Tuesday, August 7, 2018

African Swine Fever's Great Leap to China

China reported its first outbreak of African Swine Fever last week despite over a decade of preparations to block the virus from entering the country. The virus appears to have made a vast intercontinental leap to Eastern China that parallels China's "Belt and Road," raising the possibility that China's new trade links may also create new vectors for the spread of disease.

On August 3 the Ministry of Agriculture and Rural Affairs announced China's first outbreak of African Swine Fever (ASF) on a farm on the outskirts of Shenyang in northeastern China. Officials said 47 pigs had died from suspected ASF infection on a 383-head pig farm in Shenyang's Shenbei New District. Officials announced they had culled over 900 pigs in the area to prevent spread of the disease. Yesterday--4 days after the outbreak--communist party news media declared that the ASF outbreak has been brought under control.

The virus is endemic in most African countries. It jumped to the Caucasus region in 2007 and has been spreading across western Russia, the Baltics, Belarus, Poland and the Czech Republic during recent years. Recent outbreaks had been reported thousands of miles from china--in Romania during June, and in Russia during July.
skinning a wild pig at a May 2018 training session on African Swine Fever prevention

Chinese officials have been on guard against the spread of ASF for many years. Two years ago, the Ministry of Agriculture's 2016-2020 plan for the swine industry warned of continuing risk of African Swine Fever spreading to China. In April 2017, the Ministry of Agriculture ordered provinces to be on high alert to prevent ASF from spreading to China. In October 2017 China's Ministry of Agriculture published an African Swine Fever emergency program notice instructing provinces to make preparations for dealing with an ASF outbreak.

Heilongjiang Province has been a focus of concern. Heilongjiang has a long Russian border and probably has China's largest population of wild pigs--a common vector of transmission. In May 2018, a technical training was held to teach officials along China's northeastern border how to detect ASF in wild pigs, investigate and control outbreaks. The training was held in Da Hing'an Ling district in the northern reaches of Heilongjiang Province and was attended by 50 workers from Inner Mongolia, Heilongjiang and Jilin Province.

Chinese authorities have focused ASF-prevention efforts on the southeastern corner of Heilongjiang Province that borders the tip of far eastern Russia that dips down to the port of Vladivostock:

It is puzzling why southeastern Heilongjiang is a focus of concern since Russian outbreaks--including the most recent on in Belgorod--were in western Russia thousands of miles from China. The closest cases were in Irkutsk in March 2017, still 1000 km west of China.

This week, after the Shenyang outbreak was discovered, investigators were sent back to a conservation district in Da Hing'an Ling in northern Heilongjiang (where the May 2018 training session was held) and to Gan'nan County in western Heilongjiang to check for signs of ASF.

This appears to be a farm to protect native breeds of pigs in a conservation area of Da Hing'an Ling, Heilongjiang Province, where an ASF monitoring investigation was conducted August 5-6, 2018.
While ASF may be under control in the area surrounding the farm near Shenyang, it seems probable that the virus is present elsewhere in China. The first announced occurrence of ASF in Liaoning Province was far from any international border and over 900 km from southeastern Heilongjiang where authorities have been watching for the disease. It seems probable ASF had been spreading for some time in China before it reached Liaoning Province.

How did ASF jump from eastern Europe to eastern China? A logical risk factor is China's "One Belt One Road" program which has been aggressively targeting new trade links with regions where ASF is present: Africa, eastern Europe, and Russia. These new trade routes also have the potential to create dangerous new vectors for the spread of disease. While China does not allow imports of livestock or meat from these countries, the virus or ticks that spread it could potentially tag along on clothing, commodities, equipment, or other materials transported from infected regions.

On August 3, China's customs administration issued an African Swine Fever alert ordering inspectors to inspect luggage, postal items, ships, airplanes and vehicles arriving from foreign regions infected with ASF and turn away or destroy any pigs, wild pigs or their products they find. But the alert was issued after the outbreak in China occurred--too late to prevent the virus from entering the country.

Chinese farms in Russia are another possible risk factor. The southeastern Mudanjiang district in Heilongjiang is also one of the most active regions in developing farming businesses across the border in Russia. With growing traffic of people, equipment, and commodities crossing the border in recent years there have been greater opportunities for viruses to spread.

Risk analysis is a good idea, but diseases tend to spread in unexpected ways. No one ever conclusively figured out how the PED virus apparently jumped from eastern China to the United States about 5 years ago. The results were devastating in the U.S. which has a lot of experience dealing with animal disease.

It is also inconvenient that China in the midst of a big project to shift swine production to northeastern provinces--which doesn't look like such a good idea now that the region is threatened with a highly contagious disease.

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