This review assembles what is known about how African swine fever virus reaches domestic pigs. Direct contact between pigs and contaminated feed are identified as the principal routes. Aerosol transmission is documented over short distances. The review covers fomites and the wild boar interface alongside those routes, and it sets out where the evidence is thin.
Subsequent work has filled in several of the gaps it named. Olesen and colleagues in 2017 confirmed aerosol transmission with a recent European isolate from Poland, following the ducted air demonstration published by Wilkinson and colleagues in 1977. Li and colleagues in 2023 documented a complete aerosol transmission chain between two piggeries under field conditions, running through deposited dust rather than directly between air streams. Gebhardt and colleagues detected ASFV across feed manufacturing and production surfaces in Vietnam, and Vasic and colleagues recovered it from soil, feed, water and flies during the 2023 Serbian outbreak.
The route hierarchy the review establishes is the part that should shape a control programme. For ASFV specifically, air handling addresses a genuine but short range pathway, while the routes carrying the greater share of risk run through animals, feed and material moving onto the site. A building with an excellent filter bank and an unexamined feed chain has not addressed the principal route. The order of investment should follow the order of the evidence.