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  • Commentary
  • Open Access

African swine fever: an unprecedented disaster and challenge to China

Infectious Diseases of Poverty20187:111

https://doi.org/10.1186/s40249-018-0495-3

  • Received: 25 September 2018
  • Accepted: 18 October 2018
  • Published:

Abstract

Background

African swine fever (ASF), caused by African swine fever virus, is a hemorrhagic and often fatal disease of domestic pigs and wild boar, which is notifiable to the World Organization for Animal Health. On August 3, 2018, China reported the first outbreak of ASF in Shenyang, a northeastern city of China. As of October 8, a total of 33 ASF outbreaks were reported in eight provinces in China, the biggest pork producer and consumer in the world.

Main body

This commentary summarizes the current situation of ASF in China, measures that China has taken to control the disease, lessons learnt from other countries, challenges and recommendations on ASF control in China, and possible international collaborations on ASF.

Conclusions

ASF is an unprecedented disaster and challenge to the Chinese swine industry. It will be a formidable and protracted campaign to control ASF in China, which requires joint participation and coordination of stakeholders and agencies at different levels.

Keywords

  • African swine fever
  • Control
  • China

Multilingual abstracts

Please see Additional file 1 for translations of the abstract into the five official working languages of the United Nations.

Background

On August 3, 2018, China reported an outbreak of African swine fever (ASF) in Shenyang, a northeastern city of China [1]. This is the first emergence of ASF in China, which is the largest pork producer and consumer in the world. As of October 8, a total of 33 ASF outbreaks have been reported in eight provinces in the country (Fig. 1; Table 1). Though the ASF viral sequence in China is highly homologous to that of the Georgia 2007/1 strain [2], it remains a mystery where and how the virus came from [3]. It is speculated that the disease might have been introduced from an ASF-affected Eastern European country via smuggled pork or offals.
Fig. 1
Fig. 1

African swine fever outbreak locations in China. The provinces with African swine fever outbreaks are shaded in red; numbers and dots indicate the order and locations

Table 1

Summary of African swine fever outbreaks in China

Order

Date of confirmation

Locations (City, Province)

Susceptible

Cases

Deaths

Unit type

1

Aug. 3, 2018

Shenyang, Liaoning

19 420

47

47

Farm

2

Aug. 7, 2018

Shenyang, Liaoning

160

3

0

Farm

3

Aug. 7, 2018

Shenyang, Liaoning

55

1

0

Farm

4

Aug. 7, 2018

Shenyang, Liaoning

216

2

0

Farm

5

Aug.7, 2018

Shenyang, Liaoning

140

1

0

Farm

6

Aug. 16, 2018

Zhengzhou, Henan

1806

30

30

Slaughterhouse

7

Aug. 19, 2018

Lianyungang, Jiangsu

14 686

615

88

Farm

8

Aug. 22, 2018

Wenzhou, Zhejiang

1864

430

340

Farm

9

Aug. 30, 2018

Wuhu, Anhui

459

185

80

Farm

10

Sept. 2, 2018

Xuancheng, Anhui

285

63

42

Farm

11

Sept. 2, 2018

Xuancheng, Anhui

440

153

111

Farm

12

Sept. 3, 2018

Xuancheng, Anhui

308

152

83

Farm

13

Sept. 3, 2018

Wuxi, Jiangsu

97

12

9

Farm

14

Sept. 5, 2018

Jiamusi, Heilongjiang

87

39

12

Backyard

15

Sept. 6, 2018

Chuzhou, Anhui

886

62

22

Farm

16

Sept. 6, 2018

Jiamusi, Heilongjiang

203

26

10

Farm

17

Sept. 6, 2018

Wuhu, Anhui

30

13

4

Farm

18

Sept. 6, 2018

Xuancheng, Anhui

52

15

15

Farm

19

Sept. 10, 2018

Tongling, Anhui

219

63

23

Farm

20

Sept. 14, 2018

Xinxiang, Henan

2087

148

64

Farm

21

Sept. 14, 2018

XilinGol League, Inner Mongolia

237

16

16

Backyard

22

Sept. 17, 2018

XilinGol League, Inner Mongolia

159

14

8

Backyard

23

Sept. 21, 2018

Gongzhuling, Jilin

484

56

56

Farm

24

Sept. 21, 2018

Hinggan League, Inner Mongolia

138

23

22

Backyard

25

Sept. 24, 2018

Hohhot, Inner Mongolia

388

4

2

Slaughterhouse

26

Sept. 28, 2018

Songyuan, Jilin

44

8

3

Farm

27

Sept. 30, 2018

Yingkou, Liaoning

130

22

22

Village

28

Sept. 30, 2018

Yingkou, Liaoning

9

2

2

Village

29

Sept. 30, 2018

Yingkou, Liaoning

239

78

78

Village

30

Oct. 7, 2018

Yingkou, Liaoning

1337

65

20

Village

31

Oct. 7, 2018

Yingkou, Liaoning

2608

127

27

Village

32

Oct. 7, 2018

Yingkou, Liaoning

9382

142

46

Village

33

Oct. 8, 2018

Anshan, Liaoning

909

160

160

Farm

All Information of ASF outbreaks in China was retrieved through the World Organization for Animal Health Report and the Ministry of Agriculture and Rural Affairs of China

ASF is a hemorrhagic and often fatal disease of domestic pigs and European wild boar, and is notifiable to the World Organization for Animal Health (OIE). The disease is caused by African swine fever virus (ASFV), which is the sole member of the genus Asfivirus within the family Asfaviridae. ASFV is a tick-borne large DNA virus with complex transmission cycles among pigs, wild boar and soft ticks, and encodes more than 150 viral proteins with half of unknown functions. The virus shows high genetic and antigenic diversity. Up to now, 24 genotypes and 8 serogroups have been identified globally [4, 5].

What has China done up to now?

The Ministry of Agriculture and Rural Affairs (MARA) of China has issued a number of policies and regulations for the prevention and control of ASF before and after ASF outbreaks in China (Table 2). Following confirmation of ASF outbreaks in China, standard measures have been implemented to control the disease, including culling all the pigs within 3 km of the epidemic area, harmlessly destroying all the infected pigs and animal disposals and contaminants. Till now, around 50 000 infected and affected pigs in the 33 ASF outbreaks in China have been culled (data from OIE), and the infected farms and contaminated materials were cleaned and disinfected. Following confirmation of the first ASF outbreak in China, the MARA immediately reported this event to the OIE on the same day and launched the ASF Contingency Plan and Emergency Response Level II. A series of regulations and actions have been taken by the MARA, including pig movement restriction inside the country, surveillance outside containment and/or protection zones, screening, quarantine, official destruction of pig products, official disposal of carcasses, by-products and wastes, stamping out, control of wildlife reservoirs, zoning, and disinfection, etc.
Table 2

Regulations issued by the Ministry of Agriculture and Rural Affairs of China for the prevention and control of African swine fever

No.

Dates

Regulations

Sources

1

Sept. 13, 2018

To stop using pig’s blood products as raw materials to produce pig feed.

It is not allowed to feed pigs with untreated swills

MARA (Notice No. 64)

2

Sept. 11, 2018

To prohibit interprovincial transportation of pigs and related products from ASFV-affected provinces

MARA (No. 2018–33)

3

Aug. 10, 2018

To strengthen the supervision of pig transportation

MARA (No. 2018–38)

4

Aug. 3, 2018

To launch the ASF Contingency Plan and Emergency Response Level II

Information Office of MARA

5

May 7, 2018

To prohibit importing pigs, wild boar and related products directly or indirectly from Hungary.

MARA (Notice No. 35)

6

Feb. 14, 2018

About the prevention of ASF

MARA

7

Dec. 3, 2017

About the Implementation of Technical Specifications for Prevention and Control ASF (for trial implementation)

MOA

8

Oct. 20, 2017

About the implementation of ASF Emergency Plan

MOA

9

Apr. 14, 2017

Deployment to further strengthen risk prevention of ASF

MOA

10

Mar. 20, 2017

To strengthen the surveillance and epidemiological survey of ASF

MOA

11

Sept. 3, 2007

To prohibit to import pigs, wild boar and related products directly or indirectly from Armenia

MOA and AQSIQ (Notice No. 906)

12

Aug. 8, 2007

To prohibit to import pigs, wild boar and related products directly or indirectly from Georgia

MOA and AQSIQ (Notice No. 886)

MARA Ministry of Agriculture and Rural Affairs, formerly Ministry of Agriculture (MOA), AQSIQ Administration of Quality Supervision, Inspection and Quarantine

Challenges for ASF control in China

China has the largest swine population in the world, with 688.61 million pigs fattened in 2017, accounting for approximately 48% of the world’s pork production (Source: Livestock and Poultry: World Markets and Trade, United States Department of Agriculture, April 2018). Meanwhile, small-scale and backyard farms with low biosecurity produce more than 60% pigs in China. A well-recognized high risk is swill-feeding currently practiced in many countries including China, which is a frequent route of ASFV introduction into ASF-free countries, e.g. Spain, The Netherlands, Belgium, Cuba, and Georgia [6]. A total of 20 ASF outbreaks occurred in farms mainly practicing swill-feeding in Anhui and Liaoning provinces of China. And illegal movement and slaughter of sick pigs before diagnosis pose another risk. The uneven distribution of the pig production in China makes long-distance pigs/pork transportation unavoidable, resulting in a higher risk of spreading ASF. Moreover, due to the endemic or epidemic situation of ASF in the Russian Federation and other countries, the disease has a high possibility to be reintroduced into China.

Another challenge is wild boar and soft ticks, which are natural hosts of ASFV and are widely distributed in China. We need to know if ASFV has taken root in wild boar and ticks after continuous outbreaks.

Though various vaccines against ASF are under development, none is commercially available. Difficulties in vaccine development need to be overcome, including safety concerns, poor cross-protection, and the lack of markers for sero-surveillance.

Lessons learnt from other countries

China can learn a lot of lessons from other countries with a history of ASF. Take Spain as an example. ASF was introduced into Spain in 1967 and was not well controlled until 1985 when the European Union provided sufficient financial support to eradicate the disease. Spain established a network of mobile veterinary team and a reference laboratory for ASF surveillance and outbreak identification. Animal movement was under strict control and illegal pork transportation was forbidden. Reasonable compensation was provided for culling pigs [7].

Russia is another mirror for China. ASF has spread widely and become an endemic disease in Russia since the first introduction in 2007. The main reasons are: (1) illegal movement of infected pigs and pork products, swill-feeding, and improperly handling infected pigs; (2) circulation of ASFV in wild boar and anthropogenic factors; (3) lack of effective prevention and control measures and nationally funded eradication program; (4) absence of veterinary oversight for the large number of small holdings and backyard pig farms with low biosecurity [8, 9].

Recommendations on ASF control in China

ASF is mainly transmitted by direct contact with infected pigs or ingestion of ASFV-contaminated pork products, etc. ASFV infection can also take place when the susceptible animals get physically in contact with ASFV. At present, no effective vaccines are commercially available and its control mainly relies on early detection and rapid eradication [10]. All the responsible stakeholders, including backyard farms, pig transporters, slaughter houses, veterinary services and authorities should join together to successfully implement the ASF control strategies. Effective measures must be adopted to control the disease.

To the Chinese government, with focus on coordination of surveillance and response activities:
  • Establishing a multi-sectoral linkage mechanism, coordinating different departments to prevent and control ASF;

  • Establishing multi-line barriers and defenses;

  • Establishing a real-time monitoring, traceable pig/pork transportation system in line with biosecurity regulations; establishing inspection, quarantine and disinfection stations to control the movement of animal transportation vehicles from epidemic areas;

  • Establishing a comprehensive surveillance and screen program and early test/reporting/warning and response system nationwide;

  • Excluding small pig holders around the breeding units;

  • Monitoring wild boar and ticks;

  • Establishing a complete control system and strong technical support for disease prevention and control in epidemic, threatened and surrounding areas;

  • Developing diagnostic assays for specific and early detection of suspected cases;

  • Implementing a reasonable compensation policy;

  • Owners of pig farms obligatorily to report any suspicious cases, ill or dead pigs to local veterinary authorities.

To pig owners, with focus on improving farm biosecurity measures:
  • No introduction of pigs or semen from ASF-affected regions;

  • Avoid carrying pork or related products from the outside to the farm;

  • No addition of protein products of porcine origin in feed;

  • No entry of visitors from ASF-epidemic regions;

  • Clean and disinfect the trucks before and after pig transportation;

  • Quarantine personnel for 1 to 3 days after traveling;

  • Kill soft ticks, flies, and mosquitos.

International collaborations on ASF

ASF is a formidable transboundary disease. Since the ever-increasing personnel exchange and globalization, ASF has a high risk to be introduced into any ASF-free countries, especially Asian countries. Therefore, the battle against ASF needs the international participation.

A safe and effective vaccine is a priority for the cost-effective control of ASF in countries with a large swine population. Joint efforts on vaccine development should be made among international laboratories, including identification of virulence- and protection-associated proteins, generation and comprehensive evaluation of gene-deleted vaccine candidates with complete as well as cross-genotype protection, serological markers and no side-effects, and development of immunological parameters and assays for vaccine evaluation, etc.

Other activities include transboundary and inter-regional surveillance of ASF, information sharing, and training of young scientists, especially epidemiologists.

Conclusions

ASF is a highly devastating swine disease. Undoubtedly, the emergence and spread of ASF in China, the largest pork producer in the world, is an unprecedented disaster. To control ASF in China, where there are a large number of small holders and frequent pig/pork transportation, is a challenging and long-lasting battle that needs the joint participation and coordination of all stakeholders nationally and internationally.

Abbreviations

ASF: 

African swine fever

ASFV: 

African swine fever virus

MARA: 

Ministry of Agriculture and Rural Affairs

OIE: 

World Organization for Animal Health

Declarations

Acknowledgements

We thank Dr. Lihong Liu, National Veterinary Institute (SVA), Uppsala, Sweden, and Drs. Teshale Teklue and Yuzi Luo for revision of the manuscript.

Funding

This work was supported by the National Key Research and Development Program of China (No. 2017YFD0500601).

Availability of data and materials

Not applicable.

Authors’ contributions

Tao Wang and Yuan Sun wrote the manuscript. Hua-Ji Qiu conceived and revised the manuscript. All authors read and approved the final manuscript.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, 150069, China

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Copyright

© The Author(s). 2018

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