Epidemiology Of African Swine Fever Research Articles

The Effect of Partial and Temporary Vaccination on African Swine Fever Eradication Rates

African swine fever (ASF) is one of the most severe diseases of pigs, with drastic impact on pig industry. Wild boar populations play the role of ASF virus epidemiological reservoir. No effective and safe ASF vaccine is available, yet, but a future vaccine will not be 100% effective and will provide protection for no more than a few months. We present an individual-based spatially explicit model of wild boar demography and ASF epidemiology, allowing to simulate a vaccination campaign. We tested how many animals should be vaccinated in relation to vaccine efficacy and to the duration of vaccine protection. We estimated how these parameters will affect ASF eradication probabilities. We also assessed how partial vaccination will interact with a series of ecological, epidemiological, and management-related factors linked to ASF persistence. In the case of a highly effective vaccine with short duration, eradication chances were generally low, and the virus disappeared only when simulating a high effort (2.5 vaccinated wild boars/km2). A vaccine with low efficacy and long duration was even less effective in eradicating the ASFV, as none of the simulated scenarios provided acceptable eradication rates. Our results indicate that, under realistic conditions, vaccination against the ASF genotype II virus cannot be seen as an effective stand-alone tool for eradication. Its use should be integrated into a more comprehensive strategy, making use of all the available management tools, such as density control through hunting and carcass removal. If the vaccine will exhibit 12 months or longer duration of its protection, splitting the vaccination effort into two or three bait distribution campaigns during the year will be a feasible option. If the vaccine will exhibit a duration of its immunization significantly shorter than 1 year, a single distribution at the end of winter will maximize the probability of eradication.

Detection of African swine fever virus and wild boar eDNA in soil and turbid water samples: towards environmental surveillance

Since 2007, an ongoing African swine fever (ASF) pandemic has significantly impacted Eurasia. Extensive field evidence and modeling confirm the central role of wild boar in ASF epidemiology. To effectively control and eradicate the infection, rapid detection of the ASF virus (ASFV) is crucial for prompt intervention in areas of recent viral introduction or ongoing outbreaks. Environmental DNA (eDNA) is a cost-effective and non-invasive technique that has shown promising results in monitoring animal species and their pathogens and has the potential to be used for wildlife disease surveillance. In this study, we designed and evaluated an eDNA sampling method for highly turbid water and soil samples to detect ASFV and wild boar (Sus scrofa) DNA as a control using qPCR while ensuring biosafety measures and evaluating ASF epidemiology. To validate our method, we obtained samples from La Mandria Regional Park (LMRP) in northwestern Italy, an area free of ASFV, and spiked them in a laboratory setting with an ASFV’s synthetic DNA template. Our findings highlight the potential of eDNA monitoring as a reliable, rapid, and safe method for early detection of ASFV from soil and turbid water samples.

The Soft Tick Ornithodoros moubata and Its Role in the Epidemiology of African Swine Fever in Central Malawi.

African swine fever is a viral hemorrhagic disease of pigs (Sus scrofa) caused by a double-stranded DNA virus, African swine fever virus (ASFV). With up to 100% mortality in pigs and no vaccine, the socioeconomic impacts of this disease are immense. In sub-Saharan Africa, warthogs (Phacochoerus africanus) are the original vertebrate host for the virus, which is transmitted among wild suids via the soft tick Ornithodoros moubata. In Malawi, O. moubata is thought to be widely distributed, with the potential to spread ASFV beyond its historical enzootic zone in the Central Region. We surveyed 76 domestic pig farms, 18 active warthog burrows, and three bushpigs (Potamochoerus larvatus) resting sites for O. moubata in the Central Region of Malawi, and tested the ticks for ASFV using PCR. We found a limited distribution for O. moubata: 75 ticks were discovered at a single farm in the Mchinji District. Eleven percent of these ticks were ASFV positive. This suggests that wildlife and O. moubata play a limited role in the epidemiology of ASF in Malawi; thus, other factors for disease spread, such as fomites and pig-to-pig infection, need to be considered.

EVALUATION OF THE EFFECT OF HYDRATED LIME ON THE SCAVENGING OF FERAL SWINE (SUS SCROFA) CARCASSES AND IMPLICATIONS FOR MANAGING CARCASS-BASED TRANSMISSION OF AFRICAN SWINE FEVER VIRUS.

African swine fever (ASF) is a devastating hemorrhagic disease marked by extensive morbidity and mortality in infected swine. The recent global movement of African swine fever virus (ASFV) in domestic and wild swine (Sus scrofa) populations has initiated preparedness and response planning activities within many ASF-free countries. Within the US, feral swine are of utmost concern because they are susceptible to infection, are wide-spread, and are known to interact with domestic swine populations. African swine fever virus is particularly hardy and can remain viable in contaminated carcasses for weeks to months; therefore, carcass-based transmission plays an important role in the epidemiology of ASF. Proper disposal of ASF-infected carcasses has been demonstrated to be paramount to curbing an ASF outbreak in wild boar in Europe; preparedness efforts in the US anticipate carcass management being an essential component of control if an introduction were to occur. Due to environmental conditions, geographic features, or limited personnel, immediately removing every carcass from the landscape may not be viable. Hydrated lime converts to calcium carbonate, forming a sterile crust that may be used to minimize pathogen amplification. Any disturbance by scavenging animals to the sterile crust would nullify the effect of the hydrated lime; therefore, this pilot project aimed to evaluate the behavior of scavenging animals relative to hydrated lime-covered feral swine carcasses on the landscape. At two of the three study sites, hydrated lime-treated carcasses were scavenged less frequently compared to the control carcasses. Additionally, the median time to scavenging was 1 d and 6 d for control versus hydrated lime-treated carcasses, respectively. While results of this study are preliminary, hydrated lime may be used to deter carcass disruption via scavenging in the event that the carcass cannot be immediately removed from the landscape.

Three Years of African Swine Fever in South Korea (2019–2021): A Scoping Review of Epidemiological Understanding

African swine fever (ASF) is a highly contagious viral disease in domestic pigs and wild boar that causes tremendous socioeconomic damage in related industries. In 2019, the virus emerged in South Korea, which has since reported 21 outbreaks in domestic pig farms and over 2,600 cases in wild boar. In this review, we synthesize the epidemiological knowledge generated on ASF in South Korea during the first three years of the epidemic (2019–2021). We searched four international and one domestic Korean database to identify scientific articles published since 2019 and describing ASF epidemiology in South Korea. Fourteen articles met our selection criteria and were used to synthesize the origin of ASF in South Korea, the risk factors of disease occurrence, the effectiveness of the surveillance and intervention measures that were implemented, and the viral transmission dynamics. We found that timely intensive surveillance and interventions on domestic pig farms successfully blocked between-farm transmission. However, in wild boar, the ASF virus has spread massively towards the south primarily along the mountain ranges despite ongoing fence erection and intensive depopulation efforts, endangering domestic pig farms across the country. The current devastating epidemic is suspected to be the consequence of an ASF control strategy unaligned to the epidemiological context, the challenging implementation of control measures hindered by topological complexities, and inappropriate biosecurity by field workers. To improve our understanding of ASF epidemiology in South Korea and enhance disease management, future research studies should specify the ecological drivers of disease distribution and spread and devise effective control strategies, particularly in relation to Korean topography, and the latent spread of the virus in wild boar populations. Additionally, research studies should explore the psychosocial factors for ASF management, and develop tools to support evidence-based decision-making for managing ASFV in wild boar.

Descriptive epidemiology and spatial analysis of African swine fever epidemics in Can Tho, Vietnam, 2019

The objectives of this study were to describe the epidemiology of African swine fever (ASF) and to identify factors that increased commune-level risk for ASF in Can Tho, a province in the Mekong River Delta of Vietnam. In 2019, a total of 2377 of the 5220 pig farms in Can Tho were ASF positive, an incidence risk of 46 (95% CI 44–47) ASF positive farms for every 100 farms at risk. Throughout the outbreak ASF resulted in either the death or culling of 59,529 pigs out of a total population size of 124,516 (just under half of the total pig population, 48%). After the first detection in Can Tho in May 2019, ASF spread quickly across all districts with an estimated dissemination ratio (EDR) of greater than one up until the end of July 2019. A mixed-effects Poisson regression model was developed to identify risk factors for ASF. One hundred unit increases in the number of pigs per square kilometre was associated with a 1.28 (95% CrI 1.05–1.55) fold increase in commune-level ASF incidence rate. One unit increases in the number of pig farms per square kilometre was associated with a 0.91 (95% CrI 0.84–0.99) decrease in commune-level ASF incidence rate. Mapping spatially contiguous communes with elevated (unaccounted-for) ASF risk provide a means for generating hypotheses for continued disease transmission. We propose that the analyses described in this paper might be run on an ongoing basis during an outbreak and disease control efforts modified in light of the information provided.

Estimation of R0 for the Spread of the First ASF Epidemic in Italy from Fresh Carcasses.

After fifty years of spread in the European continent, the African swine fever (ASF) virus was detected for the first time in the north of Italy (Piedmont) in a wild boar carcass in December, 2021. During the first six months of the epidemic, the central role of wild boars in disease transmission was confirmed by more than 200 outbreaks, which occurred in two different areas declared as infected. The virus entered a domestic pig farm in the second temporal cluster identified in the center of the country (Lazio). Understanding ASF dynamics in wild boars is a prerequisite for preventing the spread, and for designing and applying effective surveillance and control plans. The aim of this work was to describe and evaluate the data collected during the first six months of the ASF epidemic in Italy, and to estimate the basic reproduction number (R0) in order to quantify the extent of disease spread. The R0 estimates were significantly different for the two spatio-temporal clusters of ASF in Italy, and they identified the two infected areas based on the time necessary for the number of cases to double (td) and on an exponential decay model. These results (R0 = 1.41 in Piedmont and 1.66 in Lazio) provide quantitative knowledge on the epidemiology of ASF in Italy. These parameters could represent a fundamental tool for modeling country-specific ASF transmission and for monitoring both the spread and sampling effort needed to detect the disease early.

Early-phase risk assessments during the first epidemic year of African swine fever outbreaks in Vietnamese pigs.

BackgroundAfrican swine fever (ASF) is a notifiable viral disease of pigs and wild boars that could lead to serious economic losses for the swine industry.ObjectivesThe aim of this study was to identify risk factors in the early phase of ASF outbreaks in Vietnamese swine herds during the first epidemic year.MethodsThe period of interest for this case–control study was February to July 2019. A questionnaire was administered in northern Vietnam where all early cases of ASF were reported. Producers of herds with reported cases were asked to provide information starting from the day of onset of clinical signs as well as 30 days prior to that day. The period of interest for controls was within the 6 months of the first outbreak in Vietnam (February 2019). Questionnaires included 55 questions; responses were received from 67 cases and 115 controls. Logistic regression analysis was used to identify factors associated with ASF status.ResultsThirty‐seven variables of interest (among a total of 55 variables) were associated with ASF status in univariate analysis (p < 0.05). These 37 variables were assessed for inclusion in the multivariate analysis by backward stepwise selection. Six variables remained significant as ASF risk factors in the final model: distance to farm within 500 m, distance of irrigation systems within 200 m, total number of pigs (≤500), absence of dressing rooms for workers/visitors before entering the farm, poor hygienic practices for people within the farm, and poor hygienic practices at pig loading/unloading locations.ConclusionsThese results may help in understanding the epidemiology of ASF in Vietnam and provide a scientific basis for optimization of current interventions and development of new tools and strategies to reduce transmission of ASF.

Combining hunting and intensive carcass removal to eradicate African swine fever from wild boar populations

African Swine Fever (ASF) is a highly lethal viral disease, which affects different species of wild and domestic suids. After its human-caused introduction in Georgia in 2007, the ASF virus has found a new ecological reservoir in the large and continuous wild boar (Sus scrofa) populations of Eurasia, spreading both eastward and westward. ASF has also breached into the intensive pork meat production system. Although the disease has no zoonotic potential, its consequences on wild boar populations and the economic losses for the pig industry have been dramatic. As no vaccine or effective medical treatment is available to reliably protect wild boar or domestic pigs against ASF, eradication efforts are mainly based on intensive wild boar hunting and on removing a significant portion of the infected wild boar carcasses, which are the main environmental virus reservoir. Both strategies have produced poor results, so far, and ASF is becoming endemic. We compared wild boar hunting and carcass removal as alternative and combined strategies for the eradication of ASF in its endemic state, using a spatially explicit individual-based model, which incorporated the demography and spatial dynamics of a wild boar population, the spatial epidemiology of ASF in its endemic phase, and a management system acting for the eradication of the disease from the population. When no eradication effort was simulated, ASF exhibited a clear and strong tendency to persist and remain endemic in the wild boar population. Both hunting and carcass removal, when used alone, provided either a low power to remove the virus from the population, or required unrealistic field effort. The best performing scenario corresponded to the combined use of a 30% annual hunting rate and of an intensive carcass removal, during a 2-month period in late winter (February-March). Eradicating ASF from wild boar populations remains a hard task. Managers should promote a drastic increase in the effort dedicated to systematically identify and remove as many infected wild boar carcasses as possible from the affected areas, with at least 5–15 carcasses removed for each 100 hunted wild boar.

African Swine Fever Re-Emerging in Estonia: The Role of Seropositive Wild Boar from an Epidemiological Perspective.

African swine fever (ASF) emerged in Estonia in 2014. From February 2019 to August 2020, no pigs or wild boar tested positive for ASF virus (ASFV), only ASFV-specific antibodies could be detected in shot wild boar. However, ASF recently re-emerged in wild boar. We tested three hypotheses that might explain the current situation: (i) ASFV may have been present throughout, but at a prevalence below the detection limit; (ii) seropositive wild boar may have remained infectious (i.e., virus-carriers) and kept the epidemic going; or (iii) ASF was gone for 1.5 years, but was recently re-introduced. Using Estonian surveillance data, the sensitivity of the surveillance system and the confidence in freedom from ASF were estimated. Furthermore, the detection probability was determined and cluster analyses were performed to investigate the role of serological positive wild boar. The results suggest that the surveillance system was not able to detect virus circulation at a design prevalence below 1%. With respect to the confidence in freedom from ASF, the results indicate that circulating virus should have been detected over time, if the prevalence was ≥2%. However, the decreasing wild boar population density and ongoing surveillance activities made ASFV circulation at a low prevalence unlikely. Cluster analyses provided no evidence for a significant accumulation of serologically positive wild boar in temporal connection to the re-emergence of ASFV. Further targeted research, such as long-term experimental studies and molecular epidemiology, is necessary to improve our knowledge on the epidemiology of ASF and to control the disease more effectively.

Epidemiology of African Swine Fever and Its Risk in Nepal

African swine fever (ASF) is a highly contagious viral infection of domestic and wild pigs with high mortality. First reported in East Africa in the early 1900s, ASF was largely controlled in domestic pigs in many countries. However, in recent years ASF outbreaks have been reported in several countries in Europe and Asia. The occurrence of ASF in China, the largest pork producer in the world, in 2018 and in India, the country that surrounds and shares open borders with Nepal, has increased the risk of ASF transmission to Nepal. Lately, the pork industry has been growing in Nepal, overcoming traditional religious and cultural biases against it. However, the emergence of viral infections such as ASF could severely affect the industry’s growth and sustainability. Because there are no effective vaccines available to prevent ASF, the government should focus on preventing entry of the virus through strict quarantine measures at the borders, controls on illegal trade, and effective management practices, including biosecurity measures.

Research priorities to fill knowledge gaps in wild boar management measures that could improve the control of African swine fever in wild boar populations

The European Commission asked EFSA to provide study designs for the investigation of four research domains (RDs) according to major gaps in knowledge identified by EFSA in a report published in 2019: (RD 1) African swine fever (ASF) epidemiology in wild boar; (RD 2) ASF transmission by vectors; (RD 3) African swine fever virus (ASFV) survival in the environment, and (RD 4) the patterns of seasonality of ASF in wild boar and domestic pigs in the EU. In this Scientific Opinion, the second RD on ASF epidemiology in wild boar is addressed. Twenty‐nine research objectives were proposed by the working group and broader ASF expert networks and 23 of these research objectives met a prespecified inclusion criterion. Fourteen of these 23 research objectives met the predefined threshold for selection and so were prioritised based on the following set of criteria: (1) the impact on ASF management; (2) the feasibility or practicality to carry out the study; (3) the potential implementation of study results in practice; (4) a possible short time‐frame study (< 1 year); (5) the novelty of the study; and (6) if it was a priority for risk managers. Finally, after further elimination of three of the proposed research objectives due to overlapping scope of studies published during the development of this opinion, 11 research priorities were elaborated into short research proposals, considering the potential impact on ASF management and the period of one year for the research activities.

Genetic analysis of African swine fever virus based on major genes encoding p72, p54 and p30

African swine fever (ASF) is reported as a highly contagious hemorrhage lethal disease of domestic and wild swine. The causative agent of ASF is a large enveloped DNA virus with a complex structure. There are twenty-four ASFV genotypes described to date. However, in Vietnam, only genotypes II had been previously described. The genetic characterization of ASFV enhances the understanding of ASF epidemiology in terms of the extent, severity, source, and potential genetic variations among ASFV strains circulating in Southern Vietnam. Twenty ASFV strains were collected from pigs with ASFV-infected clinical signs from 10 provinces during 2019 - 2020. Partial B646L (p72) gene, complete E183L (p54), and CP204L (p30) genes were amplified, purified, and sequenced. Phylogenetic analysis confirmed the circulation of genotype II by both the partial B646L (p72) and full-length E183 (p54) gene sequencing. Analysis of the p72, p54, and p30 regions did not indicate any change in the nucleotide and amino acid sequences among these strains. The results of this study revealed that these ASFVs shared high homology to ASFV isolates detected in Northern Vietnam and China.

Research objectives to fill knowledge gaps in African swine fever virus survival in the environment and carcasses, which could improve the control of African swine fever virus in wild boar populations.

The European Commission requested that EFSA provide study designs for the investigation of four research domains according to major gaps in knowledge identified by EFSA in a report published in 2019: i) the patterns of seasonality of African Swine Fever (ASF) in wild boar and domestic pigs in the EU; ii) the epidemiology of ASF in wild boar; iii) survival of ASF virus (ASFV) in the environment and iv) transmission of ASFV by vectors. In this Scientific Opinion, the third research domain on ASFV survival is addressed. Nine research objectives were proposed by the working group and broader ASF expert networks, such as ASF stop, ENETWILD, VectorNet, AHAW network and the AHAW Panel Experts. Of the nine research objectives, only one was prioritised and elaborated into a general protocol/study design research proposal, pertaining ASFV survival in feed and bedding. To investigate the survival of ASFV in feed, bedding and roughage, laboratory survival studies are proposed. To investigate possible risk mitigation measures, proof‐of‐concept approaches should be investigated.

Research priorities to fill knowledge gaps in the control of African swine fever: possible transmission of African swine fever virus by vectors.

The European Commission requested that EFSA provide study designs for the investigation of four research domains according to major gaps in knowledge identified by EFSA in a report published in 2019: (i) the patterns of seasonality of African Swine Fever (ASF) in wild boar and domestic pigs in the EU; (ii) the epidemiology of ASF in wild boar; (iii) survival of ASF virus (ASFV) in the environment and (iv) transmission of ASFV by vectors. In this Scientific Opinion, the fourth research domain on ASFV transmission by vectors is addressed. Eleven research objectives were proposed by the EFSA working group and broader ASF expert networks, such as ASF stop, ENETWILD, VectorNet, AHAW network and the AHAW Panel Experts. Of the 11 research objectives, six were prioritised based on the following set of criteria: (1) the impact on ASF management; (2) the feasibility or practicality to carry out the study; (3) the potential implementation of study results in practice; (4) a possible short time‐frame study (< 1 year); (5) the novelty of the study and (6) if it was a priority for risk managers. The prioritised research objectives were: (I) Studies on the potential vector fauna at the pig–wild boar interface and the feeding preference of blood‐feeding potential vectors in ASF‐affected areas; (II) Assessment of the efficacy of insect screens on indoor/outdoor pig holdings to prevent the entry of blood‐sucking vectors (i.e. Stomoxys) in ASF endemic areas; (III) Assess the role of mechanical vectors in the virus transmission in ASF‐affected areas; (IV) Distribution of the potential mechanical transmission vectors in ASF‐affected areas of the EU; (V) ASFV transmission by synanthropic birds; and (VI) Assessment on the presence/absence of the soft tick Ornithodoros erraticus in ASF‐affected areas in Europe. For each of the selected research objectives, a research protocol has been proposed considering the potential impact on ASF management and the period of 1 year for the research activities.

Expert knowledge elicitation on African Swine Fever and outdoor farming of pigs

An expert knowledge elicitation was conducted to address three tasks identified by EFSA's Animal Health and Welfare (AHAW) Panel: categorize outdoor farm types of pigs in EU MS according to the risk of African Swine Fever (ASF) introduction into these farms and the risk of ASF spread from these farms, rank biosecurity measures according to their potential to lower the risk of ASF introduction into these farms and the risk of ASF spread from these farms in ASF-affected countries, and propose improvements of biosecurity for outdoor pig farming categories and the control measures that should flank these in ASF-affected countries. The elicitation was conducted with four scientists with expertise in ASF epidemiology, biosecurity and outdoor farming practices and structures, including organic and backyard farming of pigs outdoors. The first task was addressed by eliciting estimates for the risk of new ASF outbreaks in the areas of interest in the coming year for two types of outdoor pig farms, specified by EFSA. As a worst-case scenario for assessment, the EKE considered areas of the EU where ASF is present in wild boar and in domestic pigs in indoor farms and, if outdoor farms were to be permitted in such areas, in domestic pigs in outdoor farms. The second task was addressed by developing a preliminary list of biosecurity measures, prioritising 7 measures in terms of expected effectiveness in reducing risk for each farm type, and then eliciting estimates of the effectiveness, feasibility and sustainability of each of the prioritised measures, considered separately. The third task was addressed by brainstorming of potential control measures to be considered in conjunction with improved biosecurity. The results are intended for consideration by the EFSA AHAW Panel when developing a Scientific Opinion on ASF and outdoor pig farming.

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.

The Epidemiology of African Swine Fever, Its Complexity and the Requirement for Multiple Solution Approaches

Searching for the term "African swine fever" (ASF) in the title of publications in the Web of Science, PubMed and Scopus during the period of 1955-2020 resulted in an average of 2009 detected articles [...].

Mathematical Approach to Estimating the Main Epidemiological Parameters of African Swine Fever in Wild Boar.

African swine fever (ASF) severely threatens the swine industry worldwide, given its spread and the absence of an available licensed vaccine, and has caused severe economic losses. Its persistence in wild boar (WB), longer than in domestic pig farms, and the knowledge gaps in ASF epidemiology hinder ASF virus (ASFV) eradication. Even in areas where disease is effectively controlled and ASFV is no longer detected, declaring eradication is difficult as seropositive WBs may still be detected. The aim of this work was to estimate the main ASF epidemiological parameters specific for the north of Sardinia, Italy. The estimated basic (R0) and effective (Re) reproduction numbers demonstrate that the ASF epidemic is declining and under control with an R0 of 1.139 (95% confidence interval (CI) = 1.123–1.153) and Re of 0.802 (95% CI = 0.612–0.992). In the last phases of an epidemic, these estimates are crucial tools for identifying the intensity of interventions required to definitively eradicate the disease. This approach is useful to understand if and when the detection of residual seropositive WB is no longer associated with any further ASFV circulation.

Epidemiology of African Swine Fever in Piggeries in the Center, South and South-West of Cameroon.

African Swine Fever (ASF) is enzootic in Cameroon. A cross-sectional study was conducted in the center, south and south-west regions of Cameroon in order to determine: the knowledge, skills and practices at risk of pig breeders; the prevalence of the disease in piggeries; the genome of the circulating virus. A total of 684 blood samples were collected in 209 farms for RT-PCR and ELISA analyses at the National Veterinary Laboratory (LANAVET) annex in Yaoundé. Prevalences of 15.2% (95CI: 12.5–17.9%) by ELISA, 23.8% (95CI: 20.6–27.0%) by RT-PCR, and 15.2% (95CI: 12.5–17.9%) by ELISA-PCR, were recorded. Of the farmers surveyed, 90% knew about the ASF and 55.3% have already experienced it. The 47.4% of them would not be able to recognize ASF if it occurred and, according to them, the risk of the disease introduction in farms would be 32% linked to the animal health personnel who work on farms. Molecular characterization revealed that only ASF genotype-I variable 19T-RSs is circulating. ASF is still hovering at a risky rate over the pig sector of Cameroon. The control of ASF needs an epidemiological surveillance, a better involvement of all stakeholders, sensitization of breeders and an effective State support for producers.