The statement from the Ministry of Agriculture and Rural Affairs is the government's first comment on how the deadly disease has spread in the world's top pork producer.

China has reported more than 40 outbreaks of the highly contagious disease since early August, with farms across 12 provinces and municipalities already infected.

It does not affect humans.

Beijing has not yet said how the disease first entered the country but the ministry found 62 percent of the first 21 outbreaks were related to the feeding of kitchen waste, a statement published on its website said.

"These outbreaks were mostly located in urban-rural boundaries, and were particularly evident in several cases in early September in Anhui province," the statement said. Anhui is an eastern province whose capital Hefei is located about 415 km (258 miles) west of Shanghai.

The virus was also detected in kitchen waste fed to pigs on a farm in the Inner Mongolia region, it added.

"After the provinces with outbreaks and neighbouring provinces completely banned feeding of kitchen waste to pigs, the epidemic was greatly reduced, which fully demonstrates the importance of completely prohibiting the feeding of waste," the statement said.

Kitchen waste or swill is widely used in China to feed hogs, particularly by small farmers, as it is cheaper than manufactured pig feed.

Regulations require that the swill must be heated to a certain temperature before being consumed but industry experts say that step is often skipped.

The ministry also said in the statement it will set up a registration system for vehicles transporting live hogs, poultry and other livestock to control the spread of the disease better.

The long distance transport of live hogs has been the main channel for transmitting African swine fever across different regions, it said.

Vehicles transporting pigs and other animals will also no longer be allowed to use the "green channel" for priority on roads that is normally permitted for the trucking of fresh produce, added the ministry.

It called for more slaughtering closer to farms and the use of refrigerated transportation to better manage the supply of livestock across different regions.

China has promoted construction of new farms in the north-east in recent years, closer to its grain supplies. But the policy, which has not yet been accompanied by investment in new slaughterhouses, has led to large numbers of pigs being trucked long distances south.

Source Reuters: Hallie Gu and Dominique Patton

Further Reading

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