Foot and mouth disease

Question 1

Aetiology

Answer 1

• Picornavirus family (genus Aphthovirus) - highly contagious

Question 2

Epidemiology

Answer 2

• FMD is a highly contagious disease of cloven-hoofed animals including cattle, pigs, sheep and wildlife species

Question 3

Pathogenesis

Answer 3

3 phases
- Pre-viraemia - routes of infections (respiratory, oral, AI, abrasions, contaminated instruments)

• Viraemia
  Bloodstream
  Characteristic lesions develop at these sites
  Gross lesions in areas subjected to mechanical trauma
  Epithelium of the mouth and feet, the dorsum of the snout (pigs), the teat
  Incubation period of 1 to 21 days (usually 3 to 8 days in most species)
• Post-viraemia
  Characterized by the healing of lesions
  The process can be rapid in the oral mucosa
  Often slow in the feet

Question 4

Risk factors (host and environmental)

Answer 4

• Host factors
  ◦ Some virus strains are species-specific
  ◦ Immature animals and animals in good condition are more susceptible
  ◦ Hereditary differences in susceptibility have been observed
  ◦ Wild boar are susceptible and can transmit the disease to domestic swine
• Environmental and pathogen factors
  ◦ Persistence: >1 year on infected premises
  ◦ It can survive longer at low temperatures
  ◦ The virus can survive for over 60 days in frozen bull semen
  ◦ Fomites can carry the virus for extended periods
  ◦ Birds may act as carriers
  ◦ Vaccine related

Question 5

Common clinical signs

Answer 5

◦ Salivation characteristic “smacking” jaw movements
◦ Vesicles and ruptured lesions (muzzle, inside the mouth, feet)
◦ Abortion
◦ Anorexia
◦ Lameness
◦ Recumbency

Question 6

Differentials

Answer 6

Question 7

Diagnostics

Answer 7

Question 8

Outline contigency plan

Answer 8

• Contact tracing
• Establishment of protection and surveillance zones
• Culling of infected animals
• Emergency vaccination
• National livestock movement ban
• Restriction of movement of animal products
• Cleansing and disinfection premises
• Surveillance