- If African swine fever (ASF) virus is introduced in Aberdeenshire, East Anglia, Devon or Yorkshire (four previously defined as areas of higher risk of generating epidemics; EPIC_201819_RB_002v1) and left undetected for a long period of time (e.g. 8 weeks), ASF can spread rapidly to other farms and could cover a large geographical area in Great Britain (Figure).
- If an ASF incursion occurs first in a domestic pig farm in a higher-risk area in England (e.g. East Anglia, Devon or Yorkshire), the probability that a Scottish farm will subsequently become infected with ASF within 2 or 4 weeks of pre-detection spread via animal movements and local spread (disease spread between farms located in geographical proximity) is low (0.11% and 0.83%, respectively). Within 8 weeks of pre-detection spread, the probability of ASF introduction into Scotland increases to 4.4%.
- The probability of infection of a Scottish farm decreases tenfold if only animal movements are involved in disease spread – i.e. no local spread (2 weeks: <0.001%, 4 weeks: 0.09%, 8 weeks: 0.46%). - Irrespective of the time to detect ASF (2, 4, or 8 weeks of “silent” or undetected spread), the probability that a Scottish farm will be infected with ASF will be lower if an incursion occurs in East Anglia (2 weeks: 0%, 4 weeks: <0.001%, 8 weeks: 0.005%) and Devon (2 weeks: <0.001%, 4 weeks: 0.006%, 8 weeks: 0.45%) compared to Yorkshire (2 weeks: 0.11%, 4 weeks: 0.83%, 8 weeks: 3.9%).