Topic 34 - Avian encephalomyelitis Flashcards
Causative agent of avian encephalomyelitis
Tremovirus genus, under picornavirus - due to tremor being the most important clinical sign
Used to be enterovirus, but tremovirus was created. In general characteristics, the virus is similar to the enterovirus - Non-enveloped and ssRNA
Occurence of avian encephalomyelitis:
Worldwide, widespread infection
Resistance of avian encephalomyelitis:
how long are the animal infective?
High resistance
Infective for several months
Host susceptibility of avian encephalomyelitis:
Host range = narrow, because galliforms only
Chickens, hens and pheasants
Galliformes= heavy-bodied, ground-feeding birds
Age susceptibility of avian encephalomyelitis:
All age groups
but because maternal protection last for 3-6 weeks, cowards are most susceptible
Age of clinical signs in case of avian encephalomyelitis:
1-3 weeks old up to 4-5 weeks of age. Typically seen in chickens only
How is avian encephalomyelitis spread? What is the primary way?
- Germinative route (IMPORTANT)
- Faeces = primary way
- Fast spread within the flock
For how long can avian encephalomyelitis infect via germinative route?
3 weeks after infection
When they have enough immunity, at 3 weeks, there will be no virus in the eggs
Morbidity and lethality of avian encephalomyelitis:
Morbidity = 50-60%
Lethality = high if a main flock is infected
Pathogeneses of avian encephalomyelitis:
Per os infection. There is a replication on the mucous membrane of the gut and we have a viraemia
Which parts can the virus reach with viraemia in case of avian encephalomyelitis
- Ovarium (germinative infection happens)
- liver
- spleen
- pancreas
- CNS
What will the virus reaching the CNS cause in case of avian encephalomyelitis:
causing inflammation, degeneration and necrosis
How is avian encephalomyelitis virus shed?
Via faeces, horisontal infection
Good or bad immunity of avian encephalomyelitis?
Good immunity, have maternal protection
Incubation time of avian encephalomyelitis:
1-11 days
Clinical signs in chicken in case of avian encephalomyelitis:
we see CNS clinical signs, such as:
1. Tremor
2. Inability to move
3. Paralysis
We also see:
1. No eating and drinking
2. Diarrhoea
3. Opactiy of the lens
4. death
Clinical signs in older animals in case of avian encephalomyelitis:
Not very evident, but in some cases we can see egg production drops
Pathological lesions in case of avian encephalomyelitis:
no pathological lesions, only histopathology
Histopathological lesions in case of avian encephalomyelitis:
We can see:
1. Lymphocytic inflitration
2. Degeneration of neurons
3. Glia replication in the grey matter
Diagnosis methods of avian encephalomyelitis:
- Epidemiological rules
- Clinical signs
- Histopathological lesions
Detection method of virus in case of avian encephalomyelitis:
Mainly PCR
Can detection of antibodies be done in case of avian encephalomyelitis?
Yes, but not to diagnose. If the test is positive, we can conclude that the herd is infected
Differential dianogsis of avian encephalomyelitis, name some diseases:
Any disease that causes CNS symptoms
- Avian influenza
- Marek disease
- NDV
1-3 = notifiable
Treatment of avian encephalomyelitis:
None
Prevention measures of avian encephalomyelitis:
- General epidemilogical methods
- Vaccination
- If infected: hatching is not allowed for 1 month - due to germinative infections
What type of vaccine is given in case of avian encephalomyelitis:
Live vaccine in the drinking water
Only 5-10% of the flock is vaccinated, the rest will be infected by others via shedding
When do we vaccinate against avian encephalomyelitis?
- Layers = 1 month before laying
