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Deadly in pigs but harmless to humans, why is African swine fever such a threat to China’s economy?

With the first case of the disease confirmed in Hong Kong, we look at how the latest outbreak has spread since it first resurfaced last August.

Hong Kong has now joined mainland China in responding to the outbreak of African swine fever (ASF), a deadly disease that threatens the pig population but is not harmful to humans. On Friday, the city’s first case was confirmed, despite the government taking precautionary measures, prompting it to order a cull of 6,000 pigs to prevent the spread of the plague-like virus.

What is swine fever?

ASF can be traced to Kenya, where it was found in domestic swine in 1921. According to a leading expert on the disease, Professor Dirk Pfeiffer of Hong Kong’s City University, it can be transmitted by warthogs and specific soft tick species, which in turn spreads to domestic pigs.

The virus had largely been kept under control until 2007 when it was detected in Georgia, and has remained present in domestic pigs and wild boars since then.

The latest outbreak began in Northern China last August, and led to the culling of 19,000 pigs. Photo: EPA-EFE
When did the latest outbreak start?

The premature death of pigs on a small farm in Northern China last August marked the first detection of ASF, and prompted a cull of 19,000 pigs in the vicinity.

The attempt to prevent the spread of the disease failed, and more than a million pigs have been killed or slaughtered so far. Hainan Island in late April reported its first case, meaning each of China’s 31 provinces and regions had a reported case of ASF.

Why is it fatal?

The disease is deadly to pigs because of its highly contagious qualities, and the virus has a 100 per cent mortality rate. There is no known cure and authorities have adopted an approach of culling herds in the affected areas to prevent widespread pig pandemics.

What has been done to contain the spread of the disease?

In Hong Kong, specific precautions included slaughtering all pigs on a farm if one was found to be infected. Previously, only a few would be. The government has also considered killing pigs on the day they arrive in the city. Hong Kong imports around 4,000 pigs per day from the mainland to feed demand.

Why does this outbreak matter?

Pfeiffer was part of a team of experts who published a paper in the British Medical Journal in 2017 warning that China’s “pig empire” was under threat unless action was taken.

“It is extremely concerning,” said Pfeiffer, of the latest outbreak. The expert has spent almost 15 years studying the disease, and said China provided almost half of the global pig population.

“Mainland China deals with an enormous problem, largely caused by the huge number of pigs produced by primarily low biosecurity pig farms,” he said. “The difficulty with these farms is that they are often not willing to improve their farm biosecurity, often simply because they cannot afford it.”

A worst-case scenario would see the world’s economy impacted by the spread of the disease. Photo: Edmond So
A Dutch investment bank has painted a worst-case scenario for China’s pigs, which would have global consequences for pork consumption and prices.

Rabobank suggested 200 million pigs, almost half of the nation’s animals, would need to be culled in order to control the epidemic, which is already three times the number of pigs in the United States.

According to the statistics bureau, China had 375 million sows, pigs and piglets at the end of March, a rapid fall from 428 million at the end of December.

Consumers face the impact of higher pork prices in the near term as supply tightens.