A deadly swine disease is spreading across eastern Asia, infecting thousands of pigs and threatening the world’s largest hog industry. Since emerging in China in August, African swine fever has been detected in neighboring Mongolia and Vietnam, increasing the chances of transmission to other countries. The first outbreak in Cambodia was reported in early April in backyard pigs, about 10 kilometers (6 miles) from the Vietnam border.

1. What is African swine fever?

A highly contagious viral disease which, in its most virulent form, can be 100 percent lethal to domestic pigs and wild boars. There is no vaccine. It is characterized by high fever, loss of appetite, hemorrhages in the skin and internal organs, with death coming in 2-10 days on average. Diarrhea, vomiting, coughing and breathing difficulties are other symptoms.

2. Does it threaten human health?

No. The virus infects pigs, warthogs, European wild boar, American wild pigs, bush pigs, giant forest hogs and peccaries. Still, the disease can have a significant impact on food security through decreased and lost production, as well as on food safety through the movement of disease-infected carcasses that may not be adequately chilled or frozen, leading to bacterial contamination. Culling infected animals and imposing strict containment measures are the only tools available to limit further spread.

3. What’s the concern?

Economics and trade. China has more than 400 million pigs, or over half the world’s swine, and Vietnam has about 27 million. Pork is the principal source of dietary protein in China and accounts for about a third of meat expenditure in Vietnam. The culling of pigs to stem the disease’s spread, along with restrictions on the movement of animals, have hurt the livelihoods of pig producers, cut pork production, pushed prices higher and driven consumers to other sources of protein. In Mongolia, about 10 percent of the pig population have died or been destroyed due to outbreaks in six provinces since January. The virus was detected in a number of Chinese processed pork products intercepted at airports from Japan to Australia, leading several countries to ban such goods. In the European Union, where African swine fever emerged in 2014, outbreaks have spread across the region at a rate of about 200 kilometers a year, causing an estimated several billion euros in annual losses. It’s estimated that the introduction of the virus into the U.S. would cost producers more than $4 billion in losses.

4. Where else has the disease shown up?

It’s endemic, or generally present, in sub-Saharan Africa and the Mediterranean island of Sardinia. Over the past several decades, the disease has emerged, and then been eliminated, in parts of Europe, the Caribbean and Brazil. In Europe, outbreaks have been reported this year in Belgium, Bulgaria, Hungary, Latvia, Moldova, Poland, Romania, Russia and Ukraine. In Africa, Zimbabwe and South Africa are tackling the virus. In China, the Veterinary Bureau has reported infections across 28 provinces, regions and municipalities, including in areas near Beijing, Shanghai, Chengdu, Macau and Hohhot. Vietnam has reported some 366 outbreaks in 20 provinces and cities, with more than 46,600 pigs culled. Chinese scientists studying the genetic evolution of the virus have said it closely resembles a pan-Russian strain.

5. How has China dealt with past disease outbreaks?

When the rotting carcasses of more than 16,000 pigs — some of which were reportedly diseased — were found in early 2013 in the tributaries of the main river running through Shanghai, threatening the region’s water supply, millions of small piggeries were closed in a nationwide program aimed at shifting pork production to larger, more efficient farms. It resulted in one of the largest culls in history — a reduction in hog numbers equivalent to the disappearance of the entire U.S., Canadian and Mexican pork industries in less than two years.

6. How does the virus spread?

It’s found in all body fluids and tissues of infected domestic pigs and spreads via direct contact with infected animals or ingestion of garbage containing unprocessed infected pig meat or pig meat products. It can survive in feces for several days and possibly longer in urine. Animals that recover from the illness can carry the virus for several months. Unprocessed meat must be heated to at least 70 degrees Celsius (158 degrees Fahrenheit) for 30 minutes to inactivate the virus. Analysis of China’s first 21 outbreaks found that feeding pigs swill, or food scraps, was linked to more than 60 percent of cases. Blood-sucking flies, ticks and other insects possibly spread the virus between pigs, as can contaminated premises, vehicles, equipment or clothing. Brazilian researchers blamed the outbreak there on trade and tourism.

7. What’s China doing this time round?

The government said it faces an “arduous task” to control the spread of the disease, with outbreaks in neighboring countries making prevention and tracing complicated. China has culled about 1 million hogs, banned transport of live hogs outside affected provinces and closed trading markets. The more stringent measures required by farms to implement are favoring larger operations with more than 1,000 head, accelerating consolidation in the industry. Many such farms are planning to integrate their businesses to incorporate breeding, fattening, slaughtering and distribution.

8. How are markets reacting?

The U.S. Department of Agriculture estimated in April a decline in Chinese hog production this year of 134 million head -- equivalent to the entire annual output of American pigs -- and the worst slump since the department began counting China’s pigs in the mid 1970s. That could mean a 10 percent reduction in Chinese pork production this year, leading to a 41 percent jump in pork imports and a 15 percent increase in foreign beef purchases, the USDA said. Wholesale pork prices in China are already 27 percent higher than a year ago. On the Dalian Commodity Exchange, soybean meal prices have tumbled 19 percent over the same time on concern the disease will cut demand for the animal feed ingredient. China’s stock market is predicting that the Year of the Pig will bring windfall profits to China’s large publicly owned swine operators. WH Group Ltd., the world’s biggest pork company, has surged 44 percent since the first outbreak, while shares in Muyuan Foodstuff Co., a pig breeder and animal feed producer, have more than doubled.

To contact Bloomberg News staff for this story: Jason Gale in Melbourne at j.gale@bloomberg.net

To contact the editors responsible for this story: Brian Bremner at bbremner@bloomberg.net, Grant Clark

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