Foot and mouth disease Flashcards
Describe the serotypes of Foot and Mouth disease
7 distinct serotypes Not cross protective
- Serotypes A and O can be found in most FMD endemic regions, with the exception of southern Africa
- The Asia 1 serotype can be found in the FMD endemic regions of Asia
- The African buffalo is the natural host for the Southern African Territories (SAT) serotypes
Which spp are susceptible to FMD?
- Cattle
- Sheep
- Goats
- Pigs
- Wild boar
- Water buffalo, Camels, alpacas, llamas, Deer
Describe the mortality and morbidity of FMD
- High morbidity 100%
- Low mortality 2-20%
How long is the incubation period of FMD?
2-12 days
What are the clinical signs of FMD in cattle?
- Drop in milk yield
- Rectal temperature 40.5 ºC
- Drooling thick ‘ropey’ saliva
- Lip smacking
- Depressed, ‘sick’ looking
- Uncomfortable on feet
- Abortion or still birth
- Death in young animals Myocarditis
Where do vesicles form in FMD?
- Mouth: tongue, dental pad, hard palate, lips, gums, muzzle
- Feet: coronary band, interdigital space
- Teats, udder
Describe FMD recovery
- Vesicles rupture 24 hours and heal 1 week
- Recover in two weeks unless secondary infections arise
Describe the clinical signs of FMD in sheep and goats
Mild, if any, signs: - Fever - Oral lesions - Lameness Makes diagnosis and prevention of spread difficult
Which other disease can make diagnosis of FMD in sheep and goats difficult?
Orf
What are the clinical signs of FMD in pigs?
• Foot lesions: more severe than in cattle
- Coronary band, heel, interdigital space
- Lameness
• Snout vesicles
• Oral vesicles less common
• Drooling is rare
How is FMD diagnosed?
Clinical Laboratory: - Virus isolation: Tissue culture - Antigen detection: ELISA, PCR - Antibody detection: ELISA, SNT - Genetic analysis: RT PCR, Molecular
What are some FMD differential diagnosis in swine?
- Vesicular stomatitis
- Swine vesicular disease
- Vesicular exanthema of swine
- Foot rot
- Chemical and thermal burns
What are some FMD differential diagnosis in cattle?
- IBR, BVD, MCF, Bluetongue
- Bovine mammilitis, Bovine papular stomatitis
Describe the transmission of FMD
- Inhalation of aerosol or droplets
- Oral infection poor route in ruminants
- Pigs usually initially via oral: swill feeding
- Virus excretion finished within 6 days
- Incubation period of 7 ± 4 days
Which epidemiological factors influence FMD?
- Viral serotypes
- Virus multiplication
- Virus production
- Virus stability
- Infective dose
- Carrier State
As the temperature of saliva decreases the survival time of the virus?
Increases
37 degrees = 2 days
26 degrees = 3 weeks
4 degrees = 5 weeks
Which factors inactivate the virus?
- Progressively inactivated by temperatures above 50 degrees C
- Inactivated by pH <6 or >9
- Disinfectants
Is the infective viral dose higher via the respiratory or oral route
Oral!
12iu for respiratory
1 million iu for oral
What can FMDV be shed in?
- Breath -> air
- Secretions and excretions
- Animal products e.g. milk, meat, carcass
Which factors increase the rationale for control of FMD?
- Reduced productivity
- Reduced milk production which may continue of animals recover
- Mortality in young animals
- Restricted market access
How can the UK try and ensure a FMD outbreak doesn’t occur?
- Prevent introduction of disease
- Prevention of spread
- Ensure early Detection
- Eliminate disease rapidly as possible
What is the primary objective in tacking any FMD outbreak?
To eradicate the disease as quickly as possible and regain disease-free status
What are some constraints in controlling/eradicating FMD?
- Causing least disruption
- Minimising no of animals that need to be slaughtered
- Minimise damage to environment
- Minimise the burden to taxpayer and public
What are the 5 control options for FMD?
- Do nothing
- Prophylactic vaccination
- Stamping out alone
- Stamping out with vaccination to kill (Suppresive)
- Stamping out with vaccination to live (Protective)
The stamping out policy includes the slaughter of which groups of animals?
- Animals affected or suspected of being infected
- Animals believed to have been exposed to FMD-(Dangerous contacts)
- Animals to prevent spread
Describe prophylactic vaccination for control
This involves regular vaccination of the whole country or the region of a country with strain(s) which are found in the country to reduce the level of disease
How else can FMD be controlled?
- Restrict and control national movement of animals: (Licensing)
- Identify disease (reporting and surveillance, Vet inspections)
- Impose 3km protection zone and 10km surveillance zone
- Cull all animals on confirmed infected farms within 24 hours of first report.
- Cull all animals on dangerous contact farms
- Rapid and safe disposal of carcasses.
- Cleaning, disinfection and restocking
What are the uses of vaccination?
- Prevent the spread of the disease
- Buffer pressures on disposal capacity
- Reduce livestock losses
- Reduce the economic costs of the outbreak
Describe suppressive vaccination
- No of animals culled exceeds disposal capacity. Vaccinate to slaughter
- Reduce amount of virus circulating
- Reduce risks of spread
Describe protective vaccination
- Outbreak not contained by stamping out - Vaccinate to live
- Defined category of animals identified for protection. (geographic, species)
- Protect zoo animals, genetic material and rare breeds
