Since the outbreak of African swine fever (ASF) in Shengyang, it has continued spreading in China. In the early stage of the epidemic, multi-point and concentrated outbreaks were mainly in the swill feeding areas. In this paper, we developed compartmental models to investigate the transmission of ASF in several raising units including Guquan, Jinba and Liancheng. Using the data collected from these three infected premises, we calibrated the models to estimate that the average incubation period was between 8 and 11 days, the onset period was about 2-3 days and the basic reproductive number was about 4.83-11.90. We also estimated the infection on the day before culling to be 45.24% (Guquan), 89.20% (Jinba) and 16.35% (Liancheng), respectively. The infection rate of Guquan could reach about 74.8% if culling were postponed by 2 days. We found that the infection was significantly higher than the morbidities (22.11% (Guquan), 49.35% (Jinba) and 12.94% (Liancheng)) calculated by actual statistical data. Besides, we simulated and compared the control effect of stopping transport, disinfecting, stopping swill and culling. Our findings suggest that any single measure was not enough to prevent the spread of ASF on a regional level but the combined measures is the key. Under the current situation, fully culling was recognized as most effective in controlling the epidemic, despite the culling of uninfected pigs.
Keywords: African swine fever; basic reproductive number; compartmental model; culling; incubation period; infection rate; morbidity.
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