Viruses Flashcards
1
Q
viruses
A
- small infectious agent
- replicate only inside the living cell of another organism
- too small to be seen by light microscope
- has DNA/RNA, proteins & lipids
- live in all ecosystems
2
Q
avian influenza
A
- ‘bird flu’
- infectious viral disease of birds
- mild-severe illness
- caused by > 130 of influenza A virus in wild birds
- worldwide
3
Q
HPAI
A
highly pathogenic avian influenza
4
Q
LPAI
A
low pathogenic avian influenza
5
Q
severity of avian influenza in poultry
A
- wild birds = natural host, carry LPAI
- virus colonises gut and spreads in faeces
- domestic poultry not natural host, susceptible to HPAI
- more cases of H5N1 found in domestic poultry
6
Q
H5N1
A
highly pathogenic strain of avian influenza
7
Q
wild birds introduce ai to poultry farms by:
A
- direct contact w/ domestic poultry
- faeces & other biological secretions
- contaminated drinking water & feed
8
Q
AI spreads within & between farms by:
A
- direct contact, contaminated equipment, vehicles & people
- infected faeces
- air transmission over short distances
- live bird markets or abattoirs
9
Q
clinical signs of AI H5N1 in birds
A
- swollen head
- dullness
- low egg production
- loss of appetite
- respiratory signs
- sudden death
10
Q
mild symptoms of AI H5N1 in humans
A
- fever
- sore throat
- cough
- headache
- muscle aches & pains
11
Q
severe symptoms of AI H5N1 in humans
A
- high fevers
- chest infection
- respiratory failure
- multi-organ failure
- death
12
Q
how AI virus attacks
A
- virus enters living cell
- takes over mechanisms & replicates viral DNA, leading to cell death
- travel to lungs & triggers immune system
- cytokines sent out to attack virus
- cytokines cause deadly inflammation
- blood and fluid leak into air sacs
- host drowns in own blood
- virus tricked immune system
13
Q
AI pandemic risk
A
- expanding geographic presence
- adaptive mutation enhances transmissibility
- strains readily transmitted through humans would mark start of pandemic
14
Q
AI pandemic prevention
A
- stop problem at farm level
- assistance must be given to less resourced countries
15
Q
AI surveillance
A
- early detection & rapid response mechanisms crucial for successful control
- global effort to track needed
16
Q
methods of controlling AI
A
- eradication
- in uk = animal must be slaughtered
- quarantine on infected flocks
- strict sanitary measures
17
Q
advantages of AI vaccinations
A
- stop unethical measure
- protections against infectious diseases
- economic benefits
18
Q
disadvantages of AI vaccination
A
- difficult to distinguish between vaccinated/infected & vaccinates/non-infected animals
- vaccinated animals cannot be exported
- loss of disease-free status
19
Q
human treatments for AI
A
- antiviral drugs
= both prevention & treatment
= zananmivir - vaccination
= long term solution
= large scale vaccine production won’t start until pandemic
= reliable detection methods needed
20
Q
foot and mouth disease
A
- acute, infectious viral disease
- picornavirus
-genome = 8.3kb long - affects all cloven hoofed animals
21
Q
clinical signs of F&M disease
A
- fever
- dullness
- shivering
- slavering
- anxiety
- loss of appetite & condition
- reduced milk yield
- tenderness of feet/lameness
- usual movements of mouth & blisters
22
Q
spread of F&M disease
A
- largest virus quantity in blister fluids
- incubation 2-12 days
- also present in saliva, milk & dung/urine
- direct & indirect contact
23
Q
2001 F&M epidemic
A
- 6 months
- lost 7m animals
- cost national treasury £2.7b
- first identified in Essex pig abattoir
- infection source = northumberland pig fattening unit
24
Q
F&M disease spread in uk
A
- first found in sheep
-found in cattle two weeks later
25
control procedures to F&M
- herds w/ even 1 infected animal slaughtered w/in 24 hours of detection
= contiguous cull
- reduce spread through infection
26
problems w/ response to F&M
- not enough man power
- few expertise for identification
- difficult to dispose of carcasses
27
F&M vaccination
- considered throughout pandemic
- government reluctant, faming community divided
- lose 'disease free' label
28
cost of F&M
- uk treasuring spent £8b in
= compensation
= disease eradication
= employment of vets and army
29
future responses to F&M
- 2 types of vaccinations
= suppressive
= protective
- avoiding further epidemics
= EU policy
=improve livestock health & hygiene
- legal requirements
= duty to notify suspected cases
= restrictions & culling of infected
30
suppressive vaccine
- vaccinated animals subsequently killed
31
protective vaccine
- allows animals to live a normal life
32
human cases of swine flu
- Mexico = 103 deaths
- Canada = infected
- screenings in UK, Spain & NZ
33
H1N1 update
- same strain as seasonal flu
- later H1N1 strain is diff. = genetic material t those affecting humans, birds, swine
- flu viruses swap genetic material
- pigs = excellent melting pots for viruses to mix
