Elimination of ASFV via Precise Culling in a Large-Scale Breeding Herd in China: A Field Experience

This field study presents an elimination strategy for African Swine Fever Virus (ASFV), particularly low-virulence genotype II strains, in a large-scale breeding herd in China. Since its introduction to China in 2018, ASFV has spread rapidly, causing significant economic losses. The emergence of low-virulence strains in 2020 further complicated the efforts against this virus. We describe a case study on a farm with 6000 sows in eastern China. Upon ASFV detection, pig movements were ceased immediately, strict biosecurity protocols were implemented, and an epidemiological investigation was conducted to identify high-risk zones. Pigs that tested positive or within high-risk zones were culled, followed by extensive disinfection of exposed areas and whole-herd PCR screening. Injection of a foot and mouth disease vaccine was utilized to stimulate virus excretion of latent infections for better detection. Four rounds of whole-herd tests were conducted to confirm the elimination of ASFV. This case study highlights the importance of timely monitoring, rapid culling, thorough disinfection, and enhanced biosecurity as an effort to control ASF outbreaks in a low-impact and more cost-efficient manner, so called "tooth extraction."