Topic 34 - Avian encephalomyelitis

Question 1

Causative agent of avian encephalomyelitis

Answer 1

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

Question 2

Occurence of avian encephalomyelitis:

Answer 2

Worldwide, widespread infection

Question 3

Resistance of avian encephalomyelitis:
how long are the animal infective?

Answer 3

High resistance

Infective for several months

Question 4

Host susceptibility of avian encephalomyelitis:

Answer 4

Host range = narrow, because galliforms only

Chickens, hens and pheasants

Galliformes= heavy-bodied, ground-feeding birds

Question 5

Age susceptibility of avian encephalomyelitis:

Answer 5

All age groups

but because maternal protection last for 3-6 weeks, cowards are most susceptible

Question 6

Age of clinical signs in case of avian encephalomyelitis:

Answer 6

1-3 weeks old up to 4-5 weeks of age. Typically seen in chickens only

Question 7

How is avian encephalomyelitis spread? What is the primary way?

Answer 7

1. Germinative route (IMPORTANT)
2. Faeces = primary way
3. Fast spread within the flock

Question 8

For how long can avian encephalomyelitis infect via germinative route?

Answer 8

3 weeks after infection

When they have enough immunity, at 3 weeks, there will be no virus in the eggs

Question 9

Morbidity and lethality of avian encephalomyelitis:

Answer 9

Morbidity = 50-60%
Lethality = high if a main flock is infected

Question 10

Pathogeneses of avian encephalomyelitis:

Answer 10

Per os infection. There is a replication on the mucous membrane of the gut and we have a viraemia

Question 11

Which parts can the virus reach with viraemia in case of avian encephalomyelitis

Answer 11

1. Ovarium (germinative infection happens)
2. liver
3. spleen
4. pancreas
5. CNS

Question 12

What will the virus reaching the CNS cause in case of avian encephalomyelitis:

Answer 12

causing inflammation, degeneration and necrosis

Question 13

How is avian encephalomyelitis virus shed?

Answer 13

Via faeces, horisontal infection

Question 14

Good or bad immunity of avian encephalomyelitis?

Answer 14

Good immunity, have maternal protection

Question 15

Incubation time of avian encephalomyelitis:

Answer 15

1-11 days

Question 16

Clinical signs in chicken in case of avian encephalomyelitis:

Answer 16

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

Question 17

Clinical signs in older animals in case of avian encephalomyelitis:

Answer 17

Not very evident, but in some cases we can see egg production drops

Question 18

Pathological lesions in case of avian encephalomyelitis:

Answer 18

no pathological lesions, only histopathology

Question 19

Histopathological lesions in case of avian encephalomyelitis:

Answer 19

We can see:
1. Lymphocytic inflitration
2. Degeneration of neurons
3. Glia replication in the grey matter

Question 20

Diagnosis methods of avian encephalomyelitis:

Answer 20

1. Epidemiological rules
2. Clinical signs
3. Histopathological lesions

Question 21

Detection method of virus in case of avian encephalomyelitis:

Answer 21

Mainly PCR

Question 22

Can detection of antibodies be done in case of avian encephalomyelitis?

Answer 22

Yes, but not to diagnose. If the test is positive, we can conclude that the herd is infected

Question 23

Differential dianogsis of avian encephalomyelitis, name some diseases:

Answer 23

Any disease that causes CNS symptoms

1. Avian influenza
2. Marek disease
3. NDV
   1-3 = notifiable

Question 24

Treatment of avian encephalomyelitis:

Answer 24

None

Question 25

Prevention measures of avian encephalomyelitis:

Answer 25

1. General epidemilogical methods
2. Vaccination
3. If infected: hatching is not allowed for 1 month - due to germinative infections

Question 26

What type of vaccine is given in case of avian encephalomyelitis:

Answer 26

Live vaccine in the drinking water

Only 5-10% of the flock is vaccinated, the rest will be infected by others via shedding

Question 27

When do we vaccinate against avian encephalomyelitis?

Answer 27

1. Layers = 1 month before laying