Poultry infectious diseases Flashcards
What are some examples of non-infectious diseases that may affect poultry?
- Tumours
- Behavioural issues
- Nutrition
- Management
- Chemical
- Physical
- Environmental
What are some examples of infectious disease causes that may affect poultry?
- Viruses
- Bacteria
- Mycoplasmas
- Fungi/yeasts
- Internal parasites
- External parasites
Name the 2 notifiable diseases of poultry
Avian influenza
Newcastle disease
Which proteins are expressed by avian influenza?
H and N
Which proteins are expressed by newcastle disease?
H, N and F (fusion protein)
What are some similarities between avian influenza and newcastle disease viral structure?
- both are single stranded RNA viruses
- Both contain H and N proteins
- Both can undergo antigenic drift
What is antigenic drift?
Random genetic mutation of an infectious agent resulting in minor changes in proteins called antigens, which stimulate the production of antibodies by the immune system
What are some differences between avian influenza and newcastle disease viral structure?
- Extra protein is expressed in the Newcastle virus, F-protein (fusion)
- In avian influenza the genome is segmented (8), whereas in Newcastle virus it is not segmented
- Antigenic shift can occur in avian influenza but not in Newcastle
What is antigenic shift?
Genetic alteration occurring in an infectious agent that causes a dramatic change in a protein called an antigen, which stimulates the production of antibodies by the immune system
What are the similarities of the diseases cause by avian influenza and Newcastle disease?
- Both are highly infectious and infect a wide range of avian species
- Both viruses can range from non-pathogenic to highly virulent
- Both can cause respiratory, enteric and sometimes nervous signs
- or high mortality without specific signs
What are the 3 types of Avian influenza? Which is of veterinary importance?
Types A, B & C; only A is of veterinary importance
What are the names of H and N proteins?
Haemagglutinin
Neuraminidase
How does the subtype of avian influenza affect its properties?
Controls its pathogenesis, diagnosis, immunity and control
Which species are considered to be the main mixing vessel for new influenza viruses?
Pigs
Which of the 2 H influenza subtypes if associated with high pathogenicity avian influenza (HPAI)?
H5 and H7
How does avian influenza affect the body?
- Replication in a wide range of tissues (respiratory and/or GIT initial sites) causing necrosis, congestion, haemorrhage
- Incubation: hrs to 3d (single host) & days up 14d (in flocks)
- Death without obvious signs but great variation in clinical picture & severity
What are some signs of an avian influenza infection?
- Respiratory distress (conjunctivitis, nasal discharge, coughing)
- Lack of appetite
- Diarrhoea
- Drop in egg production
- Neurological signs
Which factors can influence the clinical signs of avian influenza?
- Agent (strain, dose, infection route)
- Host: species, age, sex, immunity, stress, disease
- Environment
Which gross lesions can be seen due to avian influenza?
- Cyanosis of the comb and wattles and shanks
- Tracheal haemorrhage
- Intestinal and mesenteric haemorrhage
- Respiratory tract inflammation and exudate
- Swollen kidneys
- Haemorrhage of pericardium
Which species act as reservoirs for avian influenza?
Wild birds e.g. ducks, geese and swans
How is avian influenza diagnosed?
- Clinical signs and increased mortality
- RT-PCR
- Virus isolation in eggs
How easy is Avian influenza to control compared to Newcastle disease?
Because AIV is subject to genetic reassortment it is more difficult than Newcastle disease to control by vaccination
What are the features of Newcastle disease virus?
- Notifiable
- HN spikes and F protein spikes on envelope
- Non-segmented genome
- Single serotype
- No antigenic shift
What are the different groupings of Newcastle disease virus?
- Velogenic
- Mesogenic
- Lentogenic
- Asymptomatic enteric
Describe the 2 Velogenic groupings of Newcastle disease virus
- Viscerotropic-Velogenic: acute lethal infection, gut haemorrhagic lesions.
- Neurotropic-velogenic: respiratory and neurologic disease, gut lesions absent, high mortality
Describe mesogenic Newcastle disease virus
Respiratory and neurological signs, low mortalit y
Describe lentogenic Newcastle disease virus
Mild infections of the respiratory tract
What are some general signs of Newcastle disease?
- Loss of appetite
- Abnormal thirst
- Dehydration
- Emaciation
- Ruffled feathers
- Huddling
- Listlessness
- Depression
What are some neurotropic signs of Newcastle disease?
- Tremors
- Star-grazing
- Twisted neck
- Convulsions
- Incoordination
- Paralysis of wings/legs
What are some pneumotropic signs of Newcastle disease?
- Mild rales (clicking, bubbling, or rattling sounds in the lungs)
- Sneezing and coughing
- Nasal discharge
- Laboured breathing
- Open mouth breathing
- Head shaking
- Greenish-yellow diarrhoea
What are some viscerotropic signs of Newcastle disease?
- Greenish-yellow diarrhoea
- Haemorrhage of intestinal tract
How is Newcastle disease diagnosed?
- Clinical signs
- Serology: hemagglutination inhibition (HI) assay
- Live birds – oral pharyngeal swabs for virus inoculation but mostly RT-PCR
- Post-mortem: lesions not pathognomonic (but suggestive)
Where can PM samples be taken from for Newcastle disease diagnosis?
- Trachea
- Proventriculus
- Lungs
- Caecal tonsil
- Brain
How can Newcastle disease be controlled and prevented?
- Prevent NDV entering your farm/area: high Standard of Biosecurity and management
- Increase flock resistance: nutrition, flock management
- Vaccination
