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What is the scientific name of the virus that causes FMD?
Picornaviridae Aphthovirus
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How many serotypes of FMD are there?
7
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How many subtypes of FMD are there?
60
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Why is it so difficult to vaccinate for FMD?
vaccines aren't cross protective
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What species are primarily affected by FMD?
Swine, sheep, goats, cattle and water buffalo
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FMD has a high rate of mortality in _______ animals and a high rate of morbidity in ______ animals.
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What are some non-production animals that FMD can affect?
elephants, hedgehogs, nutrias, armadillos, capybara, rodents
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Where is FMD considered absent?
Australia, North America, Europe
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Where is FMD considered sporadic?
South America
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Where is FMD considered endemic?
Africa and Asia
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When was the last case of FMD in the USA?
1929
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When was the last case of FMD in Canada?
1952- 1343 cattle and 401 swine, sheep and goats slaughtered (estimated cost of $1million)
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When was the last case of FMD in Taiwan?
1997
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When were the last cases of FMD in the UK?
2001 and 2007
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How does the aphthovirus bind to cells?
binds to integrin proteins on cell surface (docks onto cell)
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What are the 2 special requirements for the picornavirus?
- 1). 100 nucleotide has cloverleaf structure that binds viral polypeptide 3C and host proteins to form a nucleoprotein complex: NEED for viral replication
- 2). Needs an internal ribosome entry site (IRES) to bind and perform translation of proteins
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Describe the cell manipulations performed by the picornavirus pathogen.
- 1. rapid shut down of host cell protein translation
- 2. leaves more materials (aa and ribosomes) to build more virus
- 3. switching of pro and anti apoptotic signals to keep the cell living for as long as possible
- -pro : shut down of host cell transcription and translation
- -anti : reduces interferon and tumor necrosis factor
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What are the requirements for the inactivation of picornavirus?
- pH below 6.5 or above 11
- ultra-high pasteurization
- dry surfaces and UV light
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In which products can FMD survive?
milk, milk products, bone marrow, lymph glands, dried serum, organic rich material
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Describe the ways in which FMD is transmitted.
- respiratory aerosols- direct: animal indirect: man
- fomites- contact
- feeding infected animal products- milk, meat, other organs
- Other: AI, biological (vx, hormone preparations)
- MAIN SOURCE: infected vesicle (blister)
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What is the incubation period for natural exposure of FMD?
1-21 days
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What is the incubation period for experimental exposure?
12-48 hours
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What is a maintenance host?
An animal that is sick with the disease, but doesn't show clinical signs for a prolonged period of time= Transmitters!!
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What are two common maintenance hosts of FMD?
sheep and goats- can have virus in pharynx for 4-6 months
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What are some clinical symptoms of FMD in a maintenance host?
- mild to moderate fever
- lameness
- inappetance
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What is an amplifier host?
increases the dose of a virus- ramps up virus production
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What animal is a common amplifier host of FMD?
swine- will exhale 30-1000 times more virus than sheep or cattle
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What are the clinical symptoms of FMD in an amplifier host?
- fever
- lameness- painful to stand
- anorexia- vessicles around snout
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What is an indicator host?
The host that shows obvious signs of sickness (disease)
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What is the indicator host for FMD?
Cattle
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What are the clinical symptoms of FMD in an indicator host?
- severe lesions that manifest earlier than in swine or sheep
- fever
- depression/ dullness
- drooling, serous discharge
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What are some of the production problems associated with FMD in cattle?
- low milk production
- mastitis
- abortion
- decreased fertility
- unthriftness- failure to gain weight
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What are some of the lameness issues associated with FMD in cattle?
hoof lesions in the interdigital space and coronary bands
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What is a major concern of FMD in young animals?
Tiger heart: myocardial degeneration and necrosis, usually results in 100% mortality
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How long is the incubation of FMD before vessicle formation?
1-5 days
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How many human cases of FMD have been reported since 1921?
40
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How long is the incubation period for human FMD?
4-6 days
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What are the clinical symptoms of human FMD?
- malaise
- diarrhea
- fever
- burning in hands and feet prior to vessicle formation
- inappetance
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What strain of Picornaviridae is responsible for FMD in people?
coxsackie A group virus
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Why is FMD considered the most devastating livestock disease present worldwide?
The economic impacts!!
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What are the direct costs of FMD?
- loss of capital (livestock)
- compensation to producers
- eradication costs***- infected animal and welfare slaughter
- carcass disposal
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What are the indirect costs of FMD?
- empty farms
- animals stuck in transition- at the border
- loss of export markets**
- loss of consumer confidence in product
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Describe the economic catastrophe between a small outbreak and a larger outbreak.
Quite similar both cost a lot of money due to closed borders and welfare slaughter
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What is the effect of an embargo on swine?
- Prices drop
- more animals used in domestic markets
- surplus of hogs, retail price drops 10%
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What is the effect of an embargo on cattle?
- cow prices dropped 3x faster than steer
- Surplus of beef in domestic markets= decreased breeding therefore population drops
- once markets reopen Canada can no longer meet demand for beef and other countries meat is imported instead
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Which other commodities can be affected by an embargo on beef or swine?
- Poultry or grain industries
- drop in domestic price of beef or pork= less people purchasing poultry
- less cattle to feed= lowered demand for grains
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What were the eradication costs for the 1987 FMD outbreak?
$2 billion (2006 price with inflation= $3.54 billion)
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In the 2002 government study what was the presumed cost of an outbreak affecting 50 herds in Canada?
$9.8 billion
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What are four methods of detecting FMD?
- 1. Serology
- 2. Virus isolation
- 3. Clinical examination
- 4. Nucleic acid tests
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What is the OIE FMD surveillance strategy?
have a continuing program to ensure an acceptable level of confidence that the disease is not present.
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What are the needs for FMD surveillance?
- 1.) early warning system throughout production, marketing and processing chain to report suspicious cases
- 2.) regular and frequent clinical inspection and serology testing of high risk animals
- 3.) An effective program to follow up on suspicious cases
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What are the three types of OIE surveillance?
Clinical, virological and serological
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Define clinical surveillance.
- Aims at detecting suspect animals displaying clinical signs
- -used to confirm lab testing positive animals
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Define Virological Surveillance.
used to monitor risk, population, confirm clinical cases and positive serological tested animals and to test normal mortality
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Define Serological testing.
antibody testing for positive animals (either vaccinated or infected)
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What control measure are put in place for animals that are suspect for FMD?
quarantine and kill
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What are 4 reasons not to vaccinated animals for exotic diseases?
- Vaccinated animals will be seropostive for the disease, thus difficult to differentiate
- Not all animals become 100% protected when vaccinated- could still contract disease
- Vaccination will not protect against pre-infected animals- there for could be carriers/shedders
- Vaccines could be ineffective if they are not properly stored (refrigerated)
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How can someone differentiate between an infected animal and a vaccinated animal?
- Serology- infected has non-structural proteins (NSP)
- - vaccinated has structural proteins (SP)
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What is a marker vaccine?
A vaccine that has been modified to allow for differentiation between infected and vaccinated animals.
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