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Ito S, Kawaguchi N, Bosch J, Aguilar-Vega C, Sánchez-Vizcaíno JM. What can we learn from the five-year African swine fever epidemic in Asia? Front Vet Sci 2023; 10:1273417. [PMID: 37841468 PMCID: PMC10569053 DOI: 10.3389/fvets.2023.1273417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Today's global swine industry is exposed to the unprecedented threat of African swine fever (ASF). Asia, the site of the most recent epidemics, could serve as a huge viral reservoir for the rest of the world given the severity of the damage, the huge swine industry, and the high volume of trade with other countries around the world. As the majority of ASF notifications in Asia today originate from pig farms, the movement of live pigs and associated pork products are considered critical control points for disease management. Particularly, small-scale or backyard farms with low biosecurity levels are considered major risk factors. Meanwhile, wild boars account for most notified cases in some countries and regions, which makes the epidemiological scenario different from that in other Asian countries. As such, the current epidemic situation and higher risk factors differ widely between these countries. A variety of studies on ASF control have been conducted and many valuable insights have been obtained in Asia; nevertheless, the overall picture of the epidemic is still unclear. The purpose of this review is to provide an accurate picture of the epidemic situation across Asia, focusing on each subregion to comprehensively explain the disease outbreak. The knowledge gained from the ASF epidemics experienced in Asia over the past 5 years would be useful for disease control in areas that are already infected, such as Europe, as well as for non-affected areas to address preventive measures. To this end, the review includes two aspects: a descriptive analytical review based on publicly available databases showing overall epidemic trends, and an individualized review at the subregional level based on the available literature.
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Affiliation(s)
- Satoshi Ito
- VISAVET Health Surveillance Center, Complutense University of Madrid, Madrid, Spain
- Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain
| | - Nijiho Kawaguchi
- VISAVET Health Surveillance Center, Complutense University of Madrid, Madrid, Spain
- Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain
- Division of Molecular Pathobiology, Hokkaido University International Institute for Zoonosis Control, Sapporo, Japan
| | - Jaime Bosch
- VISAVET Health Surveillance Center, Complutense University of Madrid, Madrid, Spain
- Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain
| | - Cecilia Aguilar-Vega
- VISAVET Health Surveillance Center, Complutense University of Madrid, Madrid, Spain
- Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain
| | - Jose Manuel Sánchez-Vizcaíno
- VISAVET Health Surveillance Center, Complutense University of Madrid, Madrid, Spain
- Department of Animal Health, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain
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2
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Yoo DS, Cho KH, Hong SK, Kang HE, Park JY. Data-driven risk assessment of the incursion of African swine fever virus via pig products brought illegally into South Korea by travelers based on the temporal relationship between outbreaks in China. Front Vet Sci 2023; 10:994749. [PMID: 37077945 PMCID: PMC10106568 DOI: 10.3389/fvets.2023.994749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 02/27/2023] [Indexed: 04/05/2023] Open
Abstract
Since 2018, Asian countries have been affected by the African swine fever (ASF) virus, with major socioeconomic consequences. Moreover, the number of people traveling in Asian countries has been increasing, leading to an inevitable increase in the risk of ASF spread through livestock products carried by travelers. China and South Korea have close geo-economic ties and numerous international travelers. After the ASF outbreak in China in 2018, many illegally imported pig products (IIPPs) that were confiscated from travelers from China at the port of entry in South Korea tested positive for ASF. The detection of ASF virus (ASFV)-positive IIPPs highlights the need to further assess the risk of incursion by travelers and review the existing prevention strategies. Here, we investigated the temporal relationship between ASF outbreaks in China and the detection of ASFV-positive IIPPs in randomly confiscated samples from all ports of entry, such as flights and ships to South Korea, from 2018 to 2019 using a cross-correlation analysis. Based on the significantly correlated temporal lags between the bivariate time-series data, a risk assessment model, using the Bayesian framework, was built to estimate the distribution of the parameters for the risk assessment model and the monthly probability of ASF being introduced via IIPPs from China to South Korea. ASF outbreaks in China were significantly associated with the detection of ASFV-positive IIPPs in South Korea 5 months later. Hence, the monthly probability of ASFV-infected pig products imported from China via a traveler to South Korea was estimated to be 2.00 × 10−5, corresponding to a 0.98 mean monthly probability of at least one ASF-infected pig product arriving at ports of entry via travelers, from 2018 to 2019. To our knowledge, this study is the first attempt to estimate the risk of ASF introduction via pig products carried by international travelers to all ports from neighboring countries in the Asian region using commonly exchanged observed data. The data presented in this study can be used to refine the intervention strategies to combat the spread of transboundary animal diseases.
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Affiliation(s)
- Dae-Sung Yoo
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea
- College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea
| | - Ki-Hyun Cho
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea
| | - Seong-Keun Hong
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea
| | - Hae-Eun Kang
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea
| | - Jee-Yong Park
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea
- *Correspondence: Jee-Yong Park
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Liu H, Ren Y, Wang T, Shan H, Wong KW. Fuzzy model for quantitative assessment of the epidemic risk of African Swine Fever within Australia. Prev Vet Med 2023; 213:105884. [PMID: 36848867 DOI: 10.1016/j.prevetmed.2023.105884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/17/2023] [Accepted: 02/20/2023] [Indexed: 02/23/2023]
Abstract
African Swine Fever (ASF) has spread rapidly across different continents since 2007 and caused huge biosecurity threats and economic losses. Establishing an effective risk assessment model is of great importance for ASF prevention, especially for those ASF-free countries such as Australia. With a vast territory and an economy heavily relying on primary industry, Australia faces a threat from the spread of ASF. Although ordinary quarantine measures have been well-performed throughout Australia, there is still a need to develop an effective risk assessment model to understand the spread of ASF due to the strong transmission ability of ASF. In this paper, via a comprehensive literature review, and analyzing the transmission factors of ASF, we provide a fuzzy model to assess the epidemic risk of Australian states and territories, under the assumption that ASF has entered Australia. As demonstrated in this work, although the pandemic risk of ASF in Australia is relatively low, there is a risk of irregular and scattered outbreaks, with Victoria (VIC) and New South Wales (NSW) - Australia Capital Territory (NSW-ACT) showed the highest risk. The reliability of this model was also systematically tested by a conjoint analysis model. To our knowledge, this is the first study to comprehensively analyze the ASF epidemic risk in a country using fuzzy modeling. This work can provide an understanding of the risk ASF transmission within Australia based on the fuzzy modeling, the same methodology can also provide insights and useful information for the establishment of fuzzy models to perform the ASF risk assessment for other countries.
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Affiliation(s)
- Hongkun Liu
- College of Veterinary Medicine, Qingdao Agriculture University, Qingdao, PR China; Murdoch University, 90 South Street, Murdoch, WA 6150, Australia.
| | - YongLin Ren
- Murdoch University, 90 South Street, Murdoch, WA 6150, Australia
| | - Tao Wang
- Telethon Kids Institute, the University of Western Australia, Perth, WA, 6872, Australia
| | - Hu Shan
- College of Veterinary Medicine, Qingdao Agriculture University, Qingdao, PR China.
| | - Kok Wai Wong
- Murdoch University, 90 South Street, Murdoch, WA 6150, Australia.
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4
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Development of an Effective Oral Vaccine Dissemination Strategy against Classical Swine Fever for Wild Boar in Gifu Prefecture, Japan. Transbound Emerg Dis 2023. [DOI: 10.1155/2023/9484441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
In September 2018, classical swine fever (CSF) reemerged in Japan after more than a quarter of a century. After the first notification on a pig farm, wild boars positive for CSF were found continuously in the surrounding area. Gifu was the first prefecture in Japan to disseminate oral vaccines to wild boars in March 2019, with vaccines spread to approximately 14,000 sites between 2019 and 2020. While these diligent measures seemed to have shown some effectiveness, several vaccine spray sites remained without wild boar emergence. Based on the vaccine dissemination records from these periods, this study conducted a statistical analysis to propose more effective vaccine dissemination sites. First, a generalized linear mixed model was used to identify factors correlated with wild boar emergence. Then, two spatial interpolation methods, inverse distance weighted (IDW) and Kriging, were adopted to create a probability map of wild boar emergence for the entire Gifu Prefecture. The analysis showed a positive correlation between wild boar emergence and the appearance of raccoons, raccoon dogs, and crows as well as road density and wild boar distribution index. In particular, raccoon (OR: 1.83, 95%CI: 1.25–2.68,
< 0.001), raccoon dog (OR: 1.81, 95%CI: 1.25–2.66,
< 0.001), and medium level road density (OR: 1.56, 95%CI: 1.04–2.39,
= 0.04) were strongly correlated with wild boar emergence. The spatial interpolation approach resulted in better prediction accuracy for the Kriging method than for IDW by the root mean square error, but both approaches identified a high wild boar appearance probability area in southeastern Gifu and a low appearance probability area in central Gifu. Here we have demonstrated a tool to effectively disperse oral vaccine to wildlife.
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Liu H, Meng F, Nyaruaba R, He P, Hong W, Jiang M, Liu D, Zhou W, Bai D, Yu J, Wei H. A triton X-100 assisted PMAxx-qPCR assay for rapid assessment of infectious African swine fever virus. Front Microbiol 2022; 13:1062544. [PMID: 36545208 PMCID: PMC9760672 DOI: 10.3389/fmicb.2022.1062544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/09/2022] [Indexed: 12/07/2022] Open
Abstract
Introduction African Swine Fever (ASF) is a highly infectious disease of pigs, caused by African swine fever virus (ASFV). The lack of vaccines and drugs makes strict disinfection practices to be one of the main measurements to curb the transmission of ASF. Therefore, it is important to assess if all viruses are inactivated after disinfection or after long time exposure in their natural conditions. Currently, the infectivity of ASFV is determined by virus isolation and culture in a biosafety level 3 (BSL-3) laboratory. However, BSL-3 laboratories are not readily available, need skilled expertise and may be time consuming. Methods In this study, a Triton X-100 assisted PMAxx-qPCR method was developed for rapid assessment of infectious ASFV in samples. PMAxx, an improved version of propidium monoazide (PMA), can covalently cross-link with naked ASFV-DNA or DNA inside inactivated ASFV virions under assistance of 0.1% (v/v) TritonX-100, but not with ASFV-DNA inside live virions. Formation of PMAxx-DNA conjugates prevents PCR amplification, leaving only infectious virions to be detected. Under optimum conditions, the limit of detection of the PMAxx-qPCR assay was 2.32log10HAD50/mL of infectious ASFV. Testing different samples showed that the PMAxx-qPCR assay was effective to evaluate intact ASFV virions after treatment by heat or chemical disinfectants and in simulated samples such as swine tissue homogenate, swine saliva swabs, and environmental swabs. However, whole-blood and saliva need to be diluted before testing because they may inhibit the PCR reaction or the cross-linking of PMAxx with DNA. Conclusion The Triton X-100 assisted PMAxx-qPCR assay took less than 3 h from sample to result, offering an easier and faster way for assessing infectious ASFV in samples from places like pig farms and pork markets.
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Affiliation(s)
- Huan Liu
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Fei Meng
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China
| | - Raphael Nyaruaba
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ping He
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wei Hong
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Mengwei Jiang
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China
| | - Dongqing Liu
- Comprehensive Agricultural Law Enforcement Bureau, Wuhan, China
| | - Wenhao Zhou
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Dan Bai
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Junping Yu
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China,*Correspondence: Junping Yu,
| | - Hongping Wei
- CAS Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China,African Swine Fever Regional Laboratory of China (Wuhan), Wuhan, China,Hongping Wei,
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Teng KTY, Chang CC, Tsai YL, Chiu CY, Yang CY, Chou CC. A stochastic assessment to quantify the risk of introduction of African swine fever virus to Taiwan via illegal pork products carried by international travellers. Transbound Emerg Dis 2021; 69:e592-e604. [PMID: 34564956 DOI: 10.1111/tbed.14337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/29/2021] [Accepted: 09/23/2021] [Indexed: 11/27/2022]
Abstract
The current study quantified the risk of releasing African swine fever virus (ASFV) into Taiwan from pork products illegally carried by international travellers from 157 countries or territories through six international airports and three international seaports. The association between various factors and the number of pork products detected by the border control authorities was also examined. The risk was estimated with a stochastic process after modelling the number of undetected illegal pork products, probability of pork product detection at international airports and seaports and probability of ASFV contamination of pork products from various countries. The overall annual probability of ASFV release to Taiwan was estimated to be 1 [95% confidence interval (CI): 1-1] under no enhanced mitigation measures. All the median airport-level risks were higher than .921, and four of them reached 1. The total annual risk was .570 (95% CI: .109-.937) for international seaports. The country or territory level risk was estimated to be 1 for Vietnam, China, Hong Kong, the Philippines and South Korea, .999 (95% CI: .628-1) for Macao and .967 (95% CI: .359-1) for Indonesia. After the total number of travellers was factored in, the number of detected illegal pork products was the highest in January and February, and travellers from Vietnam [risk ratio to Japan (RR): 80.45; 95% CI: 58.68-110.3], the Philippines (RR: 37.67; 95% CI: 26.9-52.74) and Cambodia (RR: 28.39; 95% CI: 12.69-63.51) were most likely to bring pork products to Taiwan. Our study indicated a high risk of ASFV introduction through international travellers and also identified the factors associated with the risk. This information can be used as empirical evidence for cost-effective risk mitigation practices.
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Affiliation(s)
- Kendy Tzu-Yun Teng
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei City, Taiwan
| | - Chao-Chin Chang
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung City, Taiwan
| | - Yi-Lun Tsai
- Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung County, Taiwan
| | - Chun-Yao Chiu
- Animal Quarantine Division, Bureau of Animal and Plant Health Inspection and Quarantine, Council of Agriculture, Executive Yuan, Taipei City, Taiwan
| | - Cheng-Yao Yang
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung City, Taiwan
| | - Chin-Cheng Chou
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei City, Taiwan
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7
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Kim YJ, Park B, Kang HE. Control measures to African swine fever outbreak: active response in South Korea, preparation for the future, and cooperation. J Vet Sci 2021; 22:e13. [PMID: 33522165 PMCID: PMC7850787 DOI: 10.4142/jvs.2021.22.e13] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/08/2020] [Accepted: 12/13/2020] [Indexed: 11/25/2022] Open
Abstract
African swine fever (ASF) is one of the most complex infectious swine diseases and the greatest concern to the pig industry owing to its high mortality and no effective vaccines available to prevent the disease. Since the first outbreak of ASF in pig farms, ASF has been identified in 14 pig farms in four cities/counties in South Korea. The outbreak was resolved in a short period because of the immediate control measures and cooperative efforts. This paper reviews the ASF outbreak and the experience of successfully stopping ASF in pig farms in South Korea through active responses to prevent the spread of ASF. In addition, suitable changes to build a sustainable pig production system and collaborative efforts to overcome the dangerous animal disease, such as ASF, are discussed.
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Affiliation(s)
- Yong Joo Kim
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea
| | - Bongkyun Park
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea.,Department of Veterinary Medicine Virology Lab, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 08826, Korea
| | - Hae Eun Kang
- Foreign Animal Disease Division, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea.
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8
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Mauroy A, Depoorter P, Saegerman C, Cay B, De Regge N, Filippitzi ME, Fischer C, Laitat M, Maes D, Morelle K, Nauwynck H, Simons X, van den Berg T, Van Huffel X, Thiry E, Dewulf J. Semi-quantitative risk assessment by expert elicitation of potential introduction routes of African swine fever from wild reservoir to domestic pig industry and subsequent spread during the Belgian outbreak (2018-2019). Transbound Emerg Dis 2021; 68:2761-2773. [PMID: 33713549 DOI: 10.1111/tbed.14067] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 01/29/2021] [Accepted: 03/08/2021] [Indexed: 12/01/2022]
Abstract
Since the introduction in Georgia in 2007 of an African swine fever (ASF) genotype 2 virus strain, the virus has rapidly spread to both Western European and Asian countries. It now constitutes a major threat for the global swine industry. The ongoing European transmission cycle has been related to the 'wild boar habitat' with closed transmission events between wild boar populations and incidental spillovers to commercial and non-commercial (backyard) pig holdings. During the epidemic in Belgium, only wild boar were infected and although the introduction route has not yet been elucidated, the 'human factor' is highly suspected. While ASF was successfully contained in a small region in the Southern part of Belgium without affecting domestic pigs, the risk of spillover at the wild/domestic interface remains poorly assessed. In this study, we used a semi-quantitative method, involving national and international experts, to assess the risk associated with different transmission routes for ASF introduction from wild boar to domestic pig holdings and subsequent dissemination between holdings in the Belgian epidemiological context. Qualitative responses obtained by our questionnaire were numerically transformed and statistically processed to provide a semi-quantitative assessment of the occurrence of the hazard and a ranking of all transmission routes. 'Farmer', 'bedding material', 'veterinarian' and 'professionals from the pig sector' were considered as the most important transmission routes for ASF introduction from the wild reservoir to pig holdings. 'Animal movements', 'farmer', 'veterinarian', 'iatrogenic', 'animal transport truck' and 'animal care equipment' were considered as the most important transmission routes posing a risk of ASF spread between pig holdings. Combined with specific biosecurity checks in the holdings, this assessment helps in prioritizing risk mitigation measures against ASF introduction and further spread in the domestic pig industry, particularly while the ASF situation in Western Europe is worsening.
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Affiliation(s)
- Axel Mauroy
- Staff Direction for Risk Assessment, Directorate General Control Policy, Federal Agency for the Safety of the Food Chain, Bruxelles, Belgium
| | - Pieter Depoorter
- Staff Direction for Risk Assessment, Directorate General Control Policy, Federal Agency for the Safety of the Food Chain, Bruxelles, Belgium
| | - Claude Saegerman
- Faculty of Veterinary Medicine, Research Unit in Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animal Health (FARAH) Centre, University of Liège, Liège, Belgium
| | - Brigitte Cay
- Service of Enzootic, Vector-Borne and Bee Diseases, Scientific Direction Infectious Diseases in Animals, Sciensano, Brussels, Belgium
| | - Nick De Regge
- Service of Enzootic, Vector-Borne and Bee Diseases, Scientific Direction Infectious Diseases in Animals, Sciensano, Brussels, Belgium
| | - Maria-Eleni Filippitzi
- Veterinary Epidemiology Unit, Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium
| | - Claude Fischer
- Dept. Nature Management, University of Applied Sciences of Western Switzerland, Geneva, Switzerland
| | - Martine Laitat
- Faculty of Veterinary Medicine, Swine Clinic, Clinical Department of Production Animals, University of Liège, Liège, Belgium
| | - Dominiek Maes
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
| | - Kevin Morelle
- Faculty of Forestry and Wood Sciences, Department of Game Management and Wildlife Biology, Czech University of Life Sciences, Prague, Czech Republic.,Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
| | - Hans Nauwynck
- Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Xavier Simons
- Veterinary Epidemiology Unit, Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium
| | | | - Xavier Van Huffel
- Staff Direction for Risk Assessment, Directorate General Control Policy, Federal Agency for the Safety of the Food Chain, Bruxelles, Belgium
| | - Etienne Thiry
- Faculty of Veterinary Medicine, Veterinary Virology, FARAH Centre, University of Liège, Liège, Belgium
| | - Jeroen Dewulf
- Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Merelbeke, Belgium
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9
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Kurian A, Hall WF, Neumann EJ. African swine fever: a New Zealand perspective on epidemiological risk factors for its occurrence. N Z Vet J 2021; 69:135-146. [PMID: 33570468 DOI: 10.1080/00480169.2021.1875934] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This article reviews key epidemiological and clinical features of African swine fever (ASF). We identify particular aspects of New Zealand's pig populations (commercial, non-commercial, and wild) that may affect the risk of disease entry or spread. Review of published literature is supplemented by analysis of demographic and spatial aspects of the New Zealand commercial, non-commercial, and feral pig populations to provide context around risk factors for the disease that are most relevant to New Zealand. The current Eurasian outbreak of ASF, including recent spread into Oceania, has increased the risk of an incursion of the disease into New Zealand. Large volumes of fresh pork importation (including from countries affected by ASF), large non-commercial pig populations with substantial spatial overlap with the country's commercial industry, limited monitoring of compliance with waste food feeding regulations, and lack of mandatory premises identification for non-commercial pig holdings would likely contribute to the risk of spread of ASF in the event of an incursion. Awareness amongst veterinarians of these risk factors will contribute to national biosecurity and disease preparedness efforts in New Zealand.
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Affiliation(s)
- A Kurian
- Epi-Insight Limited, East Taieri, New Zealand
| | - W F Hall
- William Hall and Associates, Googong, NSW, Australia
| | - E J Neumann
- Epi-Insight Limited, East Taieri, New Zealand
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10
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Patterson G, Niederwerder MC, Spronk G, Dee SA. Quantification of soya-based feed ingredient entry from ASFV-positive countries to the United States by ocean freight shipping and associated seaports. Transbound Emerg Dis 2020; 68:2603-2609. [PMID: 33064921 PMCID: PMC8359260 DOI: 10.1111/tbed.13881] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/12/2020] [Indexed: 12/01/2022]
Abstract
African swine fever virus (ASFV) can survive in soya‐based products for 30 days with T ½ ranging from 9.6 to 12.9 days in soya bean meals and soya oil cake. As the United States imports soya‐based products from several ASFV‐positive countries, knowledge of the type and quantity of these specific imports, and their ports of entry (POE), is necessary information to manage risk. Using the data from the International Trade Commission Harmonized Tariff Schedule website in conjunction with pivot tables, we analysed imports across air, land and sea POE of soya‐based products from 43 ASFV‐positive countries to the United States during 2018 and 2019. In 2018, 104,366 metric tons (MT) of soya‐based products, specifically conventional and organic soya bean meal, soya beans, soya oil cake and soya oil were imported from these countries into the United States via seaports only. The two largest suppliers were China (52.7%, 55,034 MT) and the Ukraine (42.9%, 44,775 MT). In 2019, 73,331 MT entered the United States and 54.7% (40,143 MT) came from the Ukraine and 8.4% (6,182 MT) from China. Regarding POE, 80.9%–83.2% of soya‐based imports from China entered the United States at the seaports of San Francisco, CA, and Seattle, WA, while 89.4%–100% entered from the Ukraine via the seaports of New Orleans, LA, and Charlotte, NC. Analysis of five‐year trends (2015–2019) of the volume of soya imports from China indicated reduction over time (with a noticeably sharp decrease between 2018 and 2019), and seaport utilization was consistent. In contrast, volume remained high for Ukrainian soya imports, and seaport utilization was inconsistent. Overall, this exercise introduced a new approach to collect objective data on an important risk factor, providing researchers, government officials and industry stakeholders a means to objectively identify and quantify potential channels of foreign animal disease entry into the United States.
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Affiliation(s)
| | - Megan C Niederwerder
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Gordon Spronk
- Pipestone Applied Research, Pipestone Veterinary Services, Pipestone, MN, USA
| | - Scott A Dee
- Pipestone Applied Research, Pipestone Veterinary Services, Pipestone, MN, USA
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Makita K, Steenbergen E, Haruta L, Hossain S, Nakahara Y, Tamura Y, Watanabe T, Kadowaki H, Asakura S. Quantitative Understanding of the Decision-Making Process for Farm Biosecurity Among Japanese Livestock Farmers Using the KAP-Capacity Framework. Front Vet Sci 2020; 7:614. [PMID: 33062651 PMCID: PMC7517466 DOI: 10.3389/fvets.2020.00614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/29/2020] [Indexed: 11/13/2022] Open
Abstract
In a globalized world, the frequency of transboundary livestock infectious diseases is increasing, and strengthening of farm biosecurity is vital to stabilize food production. The aim of this study was to understand the decision-making process for farm biosecurity among Japanese livestock farmers. Postal surveys using structured questionnaires were conducted on beef, dairy, pig, and layer farms in Hokkaido and Saitama Prefectures, which represent the principal production area and peri-urban Tokyo, respectively, as well as randomly selected broiler farms across Japan. The question items included the attributes of farms and owners, disease experiences, related associations and sources of hygiene information, attitude toward hygiene management, and compliance with the Standards of Rearing Hygiene Management (SRHM). The compliance rates were compared between livestock sectors. Univariable analyses were conducted using combined data from both prefectures, with the compliance rate as the outcome variable and the questionnaire items as explanatory variables, in generalized linear models. Exploratory factor analyses were conducted using the variables with p < 0.2 in the univariable analyses. The factors identified were classified into knowledge, attitude, capacity, practice, and structural equation modeling (SEM) was performed. The questionnaires were completed and returned by 97 and 66 beef cattle, 86 and 136 dairy, 67 and 45 pig, 20 and 39 layer farmers in Hokkaido and Saitama Prefectures, respectively, and 95 broiler farms. The compliance rate was significantly higher among broiler farms (88.9%) compared with the other sectors, followed by pig (77.1%), layer (67.2%), dairy (63.8%), and beef (59.1%) farms in Hokkaido Prefecture, and layer (64.9%), pig (60.0%), dairy (58.5%), and beef (57.6%) farms in Saitama Prefecture. Based on SEM, the decision-making process from greater knowledge to higher attitude, and from higher attitude to greater compliance with the SRHM were significant (p < 0.01) in all sectors. Higher capacity was significantly associated with higher knowledge in dairy, pig,break and layer farms (p < 0.01), and with higher compliance in beef, pig, and layer farms (p < 0.05). These results suggest that the provision of targeted hygiene knowledge to livestock farmers and the support to smallholder farms would improve biosecurity through elevated attitudes and self-efficacy.
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Affiliation(s)
- Kohei Makita
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Elly Steenbergen
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.,Quantitative Veterinary Epidemiology Group, Wageningen University & Research, Wageningen, Netherlands
| | - Lisa Haruta
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Saddam Hossain
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.,Department of Medicine and Surgery, Faculty of Veterinary Medicine, Chittagong Veterinary and Animal Sciences University, Chittagong, Bangladesh
| | - Yuki Nakahara
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Yuto Tamura
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Takuto Watanabe
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Hazumu Kadowaki
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Shingo Asakura
- Veterinary Epidemiology Unit, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
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12
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Lu G, Pan J, Ou J, Shao R, Hu X, Wang C, Li S. African horse sickness: Its emergence in Thailand and potential threat to other Asian countries. Transbound Emerg Dis 2020; 67:1751-1753. [PMID: 32406171 DOI: 10.1111/tbed.13625] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Gang Lu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou, China
- Guangdong Technological Engineering Research Center for Pet, Guangzhou, China
| | - Jialiang Pan
- General Station of Forest and Grassland Pest Management, National Forestry and Grassland Administration, Shenyang, China
| | - Jiajun Ou
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou, China
- Guangdong Technological Engineering Research Center for Pet, Guangzhou, China
| | - Ran Shao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou, China
- Guangdong Technological Engineering Research Center for Pet, Guangzhou, China
| | - Xue Hu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou, China
- Guangdong Technological Engineering Research Center for Pet, Guangzhou, China
| | - Caiying Wang
- Guangdong Huangcun Sports Training Center, Guangzhou, China
| | - Shoujun Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Prevention and Control for Severe Clinical Animal Diseases, Guangzhou, China
- Guangdong Technological Engineering Research Center for Pet, Guangzhou, China
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13
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Bosch J, Barasona JA, Cadenas-Fernández E, Jurado C, Pintore A, Denurra D, Cherchi M, Vicente J, Sánchez-Vizcaíno JM. Retrospective spatial analysis for African swine fever in endemic areas to assess interactions between susceptible host populations. PLoS One 2020; 15:e0233473. [PMID: 32469923 PMCID: PMC7259610 DOI: 10.1371/journal.pone.0233473] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/05/2020] [Indexed: 12/21/2022] Open
Abstract
African Swine Fever (ASF) is one of the most complex and significant diseases from a sanitary-economic perspective currently affecting the world's swine-farming industry. ASF has been endemic in Sardinia (Italy) since 1978, and several control and eradication programmes have met with limited success. In this traditional ASF endemic area, there are three susceptible host populations for this virus sharing the same habitat: wild boar, farmed domestic pigs and non-registered free-ranging pigs (known as "brado" animals). The main goal of this study was to determine and predict fine-scale spatial interactions of this multi-host system in relation to the epidemiology of ASF in the main endemic area of Sardinia, Montes-Orgosolo. To this end, simultaneous monitoring of GPS-GSM collared wild boar and free-ranging pigs sightings were performed to predict interaction indexes through latent selection difference functions with environmental, human and farming factors. Regarding epidemiological assessment, the spatial inter-specific interaction indexes obtained here were used to correlate ASF notifications in wild boar and domestic pig farms. Daily movement patterns, home ranges (between 120.7 and 2,622.8 ha) and resource selection of wild boar were obtained for the first time on the island. Overall, our prediction model showed the highest spatial interactions between wild boar and free-ranging pigs in areas close to pig farms. A spatially explicit model was obtained to map inter-specific interaction over the complete ASF-endemic area of the island. Our approach to monitoring interaction indexes may help explain the occurrence of ASF notifications in wild boar and domestic pigs on a fine-spatial scale. These results support the recent and effective eradication measures taken in Sardinia. In addition, this methodology could be extrapolated to apply in the current epidemiological scenarios of ASF in Eurasia, where exist multi-host systems involving free-ranging pigs and wild boar.
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Affiliation(s)
- Jaime Bosch
- VISAVET Health Surveillance Centre, Animal Health Department, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain
| | - Jose A. Barasona
- VISAVET Health Surveillance Centre, Animal Health Department, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain
| | - Estefanía Cadenas-Fernández
- VISAVET Health Surveillance Centre, Animal Health Department, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain
| | - Cristina Jurado
- VISAVET Health Surveillance Centre, Animal Health Department, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain
| | - Antonio Pintore
- Istituto Zooprofilattico Sperimentale della Sardegna, Sardinia, Italy
| | - Daniele Denurra
- Istituto Zooprofilattico Sperimentale della Sardegna, Sardinia, Italy
| | - Marcella Cherchi
- Istituto Zooprofilattico Sperimentale della Sardegna, Sardinia, Italy
| | - Joaquín Vicente
- Spanish Wildlife Research Institute (IREC) (CSIC-UCLM), Ciudad Real, Spain
| | - Jose M. Sánchez-Vizcaíno
- VISAVET Health Surveillance Centre, Animal Health Department, Faculty of Veterinary, Complutense University of Madrid, Madrid, Spain
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14
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Sugiura K, Lei Z, Holley C, Haga T. Assessing the risk of ASFV entry into Japan through pork products illegally brought in by air passengers from China and fed to pigs in Japan. PLoS One 2020; 15:e0232132. [PMID: 32369517 PMCID: PMC7199999 DOI: 10.1371/journal.pone.0232132] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/07/2020] [Indexed: 02/04/2023] Open
Abstract
A risk assessment was conducted to assess the risk of ASFV entry into Japan through pork products illegally brought in by air passengers from China and fed to pigs in Japan. Scenario tree modelling was used with the following entry and exposure pathway considered to be the most likely route of ASF entry: an ASFV infected pork product is illegally brought into Japan by air travellers from China; this pork product is then used in a restaurant where scrap waste is recycled for animal feed and subsequently fed to pigs without being heat-treated. Input parameter values were based on surveys conducted by the authors, scientific data gathered from the literature and official data published by government agencies. The annual probability of ASFV entry into Japan via this pathway was predicted to be 0.20 (90% prediction interval: 0.00-0.90). The wide prediction interval was mainly caused by the uncertainty regarding the dose response relation of ASFV, followed by the probability of an ASF infected pig dying on affected farms, the loading of ASFV in an infected pig and the probability of an illegally imported pork product being heat-treated in China and used in restaurants. The results of scenario analysis revealed that the annual probability of ASFV entry into Japan will increase with an increase in the number of ASF affected farms in China. The probability of ASFV entry will increase substantially even if only a small proportion of Ecofeed is not heat-treated during the production process. The probability will decrease if an increased proportion of farms that feed swill apply heat-treatment before feeding swill to their pigs. These findings indicate that stringent application of heat-treatment of Ecofeed and swill is key to protecting the Japanese pig industry from the introduction of ASFV.
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Affiliation(s)
- Katsuaki Sugiura
- Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Zhihao Lei
- Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Caitlin Holley
- Regional Representation for Asian and Pacific, World Organisation for Animal Health (OIE), Bunkyo-ku, Tokyo, Japan
| | - Takeshi Haga
- Department of Veterinary Medical Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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15
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Wang Y, Xu L, Noll L, Stoy C, Porter E, Fu J, Feng Y, Peddireddi L, Liu X, Dodd KA, Jia W, Bai J. Development of a real-time PCR assay for detection of African swine fever virus with an endogenous internal control. Transbound Emerg Dis 2020; 67:2446-2454. [PMID: 32306531 DOI: 10.1111/tbed.13582] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/22/2020] [Accepted: 04/08/2020] [Indexed: 01/17/2023]
Abstract
Real-time PCR assays are highly sensitive, specific and rapid techniques for the identification of ASF virus (ASFV) (Section 3.8, OIE Terrestrial Manual, 2019). Although an ASFV p72 gene-based real-time PCR assay (a.k.a. the Zsak assay) (Journal of Clinical Microbiology, 2005, 43, 112) has been widely used for ASFV detection, several more ASFV whole genome sequences have become available in the 15 years since the design of the Zsak assay. In this study, we developed a new ASFV p72 gene-based real-time PCR after analysis of all currently available sequences of the p72 gene and multiplexed the new assay with a modified Zsak assay aiming to have a broader coverage of ASFV strain/isolates. To reduce false-negative detections, porcine house-keeping gene, beta actin (ACTB), was applied as an internal control. Eight ACTB sequences from the GenBank and 61 partial ACTB sequences generated in this study, and 1,012 p72 sequences from the GenBank and 23 p72 sequences generated at FADDL, were used for ACTB and ASFV primer and probe designs, respectively, to ensure broader host and ASFV coverage. Multiplexing ACTB in the reaction did not affect ASFV amplification. The multiplex assay was evaluated for strain/isolate coverage, sensitivity and specificity. The in silico analysis showed high ASFV strain/isolate coverage: 98.4% (978/994) of all p72 sequences currently available. The limit of detection (LOD) was 6 plasmid copies or 0.1-1 TCID50 /ml of ASFV isolates per reaction. Only targeted ASFV isolates and the viruses in the positive clinical samples were detected, indicating that the assay is highly specific (100% specificity). The test results of 26 ASFV isolates with different country origins showed that this newly developed multiplex assay performed better than the Zsak assay that has been widely accepted and used worldwide, indicating that it may be used as an alternative assay for ASFV detection.
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Affiliation(s)
- Yin Wang
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, USA
| | - Lizhe Xu
- Foreign Animal Disease Diagnostic Laboratory, NVSL, VS, APHIS, USDA, Plum Island Animal Disease Center, Orient, NY, USA
| | - Lance Noll
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA
| | - Colin Stoy
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA
| | - Elizabeth Porter
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA
| | - Jinping Fu
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA
| | - Yuan Feng
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA
| | - Lalitha Peddireddi
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, USA
| | - Xuming Liu
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, USA
| | - Kimberly A Dodd
- Foreign Animal Disease Diagnostic Laboratory, NVSL, VS, APHIS, USDA, Plum Island Animal Disease Center, Orient, NY, USA
| | - Wei Jia
- Foreign Animal Disease Diagnostic Laboratory, NVSL, VS, APHIS, USDA, Plum Island Animal Disease Center, Orient, NY, USA
| | - Jianfa Bai
- Kansas State Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, KS, USA.,Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, USA
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16
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Risk Assessment of African Swine Fever Virus Exposure to Sus scrofa in Japan Via Pork Products Brought in Air Passengers' Luggage. Pathogens 2020; 9:pathogens9040302. [PMID: 32326040 PMCID: PMC7238144 DOI: 10.3390/pathogens9040302] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/18/2020] [Accepted: 04/18/2020] [Indexed: 02/01/2023] Open
Abstract
In recent years, African swine fever (ASF) has become prevalent in many areas, including Asia. The repeated detection of the ASF virus (ASFV) genome in pork products brought in air passenger’s luggage (PPAP) was also reported from Japanese airports. In the present study, the risk of ASFV exposure to susceptible hosts in Japan via three different pathways was assessed. Two quantitative stochastic risk assessment models were built to estimate the annual probability of ASFV exposure to domestic pigs, which could be attributed to foreign job trainees or foreign tourists. A semi-quantitative stochastic model was built to assess the risk of ASFV exposure to wild boar caused by foreign tourists. The overall mean annual probability of ASFV exposure to domestic pigs via PPAP carried by foreign job trainees was 0.169 [95% confidence interval (CI): 0.000–0.600], whereas that by foreign tourists was 0.050 [95% CI: 0.000–0.214], corresponding to approximately one introduction every 5.9 and 20 years, respectively. The risk of ASFV exposure to domestic pigs was dispersed over the country, whereas that of wild boar was generally higher in the western part of Japan, indicating that the characteristics of the potential ASF risk in each prefecture were varied.
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