Animal disease - major outbreak of African swine fever
| Impact | 5 |
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| ID | 56d |
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| Risk theme | Human, animal and plant health |
Impact & Likelihood
| 5 | Catastrophic |
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| 4 | Significant |
| 3 | Moderate |
| 2 | Limited |
| 1 | Minor |
| 5 | >25% |
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| 4 | 5-25% |
| 3 | 1-5% |
| 2 | 0.2-1% |
| 1 | <0.2% |
Background
African swine fever (ASF) is a highly contagious haemorrhagic viral disease that affects pigs and wild boar but does not infect humans. It can be spread by direct contact with infected live or dead pigs, their secretions, pork products, contaminated feed, and non-living objects such as shoes, clothes and vehicles. The only control options are culling and movement restrictions; there is no vaccine or antiviral therapy available. Although no cases of ASF have been reported in the UK, the virus is currently spreading in Europe, Asia and Africa. ASF is a notifiable disease throughout the UK and anyone who suspects disease must immediately report it. The Animal and Plant Health Agency monitors ASF outbreaks internationally and publishes outbreak assessments considering the risk posed to the UK animals on GOV.UK.
Scenario
The reasonable worst-case scenario is based on an incursion of an acute strain of ASF into a feral pig population in England, which spreads before detection to domestic and commercial pig farms. Acute forms of ASF are highly pathogenic and have case fatality rates as high as 100%, but the virus remains stable in the environment for several weeks and in frozen products such as meat for many months. Feral pigs are only found in some areas of England, Scotland and Wales. The outbreak in kept pigs could last for about 16 weeks, with restrictions on exports remaining in place for a minimum of 9 months following the last confirmed infection. The outbreak in feral pigs could persist for up to 70 weeks. However, the scale of this scenario continues to be assessed
Key assumptions
The scenario is based on an outbreak of ASF strain that causes acute infection. Disease would begin by spreading undetected through the feral pig population until it reaches nearby domestic pig farms. The incursion into a commercial pig farm is assumed to be human mediated.
Variations
Some strains of ASF produce less intense clinical signs that can be expressed for much longer periods. Case fatality rates are lower but can still range from 30-70%. An outbreak of such a strain of ASF would affect the impact and duration.
Response capability requirements
Specialist staff would be required to conduct surveillance and dispose of infected animals. These include vets, wildlife experts and marksmen, licensed slaughterers and carcass disposal logistics experts, in addition to carcass transport, rendering and incineration. Sufficient laboratory capacity to undertake surveillance in susceptible species would be needed, along with local authority staff to conduct enforcement activities, modelling experts, epidemiologists, disease experts, administrative staff and trained policy staff. Sufficient personal protective equipment (PPE), sample kits and approved disinfectant would be necessary across government and operational partners.
Recovery
For captive pigs, the minimum period to regain ASF Country-Free Status for international trade is 3 months after cleansing and disinfection of the last infected premises. In feral pigs, the minimum period to recover ASF free status is 12 months. It is expected that some of our trading partners would implement national export bans upon confirmation of ASF in captive or feral pigs.