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Epidemiology - MIDTERM 2 > Topic 60 - Infectious bursal disease > Flashcards

Topic 60 - Infectious bursal disease Flashcards

1
Q

Causative agent of infectious bursal disease

A

Avibirnavirus genus, Birnaviridae family

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2
Q

Are birniviridae RNA or DNA virus?

A

RNA

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3
Q

Are birnaviriade enveloped or non-enveloped?

A

non-enveloped = high resistance

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4
Q

How many segments does birnaviridae have?

A

Two genome segments, A and B

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5
Q

How many structural protein does birnaviriade have? Name them:

A

4 structural proteins
1. VP2
2. VP3
3. VP4
4. VP5

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6
Q

Species susceptible for infectious bursal disease:

A

chickens

But also:
Pheasant, turkey and ostrich

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7
Q

Age susceptible for infectious bursal disease:

A

3-6 week old

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8
Q

Is infectious bursal disease a acute or chronic disease?

A

acute

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9
Q

What does infectious bursal disease cause?

A

inflammation of the bursa of fabricus, which cause sevre immunosuppression

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10
Q

Occurence of infectious bursal disease:

A

Worldwide

Found at every large chicken farm

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11
Q

Does infectious bursal disease have more than one virulence variants?

A

yes

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12
Q

How many serotypes does infectious bursal disease have?

A

two

Serotype 1 and serotype 2

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13
Q

which of the two serotypes of infectious bursal disease, are pathogenic?

A

Serotype 1

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14
Q

Are there cross-reaction between the two serotypes in infectious bursal disease?

A

yes, but no cross-reaction

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15
Q

How long can infectious bursal disease survive, and where does it survive after being shed?

A

in litter up to 6 months

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16
Q

Which solutions kan kill the virus?

A
  1. Chlorine + aldehydes
  2. 0.05% NaOH + detergents at 40 degree
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17
Q

How can propogate infectious bursal disease?

A
  1. Embryonated egg
  2. Cell culture
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18
Q

How many vaccine strains are there for infectious bursal disease?

A

2

Hot, intermediate and mild

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19
Q

How many antigenic variants of serotype 1 of infectious bursal disease?

A

VP2 and VP3

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20
Q

What is the VP2 of infectious bursal disease?

A

It is the virus neutralising antigen of the virus. So the antibodies are able to neutralise the virus. It will be produced against the viral protein

Most important!!

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21
Q

What is the VP3 of infectious bursal disease?

A

It is sero-and group specific and it will cross react with antigens

Also important, but VP2 is most important

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22
Q

Route of transmission in case of infectious bursal disease:

A

Per os mainly

But can also go through the conjunctival and be air-borne as well

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23
Q

Is infectious bursal disease contagous?

A

YES, very!!

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24
Q

How early can infectious bursal disease be shed?

A

As early as 1 day after infection, but can be detected for 2 weeks in faeces

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25
Q

What is the main source of infection in case of infectious bursal disease?

A

contaminated environement, through contaminated feed or drinking water

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26
Q

What could be another source of infection in case of infectious bursal disease?

A

Mechanical transmission between farms and stables, through vehicles, people, clothes etc

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27
Q

Is there a germinative infection for infectious bursal disease?

A

not yet been confirme, BUT!! The egg-shell is contaminated with faeces

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28
Q

Pathogenesis of infectious bursal disease:

A

Infection leading to first replication, causing primary viraemia. The virus goes to the liver and reaching the bursa of Fabricius and we will have a secondary viraemia and the virus will be spread through the body

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29
Q

Site of first replication in case of infectious bursal disease:

A

Macrophages in the gut and lymphoid tissue

30
Q

What are the main target cells in case of infectious bursal disease?

A

premature b-cells and other bursal disease

31
Q

What will happen to the premature B-cells once infectious bursal disease reaches them?

A

The virus will kill the B-cell “factory” of chickens, and the B-lymphocytes will not mature. This is why we have a immunosuppression

32
Q

At which age is the activity of the bursa fabricius the highest?

A

at 2-8 weeks of age

33
Q

Mortality rate in case of infection of infectious bursal disease in 0-3 weeks of age:

A

0-30%

34
Q

Mortality rate in case of infection of infectious bursal disease in 2-8 weeks of age:

A

5-100%

35
Q

outcome of infectious bursal disease in 0-3 weeks of age:

A

Permanent immunosuppression

36
Q

Outcome of infectious bursal disease in 2-8 weeks of age:

A

If survive = immuno-competence after recovery

37
Q

Clinical signs in chickens over 8 weeks of age in case of infectious bursal disease:

A

no clinical signs

38
Q

What can we expect if there is a infectious bursal disease infection at a young age?

A

Damage of B-cell receptor expression, causing a weak immune response against other antigens and we can expect inefficient vaccinations

39
Q

Factors influencing the severity of infectious bursal disease:

A
  1. Age
  2. Level of maternal antibodies
  3. Breed of the chicken
  4. Virulence of the virus strain
  5. Antigenicity of the virus
  6. Immunosuppression
40
Q

Incubation time of infectious bursal disease:

A

2-3 days

41
Q

At which age can we see clinical signs in case of infectious bursal disease?

A

3-6 week of age

42
Q

Clinical signs in 3-6 week old chickens in case of infectious bursal disease:

A
  1. Fever
  2. ruffled feathers
  3. Watery diarrhoea
  4. Swollen, bloody-stained stunt
  5. Anaemia
  6. Cyanosis can be observed
43
Q

Can there be subclinical form of infectious bursal disease? if yes, what is the outcome?

A

Immunosuppression

44
Q

Consequences of subclinical form and immunosuppression of infectious bursal disease:

A
  1. Retarded growth
  2. Decreased food consumption
  3. Ineffective vaccinations
  4. Clinical signs of other diseases may change
45
Q

Which organs are pathologically affected in acute phase of infectious bursal disease?

A
  1. Bursa of Fabricius
  2. Spleen
  3. Liver
  4. Thymus
  5. Bone marrow
  6. kidney
46
Q

Pathological signs in bursa of fabricius in acute phase of infectious bursal disease:

A
  1. Oedema
  2. Inflammation
  3. Haemorrhages
  4. Caseous exudate
47
Q

Pathological signs in spleen in acute phase of infectious bursal disease:

A
  1. Enlarged
  2. Haemorrhages
48
Q

Pathological signs in kidney in acute phase of infectious bursal disease:

A
  1. nephtirits
49
Q

Pathological signs in liver in acute phase of infectious bursal disease:

A
  1. Oedema
  2. Dystrophy
  3. necrotic foci
50
Q

Pathological signs in thymus in acute phase of infectious bursal disease:

A
  1. Lymphoid depletion in the cortex and medulla
51
Q

Pathological signs in bone marrow in acute phase of infectious bursal disease:

A
  1. Necrosis
52
Q

Which organs are pathologically affected in chronic phase of infectious bursal disease?

A

bursa of fabricius

53
Q

Pathological signs in bursa of fabricius in chronic phase of infectious bursal disease:

A

Atrophy and early involution

54
Q

How do we diagnose infectious bursal disease?

A

By age, clinical signs and pathology we will have a good diagnosis.

But we have to detect which virus:

55
Q

Which laboratory work do we do to detect virus in case of infectious bursal disease?

A

RT-PCR

56
Q

In infectious bursal disease, what is very important to differentiate in laboratory work and how is it done?

A

Differentiate between wild-type and vaccine strain, this is done with RT-PCR og sequencing

57
Q

Why is serology important in infectious bursal disease?

A

So supply with information of which antibody level the animal have in regards to vaccination

58
Q

Differential diagnosis of infectious bursal disease:

A
  1. Newcastle disease
  2. Bacterial septicaemia
  3. Chicken anaemia
  4. Coccidiosis
59
Q

Prevention of infectious bursal disease:

A
  1. Hygiene and epidemiological measures
  2. Prevention of infection in the first two months (because this is the most susceptible age)
  3. Vaccine
60
Q

How to prevent infectious bursal disease in the first two months?

A
  1. Disinfection of the egg shell
  2. Decontamination of fomites
  3. Cleaning and disinfection of stable
  4. All-in-all-out
61
Q

How do we determine the timing of vaccination for infectious bursal disease:

A

Based on the maternal antibody level of the flock. To measure we can use a virus neutralising essay or ELISA

62
Q

Type of vaccine used for infectious bursal disease:

A
  1. live, attenuated vaccine
  2. Inacitvated vaccine
  3. Recombinant HVT vector
  4. immune-complex vaccine
63
Q

Live, attenuated vaccine for infectious bursal disease:

A

3 different levels of vaccine: mild, intermediate and strong strains

64
Q

Recombinant HVT vector vaccine of infectious bursal disease:

A
  1. Efficient at high maternal antibody levels (can be used at an earlier time)
  2. Constant antigen stimuli
  3. safe
65
Q

Immuno-complex vaccine of infectious bursal disease:

A

Live virus are used in combination with specific antibodies

66
Q

Inactivated vaccine of infectious bursal disease:

A
  1. Usually for booster vaccine
67
Q

Route of application for live attenuated vaccine of infectious bursal disease:

A

per os, mainly in the drinking water

68
Q

Route of application for recombinant vector vaccines of infectious bursal disease:

A

In ovo or SC in the hatchery

69
Q

Route of application for immune-complex vaccines of infectious bursal disease:

A

In ovo or SC in the hatchery

70
Q

Propagation area of live attenuated vaccine of infectious bursal disease

A

Propagates in the bursa

71
Q

Propagation area of immune-complex vaccine of infectious bursal disease

A

NO propagation in the bursa

72
Q

Propagation area of recombinant vector vaccine of infectious bursal disease

A

Vaccine STRAIN propagates in the bursa

Epidemiology - MIDTERM 2 (35 decks)

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