Chen Yun’s pigs stopped eating, then developed a fever. Within a week, all 10,000 on his farm in Jiangxi, in southeast China, had died of African swine fever (ASF). In 2018-19 the virus affected every province and led to the slaughter of half the country’s pigs. The outbreak spread from China to Southeast Asia; the virus, already present in central Europe, reached Belgium in 2018. France and other European nations remain braced for its possible arrival. ASF, which was identified over a century ago, does not infect humans but mortality can be up to 100% among pigs.
To tackle the epidemic, China is favouring farms with at least 500 pigs, following the biosecurity precept that bigger is better. ‘Family farms will tend to disappear in favour of industrial production,’ said Jian Huang, an expert at China’s national pig institute. China is following health advice from international bodies for epizootic diseases (epidemics that affect animals), said Wantanee Kalpravidh, an animal health expert at the UN Food and Agriculture Organisation (FAO); farms are classified according to their presumed risk of infection, from sector 1, deemed to have the highest level of biosecurity, to sector 4, with the lowest.