Asfarviridae

Question 1

What is the general structure?

Answer 1

Enveloped
Complex icosahedral capsid
Linear double-stranded DNA
Replication mostly in cytoplasm (initial stage in nucleus)

Question 2

How many genotypes have been identified?

Answer 2

22

Some strains have 100% mortality while some have no infection.

Question 3

What is the common name?

Answer 3

African Swine Fever

Question 4

Who are the hosts for ASF?

Answer 4

Domestic pigs & European Wild Boar

Question 5

Who are the inapparent carriers?

Answer 5

Warthods, bush pigs, and giant forest hogs
Sylvatic cycle (wild, jungle)

Question 6

Is ASF reportable?

Answer 6

Yes! OIE List A Disease
High morbidity and mortality
Import and export bans
Quarantine and depopulation
Can become prolonged epidemic

Question 7

Where is ASF endemic?

Answer 7

Most sub-Saharan Africa
Island of Sardinia in Italy
Georgia, Armenia
Russia
Poland
Latvia

Question 8

How long can the virus survive?

Answer 8

30 days in pens
They are resistant to a wide range 4-13 of pH
Can survive in chilled carcass for 6 months
Frozen carcass - 2 years

Question 9

What is a distinguishing characteristic of ASF-virus?

Answer 9

It does not hemagglutinate!
RBC’s will adhere to the surface of pig monocyte or macrophage infected with ASF-vurus.
Hemadsorption (HAD) is attributed to a virus specific protein that appears on the plasma membrane of infected cells during late infection.

Question 10

Who are the vectors for transmission?

Answer 10

Soft ticks including;
- Ornithodorus spp. (specifically O. moubata)
O. erraticus

Question 11

How does tick to tick transmission occur?

Answer 11

Trans-stadial
Transovarial
Sexual

Question 12

How does the sylvatic cycle occur?

Answer 12

Transmission between warthogs and soft ticks

Young warthogs infected develop a viremia with high enough virus titers to infect ticks feeding on them

Question 13

How does the domestic cycle occur?

Answer 13

Bite from an infected tick
Direct contact with infected animal (oronasal)
Indirect contact on fomites
Eat infected pork
Aerosol spread
Biting flies

Question 14

What are the pathogenic effects of ASF virus?

Answer 14

Hemorrhage
Apoptosis
Leukopenia, lymphopenia, thrombocytopenia

Question 15

Where does the virus replicate?

Answer 15

Pharyngeal mucosa, tonsils
Endothelial cells
Megakaryocytes
Macrophages

Question 16

What protein of the virus induces apoptosis of the cells?

Answer 16

p54

Question 17

What are the clinical signs of per-acute infection?

Answer 17

1-3 days of pyrexia, hyperpnea, hyperemia before death or sudden death

Question 18

What are the clinical signs of acute infection?

Answer 18

High fever
Moderate anorexia
Erythema
Cyanotic skin blotching on ears, tail, lower legs
Respiratory Distress
Diarrhea & Vomiting
Abortion (sometimes first sign)

Question 19

What are the clinical signs of the chronic form?

Answer 19

Emaciation & stunting
Swollen joins
Ulcers and reddened or raised necrotic skin foci
Pneumonia

Question 20

How is ASF diagnosed?

Answer 20

Virus isolation from blood, spleen, LN, tonsils
Hemadsorption
Serology: FAT
PCR to detect viral DNA

Question 21

How is ASF prevented?

Answer 21

Control hygiene
Movement of pigs outside the country should be controlled.
Do not feed swill that contains pig remnants

Question 22

Is ASF reportable?

Answer 22

YES!

Immediately notify authorities since infected farms must be placed on quarantine.

Question 23

How is ASF controlled once diagnosed?

Answer 23

Cull all infected and in-contact with animals
Carcasses must be burnt or buried deeply on site
Disinfect fomites