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