Poultry Resp Diseases: mainly AI Flashcards
Lis the notifiable diseases
Avian influenza virus [AIV] is an orthomyxovirus
Newcastle disease virus [NDV] is a paramyxovirus
Pigeon paramyxovirus which s a close relative of NDV
6 mark question:
Differentiate between avian influenza and Newcastle disease MORPHOLOGICAL STRUCTURE NDV and AIV
Differences in MORPHOLOGICAL STRUCTURE
- Segmented genome difference:
Avian influenza = 8 diff segments
N = 1 single strand - Antigenic Shift difference
Can occur in AI not Newcastle as single strand - Differences in surface glycoprotein:
AIV has 2: HN
NDC has 3: HNF
H = hemagglutinin N = neuraminidase F = fusion glycoprotein
What are the similarities in these 2 viruses morphologically? NDV and AIV
Morphologically: Both are single stranded RNA genome
Antigenic Drift can occur in both
Both are helical nucleocapsid
How can NDV and AIV disease caused be similar?
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
Disease they cause = pretty much the same
Entire population in UK highly susceptible to A as no vaccination. Some birds are vaccinated against N
Avian influenza:
which strain is important?
There are types A,B,C and potentially D starting
Only A is of veterinary importance
Disease mainly in man, pigs, poultry, horses
Only this virulent AI is notifiable
Huge reservoirs in wild birds, main RESERVOIR = ducks
but also geese and swans
Why does AI happen every year?
8 segmented genome
means that there are lots of possible combinations
also unstable H and N and antigenic drift AND shift can occur
Haemagglutinin (1-20)
and Neuraminidase (1-9) = soo many combs possible in bird
What species other than birds are important in AI?
What issue does this bring up?
Pigs are considered to be the main ‘mixing vessel’ for new influenza viruses
But cats could be important
Issue = re-assortment or mutation can occur in these species and emerge as a new variant
Talk about AI high pathogenicity vs low
H5 and H7 viruses are associated with high pathogenicity avian influenza (HPAI) high path, avian influenza
but
Low pathogenicity avian influenza (LPAI) H5 and H7 viruses are able to mutate to HPAI viruses due to alterations in the H gene (especially in poultry)
AI
where does replication occur?
Incubation period?
Clinical signs?
What is important to remember with clinical signs?
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
Clinical signs exacerbated in the presence of other pathogens or/and immunosuppression and clinical signs change over time
How does the agent influence AI’s clinical signs?
Agent: Pathotype Strain Dose Infection route Co-infection Avian flu into flock with something else e.g. mycoplasma = worse disease
How does the host influence AI’s clinical signs
Species Age (younger, immunosuppressed) Sex Immunity (passive/acquired) Stress
How does the environment influence AI’s clinical signs?
Environment
Micro-environment
Marco-environment
e.g. too much ammonia in house = more death
General clinical signs of AI
General Lesions
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
General lesions:
Dehydration, haemorrhage of skin and visceral organs,periorbital eodema, cynosis,
Others include:
Peritonitis, haemorrage of pericardium, haemorrhage of abdominal fat/serosal surface of the crop/
GIT clinical signs of AI
GIT lesions
Diarrhoea, pasty vent
GIt lesions: Firm pale mottling and haemorrhage pancreas, hyperplasia and necrosis of spleen,
Intestinal and mesenteric haemorrhage
Resp clinical signs with AI
Resp lesions
Conjunctivitis, nasal discharge, lachrymation, sneezing and coughing, rales, dyspnea
Lesons:
Sinus: Catarrhal, fibrinous, serofibrinous, mucopurulent infammation.
Trachea – edematous, congestion, haemorrhage, tracheal exudate – bification, fibrinopurulent bronchopneumonia – E coli?
