Meanwhile, authorities in Beihai City, located in the southern region of Guangxi, culled 924 pigs in two pig farming communities due to the highly contagious disease, which kills nearly all pigs that contract it.
An additional 1,629 pigs there showed symptoms of the disease, according to an online statement by China’s Ministry of Agriculture and Rural Affairs on Feb. 19.
The current epidemic in mainland China—the world’s largest producer and consumer of pork—was first detected in Shenyang City, in the far-north province of Liaoning, in August 2018. Since then, more than 1 million pigs have been culled in China.
In addition to the 25 provinces, all four of China’s directly-governed municipalities, Chongqing, Tianjin, Shanghai, and Beijing, have also reported cases of the disease.
Two days earlier, on Feb. 17, China’s state-run media China Youth Daily reported that an unnamed Chinese netizen posted online photos of three documents appearing to be from Gansu authorities, revealing that 83 samples of pork products collected from more than five different cities in Gansu had tested positive for the disease.
An unnamed official from Gansu’s Ministry of Agriculture and Rural Affairs confirmed the authenticity of the three documents with state-run media Beijing News on Feb. 15. But the official stated that the positive testings were only preliminary and that authorities would continue to investigate.
Infected pork products are not known to have harmful effects on humans who consume them.
The affected products were made by 11 different companies, including Kedi Food Group, which is based in central China’s Henan Province, and the Shanghai-based Guofu Longfeng Food.
On Feb. 15, frozen pork dumplings made by Sanquan Foods were found to contain traces of the African swine fever virus by local authorities in Xiangxi prefecture in Hunan Province and Jiuquan City in Gansu, according to Chinese state-run media China News Service.
Xiangxi authorities have ordered online retailers operating in its cities and counties to recall Sanquan Foods-produced dumplings with the same batch numbers as those that tested positive for the disease, according to China Youth Daily.
It is unclear why the withdrawal was limited to online retailers and did not include brick-and-mortar stores.
In a recent interview with Radio Free Asia, Mr. Zhu, a person with knowledge of the outbreak, said that much of the information about the African swine fever outbreak so far has not been released officially by the government, but through netizens.
“This is very irresponsible,” Zhu added. He said the Sanquan case was also first exposed by a Chinese netizen.
It is currently unknown if the Vietnam case has any connection to China’s outbreak.
All pigs were culled on farms in Hung Yen and Thai Binh provinces, located southeast of the capital Hanoi, according to a statement by Vietnam’s Animal Health Department.
According to Reuters, U.N. experts said in September 2018 that the spread of the virus to China’s neighbors was a near certainty, and would likely be through movements of infected pork products.
Vietnam is the third country in Asia to be hit with the disease. Mongolia reported the disease in four provinces in mid January, resulting in the deaths of thousands of pigs, according to China’s state-run media Xinhua. There have not been established reports linking the Mongolia case to China.