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Epidemiology - MIDTERM 3 > Topic 68 - Newcastle disease (RED) > Flashcards

Topic 68 - Newcastle disease (RED) Flashcards

1
Q

What is the newcastle disease?

A

A contagious and fatal viral disease affecting the respiratory, nervous and digestive systems of birds and poultry

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2
Q

Definition of the newcastle disease, according to the OiE:

A

It is an infection of poultry caused by a virus of avian paramyxovirus serotype 1 (APMV-1) that meets one of the following criteria for virulence:

  1. The virus has an intracerebral pathogenicity index (ICPI) in day-old chicks of 0.7 or greater.

OR

  1. Correlation of multiple basic amino acids
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3
Q

Causative agent for newcastle disease:

A

avian paramyxovirus serotype type 1

Genus: Avulavirus
Family: Paramyxoviridae

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4
Q

How many pathotypes does avian paramyxovirus serotype type 1 have? Name them.

A

4

1. Velogenic
2. Mesogenic
3. Lentogenic
4. Apathogenic

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5
Q

Which of the pathotypes of avian paramyxovirus serotype type 1 are most and less virluent?

A

Least virulent = Lentogenic strains
Moderately virulent = Mesogenic strains
Most virulent = Velogenic strains

Apathogenic - asymptomatic !!

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6
Q

How can we determine the virulence of avian paramyxovirus serotype type 1?

A
  1. We use a intracerebral pathogenicity index test (ICPI)
  2. Chicken embryo survival index
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7
Q

How can we read the ICPI test of avian paramyxovirus serotype type 1?

A

Most virulent = maximum score of 2.0,
Less virulent - lentogenic = values close to 0.0.

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8
Q

The newcastle disease virus have protein(s) enveloping the virus, name them

A

Two glycoproteins:
1. Hemagglutinin-neuraminidase (HN)
2. Fusion (F) proteins.

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9
Q

What are the function of the glycoproteins regarding the newcastle disease virus?

A

HN glycoprotein is involved in attachment and release of virus.

F glycoprotein mediates fusion of the virus with the cellular membranes

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10
Q

The F-protein plays a major role in the virulence of newcastle disease, why?

A

The amino acid sequence at the F protein cleavage site is different among most lentogenic, mesogenic and velogenic NDV strains

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11
Q

How long can the Newcastle disease virus survive in the environment?

A

The survival is prolonged by the presence of faeces, excretes, secretes and raw meat

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12
Q

Host range of Newcastle disease virus:

A

All avian species are susceptible,

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13
Q

What is the main host and reservoir host?

A

domestic chicken

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14
Q

Shedding of Newcastle disease virus:

A

with excretes

shedding starts during the incubation period !!

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15
Q

What is the route of transmission for Newcastle disease virus?

A

Airborne, spread by droplets and inhaled or ingested with direct contact with excretes.

NO germinative transmission !!

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16
Q

Pathogenesis of Newcastle disease virus:

A
  1. Infection by per os
  2. Replication of the respiratory mucosa
  3. Viraemia is present, causing a generalised infection⭢lung, intestines, CNS, oviduct
  4. We will see blood vessel damage, causing hamoerrhages, oedema
  5. There is an immunosuppression.
17
Q

Clinical signs of Newcastle disease virus:

A

Depends on the virulence

18
Q

Clinical signs of Newcastle disease virus, lentogenic strain:

A

Usually subclinical, but with co-infections it can result in severe clinical signs

19
Q

Clinical signs of Newcastle disease virus, mesogenic strain:

A

Can cause acute respiratory disease and CNS symptoms in some species

With co-infections it can result in severe clinical signs

20
Q

Clinical signs of Newcastle disease virus, velogenic strain:

A
  1. Fever
  2. Later: watery diarrhoea, respiratory signs
  3. Later stages: CNS signs such as tremors, paralysis and torticollis (=twisted neck)
  4. Sharp egg drop production
  5. Sudden death

If survive: may develop neurological, partial or complete cessation of the egg production

21
Q

Mortality of mesogenic strain of Newcastle disease virus:

A

usually low, less than 10%

22
Q

Mortality of velogenic strain of Newcastle disease virus:

A

100% in unvaccinated chickens !!

23
Q

Pathological lesions of Newcastle disease virus

A

Only seen in the velogenic strains:

  1. Haemorrhages in the proventriculus
  2. Torticollis
  3. Haemorrhages all over
24
Q

How to diagnose the Newcastle disease virus:

A

We use PCR to identify both virulent and avirulent strains. We can also do serology tests:
1. Haemagglutination inhibition test
2. ELISA
Virus isolation
Virus identification using a specific antiserum in a haemaglutnation inhibition test

25
Q

Differential diagnosis of Newcastle disease virus

A
  1. Fowl cholera
  2. Fowl pox
  3. Mycoplasmosis

But none of these have CNs symptoms

26
Q

Treatment for Newcastle disease virus:

A

There is no treatment

27
Q

Prevention for Newcastle disease virus:

A

Use epidemiological rules:
1. All-in-all-out principal
2. Control of trafic/vehicles
3. Proper caracass disposal
4. Vaccine

28
Q

Prevention for Newcastle disease virus, in case of an outbreak:

A
  1. Quarantine
  2. Movement controls
  3. Destruction of all birds, wait 21 days before reintroducing birds
  4. Cleaning, disinfect
29
Q

Type of vaccine available for Newcastle disease virus:

A

Live attenuated vaccine, 2 groups
Inactivated vaccine
Recombinant vaccine

30
Q

How can we administer the live vaccine for Newcastle disease virus?

A

Dissolved in drinking water
Aerosol spray
Intranasal spray

31
Q

What are the 2 groups of live vaccine given for Newcastle disease virus?

A

Lentogenic vaccine - Used in pracitce
Mesogenic vaccine

32
Q

How can we administer the inactivated vaccine for Newcastle disease virus?

A

Injection

33
Q

How is inactivated vaccines made?

A

produced by harvesting the infective allantoic/amniotic fluids from inoculated embryonated chickens, usually produced by the addition of formaldehyde to infective virus preparations.
They are incorporated into an emulsion with
mineral oil or vegetable oil, and is administered intramuscularly or subcutaneously

Epidemiology - MIDTERM 3 (34 decks)

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