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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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Oh SI, Bui NA, Bui VN, Dao DT, Cho A, Lee HG, Jung YH, Do YJ, Kim E, Bok EY, Hur TY, Lee HS. Pathobiological analysis of african swine fever virus contact-exposed pigs and estimation of the basic reproduction number of the virus in Vietnam. Porcine Health Manag 2023; 9:30. [PMID: 37386526 PMCID: PMC10311738 DOI: 10.1186/s40813-023-00330-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023] Open
Abstract
BACKGROUND African swine fever (ASF), caused by African swine fever virus (ASFV), is a fatal disease affecting wild and domestic pigs. Since China reported the first ASF outbreak in August 2018, ASFV has swept over the neighbouring Asian countries. However, studies involving experimental pig-to-pig ASFV transmission in Vietnam are lacking. The main objective of this experimental study was to demonstrate the pathobiological characteristics of ASFV contact-exposed pigs and estimate their basic reproduction number (R0) in Vietnam. Fifteen pigs were randomly divided into two groups: experimental (n = 10) and negative control (n = 5) groups. One pig in the experimental group was intramuscularly inoculated with ASFV strain from Vietnam in 2020 and housed with the uninoculated pigs during the study period (28 days). RESULTS The inoculated pig died 6 days post-inoculation, and the final survival rate was 90.0%. We started observing viremia and excretion of ASFV 10 days post-exposure in contact-exposed pigs. Unlike the surviving and negative control pigs, all necropsied pigs showed severe congestive splenomegaly and moderate-to-severe haemorrhagic lesions in the lymph nodes. The surviving pig presented with mild haemorrhagic lesions in the spleen and kidneys. We used Susceptible-Infectious-Removed models for estimating R0. The R0 values for exponential growth (EG) and maximum likelihood (ML) were calculated to be 2.916 and 4.015, respectively. In addition, the transmission rates (β) were estimated to be 0.729 (95% confidence interval [CI]: 0.379-1.765) for EG and 1.004 (95% CI: 0.283-2.450) for ML. CONCLUSIONS This study revealed pathobiological and epidemiological information in about pig-to-pig ASFV transmission. Our findings suggested that culling infected herds within a brief period of time may mitigate the spread of ASF outbreaks.
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Affiliation(s)
- Sang-Ik Oh
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
- Bio-Safety Research Institute and Laboratory of Veterinary Pathology, College of Veterinary Medicine, Jeonbuk National University, Iksan, 54596, Republic of Korea
| | - Ngoc Anh Bui
- Virology Department, National Institute of Veterinary Research, Hanoi, Vietnam
| | - Vuong Nghia Bui
- Virology Department, National Institute of Veterinary Research, Hanoi, Vietnam
| | - Duy Tung Dao
- Virology Department, National Institute of Veterinary Research, Hanoi, Vietnam
| | - Ara Cho
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Han Gyu Lee
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Young-Hun Jung
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Yoon Jung Do
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Eunju Kim
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Eun-Yeong Bok
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Tai-Young Hur
- Division of Animal Diseases & Health, Rural Development Administration, National Institute of Animal Science, Wanju, 55365, Republic of Korea
| | - Hu Suk Lee
- International Livestock Research Institute, Hanoi, Vietnam.
- College of Veterinary Medicine, Chungnam National University, Daejeon, 34134, Republic of Korea.
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Mai NT, Tuyen LA, Van Truong L, Huynh LTM, Huong PTL, Hanh VD, Anh VV, Hoa NX, Vui TQ, Sekiguchi S. Early‐phase risk assessments during the first epidemic year of African swine fever outbreaks in Vietnamese pigs. Vet Med Sci 2022; 8:1993-2004. [PMID: 35733347 PMCID: PMC9514500 DOI: 10.1002/vms3.852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Background Objectives Methods Results Conclusions
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Affiliation(s)
- Ngan Thi Mai
- Department of Veterinary Microbiology and Infectious Diseases Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Le Anh Tuyen
- Department of Veterinary Microbiology and Infectious Diseases Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Le Van Truong
- Department of Veterinary Microbiology and Infectious Diseases Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Le Thi My Huynh
- Department of Veterinary Microbiology and Infectious Diseases Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Pham Thi Lan Huong
- Department of Pharmacology, Toxicology, Internal Medicine and Diagnostics Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Vu Duc Hanh
- Department of Veterinary Anatomy, Histology and Embryology Faculty of Veterinary Medicine Vietnam National University of Agriculture Hanoi Vietnam
| | - Vu Viet Anh
- Central Laboratory Faculty of Animal Science Vietnam National University of Agriculture Hanoi Vietnam
| | - Nguyen Xuan Hoa
- Department of Veterinary Medicine Faculty of Animal Husbandry and Veterinary Medicine Hue University of Agriculture and Forestry Hue Vietnam
| | - Tran Quang Vui
- Department of Veterinary Medicine Faculty of Animal Husbandry and Veterinary Medicine Hue University of Agriculture and Forestry Hue Vietnam
| | - Satoshi Sekiguchi
- Center for Animal Disease Control University of Miyazaki Miyazaki Japan
- Department of Veterinary Science Faculty of Agriculture University of Miyazaki Miyazaki Japan
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The SLI-SC Mathematical Model of African Swine Fever Transmission among Swine Farms: The Effect of Contaminated Human Vector. AXIOMS 2022. [DOI: 10.3390/axioms11070329] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this paper, a mathematical model for African swine fever is modified by considering the swine farm with the contaminated human vector that is able to infect and spread the disease among swine farms. In the developed model, we have divided the swine farm density into three related groups, namely the susceptible swine farm compartment, latent swine farm compartment, and infectious swine farm compartment. On the other hand, the human vector population density has been separated into two classes, namely the susceptible human vector compartment and the infectious human vector compartment. After that, we use this model and a quarantine strategy to analyze the spread of the infection. In addition, the basic reproduction number R0 is determined by using the next-generation matrix, which can analyze the stability of the model. Finally, the numerical simulations of the proposed model are illustrated to confirm the results from theorems. The results showed that the transmission coefficient values per unit of time per individual between the human vector and the swine farm resulted in the spread of African swine fever.
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Lee HS, Dao TD, Huyen LTT, Bui VN, Bui AN, Ngo DT, Pham UB. Spatiotemporal Analysis and Assessment of Risk Factors in Transmission of African Swine Fever Along the Major Pig Value Chain in Lao Cai Province, Vietnam. Front Vet Sci 2022; 9:853825. [PMID: 35425836 PMCID: PMC9002011 DOI: 10.3389/fvets.2022.853825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/21/2022] [Indexed: 11/13/2022] Open
Abstract
African swine fever (ASF) is a contagious and lethal hemorrhagic disease with a case fatality rate approaching 100% in domestic pigs. The main objectives of this study were to describe the spatiotemporal analysis as well as to assess the potential risk factors along the pig value chain in Lao Cai province, Vietnam. A total of 925 outbreaks were reported from 2019 to 2020. The three clusters (primary, secondary and 5th) were observed near the Chinese border. The most temporal clusters were detected between May and August during the study period. In addition, we evaluated the association between ASF outbreak locations to the nearest main roads and elevation. For ASF outbreak locations to the nearest main roads, compared with the reference (<5,000 m), <1,000 m (10.22 times) and 1,000–2,000 m (1.98 times) were significantly higher occurrences of ASF. For elevation, compared to the reference (>1,500 m), the farm locations with <500 m (55.31 times) showed a significantly increased risk of ASF outbreaks. Farmers perceived that the highest risk of ASF transmission may come from collectors and slaughterers, intermediaries inside and outside the commune, feed agents and maize agents in the commune, and pig retailers. Both commercial and household pig producers considered minimizing the number of people going in and out of pig stables and improving healthcare and husbandry procedures to be both very important and feasible. There is a need for compliance by all pig producers and other actors in the pig value chain to adopt biosecurity practices. Therefore, awareness, knowledge and understanding of infection and risks of ASF need to be improved. Veterinary officials at the provincial and district levels need to improve capacity and resources to perform laboratory analysis for ASF and need to coordinate with local actors on the control and prevention of ASF in the community.
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Affiliation(s)
- Hu Suk Lee
- International Livestock Research Institute (ILRI), Animal and Human Health Program, Hanoi, Vietnam
- *Correspondence: Hu Suk Lee
| | - Tung Duy Dao
- Virology Department, National Institute of Veterinary Research, Hanoi, Vietnam
| | - Le Thi Thanh Huyen
- Livestock System and Environment Research Department, National Institute of Animal Science, Hanoi, Vietnam
| | - Vuong Nghia Bui
- Livestock System and Environment Research Department, National Institute of Animal Science, Hanoi, Vietnam
| | - Anh Ngoc Bui
- Livestock System and Environment Research Department, National Institute of Animal Science, Hanoi, Vietnam
| | - Dung Tien Ngo
- Lao Cai Animal Husbandry and Veterinary Branch, Lao Cai, Vietnam
| | - Uyen Ba Pham
- Lao Cai Animal Husbandry and Veterinary Branch, Lao Cai, Vietnam
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Huang Y, Li J, Zhang J, Jin Z. Dynamical analysis of the spread of African swine fever with the live pig price in China. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:8123-8148. [PMID: 34814292 DOI: 10.3934/mbe.2021403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Pork makes up the highest proportion of household expenditure on meat in China and supply and demand have been basically stable in the past decade. However, the catastrophic outbreak of African swine fever (ASF) in August 2018 disrupted the balance and reduced the national herd by half within six months. The consequence was a gross lack of supply to the market and consumer demand was unable to be met. Accordingly, live pig prices rose sharply from 2019. In order to assess the influence of ASF on the price of the live pigs, we use a price function to characterize the relationship between price of the live pigs and the nation's pig stock, and then establish a time delay ASF epidemic dynamical model with the price function. By analyzing the dynamical behaviors of the model, we calculate the basic reproductive number, discuss the stability of equilibrium, and obtain the critical conditions for Hopf bifurcation. The model reasonableness is confirmed by carrying out data fitting and parameter estimation based on price data of the live pigs, the pig stock data and the outbreak data of ASF. By performing sensitivity analysis, we intuitively show the impact of ASF on the price of live pigs and the pig stocks, and assess the key factors affecting the outbreak of ASF. The conclusion is drawn that, with the control measures adopted by related government department in China, the basic reproductive number ($ R_0 = 0.6005 $) means that the ASF epidemic has been controlled. Moreover, the price of the live pig increases linearly with $ R_0 $, while the effect of the number of infected pigs on the subsequent price is non-linear related. Our findings suggest that society and the government should pay more attention to the prevention of animal disease epidemics.
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Affiliation(s)
- Yihao Huang
- School of Computer and Information Technology, Shanxi University, Taiyuan 030006, China
- Complex Systems Research Center, Shanxi University, Taiyuan 030006, China
| | - Jing Li
- School of Applied Mathematics, Shanxi University of Finance and Economics, Taiyuan 030006, China
| | - Juan Zhang
- Complex Systems Research Center, Shanxi University, Taiyuan 030006, China
| | - Zhen Jin
- Complex Systems Research Center, Shanxi University, Taiyuan 030006, China
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