Background Since the first report of ASFV in China in 2018, conventional whole herd depopulation method to control ASF has proved unwieldly because of high production intensity and complex trade network. To provide an alternative to conventional methods, we evaluated the feasibility of implementating an extensive sampling method and qPCR tests to determine the status of ASFV in herds, with a rapid response to identified outbreaks. Case presentations By assessing and applying these methods without whole herd depopulation, we successfully controlled ASF and eliminated the virus from 4 large swine herds. The time to negative herd was 19, 28, 14, and 1 days in farms 1-4 respectively. Retention rates of pigs of farm 1 to farm 4 was 69.7% , 65%, 99.4% and 99.72% respectively.Conclusions We anticipated that this innovative method would replace the conventional stamping out one and greatly facilitate the control and eradication of ASFV in China and worldwide.

BackgroundAfrican swine fever (ASF) is a devastating and economically significant infectious disease and has caused huge losses in the commercial pig sector in China since 2018. The major transmission route of African swine fever virus (ASFV), the causative agent of ASF, is direct pig-to-pig contact or indirect contact with virus-contaminated objects. Although aerosol transmission route of ASFV has been reported under experimental conditions previously, whereas no reports described under field conditions.Case presentationIn the three ASFV-positive piggeries, environmental samples, including floors, aerosols, dusts and air outlets, tested positive in the monitoring period. Aerosol and floor samples always tested positive firstly at the same time. ASFV-positive aerosols were associated with live ASFV-positive pigs in piggeries. Dust and air outlet samples remained positive for several days after all positive pigs were eliminated, and the times of positive and persistent positive of dust and air outlet samples were always close.ConclusionsThis is the first report to provide some evidence of airborne transmission route of ASFV in field piggeries, and more research is needed to study aerosol-spread laws of ASFV under field conditions, assess the risk of ASFV aerosol transmission, and develop effective strategies for air disinfection to create low-risk fresh air for pig herds.