Given the recent developments of African Swine Fever (ASF) in China, the Leman Conference is planning a special breakout session on Tuesday morning. The session will cover key aspects of the ASF virus as well as the spread of ASFV in Eastern Europe and China, important elements of ASFV transmission, and implications of the recent developments in China.
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African Swine Fever: an update as of September 3rd
Recent outbreak of African swine fever in china may have influence in the global trade market of pork during the following months.
Prevention focusing on imports and international movements is the best strategy in absence of a vaccine.
Rapid diagnostics and culling are key components of an effective eradication.
After the recent outbreak of African swine fever in China and the implications for international trade, swine health, and production we thought it would be a good idea to review the characteristics of the disease.
African swine fever (ASF) ranks third as a potential risk that could threaten the US swine industry in the swine disease matrix, from the Swine Health Information Center (SHIC). ASF is a highly contagious disease that causes hemorrhages in pigs. It is caused by a DNA virus from the Asfaviridae family. It affects pigs, warthogs, and European and American wild boars.
Clinical signs vary depending on the virulence of the virus. Severe infections can cause up to 100% mortality in 2Ͳ7 days with high fever as the main characteristic. Other relevant clinical signs are bleeding (nose or rectum), diarrhea, redness of ear, abdomen, or leg skin, respiratory disorder, loss of appetite and depression. Moderately virulent strains cause less intense symptoms as the beforehand mentioned but mortality can still range between 30-70%. ASF can also be found in a chronic form with loss of weight, discontinuous fever, respiratory signs, skin ulcers and arthritis.
Appearance of clinical signs and high mortality rates may trigger suspicion of ASF but confirmation has to be done through laboratory test. Differential diagnosis includes classical swine fever (CSF), high pathogenic porcine reproductive and respiratory syndrome (HPͲPRRS), swine erysipelas, septicemic salmonellosis and porcine dermatitis nephropathy syndrome (PDNS).
Diagnostic techniques include detection of antibodies in serum or the etiologic agent in different tissues (blood, spleen, lymph nodes, tonsil and kidney). Isolation, PCR,Haemadsorption test and Antigen detection by fluorescent antibody test are the techniques for the virus identification.
The warthog is the main reservoir of the disease and it transmits form pig to pig through a soft tick. Wild boars and other wild pigs can also carry and spread the disease. Domestic pigs usually become infected through direct contact with sick pigs or eating pig meat containing ASF virus. Also indirect spread can occur through contaminated vehicles, premises, equipment or clothes.
PREVENTION AND CONTROL
No treatment or vaccines are available at this point. Therefore the best strategies are implement strategies to avoid the introduction of the virus is to focus on import policies and movement of vehicles and people from infected countries. Rapid diagnosis and culling are the key features of a successful eradication program along with surveillance, movement controls, cleaning, and disinfection of the affected premises.
Since the disease landed in Georgia in 2007 ASF has made steady progress through Europe.Latvia, Lithuania, Poland and more recently Hungary are the last countries that reported the presence of the disease in Europe. The outbreak occurred in one of the most swine dense regions China, relatively close to the Korean peninsula. Three other cases have been reported to date. The effects of the outbreak will probably shape the global
trade of pork in the following months.
There is now a second case of African swine fever (ASF) in China. It was found in a slaughterhouse where 30 pigs died of ASF. The slaughterhouse is located in the city of Zhengzhou in the Henan province. The pigs came from Tangyuan district of the city of Jiamusi, in the Heilongjiang province, over 500 miles to northeast of the first reported herd, which was detected approximately two weeks ago.
By road, the distance from the farm to the slaughterhouse is approximately 1,400 miles, travelling through areas with high pig density. The slaughterhouse is a large commercial facility, owned by Shuanghui, part of the WH Group, the world’s largest pork producer.
Government officials are moving quickly to try to isolate the disease. The slaughterhouse has been closed with a no movement zone within a radius of approximately of 6 miles and a zone of 2 miles for destroying all pigs.
This news outbreak signals that there may be a number of concerns about the status of ASF in China. The distance between the original detection in Shenyang and this newly identified farm, as well as slaughterhouse, shows that the disease is being transported widely. The areas of concern now involve multiple Chinese provinces and heighten the likelihood of further cases.
4 key locations: Red dot, new ASF outbreak reported in slaughterhouse is located in the city of Zhengzhou in the Henan province; blue: first ASF outbreak reported in a small pig farm in district of Shenbei New, in the province of Liaoning; green dot: farm (owner Wang) located in the Hunnan District, Shenyang city, Liaoning province; purple: Tangyuan district of the city of Jiamusi, in the Heilongjiang province.
The first ASF case was officially confirmed on Aug 3, 2018 on a small farm (owner Zhang) located in the Shenbei District, Shenyang city, Liaoning province. Further investigations indicated that the owner of the ASF index farm purchased 45 pigs on July 5, 2018 from a farm (owner Wang) located in the Hunnan District, Shenyang city, Liaoning province. Fecal samples collected from Wang’s farm were confirmed ASFV RNA positive by PCR.
Wang said that the last entry of pigs onto the farm occurred on March 24, 2018. There were 100 piglets purchased from Chuanying District, Jilin city, Jilin province. In April, some pigs started to become sick and then died on the Wang farm. Wang did not report the abnormal pig death; instead the remaining live pigs were sold to the Zhang farm in Shenyang and other people. So far, all of the pigs initially from the Wang farm have been tracked and culled. Wang was held in a detention center due to violation of the laws.