Picornaviridae (FMD) Flashcards
What virus is highly resistant in the environment but variably sensitive to acid?
FMD
FMD is enveloped or non-enveloped?
non-enveloped
What shape does FMD have?
icosahedral
FMD has a RNA or DNA genome and double or single stranded?
single stranded RNA genome
True or false - FMD has many serotypes but immunity is not cross protective?
TRUE
How many different serotypes does FMD have?
7
how many subtypes does FMD have?
80
FMD has cytoplasmic replication but ____ inclusion bodies
no
how many hours does it take for the replication cycle to be completed in FMD?
5-10 hours
Host cell protein synthesis is shut off within _____ in FMD?
30 minutes
What pH is FMD unstable at?
unstable below 7
FMD is enzootic in parts of?
Asia, Africa, and South America
Up to ______ of virus is present in vesicular fluid in FMD
10^9 TCID(tissue cultured)/ml
There are high virus titres in ____ secretions in FMD
respiratory
Large volume of ____ & ______ of virus is shed from infected animals in FMD
droplets & aerosol
True or False – FMD virus can become airbourne and spread up to 100-200 km
TRUE
FMD has a _____ incubation period?
short
True or false – FMD virus shedding happens during incubation or before clinical disease
TRUE
in FMD, cattle act as _____ hosts
indicator
in FMD, pigs act as _____ hosts
amplifier
in FMD, sheep act as _____ hosts
maintenance
Which species has severe disease manifestations?
cattle
Which species has high virus output?
pigs
which species has mild or subclinical disease?
sheep
Where does a recovered animal carry the virus in the presence of FMD-antibody?
its pharynx
True or false – strong immunity to reinfection by the same but it des not last for life (~1 - 2 yrs)
TRUE
True or false - many disinfectants are not effective against FMD?
TRUE — sodium carbonate is most effective
What disinfectants are resistant to FMD?
Resistant to iodophores, quaternary ammonium compounds, hypochlorite and phenol, especially in the presence of organic matter
How do we prevent contact between susceptible animals and the virus
Household meat/bone scraps have to be boiled for 1 h before fed to pigs in NZ
What 4 things can we do to stop further production of virus by infected animals
– Control (stop) animal movements
– Tracing (at least 14 days before clinical signs) and surveillance
– Eliminate possible sources of virus by slaughtering infected animals and known in-contact animals. Destroy carcasses properly.
– Eliminate environmental contamination: decontaminate infected premises, vehicles, equipment, etc. Exterminate wild animals
Is a FMD vaccine used in non-endemic regions?
NO
Why wouldn’t we use a vaccine in non-endemic regions?
– Masking of infected (shedding) animals
– Vaccinated animals cannot be differentiated from infected serologically
Is FMD an important and current virus in humans?
no very rare and unimportant
What are clinical signs in humans if they do get FMD?
- Fever, anorexia
- Vesiculation at the site of exposure (usually a skin abrasion)
- Secondary vesiculation (mouth, hands, feet)
What are the possible routes of infection for FMD to get into NZ?
Via imported live animals
Via imported animal-derived products (meat, dairy, milk…etc) Via genetic material (embrios, semen)
via travellers (clothing, shoes, goods)
via imported farm equipment
Clinical features of FMD in cattle:
– They get severe disease
– Vesicles on the the tongue [dorsum], lips, gums, dental pad, cheeks and around the muzzle
– Excessive salivation, smacking of the lips, anorexia
– Vesicles or erosions also around the coronary band and in the
interdigital cleft→lameness
– Loss of hooves (exungulation) may follow laminitis
– Vesicles and erosions on the skin of the teats→rapid drop in milk yield ± acute mastitis
Clinical features of FMD in pigs:
– Also severe disease; lameness may be seen first
– Vesicles commonly seen on, and especially around the edge of, the rostrum of the snout
– Vesicles also on the feet [as in cattle] and around the supernumerary digits
– Exungulation is common
– In young pigs (and calves up to 6 months old) virus may localise in the heart and produce a severe myocarditis with sudden early death before vesicle formation
Clinical features of FMD in sheep:
– Causes mild or subclinical disease
– FMD is an important differential diagnosis for sudden-onset lameness in a flock
