Biosecurity Versus African Swine Fever—Making, Acceptance, and Results of a German Online Assessment Tool

African swine fever (ASF), a viral hemorrhagic disease with exceptionally high lethality in domestic pigs and Eurasian wild boar, reached Germany in 2020, with the confirmation of the first case in a wild boar next to the border to Poland. Since then, 6621 cases in wild boar but only 19 outbreaks in domestic pigs were confirmed. Biosecurity is crucial in preventing the infection of domestic pig holdings. Already in 2019, an online assessment tool, the so-called "ASP-Risikoampel" (ASF risk traffic light), was launched. It enables farms to identify ASF-specific weaknesses and take targeted measures to minimize risks/optimize the biosecurity standard anonymously and free of charge. The development of the tool incorporating expert opinion elicitation in a Delphi process is detailed and the results of 2290 self-assessments of farms between 2019 and 2023 are evaluated. The proportion of tool utilization relative to the average number of holdings in Germany in this time span was 11.9% with marked differences between the federal states. Most of the farms achieved biosecurity scores above 66.7%, qualifying for a "green traffic light". The results were significantly different among the federal states. The best performing states were those with the largest mean farm size. The latter was significantly correlated with performance on the farm level.