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Epidemiology - MIDTERM 2 > Topic 31 - African swine fever > Flashcards

Topic 31 - African swine fever Flashcards

1
Q

In which country could we find the first sign of african swine fever?

A

British East Africa

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2
Q

In which animal was the first outbreak of african swine fever observed?

A

Wart hog

Outbreak in domestic pig was observed after contact with wart hogs

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3
Q

Which continent could we in 2020 observe the most causalities of African swine fever?

A

Europe

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4
Q

How many types of African swine fever was there?

A

2

Genotype 1 and genotype 2

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5
Q

Which genotype caused which outbreak of African swine fever?

A

Genotype 1 = 1st outbreak

Genotype 2 = 2nd outbreak

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6
Q

what type of virus is African swine fever?

A

DNA virus. VERY big

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7
Q

Is the African swine fever enveloped of non-enveloped?

A

Enveloped

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8
Q

What is the “thumb rule” of enveloped viruses?

A

They have a low resistance

Non-enveloped viruses have HIGH resistance

African Swine fever is the exemption

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9
Q

Does african swine fever have high or low resistance?

A

HIGH

AFV are the exception of the “thumb rule”

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10
Q

Which genus does African swine fever belong?

A

Asfaviridae

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11
Q

How does the AFV block the immune system?

A

By blocking of interferon production and the antiviral defence mechanism. So there are no interferon and no antiviral protection

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12
Q

What is interferon production?

A

Direct antiviral compound

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13
Q

Are antibodies produced in case of African Swine fever?

A

Yes, antibodies are produced against the proteins, but there are no NEUTRALISING ONES

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14
Q

Is AFV a swine virus?

A

No. It is a tick virus.

This is why there are no related virus in the domain of animal pathogenic viruses

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15
Q

Is there replication with other species in case of African swine fever?

A

No

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16
Q

How is AFV isolated?

A

on the primary cell lines.

Meaning that we isolate the macrophages or the leucocytes from a live animals - This is very time consuming and expensive

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17
Q

What can isolation of cells do in case of African swine fever?

A

Cause cytoplasmic inclusions

= non-living substances that are not able to carry out any metabolic activity and are not bound by membranes

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18
Q

How many genes are responsible for the transcription mechanism in AFV? and what does this mean?

A

40!

IT means that the virus can replicate BOTH in the vector and in the swine

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19
Q

What does it mean when we say “multiplication of macrophages”?

A

It results in an efficient blocking of the immune system.

The macrophages impairs the function and can be spread on the macrophagic membrane as a coat. Meaning it can travel without being disturbed by the immune system.

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20
Q

How long can AFV survive in rotten blood?

A

4 months

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21
Q

How long can AFV survive in smoked or salted marinated ham?

A

5-6 months

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22
Q

How long can AFV survive in bone marrow?

A

7-8 months

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23
Q

What is the vector of AFV?

A

The tick

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24
Q

what is the difference between the African swine fever situation in Europe and Africa?

A

In Africa the virus is maintained by the warthog, the tick and the domestic pig

In Europe the virus is spread by wild boars and by humans - Transport, airports etc

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25
Q

mortality rate of newly infected herds with African swine fever:

26
Q

What are the chances of tick transmission of African swine fever in Europe?

A

Low. The tick only lives in southern of Europe, so Spain and Portugal are at risk

27
Q

What is the pathogenesis of the African swine fever virus dependent on?

A
  1. Virulence of the strain
  2. Immune status of the pigs
  3. Age
  4. Infective dose
  5. Place of entry
28
Q

How is AFV transmitted?

A

Per os, through saliva and nasal discharge

29
Q

First replication site of AFV:

A

Tonsilla and the regional lymph node

30
Q

Does AFV cause viraemia?

31
Q

After AFV caused viraemia, where does the virus multiply/replicate?

A

In leukocytes, monocytes, macrophages and it will increase the virus dose. It is NOTmultiplied in lymphocytes

32
Q

after second replication/multiplication if AFV, where is the virus going next?

A

To the spleen, lymphatic tissue, endothel cells and parenchymal organs and we have a further multiplication after travelling with the immuno cells.

33
Q

How early can shedding happen in AFV?

A

48 hours BEFORE first appearance of symptoms

34
Q

What are the consequences of AFV?

A
  1. Persistent viraemia, because the organims is unable to eliminate the virus.
  2. Immuno complexes
  3. Haemorrhages
  4. Abortions
35
Q

What is the ultimate outcome of AFV? and why?

A

The formation of immune complexes.

Because huge number of virus, huge copy number, huge loads of antibodies - ultimately the body produces too much antibodies

36
Q

How many virulence variants are there in AFV and which form do they cause?

A

3

Very virulent = peracute course
Moderately virulent - acute, subacute course
Weakly virulent = chronic course

37
Q

thumb rule of consequence of AFV?

A

ALWAYS causes abortion, regardless of the virulence strain

38
Q

Incubation time of AFV:

A

Usually 2-7 days, but can be as long as 19 days

39
Q

Symptoms of Peracute form of AFV:

A

Rapid death without any prior symptoms

40
Q

Mortality rate in acute form of AFV:

A

90-100%, but closer to 100%!

41
Q

Symptoms of AFV acute form:

A
  1. Fever - due to the viraemia
  2. Animals lie on each other
  3. No apetite
  4. Inability to move
  5. Rapid death (few days or even hours)
  6. dyspnoea
  7. Bloody-serous nasal discharge
  8. Conjunctivitis
  9. Diarrhoea with blood
  10. skin hemorrhages

AFV means haemorrhages everywhere !,

42
Q

Why does AFV cause skin haemorrhages?

A

Because the virus goes to the endothel cells, also in the skin.

43
Q

symptoms in subacute form of AFV:

A

Similar as to acute form, only milder

Also CNS problems, because the course is longer.

Focal skin necrosis

44
Q

Mortality rate in chronic form of AFV:

A

less than 30%

45
Q

Symptoms in case of chronic AFV:

A
  1. recurrent fever
  2. Arthritis
  3. Focal skin necrosis
  4. Respiratory signs
46
Q

Pathological findings in peracute form of AFV:

A

No findings

47
Q

Pathological findings in acute form of AFV:

A

AFV means haemorrhages everywhere, because the endothel cells are attacked.

  1. The lung septa is widened
  2. Enlarged spleen
  3. Gelatinous infiltration of the wall of gallbladder and chloeductus
48
Q

Most important difference pathologically between african swine fever and classical swine fever:

A

In AFV the wall of the gallbladder and the choleductus regions shows a gelatinous infiltration

Choleductus = common bile duct.

49
Q

Pathological findings of chronic form of AFV:

A
  1. Muscle necrosis
  2. Ulcers in the skin
50
Q

Differential diagnosis of AFV:

A

Classical swine fever

51
Q

Which laboraty test can we use to diagnose AFV?

A
  1. PCR
  2. Culture
  3. Hemadsorption
52
Q

What is Hemadsorption?

A

We culture the virus. Having the RBC on the culture and on the surface of the cells, the antigens are expressed and there is a Hemadsorption of the cells.

53
Q

Prevention of AFV:

A
  1. There is no specific prevention
  2. no neutralising antibodies
  3. No reconvalesent immunity = after being healed, the animal can be infected again
54
Q

What can we do to prevent AFV?

A

Epidemiological rules only, no vaccines

  1. Stamping out
  2. Closed herd because wild boars can infect the domestic pigs
  3. Ban on import of pigs
55
Q

Is there a vaccine for AFV?

A

NO

He will be very angry if we say there is a vaccine

56
Q

what is it called if the animal can be infected again after being healed?

A

No reconvalesent immunity

57
Q

Why is there a shedding of the virus before clinical signs in case of AFV?

A

The virus polymerase is replicating in the cells and the genus are being expressed rapidly causing shedding of the virus PRIOR to clinical signs and even early onset of the clinical signs

58
Q

Subacute form of AFV, death within how long?

A

14-30 days

59
Q

Chronic form of AFV, death within how long?

A

as long as 2-15 MONTHS

60
Q

How is AFV shed?

A

Through excretes and saliva

Epidemiology - MIDTERM 2 (35 decks)

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