New outbreak shows African swine fever moving south through China’s pig farms

China, home to the world’s largest pig herd, has reported a fourth outbreak of the deadly African swine fever on Thursday, with worries growing about its rapid spread.

More than 400 pigs have been infected and the disease has now entered Zhejiang province, more than 2,000km from where it was first reported.

The infection has killed 340 hogs on three farms in Wenzhou, in eastern Zhejiang province, the Ministry of Agriculture and Rural Affairs said in a statement.

Wenzhou is a 2,150km (1,335 mile) drive south from Shenyang, capital of northeastern Liaoning province, where the first case was reported. It is the furthest site from the original infection so far reported.

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The road from Shenyang to Wenzhou travels through the pig producing provinces of Hebei and Shandong, as well as Jiangsu, another infected region.

The third infection, detected at the weekend, was just 890km to the north in another coastal city, Lianyungang. There have also been cases inland in central Henan province.

This may stoke concerns that the disease is being transmitted along busy trade routes that take pigs from markets and farms in the northeast to slaughter and processing in the south. Some farmers have called for a nationwide ban on transporting live pigs.

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Authorities have already culled more than 20,000 animals in an attempt to halt the spread of the highly contagious disease, which was first reported in China just three weeks ago.

But the vast distance between the new cases and the original outbreak will escalate worries about how to control the disease across China’s vast hog herd.

The rapid expansion of pig farms in recent years in China’s north-eastern cornbelt has increased the number of pigs being moved across country.

Local authorities in Wenzhou have banned the movement of live hogs, related products, and animals that are easily infected in to and outside the affected area, the ministry said.