Poultry Let 1: Intro to AI and ND

Question 1

What are notifiable diseases of poultry in the uK?

Answer 1

There are two notifiable diseases of poultry and one of pigeons

Avian Influenza (but also non-notifiable AI can be important)
Newcastle disease

Pigeon paramyxovirus (new castle’s twin but pigeons)

Question 2

what type of viruses are AI and NDV?

Answer 2

Avian influenza virus [AIV] is an orthomyxovirus

Newcastle disease virus [NDV] is a paramyxovirus

Question 3

Classic exam question:

Differentiate between avian influenza and Newcastle disease

Answer 3

Morphological/ structural differences:

1. AI has 2 glycoproteins on its surface H (hemagglutinin) and N (neuraminidase) whereas NDV has 3: H, N and F (Fusion)
2. AI has a segmented genome into 8 diff segments. NDV is 1 single strand
3. Antigenic shift occurs in AI but not NDV as it is SS

Question 4

What are similarities between AI and ND morphology/ structure?

Answer 4

Both have helical nucleocapsid
Both are SS RNA genome
Antigenic Drift occurs in both

Question 5

What is similar/ different in the disease caused by AI and NDV?

Answer 5

• Both are highly infectious and infect a wide range of avian species
• Both viruses can range from apathogenic to highly virulent in some species of bird
• Both can cause respiratory, enteric and sometimes nervous signs
  or high mortality without specific signs

Overall the disease caused is pretty much the same

Question 6

How susceptible is the UK bird population to AI and NDV?

Answer 6

Entire population in UK highly susceptible to A as no vaccination. Some birds are vaccinated against N

Question 7

Which type of AI is important?

Answer 7

There are types A, B, C and A is of veterinary important as it causes disease in main, horses, pigs, poultry

Only the virulent AI is notifiable

Question 8

Why is AI notifiable?

Answer 8

Because devastating to birds and can be zoonotic

Question 9

Why are there many diff outbreaks of AI?

Answer 9

The genome is segmented into 8 = lots of different possible combinations

H and N are not stable properties - can undergo antigenic shift and drift

Also there is no cross immunity between subtypes therefore vaccination is such a problem

Question 10

What animal is the most important reservoir for AI (exam)

Answer 10

Ducks

Question 11

What animal is the most important reservoir for AI

What animal is considered the main mixing vessel for new AI

Answer 11

Ducks = most important res

Pigs considered main mixing vessel for new I viruses

cats also important - humans infected with H5N1, 1 in 5 cats found to be seropositive

Question 12

What is the human corner of AI?

Answer 12

Re assortment or mutation
If human flu virus and another virus meet in people they can emerge as a new variant!! Where obtained certain properties from previous and mix in pig/ cat
Not each and every new variant can survive, only 1 or 2 = go through population, become established and new problem to human

Avian influenza 8 segments within virus, lot of antigenic drift =. Issue!

Question 13

Talk about pathogenicity within AI

Answer 13

H5 and H7 viruses are associated with high pathogenicity avian influenza (HPAI)

Low pathogenicity avian influenza (LPAI) H5 and H7 viruses are able to mutate to HPAI

Question 14

AI
Where virus replicates
Incubation
Clinical sings

Answer 14

Replication in a wide range of tissues (respiratory and/or GIT initial sites) causing necrosis, congestion, haemorrhage
Incubation: hrs to 3 d(single host) & days up 14d (in flocks)
Death without obvious signs but great variation in clinical picture & severity as viraemic is so intense
Respiratory distress, lack of appetite, diarrhoea, drop in egg production

Question 15

What affects clinical signs of AI

Answer 15

• Agent: pethotype, strain, dose, infection route, confection with another disease?
• Host - species, young, immunosuppressed, sex, immunity (passive/ acquired), stress
• Environment e.g. too much ammonia = more death

Question 16

General clinical signs of AI

Answer 16

Depression, dullness, ruffled feather, cyanotic/necrotic comb/wattle, swollen head, reduced intake of water and/or feed (sudden and high), increased mortality (sudden and very high, eg. >90% in 3 days),
Not eating, drink, moving

Question 17

GI signs of AI

Rest signs

Answer 17

Diarrhoea, pasty vent

Conjunctivitis, nasal discharge, lachrymation, sneezing and coughing, rales, dyspnea

Question 18

Urinary nd repro signs of AI

neurological

Answer 18

Drop in egg production and quality (sudden and high drop)
Duck/chick – no resp signs but drop egg production?

Severe and diverse neurological signs- head tremor

Question 19

What exacerbates clinical signs of AI ?

Answer 19

the presence of other

pathogens or/and immunosuppression

Question 20

What general lesions are seen with aI?

Answer 20

Dehydration, haemorrhage of skin and visceral organs,periorbital eodema, cynosis,

Question 21

What GI lesions are seen with AI?

Answer 21

Firm pale mottling and haemorrhage pancreas, hyperplasia and necrosis of spleen (remember chicken spleen is rounded)

Question 22

What response lesions associated with of AI

Answer 22

Sinus: Catarrhal, fibrinous, serofibrinous, mucopurulent infammation.
Trachea – edematous, congestion, haemorrhage, tracheal exudate – bification, fibrinopurulent bronchopneumonia – E coli?

Question 23

What urinary and repro lesions associated with AI?

Answer 23

Oviduct inflammaiton, swollen kidneys

other lesions can be: Peritonitis, haemorrage of pericardium, haemorrhage of abdominal fat/serosal surface of the crop/

Question 24

how do we diagnose AI

Answer 24

FIRSTLY if you suspect it then NOTIFY DEFRA on clinical suspicion

Diagnosis:
Clinical signs/increased mortality (suspicion: notify Defra)
Samples to international reference lab (VLA) APHA
RT-PCR; then H5 and H7 specific primers
Virus isolation in eggs; HA activity indicates flu or NDV
Subtyping by specialist labs
Pathogenicity testing: IVPI and HA cleavage site sequence
Work out if high path or low

Question 25

How stable is the virus aI outside of host?

Answer 25

Not very stable outside host
Killed by phenol, formalin, u.v. etc

2 wks in dust but much longer in cold moist conditions (surface water, lakes)

Question 26

How is AI spread?

Answer 26

Rapid : aerosol, respiratory excretions
Faecal excretion – high titres
Waterfowl carry virus (until recently, no disease)
Migratory birds waterfowl  poultry
No egg transmission, but surface contamination (egg shell)
Easily spread by people, equipment, vehicles, etc.
Feathers
Contamination of water courses
Many countries keep ducks on paddy field = hugh amount of virus in water – sucked into cloaca,

Question 27

How do we control AI?

Answer 27

CALL DEFRA and STAMP OUT is the policy
Stamping out – combo of culling infected flock and preventative destruction of contact flocks or farms within a close range

Because AIV is subject to genetic reassortment it is more difficult than Newcastle disease to control by vaccination