Essay On African Swine Fever

Summary

African Swine Fever is a very complex disease which currently has no treatment. The disease must be controlled with movement restrictions, biosecurity and culling infected pigs. ASF was first identified nearly 100 years ago in Kenya and since then it has spread all around the world. The disease is spread by direct contact between infected domestic and wild pigs, consumption of infected pork, soft ticks or by contaminated clothing, vehicles and equipment. ASF can live in faeces, blood and urine for many months. China has had to cull millions of pigs due to ASF and has lost 30% of its herd. This has drastically reduced China’s pork production, lead to increased imports and consumers and producers are now moving to other sources of protein. The UK has yet to be affected by ASF and this is due to the strict control measures and legislations set out by the government. This includes strict import measures and biosecurity implementations.

1.0  Introduction

African swine fever (ASF) was first discovered by Montgomery in Kenya 1921. The disease was confined to Africa until it spread to Europe and later South America. The disease was eradicated in Europe (apart from Sardinia) in the 1990s with radical control. In 2007 the disease spread out of Africa and into Georgia and in 2014 reached eastern Europe (Alonso and Galindo, 2017). Since then the disease has affected areas of Africa, America, Asia and Europe. In its acute form ASF results in high mortality, with death usually occurring within 10 days (DEFRA, not dated). It was quickly established that wild boar, along with soft ticks could be a source of infection and could be persistently infected with the virus and not show signs of the disease (Dixon et al., 2018). ASF is one of the most economically devastating and complex viral diseases in pig herds. For this reason, it is a notifiable disease (Martinez-Lopez et al., 2012). This report is going to focus on the epidemiology of transmission and legislative control of ASF. This includes the impact ASF has on economics and trade, the relevant legislation and control methods in the UK and the EU and the epidemiology of ASF.

2.0 Notifiable Disease: The Epidemiological and Legislative Basis for Control

2.1 The Significance of African Swine Fever

ASF is one of the most devastating diseases in pigs due to the infectious nature and the severe socioeconomic impacts on affected countries. Dixon et al., (2018) stated that ASF is a complex disease with a large double stranded DNA, meaning there is currently no available treatment or vaccine. Therefore, the control of ASF is based on strict quarantine, early detection, animal movement restrictions, biosecurity and slaughtering of affected animals (Dixon et al., 2018).  It is important to be able to recognise the clinical signs of AFS, however, in most cases the first introduction does not show high mortality or symptoms. Carrasco et all., (2015) said that knowledge of the characteristics of this infection, including routes of transmission, are essential for controlling and preventing ASF. In a guidance of ASF published by DEFRA (2014a) it stated that ASF is currently confirmed in many European countries, parts of Asia including Cambodia, China, Korea, Laos, Vietnam and also African countries such as South Africa.

The mass culling, pig movement restrictions and death rate contribute to the socioeconomic impacts of ASF on farmers livelihoods and pig production. Global trade is also affected as it is illegal to trade pork if it is infected with ASF (DEFRA, 2014a). ASF often impacts developing countries with resource poor farmers who rely on pigs as a cheap protein source and an additional source of income (Dixon et al., 2018). In a review by Dixon et al., (2018) it was said that as a result of outbreaks of AFS in 2014 and 2015 exports of pork in Lithuania, Poland, Estonia and Latvia were reduced by $961 million, representing up to 50% of these countries exports. This is a significant loss of exporting power and money for these countries.

Since the first outbreak of ASF in China in 2018 it has now spread to every province (Driver, 2019). ASF has had socioeconomic impacts for China and has meant there is less income from pork exports and high costs associated with importing pork and trying to eradicate the disease. These impacts would be similar in other countries currently affected with ASF. China contains more than half the world’s pig population. This could be detrimental to global trade, the pig industry and spread of the disease (Dixon et al., 2018).  The serious outbreak of ASF in China has led to a reduction in its breeding herd by over 30% resulting in 100 million pigs lost already. Losses are either due to the disease itself or producers choosing to slaughter herds and leave the industry. The shortages in pork can be met by importers from abroad which means there is a large market for exporting pork. The high demand means there has been a positive trend for pork price in recent years. However, the demand for pork in China and high global prices for pig meat may not last much longer as Chinese consumers are moving to other sources of protein including poultry, fish, eggs, sheep and beef. Chinese producers are also shifting from pig production to chicken and ducks (Stark, 2019).

2.2 Risk to the UK Pig Industry

ASF has not yet affected the UK. However, the UK is at risk from introduction of the disease as many countries in the EU are infected including; Ukraine, Serbia, Slovakia, Russia, Romania, Poland, Moldova, Lithuania, Latvia, Hungary, Bulgaria, Belgium and Estonia (DEFRA, 2014a). The UK could contract ASF from infected pigs or pig meat through imports or poor biosecurity measure such as allowing pigs to travel in contaminated lorries. Within the EU people can travel freely between countries, this puts the UK at high risk of people unknowingly bringing ASF into the country on contaminated clothing or footwear. The National Pig Association says that many UK pig workers are from infected areas of Europe which puts UK pig unit at high risk of contamination. However, the most likely route of disease into UK is from infected pig meat getting onto a pig unit. ASF will survive for months in meats and on objects such as clothes, equipment and vehicles (NPA, 2019).  As the UK is an island it does not have the risk of infection from wild boars or ticks, which is how many countries in the EU were affected. If the UK was to be infected with ASF it would devastate the UK pig industry as it would put a stop to all exports and lead to high culling of herds. The UK would struggle economically as it would have to import large amounts of pig meat to meet consumer demand.

2.3 Epidemiology of Transmission

The main way ASF virus can be transmitted between animals and countries is during direct contact between susceptible and infected pigs and wild boar. It can also be spread indirectly by consumption of meat from infected pigs (Blome et al., 2016), by bites from infected Ornithodoros spp. soft ticks by passing on infected blood and by contact with feed, clothes, equipment, bedding, footwear and vehicles contaminated by faeces, urine, blood or saliva (Penrith, 2009). ASF will survive for 70 days in blood on wooden boards, 15 weeks in putrefied blood, 140 days in salted dried hams and 11 days in faeces at room temperature (NPA, 2019). Martinez-Lopez et al., (2012) stated that socioeconomic factors such as the lack of compensation for farms to cull animals, veterinary services and clinical signs of ASF in the first stages lead to the spread of the disease within the countries and to neighbouring ones.

Wild boar and bush pigs can be persistently infected and act as a reservoir for ASF (Martinez-Lopez et al., 2012). It has been demonstrated that the virus is unable to transmit directly to domestic pigs from warthogs (Penrith and Vosloo, 2009) However, the soft ticks that inhabit warthog burrows are involved in transmission of ASF (Dixon et al., 2018). Martinez-Lopez et al., (2012) wrote that soft ticks also act as a reservoir of ASF. The ticks can transmit the disease one year after removal of the infected domestic pigs or wild pigs and allows persistence of ASF for five years. The presence of infected soft ticks and wild boars makes the eradication of ASF difficult. In Dixon et al., (2018) it is demonstrated that ASF can survive for long periods of time in a protein rich environment due to the large amount of virus shed during the infectious period. This means that wild boar and carcasses should be included in control methods.

2.4 Legislation and Control Measures for African Swine Fever in the United Kingdom and European Union

The legislation in the UK concerning ASF is The Disease of Swine Regulation 2014. This regulation implements the provisions for the control of ASF contained in Council Directive 2002/60/EC (DEFRA, 2014a). This legislation published by DEFRA (2011) includes the requirement for disease notification, measures to be taken on infected premises where disease is confirmed; such as slaughterhouse and feral pigs. It makes provisions for the establishment of protection, surveillance and infection zones following the conformation of the disease and contains provisions relating to inspection and enforcement. Failing to comply with these regulations can be a punishable offence with a fine or imprisonment.

If ASF is confirmed in the UK there is a disease control strategy set out by the Government and DEFRA. The main objective is to contain and eradicate the spread of ASF in domestic pigs and to prevent the exchange of ASF between wild and domestic pigs (DEFRA, 2014b). To prevent the spread of ASF animals must be registered to allow the government to track the movement and location of livestock (DEFRA, 2014a).

It is illegal to feed domestic or catering food waste to pigs or wild boar. This is because there is a risk of spreading ASF. Leftovers and waste food should be disposed of in secure bins where pigs and wild boar cannot eat it. In a study conducted by Cao et al., (2018) all 400 pigs in an area of China which had been fed table scraps, died a month after the first clinical signs.

There is a risk of bringing ASF to the UK if visiting one of the affected countries mentioned in section 2.2. This can happen if there is contact with pigs or wild boars and visiting any areas where wild boar may live. Before returning to the UK all clothing, footwear, vehicles and equipment should be disinfected and cleaned. This is because ASF can survive on infected faeces, blood and urine for months at a time. It is important that this is completed before any contact is made with pigs or visiting areas where wild boar live. Visitors should only be allowed on pig farms if necessary and must have entered the UK three days before the visit (NPA, 2019). If this was to be neglected then there is potential to infect a herd in the UK and if the pigs did not show any clinical signs then it could easily spread across the UK (DEFRA, 2014b).

If visiting an ASF affected area in Europe there are strict rules about bringing back any pork into the UK. This could lead to prosecution and large fines if found when entering the country. No pork should ever be allowed on pig unit as there is potential to introduce serious disease (NPA, 2019). This is due to the fact that ASF can live on pork for months and if that was to get onto a pig unit or where wild boar live it could be ingested and end up infecting UK pigs with ASF (DEFRA, 2014a).

3.0 Conclusion

ASF is an infectious, complex disease that has no treatment. The only way to control the disease is to have movement restrictions, biosecurity and eradication of infected pigs. This means ASF can have devastating socioeconomic impacts on the countries infected due to reduced income from exports and loss of production. The disease is spread by direct contact between infected and suspectable domestic and wild pigs, consumption of infected pork, soft ticks or by contaminated clothing and equipment as ASF can live in faeces, blood and urine for many months. China has lost 30% of its breeding herds due to culling measure to try to combat ASF. This has reduced the pork production greatly and lead to increased imports of pork into China, however, many consumers and producers are now moving to other sources of protein. The UK has yet to be affected by ASF and this is due to the strict control measures and legislations set out by the government. This includes biosecurity measures and good farm management. In the future it would be important to do more research into discovering a treatment or vaccine and potential resistant genes in pigs.

Reference

• Alonso, C. and Galindo, I. 2017. African swine fever virus: a review. Viruses, 9 (5), 103. [Online]. MDPI. Available from: https://www.mdpi.com/1999-4915/9/5/103 [Accessed 26th November 2019]
• Blome, S. Dixon, L. Gogin, A. Guenther, K. Guinat, C. Pfieffer, D. and Pollin, R. 2016. Transmission Routes of African Swine Fever Virus to Domestic Pigs: Current Knowledge and Future Research Directions. Veterinary Record, 178 (11). [Online]. British Veterinary Association. Available from: https://veterinaryrecord.bmj.com/content/178/11/262 [Accessed 26th November 2019] 
• Cao, P. Chen, T. Hu. R, Li. N, Li. X, Liu. Y, Luo, Y. Miao, F. Tian, K. Qiu, H. Zhang, S. and Zhou, X. 2018. Emergence of African Swine Fever in China. Transboundary and Emerging Diseases, 65 (6). [Online]. Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/tbed.12989 [Accessed 26th November 2019]
• Corrasco, L. Gomez-Villamandos, J. Mur, L. and Sanchez-Vizcaino J. 2015. An Update on the Epidemiology and Pathology of African Swine Fever. Journal of Comparative Pathology, 152, 1, 9-12. [Online]. Elsevier. Available from: https://www.sciencedirect.com/science/article/pii/S002199751400142X [Accessed 20th November 2019]
• Department for Environment, Food and Rural Affairs. 2014a. African Swine Fever: How to Spot and Report the Disease. [Online]. GOV.UK. Available from: https://www.gov.uk/guidance/african-swine-fever#history [Accessed 22nd November 2019]
• Department for Environment, Food and Rural Affairs (DEFRA). 2014b.Diease Control Strategy for African and Classical Swine Fever in Great Britain. [Online]. DEFRA. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/343406/swine-fever-asf-control-strategy-140812.pdf [Accessed 26th November 2019]
• Department for Environment, Food and Rural Affairs (DEFRA). 2011. The Disease of Swine Regulations 2014. [Online]. Agricultural Document Library University of Hertfordshire. Available from: http://adlib.everysite.co.uk/adlib/defra/content.aspx?id=1OXH0BEN62.A5NTDX8DPS9A3 [Accessed 26th November 2019]
• Department for Environment, Food and Rural Affairs (DEFRA). Not Dated. African Swine Fever. [Online]. DEFRA. Available from: https://www.daera-ni.gov.uk/articles/african-swine-fever [Accessed 26th November 2019]
• Dixon, L. Montoya, M, Reis, A and Sanchez-Cordon, P. 2018. African swine fever: A Re-emerging Viral Disease Threatening the Global Pig Industry. The Veterinary Journal, 223, 41-48. [Online]. Elsevier. Available from: https://www.sciencedirect.com/science/article/pii/S109002331730268X [Accessed 25th November 2019]
•  Driver, A. 2019. How Asia’s African Swine Fever Crisis is Transforming the Global Protein Market. [Online]. Pig World. Available from: http://www.pig-world.co.uk/news/how-asias-african-swine-fever-crisis-is-transforming-the-global-protein-market.html [Accessed 20th November 2019]
• Martinez-Lopez. B, Mur. L and Sanchez-Vizcanio. J. 2012. African Swine Fever: An Epidemiological Updated. Transboundary and Emerging Disease, 59 (1), 27-35. [Online]. Wiley Online Library. Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1865-1682.2011.01293.x [Accessed 20th November 2019]
• National Pig Association (NPA). 2019. African Swine Fever. [Online]. NPA. Available from: http://www.npa-uk.org.uk/African_Swine_Fever1.html [Accessed 22nd November 2019]
• Penrith, M and Vosloo, W. 2009. Review of African Swine Fever: Transmission, Spread and Control. Oorsigartikel, 80 (2), 58-62. [Online]. PubMed.gov. Available from: http://www.scielo.org.za/pdf/jsava/v80n2/01.pdf [Accessed 25th November 2019]
• Penrith, M. 2009. African Swine Fever. Onderstepoort Journal of Veterinary Science, 76, 91-95. [Online]. AOSIS Publishing. Available from: http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0030-24652009000100018 [Accessed 26th November 2019]
• Stark, J. 2019. Quarterly Updated: The Global Pig Price Cycle Moves Up. [Online]. Pig Progress. Available from: https://www.pigprogress.net/World-of-Pigs1/Articles/2019/9/Quarterly-update-The-global-pig-price-cycle-moves-up-478763E/ [Accessed 20th November 2019]