EFSA has devised surveillance strategies that will help countries affected by African swine fever (ASF) to determine  when the virus has stopped circulating among their wild boar populations.

The scientific opinion recommends an “exit strategy” comprising two phases: a period of routine surveillance of wild boar (the screening phase) followed by a shorter period of intense surveillance (the confirmation phase).

Modelling demonstrated that:

• The accuracy of the approach rises in line with the number of wild boar carcasses collected and tested. 
• Lengthening the monitoring period increases the chances of verifying that the ASF virus is no longer circulating.
• The use of active surveillance based on hunting has limited impact on the effectiveness of the exit strategy. 

The opinion gives practical examples of how to apply the exit strategy to both large and small affected areas. It also makes recommendations on the minimum monitoring periods needed to make the strategy effective.