African Swine Fever Outbreaks Research Articles

Web-scraping applied to acquire difficult to access animal disease outbreak information, using African Swine Fever in Europe as an example.

Surveillance data are key to informing decisions on the control and prevention of transboundary and emerging diseases. Here, we describe new methods for acquiring difficult to access, publicly available disease surveillance data. We use World Organisation for Animal Heath (OIE) data on African Swine Fever (ASF) outbreaks in European countries to showcase the importance of adequate disease surveillance data to inform decision-making. The data acquired using these methods allow for large scale, geospatial outbreak mapping and estimation of summary statistics for any listed terrestrial disease in the OIE World Animal Health Information System (WAHIS) database. These techniques will make valuable epidemiological data more accessible to the scientific community, aiding further insight into the occurrence and spread of transboundary and emerging diseases in a timely manner, fulfilling an important function of disease surveillance.

Genome Sequence of a Virulent African Swine Fever Virus Isolated in 2020 from a Domestic Pig in Northern Vietnam.

This study reports the genome sequence of an isolated African swine fever (ASF) virus (VNUA-ASFV-05L1/HaNam) obtained at the fourth passage on pulmonary alveolar macrophages. The virus was isolated during a typical acute ASF outbreak in pigs in a northern province of Vietnam in 2020.

Epidemic situation and control measures of African Swine Fever Outbreaks in China 2018-2020.

As of 21 April 2020, 176 ASF outbreaks have occurred in China. For each outbreak, an investigation was conducted, including historical data retrieval and traceability of potential contacts. The purpose of this study is to conduct a preliminary analysis of the data obtained from the outbreak investigations, including an investigation of the possible contributing factors of the spread of ASF in China. Based on the epidemic situation and the policies issued, the entire epidemic can be divided into three phases. 71 outbreaks were reported between 3 August 2018 and 17 November 2018; 44 outbreaks between 19 November 2018 and 30 March 2019; and 61 outbreaks between 4 April 2019 and 12 April 2020. Based on the reported outbreaks, the proportional rate of outbreaks in small farms (livestock≤500, 127/168) is significantly higher than that of medium (501≤livestock<2,000, 14/168; 2001≤livestock≤5,000, 9/168) and large farms (livestock≥5,001, 18/168). The odds of infection related to swill feeding (OR=2.5, 95% CI, 1.5-4.3) and the mechanical dissemination of vehicles and personnel (OR=2.7, 95% CI, 1.6-4.5) are significantly higher than those of pigs and pig production transportation. Swill feeding is the major contributing factor for small farms while mechanical dissemination of vehicles and personnel is the major contributing factor for large farms. The average duration from the beginning of the infection to the official outbreak report is gradually decreasing, which means that response speed of industry entities and the animal husbandry and veterinary departments from the beginning of the infection to the outbreak report is gradually increasing. Based on the analysis for ASF outbreaks, some policies and suggestions were put forward, such as improving the biosecurity level of the farms, as well as strengthening the supervision of breeding, transportation and slaughter.

Disease surveillance in England and Wales, April 2021

Disease surveillance in England and Wales, April 2021

Impacts of African swine fever on water quality in China

The outbreak of African swine fever (ASF) in China has significantly reduced the country’s pig production capability, whilst also having far-reaching impacts on livestock products supply in the wider food system. Previous studies have quantified the potential long-terms impacts on food prices, however, little information is available regarding the direct short-term impacts on food system changes (livestock products supply and consumption patterns) and water quality protection associated with the outbreak. Here, we used multiple sources of data in relation to consumption patterns and water quality to fill this knowledge gap. Our results indicate that the ASF outbreak has changed the short-term livestock products consumption pattern in China, with increasing reliance on importation of livestock products. A rapid change in pork self-sufficiency rate has also driven a rapid increase in the consumer price index of many cities. Banned swill feeding and reversed environmental regulations in the watercourse intense regions has unintended consequences, especially on water quality. Swill, which is no longer fed, was dumped into water waste streams and lowered the sewage treatment efficiency. The re-establishment of pig production back into watercourse intense regions has led to exceedance of local manure nutrient loading capacity of agricultural land. We suggest (a) a short-term intermediate policy to prohibit discharge of swill to sewage systems, to return their previous efficiency, (b) the development of new technologies for the safe recycling of swills, and (c) the design of a long-term intelligent spatial planning of pig production, slaughter and transportation within China to ensure continued protection of water quality vulnerable zones.

Doing the “dirty work”: how hunters were enlisted in sanitary rituals and wild boars destruction to fight Belgium's ASF (African Swine Fever) outbreak

In the early autumn of 2018, a virus as contagious as it is deadly, carried by wild boars (Sus scrofa Linnaeus, 1758) with the probable involvement of humans, crossed the Belgian border. African swine fever, which only affects suidae, is rapidly spreading in the forests of Gauma. The boar, whose status has gradually shifted from a regional emblem to a symbol of hunting abuses, finds itself abruptly transformed into a sanitary threat needing to be eliminated. The wild swine can contaminate its domestic cousin, the farmed pig (Sus domesticus Erxleben, 1777). Therefore, the spread of the virus would jeopardise the fragile Belgian pig farming sector concentrated in the north of the country. This is the start of a crisis that will last for more than 24 months; the infected forest is zoned and then isolated for the purpose of sanitisation, while “biosecurity” and “white zone” become the only watchwords. Mass destruction measures for wild boars are imposed by the administration and its experts through new so-called “sanitary rituals”. To achieve a rapid “return to normal”, hunters – mostly local ones – are enlisted in the name of their hunting skills, which, although they are usually contested by a part of Belgian society and media, are considered essential in this case. This event brings us to an exploration of the practices actors are attached to and forced to renounce to in the name of good crisis management. On-the-ground realities as related by field men bear witness to the unease felt in the face of the “dirty work” asked of them, while the upheaval of coexistence reveals ethical, tradition- and identity-related questions already existing before the crisis.

An outbreak of African swine fever in small-scale pigs, Gauteng, South Africa, July 2020

ObjectivesSince 2012, outbreaks of African swine fever (ASF) in domestic pigs have increased outside of South Africa’s ASF control zone. This study describes the epidemiological investigation and findings of an ASF outbreak in a small-scale pig unit in Gauteng Province and makes recommendations to prevent future outbreaks. MethodsPCR testing and molecular analysis were performed on pig tissue samples. Veterinary services conducted epidemiological investigations, forward and backward tracing, and surveillance. Farm management and biosecurity practices were assessed. Quarantine, culling, carcass disposal, and disinfection were implemented. ResultsASF virus genotype I was detected. A concurrent ASF outbreak in neighbouring Mpumalanga Province was identified as a possible source. Inadequate biosecurity measures probably facilitated viral transmission. Potential mechanisms for the introduction of the ASF virus include swill feeding practices, free roaming of pigs, scavenging, illegal slaughter, and trade of pig products within the community. ConclusionsMolecular typing of the ASF virus linked the outbreak to an ongoing ASF outbreak in Mpumalanga Province. Pig enterprises with poor biosecurity practices may face greater risk of ASF introduction. Small-scale pig keepers should be targeted for ASF awareness and education campaigns. Innovative and cost-effective biosecurity solutions are needed in this resource-poor setting.

African swine fever virus genotype II in Mongolia, 2019.

African swine fever (ASF) is a severe haemorrhagic disease of domestic and wild pigs caused by the African swine fever virus (ASFV). In recent years, ASF has steadily spread towards new geographical areas, reaching Europe and Asia. On January 15th, 2019, Mongolia reported its first ASF outbreak to the World Organization for Animal Health (OIE), becoming, after China, the second country in the region affected by the disease. Following an event of unusual mortality in domestic pigs in Bulgan Province, a field team visited four farms and a meat market in the region to conduct an outbreak investigation and collect samples for laboratory analysis. Different organs were examined for ASF associated lesions, and total nucleic acid was extracted for real-time PCR, virus isolation and molecular characterization. The real-time PCR results confirmed ASFV DNA in 10 out of 10 samples and ASFV was isolated. Phylogenetic analysis established that ASFVs from Mongolia belong to genotype II and serogroup 8. The viruses were identical to each other, and to domestic pig isolates identified in China and Russia, based on the comparison of five genomic targets. Our results suggest a cross-border spread of ASFV, without indicating the source of infection.

Mechanistic modelling of African swine fever: A systematic review

The spread of African swine fever (ASF) poses a grave threat to the global swine industry. Without an available vaccine, understanding transmission dynamics is essential for designing effective prevention, surveillance, and intervention strategies. These dynamics can often be unraveled through mechanistic modelling. To examine the assumptions on transmission and objectives of the mechanistic models of ASF, a systematic review of the scientific literature was conducted. Articles were examined across multiple epidemiological and model characteristics, with filiation between models determined through the creation of a neighbor-joined tree using phylogenetic software.Thirty-four articles qualified for inclusion, with four main modelling objectives identified: estimating transmission parameters (11 studies), assessing determinants of transmission (7), examining consequences of hypothetical outbreaks (5), assessing alternative control strategies (11). Population-based (17), metapopulation (5), and individual-based (12) model frameworks were represented, with population-based and metapopulation models predominantly used among domestic pigs, and individual-based models predominantly represented among wild boar. The majority of models (25) were parameterized to the genotype II isolates currently circulating in Europe and Asia.Estimated transmission parameters varied widely among ASFV strains, locations, and transmission scale. Similarly, parameter assumptions between models varied extensively. Uncertainties on epidemiological and ecological parameters were usually accounted for to assess the impact of parameter values on the modelled infection trajectory. To date, almost all models are host specific, being developed for either domestic pigs or wild boar despite the fact that spillover events between domestic pigs and wild boar are evidenced to play an important role in ASF outbreaks. Consequently, the development of more models incorporating such transmission routes is crucial. A variety of codified and hypothetical control strategies were compared however they were all a priori defined interventions. Future models, built to identify the optimal contributions across many control methods for achieving specific outcomes should provide more useful information for policy-makers. Further, control strategies were examined in competition with each other, which is opposed to how they would actually be synergistically implemented. While comparing strategies is beneficial for identifying a rank-order efficacy of control methods, this structure does not necessarily determine the most effective combination of all available strategies. In order for ASFV models to effectively support decision-making in controlling ASFV globally, these modelling limitations need to be addressed.

Tantangan dan Kendala Pengendalian African Swine Fever

African Swine Fever (ASF) is a highly contagious hemorrhagic viral disease that attacks pigs and wild pigs causing economic losses for farms small and large scale. ASF outbreaks that occurred in several regions in the world have caused unrest for the livestock sector. The rapid spread of the ASF virus has resulted in very high pig mortality. ASF virus transmission can occur through direct or indirect contact. Urine and faecal excretion of pigs is an important route of ASF transmission. The ASF virus has three transmission cycles, namely the silvatic, domestic and wild boar cycles. Outbreaks that occur in several countries encourage the strategy of controlling and overcoming the disease through surveillance. ASF disease control that has been carried out includes improving farm biosecurity management systems and limiting the movement of animals and animal products before the ASF vaccine is found.

The impact of an African swine fever outbreak on endemic tuberculosis in wild boar populations: A model analysis.

A mathematical model is developed and analysed to examine the impacts of African swine fever (ASF) introduction into a wild boar population that supports endemic animal tuberculosis (TB). TB is a widespread infectious disease caused by the Mycobacterium tuberculosis bacteria belonging to the Mycobacterium tuberculosis complex (MTC) that can persist in reservoir wildlife hosts. Wild boar (sus scrofa) are a key reservoir for MTC, and an increasing trend in wild boar density is expected to lead to an increase in TB prevalence with spill-over to livestock. MTC infection is presently controlled through a variety of strategies, including culling. African swine fever (ASF) is a virulent, viral infection which affects wild boar and is spreading across Eurasia and Oceania. ASF infection leads to near 100% mortality at the individual level, can cause a dramatic decrease in population density and may therefore lead to TB control. We extend an established model that captures the key demographic and infection processes for TB in wild boar to consider the impact of ASF introduction on wild boar populations that support different levels of endemic TB. Our model results indicate that an ASF infection will reduce wild boar population density and lead to a decrease in the prevalence of TB. If ASF persists in the local host population the model predicts the long-term decline of TB prevalence in wild boar. If ASF is eradicated, or fades-out in the local host population, the model predicts a slower recovery of TB prevalence in comparison to wild boar density after an ASF epidemic. This may open a window of opportunity to apply TB management to maintain low TB prevalence.

The role of Pig production and Market value chain in the occurrence of African Swine Fever in Songwe and Ruvuma regions, Tanzania

Background: In recent years, the pig industry in Tanzania has faced frequent occurrence of outbreaks of African swine fever (ASF). However, there is inadequate information on the pig value chain operation in relation to occurrence of ASF. This study aimed at mapping pig value chain and assess its contribution to the occurrence and spread of ASF in Tanzania.&#x0D; Methods: A cross sectional study was carried out in Songwe, Momba, Songea and Mbinga districts of Tanzania. Study districts were purposively selected based on the density of pig population, differences in production systems and history of ASF outbreaks. A total number of 484 pig producers and 28 traders were involved in the study. Random sampling was used to select pig producers. Pig traders were selected using snowball technique. Structured questionnaires were used to collect data on pig management and production practices, veterinary services, pig marketing practices and biosecurity measures using Open Data Kit (ODK) software. Semi structured interviews were conducted with key informants on perceived risk practices that are related to ASF outbreaks, challenges and recommendations on ASF prevention and control measures. Observation method was used to assess structure, facilities and practices within the pig production chain. &#x0D; Results: The main actors in the pig production chain were pig producers, assemblers, wholesalers and retailers. Unknown stock source (30%), poor husbandry practice such as free ranging (5%), poor management of waste products (73%) and poor handling of feed (73%) were risk practices in the production node. Transportation nodes operated under high risk due to frequent movements and pick-ups of ≥ 30 pigs per trip.&#x0D; Conclusion: The results demonstrated that different actors operate in the pig production, distribution and marketing chain. Each node operated under low biosecurity measures, and poor infrastructures that are likely to contribute to occurrence of ASF. There is need to improve good husbandry practices, marketing and infrastructures to increase production while ensuring pork safety.

Of Mad Cows and Dead Pigs: Negotiating Food Safety and Everyday Sovereignty in Taiwan

ABSTRACT The globalisation of food and agricultural trade has brought issues of food safety and biosecurity to the centre of geopolitical research. This paper explores the relationship between food risks and sovereignty practices, a topic that has received relatively scant attention in the scholarship. Going beyond conventional conceptualisations of sovereignty as an external-legal notion that is delimited to the realm of ‘high politics’ in international relations, this paper points to how it is also expressed and negotiated in quotidian practices of food import and consumption, and how this has contributed to the politicisation of food safety. Focusing on the case of Taiwan, a de facto island state with contested sovereignty status, and comparing the food safety discourses that arose during the outbreaks of Mad Cow Disease and African Swine Fever, we argue that food risks provide opportunities for social and political actors to participate in the everyday construction of sovereignty. While the Taiwanese government’s handling of the Mad Cow Disease shows it to be ultimately constrained by the geopolitical reality of fragile sovereignty, the outbreak of African Swine Fever enabled it to legitimise the securitisation of borders and bolster its legitimacy by staging collective defensive actions against perceived external risks. By drawing attention to how sovereignty is produced and performed through practice, this paper further advances recent discussions of sovereignty as a dynamic, social process.

Penning Pigs: Pig Rearing Practices, Biosecurity Measures, and Outbreaks of African Swine Fever in Central Uganda

In this article, I explore why a number of smallholder pig farmers in central Uganda decided not to implement the biosecurity measures advocated by veterinarians. I focus on the infectious disease, African swine fever, to illustrate how the biosecurity measures intended to limit the risk of disease, inadvertently constrained the future returns on pigs for farmers and their families. I draw on ethnographic research from Mukono, a district in central Uganda, to show how farmers considered pigs to be “quick money”—a type of household wealth that could be rapidly generated and liquidated with ease. I suggest that farmers’ conceptualization of their pigs as a specific type of wealth influenced the ways in which they integrated pigs into their lives and homes. Based on smallholder farmers’ accounts, I conclude this article by calling for a reconsideration of biosecurity measures as a universal solution for controlling diseases on farms. I argue that instead of designing protocols that separate species, disease prevention strategies need to recognize the ways in which different livestock animals become part of farmers’ lives and acknowledge how this influences farmers’ disease management practices.

African Swine Fever Virus Circulation between Tanzania and Neighboring Countries: A Systematic Review and Meta-Analysis.

For over 100 years after the description of the first case of African swine fever (ASF) in Kenya, ASF virus (ASFV) cross-border spread in eastern and southern Africa has not been fully investigated. In this manuscript, we reviewed systematically the available literature on molecular epidemiology of ASF in Tanzania and its eight neighboring countries in order to establish the transmission dynamics of ASFV between these countries. Data were retrieved from World Animal Health Information System (WAHIS), Google Scholar, PubMed, Scopus, and CrossRef databases, using the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and reviewed to document ASF outbreaks and ASFV genotypes distribution. Using phylogeographic approach applied to ASFV p72 sequence dataset, the evolutionary history and the dispersal pattern of the ASFV strains were assessed. From 2005 to 2019, a total of 1588 ASF outbreaks affecting 341,742 cases that led to 302,739 domestic pig deaths were reported. The case fatality rates (CFR) varied from 15.41% to 98.95% with an overall CFR of 88.58%. Fifteen different p72 ASFV genotypes were reported and the time to the most recent common ancestor (TMRCA) for ASFV strains dated back to 1652.233 (1626.473, 1667.735) with an evolutionary rate of 4.805 × 10−5 (2.5857 × 10−5, 9.7789 × 10−5). Phylogeographic dispersal analysis revealed several transboundary spread events of ASFV strains between these countries. These results suggest persistent circulation of ASFV in these countries and advocate for more research to improve our understanding of the transmission dynamics of the virus and for a regional approach to mitigate the spread of ASFV.

With or without a Vaccine-A Review of Complementary and Alternative Approaches to Managing African Swine Fever in Resource-Constrained Smallholder Settings.

The spectacular recent spread of African swine fever (ASF) in Eastern Europe and Asia has been strongly associated, as it is in the endemic areas in Africa, with free-ranging pig populations and low-biosecurity backyard pig farming. Managing the disease in wild boar populations and in circumstances where the disease in domestic pigs is largely driven by poverty is particularly challenging and may remain so even in the presence of effective vaccines. The only option currently available to prevent ASF is strict biosecurity. Among small-scale pig farmers biosecurity measures are often considered unaffordable or impossible to implement. However, as outbreaks of ASF are also unaffordable, the adoption of basic biosecurity measures is imperative to achieve control and prevent losses. Biosecurity measures can be adapted to fit smallholder contexts, culture and costs. A longer-term approach that could prove valuable particularly for free-ranging pig populations would be exploitation of innate resistance to the virus, which is fully effective in wild African suids and has been observed in some domestic pig populations in areas of prolonged endemicity. We explore available options for preventing ASF in terms of feasibility, practicality and affordability among domestic pig populations that are at greatest risk of exposure to ASF.

Genetic characterization of African swine fever virus from domestic pigs in India.

African swine fever (ASF) is the most dreaded disease of pigs, which can cause mortality of up to 100%. Following disease outbreaks with high mortality in pigs in two states of north-east India, namely Arunachal Pradesh and Assam in early 2020, we confirmed the first occurrence of African swine fever (ASF) in domestic pigs in India by real-time PCR, virus isolation and nucleotide sequencing. Genetic analyses in three independent genomic regions (B646L gene encoding the p72 protein, E183L gene encoding the p54 protein and the central variable region (CVR) of B602L gene) showed that the Indian ASF viruses are similar to the post-2007-p72-genotype II viruses reported from Asia and Europe, suggesting the transboundary expansion of ongoing ASF outbreaks in the region.

Spatiotemporal clustering and Random Forest models to identify risk factors of African swine fever outbreak in Romania in 2018\u20132019

African swine fever (ASF) has affected Romania since July 2017, with considerable economic and social consequences, despite the implementation of control measures mainly based on stamping out of infected pig populations. On the basis of the 2973 cumulative recorded cases up to September 2019 among wild boars and domestic pigs, analysis of the epidemiological characteristics could help to identify the factors favoring the persistence and spread of ASF. A statistical framework, based on a random forest methodology, was therefore developed to assess the spatiotemporal features of the epidemics and their relationships with environmental, human, and agricultural factors. The landscape of Romania was associated with the infection dynamics, particularly concerning forested and wetland areas. Waterways were also identified as a pivotal factor, raising questions about possible waterborne transmission since these waterways are often used as a water supply for backyard holdings. However, human activity was clearly identified as the main risk factor for the spread of ASF. Although the situation in Romania cannot be directly transposed to intensive pig farming countries, the findings of this study highlight the need for strict biosecurity measures on farms, and during transportation, to avoid ASF transmission at large geographic and temporal scales.

Molecular profile of African swine fever virus (ASFV) circulating in Vietnam during 2019-2020 outbreaks.

African swine fever (ASF) is a highly infectious disease of pigs caused by African swine fever virus (ASFV). In order to identify potential genetic variations among ASFV strains circulating in Vietnam, 26 ASFV isolates from organs and blood samples collected from domestic pigs from 23 different provinces of northern, central and southern Vietnam during 2019-2020 ASF outbreaks were genetically characterized. Nucleotide sequences were determined for a portion of the B646L (p72) gene, the complete E183L (p54) gene, the variable region of EP402R (CD2v), the central variable region (CVR) of pB602L, and a tandem repeat sequence (TRS) between the I73R and I329L genes. Analysis of the partial B646L (p72) and EP402R (CD2v) gene sequences and the full-length E183L (p54) gene sequence showed that all 26 ASFV isolates belonged to genotype II and serotype VIII and that they were identical to the strain Georgia/2007/1 and all ASFV strains sequenced in China. The TRS between the I73R and I329L genes contained a 10-nucleotide insertion that was observed in the Chinese ASFV strain CN201801 isolated from domestic pigs in 2018, but not in the Georgia/2007/1 and China/Jilin/2018/boar strains isolated from wild boar in China. This is the first intra-epidemic genome analysis reported for the ASFV strains circulating in Vietnam.

Lower seroprevalence of Toxoplasma gondii in swine from central China after an outbreak of African swine fever.

Toxoplasma gondii is widespread worldwide and can infect swine. This study evaluated the seroprevalence of T. gondii in swine from central China after an outbreak of African swine fever (ASF). A total of 2683 swine serum samples were collected from farms in four provinces. Of the serum samples, 1.42% (38/2683) (95% CI, 1.03–1.94) tested positive for T. gondii IgG antibody by a modified agglutination test (MAT) (cut-off: 1:25). Comparing with the results of previous studies, specifically our survey from before the outbreak, the seroprevalence of T. gondii in swine from central China was significantly decreased after the occurrence of ASF (OR = 7.679, 2015–2017 vs. 2019–2020). In general, the proportion of seropositive animals increased with the age of the swine, indicating post-natal transmission of T. gondii. Furthermore, there was a significant difference in seroprevalence between suckling pigs and weaned pigs (p < 0.05). This is the first large-scale investigation of T. gondii infection in swine after an ASF outbreak in China. The lower seroprevalence of T. gondii in swine after ASF may be due to stricter biosecurity measures on the farms, but results indicated swine exposure to zoonotic parasites despite these measures. This highlights that pigs must be considered a potential source of human T. gondii infections.