defined as an animal from which infectious FMDV can be recovered by virus isolation 28 days after infection), where the virus persists in the esophageal–pharyngeal region.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Jamal S M & Belsham G J (2015) Development and Characterization of Probe-Based Real Time Quantitative RT-PCR Assays for Detection and Serotyping of Foot-And-Mouth Disease Viruses Circulating in West Eurasia. Plos One 10 (8), Plos.org.
  • Fowler V L et al (2014) Recovery of Viral RNA and Infectious Foot-and-Mouth Disease Virus from Positive Lateral-Flow Devices. PloS one 9 (10), PubMed.
  • Hall M D et al (2013) Reconstructing geographical movements and host species transitions of foot-and-mouth disease virus serotype SAT 2. mBio 4 (5), PubMed.
  • Knight-Jones T J D & Rushton J (2013) The economic impacts of foot and mouth disease – What are they, how big are they and where do they occur? Preventive Veterinary Medicine 112 (3-4), 161–173 Linkinghub.
  • OIE (2013) Foot and mouth disease. Oie, 1–5.
  • Robinson T P & others (2011) Global livestock production systems, 152.
  • Paton D J, Sumption K J & Charleston B (2009) Options for control of foot-and-mouth disease: knowledge, capability and policy. Philosophical Transactions of the Royal Society B: Biological Sciences 364 (1530), 2657–2667 Royalsocietypublishing.
  • FAO (2011) The progressive control pathway for FMD control principles, stage descriptions and standards.
  • Parida S (2009) Vaccination against foot-and-mouth disease virus: strategies and effectiveness. Expert review of vaccines, 8 (3), 347–365.
  • Ferris N P et al (2009) Development and laboratory validation of a lateral flow device for the detection of foot-and-mouth disease virus in clinical samples. Journal of virological methods 155 (1), 10–7. Sciencedirect.
  • Grubman M J & Baxt B (2004) Foot-and-mouth disease. Clinical microbiology reviews 17 (2). 465–93 PubMed.
  • Alexandersen S et al (2003) The Pathogenesis and Diagnosis of Foot-and-Mouth Disease. Journal of Comparative Pathology, 129 (1), 1–36. Linkinghub
  • Reid S M et al (2003) Evaluation of automated RT-PCR to accelerate the laboratory diagnosis of foot-and-mouth disease virus. Journal of Virological Methods, 107 (2), 129–139 Sciencedirect.
  • Kitching R P (2002) Clinical variation in foot and mouth disease: cattle. Revue scientifique et technique (International Office of Epizootics), 21 (3), 499–504.
  • Reid S M et al (2001) Diagnosis of foot-and-mouth disease by RT-PCR: use of phylogenetic data to evaluate primers for the typing of viral RNA in clinical samples. Archives of virology, 146 (12), 2421–34 PubMed.
  • Ferris N P & Dawson M (1988) Routine application of enzyme-linked immunosorbent assay in comparison with complement fixation for the diagnosis of foot-and-mouth and swine vesicular diseases. Veterinary Microbiology, 16 (3), 201–209. Sciencedirect.
  • Reid S et al (1998) Comparison of reverse transcription polymerase chain reaction, enzyme linked immunosorbent assay and virus isolation for the routine diagnosis of foot-and-mouth disease. Journal of Virological Methods, 70 (2), 213–21 Sciencedirect.
  • Sørensen K J et al (1998) Differentiation of infection from vaccination in foot-and-mouth disease by the detection of antibodies to the non-structural proteins 3D, 3AB and 3ABC in ELISA using antigens expressed in baculovirus. Archives of virology, 143 (8), 1461–76 PubMed.
  • Hamblin C, Barnett I T R & Hedger R S (1986) A new enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against foot-and-mouth disease virus I. Development and method of ELISA. Journal of Immunological Methods, 93 (1), 115–121 Sciencedirect.
  • Robson K J, Harris T J & Brown F (1977) An assessment by competition hybridization of the sequence homology between the RNAs of the seven serotypes of FMDV. J Gen Virol, 37 (2), 271–276 PubMed.
  • Snowdon W A (1966) Growth of FMDV in monolayer cultures of calf thyroid cells. Nature, 210, 1079–1080.


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