Final - Lecture 17 Flashcards
What is the single greatest determinant of economic costs of a FMD outbreak?
- immediate closure of all export mkts for Canada’s livestock and meat products
What is the virus that causes FMD?
Picornaviridae, Aphthovirus
What are 4 characteristics of Apthovirus?
- positive sense RNA virus
- 7 distinct serotypes
- 60 subtypes and periodic de novo generation of new subtypes
- not cross protective
What animals are primarily affected by FMD?
- cloven-hoofed domestic and wildlife animals
- swine, sheep, goats, cattle, water buffalo
Does FMD have a high mortality rate in young animals?
- yes
FMD is usually considers a disease that reflects…
‘economic development’
- absent: Australia, North America, Europe
- sporadic: South America
- endemic: Africa and Asia
Where does aphthovirus bind to?
- binds to integrin proteins on cell surfaces (docks onto the cell)
What are the 2 special requirements for a picornavirus?
- 100 nucleotide of the virus has a ‘cloverleaf’ structure that binds viral polypeptide 3C and host proteins to form a nucleoprotein complex: absolute requirement for viral replication
- Has an internal ribosome entry site; needed host ribosome’s to bind and translation of proteins
What are the ‘clever cell manipulations’ of Picornavirus?
- rapid shut-down of host cell protein translation
- leaves more materials (aa and ribosomes) to build more virus
- switching off pro- and anti-apoptotic signals to keep the cell living as long as possible
- reduces interferon and tumor necrosis factor response
When is Picornavirus inactivated?
- pH below 6.5 and above 11
- ultra-high pasteurization
- dry surfaces and UV light (sunlight)
Where can Picornavirus survive?
- milk, milk products, bone marrow, lymph glands, some meat products
Where will Picornavirus survive for weeks?
- organic rich material
How is FMD transmitted?
- respiratory aerosols - direct (animal) and indirect (man)
- fomites (contact) - boots, clothing, hands
- feeding: infected animal products
- others: AI, biological
What is the main source of FMD transmission?
- infected vesicle (blister)
What is the incubation period of FMD?
- develop clinical signs in 1-21 days
Can FMD be shed prior to clinical signs?
yes
What 2 animals are considered maintenance hosts for FMD? Where do they harbor the virus?
sheep and goats
- harbor virus in pharynx for 4-6 months
What animal is considered an amplifier host for FMD?
PIGS
- will exhale 30-1000 times more virus than sheep or cattle
- clinical signs can be severe: fever, lameness, anorexia
What animal is considered an indicator host for FMD?
CATTLE
- lesions are more severe and manifested earlier than swine and small ruminants
- clinical signs: fever, depression/dullness, drooling/discharge
How does FMD affect cattle?
- low milk production
- mastitis
- abortion
- decrease fertility (breeding problems)
- ill-thriftiness: failure to gain wt
- hoof lesions = lameness
How are young animals affected by FMD?
‘Tiger heart’ = myocardial degeneration and necrosis
What are some clinical observations of FMD before and after vesicle formation?
Before vesicle formation:
- mobidity: ~100%
- mortality: 50% young animals, 5% adults
- dull
- lack of appetite
- fever
- milk production drops
- muscle tremors
Vesicle formation
- continuation of previous signs
- smacking and quivering lips
- salivation and drooling
- shaking of feet and lameness
How does FMD affect humans?
- zoonotic but not a public health concern
What are the clinical symptoms of a human infected with FMD?
- diarrhea
- fever
- ‘burning sensation’ in hands and feet prior to appearance of vesicles and oral blisters
- inappetence
What virus causes hand foot and mouth disease in ppl?
Coxsackie A group virus
What is considered the most devastating livestock disease world-wide?
FMD!
Why is FMD considered the most devastating livestock disease world-wide?
Economic devastation
How does FMD impact the economy (direct vs indirect costs)?
Direct costs
- loss of capital (livestock)
- compensation to producer
- eradication costs (stamping out) - infected animals AND welfare slaughter
- carcass disposal
Indirect costs
- empty farms (down time)
- animals stuck in transition (at border)
- loss of export markets
- loss of public confidence in the product
What is the issue with embargo aka a ban of exports?
- more animals used in domestic markets = over supply and decrease in commodity prices
- decrease breeding animals so cattle population drops (less births)
- eventually the mkt balances and borders open BUT some of the mkt sh`are may be lost since not enough inventory not for export; other countries may fulfill the demand
How are other commodities affected by embargo?
Feed grains and poultry industry affected
- drop in domestic prices in beef and pork = less ppl purchasing poultry
- less cattle to feed = drop in demand for cattle feed
What is more costly, eradication or economic losses?
Eradication: 2 million
Economic: 2 BILLION
How is FMD detected?
- Serology
- antibodies to structural proteins (vaccine strain) and/or non-structural proteins (field strain) - Virus isolation
- Clinical examination
- vesicles and general health - Nucleic acid tests
- PCR - Pathology
What is a surveillance strategy?
continuing program to ensure acceptable level of confidence the disease is not present
What are the OIE requirements for an FMD surveillance system?
1) early warning system throughout the production, marketing and processing chain
2) regular and frequent clinical inspection and serology testing of high risk animals
3) an effect program to ‘follow up’ on suspicious cases
4) random and targeted surveys acceptable
Clinical surveillance
aims at detecting suspect animals displaying clinical signs and used to confirm lab testing positive animals
Virological surveillance
used to monitor risk population, confirm clinical cases and positive serological tested animals, and to test ‘normal’ mortality
Serological testing
antibody testing for positive animals (either vaccinated or infected)
How do we control FMD spread?
- prior to handling or collecting tissues for animals of vesicular disease suspect, contact authorities
- quarantine suspected animals
- stamping out eradication program
- used by all non-endemic countries to eradicate FMD - decontamination
- disinfect immediately following virus detection
