A new form of African swine fever identified in Chinese pig farms is most likely caused by illicit vaccines, industry insiders say, a fresh blow to the world's largest pork producer, still recovering from a devastating epidemic of the virus.
Two new strains of African swine fever have infected more than 1,000 sows on several farms owned by New Hope Liuhe , China's fourth-largest producer, as well as pigs being fattened for the firm by contract farmers, said Yan Zhichun, the company's chief science officer.
Though the strains, which are missing one or two key genes present in the wild African swine fever virus, don't kill pigs like the disease that ravaged China's farms in 2018 and 2019, they cause a chronic condition that reduces the number of healthy piglets born, Yan told Reuters. At New Hope, and many large producers, infected pigs are culled to prevent the spread, making the disease effectively fatal.