Six weeks after African swine fever emerged in China, scientists are racing to pinpoint how the deadly pig virus entered the world’s biggest pork market and spread between farms hundreds of miles apart.
Finding answers is critical for stopping the further international spread of what Russian researchers consider the most dangerous swine disease. The virus has been reported in seven Chinese provinces since Aug. 1, causing the deaths of about 40,000 pigs and threatening major disruption of a $128 billion industry. It’s also widened its grip on Europe, with the first cases in Belgium reported Sept. 13.
With no vaccine to protect animals, researchers say the lethal virus — which can survive for more than a year in dry-cured ham — is likely to spread rapidly among China’s 433 million pigs and reach other countries, potentially even the U.S.
“What we’re seeing so far is just the tip of the iceberg,” Juan Lubroth, chief veterinary officer with the Food and Agriculture Organization of the United Nations in Rome, said after an emergency three-day meeting in Bangkok this month. The emergence of the disease in other countries “will almost certainly occur,” he said.
Researchers at China’s Academy of Military Medical Sciences in Changchun said the pig pathogen on local farms matched a highly virulent strain that emerged in the former Soviet republic of Georgia in 2007 and subsequently dispersed across Russia and Estonia.
That led them to speculate that the disease, which doesn’t harm humans, might have been introduced via trade in live pigs with Russia and the European Union, or through the illegal importation and disposal of products containing pig meat.
About 800,000 pigs have been destroyed in Russia as part of measures to control more than 1,000 separate outbreaks. Subsequently, backyard or small-scale pork production has declined by almost half, researchers from Russia’s Federal Research Center for Virology and Microbiology said in April.
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In 2011, when about 12,000 pigs were destroyed, authorities estimated the disease could cause as much as $267 million in direct losses.
“The fight against the disease is not a public health issue, but an animal and economic health issue,” Belgium’s Federal Agency for Food Chain Security said Sept. 13, announcing the discovery of infected wild boars in a southern province. “In recent months, it has spread more rapidly and further west, affecting countries that were previously unscathed.”
In a March report forewarning the threat of African swine fever to China, the FAO concluded that the disease would have “devastating consequences” for animal health, and food safety and security. From there it could spread through Asia, including the neighboring Korean Peninsula.
The outbreaks in China mean the country, which eats more than half the world’s pork, may need to increase imports of pig meat and possibly beef, impacting global supply chains, said Angus Gidley-Baird, a senior animal proteins analyst with Rabobank Australia.
Pork may account for almost 3 percent of China’s consumer price index, a key measure of inflation. An index of national pig prices has risen 6.4 percent since authorities first reported the outbreak on Aug. 3. Hong Kong-listed shares of WH Group Ltd., the world’s biggest pork producer, simultaneously declined 15 percent.
“We still don’t know how the virus got into China, and it’ll be very difficult to tell exactly how it happened,” said Wantanee Kalpravidh, the Bangkok-based regional manager of FAO’s Emergency Centre for Transboundary Animal Diseases.
The smuggling of pigs from Russia couldn’t be ruled out, the UN agency said in March. Pig meat was estimated in 2015 to be 15 percent cheaper in Russia than in China, providing an economic incentive for cross-border hog movement.
Understanding the route will help authorities prevent further introductions, said Dirk Pfeiffer, a professor of veterinary medicine and life science at the City University of Hong Kong. The construction of thousands of kilometers of road and railway in northern Asia as part of the Chinese government’s “Belt and Road” economic initiative increases the risk of exotic-disease transmission, he said.
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“We’ve always said be aware of the diseases that this might bring,” Pfeiffer said. “It’s economic development, but it might enhance the ability for disease to spread from one country to another.”
The virus doesn’t need traveling swine to spread. Germs can move long distances by being carried in dirt and dust — such as on truck tires or shoes of farmworkers, said Andrzej Jarynowski, a computational epidemiologist at the Interdisciplinary Research Institute in Wroclaw, Poland, who studied outbreak patterns in Eastern Europe. Virus-carrying pig feces can be infectious for a week or more, studies found.
“It seems that it has spread so far that they cannot stop it,” Jarynowski said.
The virus can survive for a month in pepperoni and salami, for 140 days in Iberian cured pork products and for 399 days in Parma hams, scientists found. That means pigs can become infected if they eat contaminated food scraps.
That’s probably how the disease took hold on a backyard farm in Russia’s Irkutsk region, near the border with Mongolia, last year and in Georgia a decade earlier. Scraps often are fed to pigs in small backyard farms in China, scientists from the National Research Center for Veterinary Medicine in Luoyang wrote in a Sept. 8 research paper.
Countries receiving large numbers of international travelers carrying clandestine food parcels also are vulnerable. Some 8,000 pork-derived products are confiscated by U.S. Customs and Border Protection officials annually, researchers reported last month.
American pork producers could suffer as much as $8 billion in losses from African swine fever in the first year of an outbreak, said Dermot Hayes, leader of the Center for China-U. S. Agricultural Economics at Iowa State University.
China’s most recent outbreaks, involving backyard pigs in Inner Mongolia, were reported Sept. 14. Now that African swine fever, or ASF, has taken hold, the virus could disseminate rapidly via the illegal sale of moribund pigs by farmers trying to minimize their losses, according to scientists at the Institute of Military Veterinary Medicine in Changchun.
It’s common for pigs to travel long distances in China due to the disparity of pork prices in different provinces, the scientists at the National Research Center for Veterinary Medicine said. This could explain how it reached places like Lianyungang and Yueqing, more than 534 miles (860 kilometers) apart.
—With assistance from Bloomberg’s Hannah Dormido.