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| Reported ASF Outbreaks As Of August 23rd |
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Published with remarkable speed, we've an analysis of the first ASF (African Swine Fever) virus isolated in China, just three weeks after that first outbreak was reported (see Aug 3rd's China MOA: 1st Reported Outbreak Of African Swine Fever (ASF)).
Since then, and all in the last week, we've seen 3 additional outbreaks involving 4 provinces (see map above).Although widespread in Africa, it wasn't until June of 2007 that the ASF virus was detected in Europe (see African Swine Fever Virus Isolate, Georgia, 2007), possibly brought in by ASFV contaminated feed products. Within 6 months, the virus was detected in the Russian Federation (cite).
Since then the virus has been steadily making its way both west and east, increasingly affecting parts of Eastern Europe, and spreading inexorably across Russia.
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| Europe & Western Russia ASF Outbreaks In 2018 - Credit OIE WAHIS Map |
Although wild boar are a known reservoir and important vector for the virus, poor biosecurity, along with the legal and illegal transport and sale of pigs and pork products (including contaminated pig feed and bedding) are also contributors to its spread.
Exactly how ASF arrived in China (or even when) remains unknown. As the following report states, pig deaths on the first affected farm began in early July, a full month before the initial outbreak was announced.Molecular analysis, however, shows the Chinese strain is very similar to strains reported both in Africa, and Eastern Europe.
Volume 24, Number 11—November 2018
Research Letter
Molecular Characterization of African Swine Fever Virus, China, 2018
Abstract
On August 3, 2018, an outbreak of African swine fever in pigs was reported in China. We subjected a virus from an African swine fever–positive pig sample to phylogenetic analysis. This analysis showed that the causative strain belonged to the p72 genotype II and CD2v serogroup 8.
African swine fever (ASF) is a disease that is reportable to the World Health Organisation for Animal Health. This disease causes high fever, hemorrhages, ataxia, and severe depression in domestic pigs and has mortality rates approaching 100%.
Its causative agent is African swine fever virus (ASFV; family Asfarviridae, genus Asfivirus), a large, enveloped, double-stranded DNA virus (1). ASF was first described in Kenya in 1921, and was introduced into the Republic of Georgia in 2007, after which it spread into other countries in eastern Europe, including Russia (2007), Ukraine (2012), Belarus (2013), Lithuania (2014), Estonia (2014), Poland (2014), Latvia (2014), Romania (2017), the Czech Republic (2017), and Hungary (2018).
During July 1–August 1, 2018, a total of 47 of 383 pigs died on a farm in the Shenbei District of Shenyang, Liaoning Province, China. Postmortem analysis performed by local veterinarians showed an ASF-typical lesion in pig spleens that were extremely swollen and severely necrotic. Other pathologic changes included hemorrhages in tonsils and lungs, marbled lesions in mandibular and mesenteric lymph nodes, and diffuse hemorrhages in a large part of gastric serosa.
We collected samples from 2 dead pigs and 6 live pigs on this farm and sent these samples to our Biosafety Level 3 laboratory for confirmation of ASFV infection. We performed a real-time PCR for ASFV as recommended by the World Health Organisation for Animal Health protocol. Results confirmed ASFV infections in China (2).(SNIP)
ASF causes devastating socioeconomic consequences in the global pig industry, especially for countries with large-scale pig production and pork consumption. After the confirmation of ASF outbreak in China in August 2018, we characterized the causative strain, China 2018/1, by phylogenetic comparison with previous strains.
We classified this new strain as having the p72 genotype II and 100% p72 sequence identity with several strains from eastern Europe and Africa, such as Bel13/Grodno, Voronezh 2016, Mal 2011/01, and ZIM/2015/01.
On the basis of serologic typing, we found that China 2018/1 belonged to the CD2v serogroup 8. In addition, this strain had a 10-bp additional fragment (5′-GGAATATATA-3′) in its TRS when compared with several others in the homogenotype.
Because ASFV is a large DNA virus with a stable genome, it is hardly unexpected that the sequence of China 2018/1 had extremely high homology with sequences in genotype II over a wide geographic area. However, it remains to be elucidated from where China 2018/1 was introduced into China.
Dr. Ge is a virologist at the National Research Center for Exotic Animal Diseases, Animal Health and Epidemiology Center, Qingdao, China. His primary research interest is prevention and control of exotic animal diseases.
