Taipei: Unsterilized food waste was likely the source of an African swine fever (ASF) outbreak that occurred at a pig farm in Taichung’s Wuqi District last month, Deputy Minister of Agriculture Tu Wen-jane said Monday. Tu told a news conference in Taichung held by the African Swine Fever Forward Command Center that an investigation of the outbreak that was confirmed on Oct. 21 had ruled out people, vehicles, and pigs from outside the farm as possible sources of infection.

According to Focus Taiwan, researchers inferred that the most likely source was food waste that had not been properly sterilized before it was fed to pigs on the farm. Supporting this conclusion, the command center’s investigation report noted that pigs on the Taichung farm fed food waste had died at a significantly higher rate than those given regular animal feed. Another pig farm, which obtained its food waste from the same source as the farm with the outbreak but properly sterilized it, had no positive cases among its pigs, the report said.

Agriculture Minister Chen Junne-jih said the central government has historically discouraged farmers from using food waste as pig feed. Over time, however, local governments began granting pig farmers permits to use food waste, on the condition that they upload photos showing that it had been sterilized at above 90 degrees Celsius for at least one hour, he said. It appears that those rules were not strictly enforced. The farm where the ASF cases occurred is being investigated by prosecutors for not submitting any documentation of food waste sterilization from May through September and then submitting multiple photos in October with fake dates for the previous months, the command center’s report said.

In light of the outbreak, Chen said his ministry would require pig farmers to upload proof of sterilization “immediately,” ask local governments to scrupulously carry out all scheduled inspections, and seek related regulatory changes. Only after these changes are enacted will the government open a discussion on whether or not to ban feeding pigs food waste, Chen said. Even if a ban is decided upon, “we won’t do it immediately, but will give farmers some time [to adjust],” he added.

The command center’s report on Monday said that the outbreak appears to be contained, with no positive cases found at any other domestic pig farms, processing facilities, meat markets, or slaughterhouses. Over the weekend, Chen had suggested that the government’s current 15-day ban on the slaughter and transport of pigs in Taiwan, which extends through Thursday, may be allowed to expire if no additional cases are found. Taiwan in May became the first country in Asia to self-declare itself free of African swine fever, classical swine fever, and foot-and-mouth disease. The government has said Taiwan could regain its ASF-free status if no new cases are discovered in the next three months. According to the command center, the strain of the virus found on the Taichung farm was highly similar to strains of ASF found in both China and Vietnam.