African swine fever

A virus of the Asfarviridae family.

ASF is present in most of sub-Saharan Africa and in Sardinia. Since 2018, there have been outbreaks in Europe and across Asia. Outbreaks have recently occurred in the Dominica Republic and Haiti. Outbreaks are managed by respective authorities.

There are no recorded occurrences in Australia.

The course of the acute form of the disease is from 1–7 days. In less acute forms, clinical signs can last 3–4 weeks.

Clinical signs vary according to the strain of virus infecting pigs.

Genotype II ASF viruses have been the predominant cause of ASF outbreaks in Europe and Asia since 2018. These genotypes typically cause severe disease resulting in most infected pigs dying.

More recently, less virulent ASF viruses have been identified in China. Less severe clinical signs and lower death rates have been observed in pigs infected with these strains, which in turn, makes early detection more difficult.

In the peracute form, pigs may:

• be found dead with no prior clinical signs.

In the acute form, pigs may:

• have a fever
• lose their appetite, or have an irregular appetite
• show incoordination
• be reluctant to move and often lie down
• display redness or blue blotching of the skin on ears, nose and limbs
• produce nasal and eye discharges
• abort a pregnancy
• vomit
• develop dysentery or diarrhoea.

In the subacute form, pigs will:

• display clinical signs as per the acute form
• generally display milder clinical signs that may last 3–4 weeks.

In the chronic form, pigs may:

• have recurrent fever
• fail to thrive
• develop pneumonia
• develop arthritis
• develop skin ulcers
• suffer complicating secondary infections often resulting in death.

This disease would have a significant impact on pig health and production in Australia, and contribute to wider economic impacts, including those caused by a loss of access to overseas markets for our pork products.

The soft argasid tick maintains a source of ASF virus in African warthog populations. Similar ticks are associated with kangaroos in Australia though their role under Australian conditions is not known.

Pigs can become infected by:

• eating contaminated pork products or feed
• direct contact with infected pigs
• contact with contaminated equipment.

Bloodsucking insects feeding on infected pigs can mechanically transmit the virus within herds, and possibly between herds in close proximity.

International spread has been associated with the feeding of contaminated garbage. All Australian states and territories have laws against feeding prohibited feed to pigs.

The virus:

• is stable in a wide range of acid and alkaline levels (pH 4–10) and temperatures, including below freezing
• remains viable in the environment for varying periods of time, depending on the initial virus load, temperature, water content and substrate (e.g. urine, faeces, blood)
• may remain viable for many months in raw unprocessed frozen meat
• is inactivated by heating to above 70°C for 30 minutes.

Prevention

We all have a role to play to protect against African swine fever.

Pig keepers

• Have a biosecurity plan in place and ensure all workers and visitors are aware of your biosecurity rules.
• Do not feed pigs prohibited feed for pigs—it is best to feed pigs commercial pig feed.
• Prohibited feed for pigs is material that:
• contains, or may contain, the carcass of a mammal or bird
• contains, or may contain, material derived from a mammal or bird (including meat, eggs, blood, faeces)
• has been in contact with either of these (including food or food scraps from a restaurant, hotel or home that may have been in contact with meat or meat products or other material derived from a mammal or bird).
• Ensure items and equipment coming on to or going off of your farm are clean.
• Clean and disinfect any equipment shared with other farms.
• Practice good hygiene—wear clean clothes and footwear when visiting a property with pigs.
• Prevent visitors from having unnecessary indirect or direct contact with your pigs.
• Prevent contact between farmed and feral pigs.
• Check you are registered as a biosecurity entity and make sure your contact and registration details are up to date.
• Ensure you complete all movement requirements when moving pigs.
• If you suspect the presence of ASF, you must report it immediately to Biosecurity Queensland on 13 25 23.
• Find information to protect your farm from African swine fever and stay up to date about the outbreaks overseas.

Veterinarians

• View the African swine fever guide for veterinarians which provides information about clinical signs, sampling, testing and other important details.

Everyone

• Keep illegal imports out of Australia.
• Declare all meat and meat products at all international air and sea ports.

Responding to an outbreak of ASF will be determined by:

• how early the outbreak is detected
• the extent of the outbreak
• location of affected premises
• virus virulence factors
• whether feral pigs are involved.

The Australian Veterinary Emergency Plan (AUSVETPLAN) policy is to control and eradicate the disease in the shortest possible time using a combination of strategies. This will involve:

• an epidemiological study to establish the potential role of vectors in the transmission of the disease in Australia
• movement controls to prevent further spread of the virus by animals, people, products and equipment
• tracing and surveillance to determine the source and extent of infection
• destruction of all infected and exposed susceptible animals
• sanitary disposal of destroyed animals and contaminated animal products to remove the source of infection
• decontamination to eliminate the virus on infected premises and equipment
• surveillance of tick vector populations, if implicated in the epidemiology of the incident
• a public awareness campaign.

Phone 13 25 23 or the Emergency Animal Disease Hotline on 1800 675 888 if you suspect ASF.