Poultry immunosuppressive diseases Flashcards
What are some immunosuppressive diseases?
*Infectious bursal disease virus
*Chicken anaemia virus
*Marek’s virus
*Reticuloendotheliosis virus
*Reovirus
*Haemorrhagic enteritis virus
*Mycotoxins
What are the different pathotypes of infectious bursal disease virus? IBDV +What do they cause?
*Mild strains = no clinical signs or mortality - causes bursal lesions
*Classical strain = mortality <20%, bursal lesion, moderate break through of MDA
*Very virulent strains = severe mortality >20%, bursal lesions + Break through high MDA levels
*Variant strains = <5%mortality, severe bursal lesions + immunosuppression
What are the effect of an IBDV infection?
*Destruction of B-cells
*Decrease in no. and function of plasma cells
*Decrease in antibody production
*Decreased immune response to vaccinations
*Increased susceptibility to other pathogenic + opportunistic agents
What are the signs of acute clinical IBD?
- Sudden onset
- Depression, ruffled feathers, vent pecking
- After 3 days of infection, mortality (normal % – 90+%)
and morbidity peaks and slows down by 5-7 days later - Mortality in layer-type tend to be higher than meat-type
- Dehydration
- Muscular haemorrhage
- Variable size and bursal lesion depending on disease
progress
What is seen with very virulent IBD (VVIBD)?
*Higher morbidity + mortality
*More prominent haemorrhage on muscle, proventriculus + bursa
*More severe lesions on bursa
What is seen with subclinical IBD?
*No mortality pattern
*Increased 2ary infection
*Lesions = bursal atrophy + associated with other secondary pathogens
How is IBDV diagnosed?
*Clinical signs
*Necropsy
*Histopathology
*Serology
What are differential diagnoses to IBDV?
- Coccidiosis
- Nephrogenic IBVs
- Newcastle disease
- Marek’s disease
- Adenoviruses
How is IBDV controlled?
*Biosecurity
*Management
*Vaccination
How is IBDV transmitted?
Horizontal transmission
What type of virus is Chicken anaemia virus?
DNA virus
What are different transmission routes of Chicken anaemia virus?
*Vertical
*Horizontal - faeco-oral
What organs does chicken anaemia virus affect? What does it cause?
*Thymus
*Spleen
*Bone marrow
-atrophy
-immunosuppression
-anaemia
What are clinical signs of chicken anaemia virus?
*anorexic
*Weak + depressed
*Pale
*Low PCV
*anaemic on blood smears
*Leukopenia / pancytopenia
What do chicken anaemia lesions look like? where are they found?
*Thymus = pale + atrophy
*Bursa of fabricous = small
*Bone marrow = pale / yellow
How is chicken anaemia virus diagnosed? + confirmed?
*Dx = history, clinical signs + lesions
*Confirmatory Dx = PCR detection of CAV DNA
What is the prevention + treatment of CAV? (chicken anaemia virus)
*No Tx
*Prevention = Live vaccines via injection / drinking water
What is Marek’s disease? - characteristics? Cause? Control?
*Tumour caused by virus
- Characterised by nerve swellings and tumours
- Caused by an oncogenic herpesvirus of the genus Mardivirus
- Controlled by vaccines given by injection at do
How is marek’s disease transmitted?
*Excreted from feather follicles
-inhaled by other birds
What does neurological MD (marek’s disease) cause?
*Infiltrate CNS = ‘floppy broiler syndrome’
*Paralysis of legs, wings + eye lesions
*Sciatic + brachial nerve affected
What does visceral MD cause?
*Tumours in heart, ovary, testes, muscles + lungs
What does cutaneous MD cause?
*Tumour of feather follicles
What does ocular MD cause?
Tumour of uni/bilateral eyes
How is MD diagnosed + controlled?
Dx = Clinical signs, lesions, histopathology + PCR
*Control = Live vaccines by injection
What are the most important poultry respiratory diseases?
- Infectious Bronchitis
- Avian metapneumovirus infection
- Infectious laryngotracheitis
- Mycoplasmosis
- Ornithobacterium rhinotracheale infection
- Aspergillosis
What is infectious bronchitis caused by?
Type 3 coronavirus
What are the signs of infectious bronchitis in layers + broilers?
*Broilers
–Respiratory disease
–reduced bodyweight
*Layers
–Respiratory signs
–Egg drop, recovery
after 4-6 weeks
–Poor egg quality
–Poor chick quality?
How is infectious bronchitis diagnosed?
*Virus identification - isolation in eggs
*Serology - paired samples
How is infectious bronchitis controlled?
*Live vaccines for broilers
*Live + killed vaccines for breeders
*Biosecurity
