scholarly journals How do genetic relatedness and spatial proximity shape African swine fever infections in wild boar?

2021 ◽  
Author(s):  
Tomasz Podgórski ◽  
Kim Pepin ◽  
Anna Radko ◽  
Angelika Podbielska ◽  
Magdalena Łyjak ◽  
...  
Keyword(s):  
Wild Boar ◽  
Contact Zone ◽  
Disease Transmission ◽  
Genetic Relatedness ◽  
African Swine Fever ◽  
Infection Risk ◽  
Disease Spread ◽  
Spatial Proximity ◽  
Transmission Rates ◽  
Close Relatives

The importance of social and spatial structuring of wildlife populations for disease spread, though widely recognized, is still poorly understood in many host-pathogen systems. In particular, system specific kin relationships among hosts can create contact heterogeneities and differential disease transmission rates. Here, we investigate how distance-dependent infection risk is influenced by genetic relatedness in a novel wild boar ( Sus scrofa) - African swine fever (ASF) system. We hypothesized that the infection risk would correlate positively with proximity and relatedness to ASF-infected individuals but expected those relationships to weaken with distance between individuals due to decay in contact rates and genetic similarity. ASF infection risk was shaped by the number of infected animals throughout the zone of potential contact (0-10 km) but not beyond it. This effect was the strongest at close distances (0-2 km) and weakened further on (2-10 km), consistent with decreasing probability of contact. Overall, there was a positive association between genetic relatedness to infectees and infection risk within the contact zone but this effect varied in space. In the high-contact zone (0-2 km), infection risk was not influenced by relatedness when controlled for the number of ASF-positive animals. However, infections were more frequent among close relatives indicating that familial relationships could have played a role in ASF transmission. In the medium-contact zone (2-5 km), infection risk and frequency of paired infections were associated with relatedness. Relatedness did not predict infection risk in low- and no-contact zones (5-10 and >10 km, respectively). Together, our results indicate that the number of nearby infected individuals overrides the effect of relatedness in shaping ASF transmission rates which nevertheless can be higher among close relatives. Highly localized transmission highlights the possibility to control the disease if containment measures are employed quickly and efficiently.

scholarly journals How do genetic relatedness and spatial proximity shape African swine fever infections in wild boar?

2021 ◽  
Author(s):  
Tomasz Podgórski ◽  
Kim M. Pepin ◽  
Anna Radko ◽  
Angelika Podbielska ◽  
Magdalena Łyjak ◽  
...  
Keyword(s):  
Wild Boar ◽  
Genetic Relatedness ◽  
African Swine Fever ◽  
Spatial Proximity

scholarly journals African Swine Fever Status in Europe

Viruses ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 310 ◽  
Author(s):  
Przemyslaw Cwynar ◽  
Jane Stojkov ◽  
Klaudia Wlazlak
Keyword(s):  
Eastern Europe ◽  
Wild Boar ◽  
Western Europe ◽  
African Swine Fever ◽  
Disease Spread ◽  
Wild Boar Population ◽  
Domestic Pig ◽  
Domestic Pigs ◽  
In The Wild ◽  
Virus Spreading

African Swine Fever (ASF) is a highly contagious disease that affects the domestic pig and wild boar population. The aim of this study was to describe the introduction and spread of the ASF virus in Western Europe (1960–1995) and in Eastern Europe (2007–2018), with particular emphasis on the current ASF situation in Poland and its challenges and future perspectives. The first ASF outbreak in Europe was reported in Portugal in 1957, with the virus spreading over most of Western Europe over the next 30 years. In Eastern Europe, the virus was first observed in Georgia in 2007, from where the disease spread quickly to other neighboring countries, reaching Poland in 2014. Since then, there have been 3341 confirmed cases in the wild boar population in Poland. Although there have been no confirmed cases of wild boars coming into contact with domestic pigs, the first notified case concerning domestic pigs was reported in July 2014. Since then, there have been a total of 213 confirmed outbreaks of ASF on Polish pig farms. Given the virulence of the ASF virus and the myriad of transmission routes across Europe, the monitoring of this disease must be a priority for Europe.

scholarly journals Towards risk-based surveillance of African Swine Fever in Switzerland

2021 ◽  
Author(s):  
Maria Elena Vargas-Amado ◽  
Luís Pedro Carmo ◽  
John Berezowski ◽  
Claude Fischer ◽  
Maria João Santos ◽  
...  
Keyword(s):  
High Risk ◽  
Wild Boar ◽  
Disease Transmission ◽  
Forest Cover ◽  
Disease Risk ◽  
Animal Health ◽  
African Swine Fever ◽  
Early Disease ◽  
Domestic Pig ◽  
Domestic Pigs

African Swine Fever (ASF) has emerged as a disease of great concern to swine producers and government disease control agencies because of its severe consequences to animal health and the pig industry. Early detection of an ASF introduction is considered essential for reducing the harm caused by the disease. Risk-based surveillance approaches have been used as enhancements to early disease epidemic detection systems in livestock populations. Such approaches may consider the role wildlife plays in hosting and transmitting a disease. In this study, a novel method is presented to estimate and map the risk of introducing ASF into the domestic pig population through wild boar intermediate hosts. It makes use of data about hunted wild boar, rest areas along motorways connecting ASF affected countries to Switzerland, outdoor piggeries, and forest cover. These data were used to compute relative wild boar abundance as well as to estimate the risk of both disease introduction into the wild boar population and disease transmission to domestic pigs. The way relative wild boar abundance was calculated adds to the current state of the art by considering the effect of beech mast on hunting success and the probability of wild boar occurrence when distributing relative abundance values among individual grid cells. The risk of ASF introduction into the domestic pig population by wild boar was highest near the borders of France, Germany, and Italy. On the north side of the Alps, areas of high risk were located on the unshielded side of the main motorway crossing the Central Plateau, which acts as a barrier for wild boar. The results of this study can be used to focus surveillance efforts for early disease detection on high risk areas. The developed method may also inform policies to control other diseases that are transmitted by direct contact from wild boar to domestic pigs.

scholarly journals The African Swine Fever Epidemic in Wild Boar (Sus scrofa) in Lithuania (2014–2018)

2020 ◽  
Vol 7 (1) ◽  
pp. 15 ◽  
Author(s):  
Petras Mačiulskis ◽  
Marius Masiulis ◽  
Gediminas Pridotkas ◽  
Jūratė Buitkuvienė ◽  
Vaclovas Jurgelevičius ◽  
...  
Keyword(s):  
Wild Boar ◽  
Population Decline ◽  
African Swine Fever ◽  
Control Measures ◽  
Disease Spread ◽  
Wild Boar Population ◽  
Baltic States ◽  
Long Distance ◽  
First Case ◽  
The Baltic

In January 2014 the first case of African swine fever (ASF) in wild boar of the Baltic States was reported from Lithuania. It has been the first occurrence of the disease in Eastern EU member states. Since then, the disease spread further affecting not only the Baltic States and Poland but also south-eastern Europe, the Czech Republic and Belgium. The spreading pattern of ASF with its long-distance spread of several hundreds of kilometers on the one hand and the endemic situation in wild boar on the other is far from being understood. By analyzing data of ASF cases in wild boar along with implemented control measures in Lithuania from 2014–2018 this study aims to contribute to a better understanding of the disease. In brief, despite huge efforts to eradicate ASF, the disease is now endemic in the Lithuanian wild boar population. About 86% of Lithuanian’s territory is affected and over 3225 ASF cases in wild boar have been notified since 2014. The ASF epidemic led to a considerable decline in wild boar hunting bags. Intensified hunting might have reduced the wild boar population but this effect cannot be differentiated from the population decline caused by the disease itself. However, for ASF detection sampling of wild boar found dead supported by financial incentives turned out to be one of the most effective tools.

scholarly journals African Swine Fever: Disease Dynamics in Wild Boar Experimentally Infected with ASFV Isolates Belonging to Genotype I and II

Viruses ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 852 ◽  
Author(s):  
Sánchez-Cordón ◽  
Nunez ◽  
Neimanis ◽  
Wikström-Lassa ◽  
Montoya ◽  
...  
Keyword(s):  
Immune Response ◽  
Wild Boar ◽  
Western Europe ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Relevant Information ◽  
Disease Spread ◽  
Wild Boar Population ◽  
Disease Pathogenesis ◽  
Genotype I

After the re-introduction of African swine fever virus (ASFV) genotype II isolates into Georgia in 2007, the disease spread from Eastern to Western Europe and then jumped first up to Mongolian borders and later into China in August 2018, spreading out of control and reaching different countries of Southeast Asia in 2019. From the initial incursion, along with domestic pigs, wild boar displayed a high susceptibility to ASFV and disease development. The disease established self-sustaining cycles within the wild boar population, a key fact that helped its spread and that pointed to the wild boar population as a substantial reservoir in Europe and probably also in Asia, which may hinder eradication and serve as the source for further geographic expansion. The present review gathers the most relevant information available regarding infection dynamics, disease pathogenesis and immune response that experimental infections with different ASFV isolates belonging to genotype I and II in wild boar and feral pigs have generated. Knowledge gaps in areas such as disease pathogenesis and immune response highlights the importance of focusing future studies on unravelling the early mechanisms of virus-cell interaction and innate and/or adaptive immune responses, knowledge that will contribute to the development of efficacious treatments/vaccines against ASFV.

scholarly journals African swine fever virus (ASFV) in Poland: Prevalence in a wild boar population (2017–2018)

2020 ◽  
Vol 65 (No. 4) ◽  
pp. 143-158 ◽  
Author(s):  
MP Frant ◽  
M Lyjak ◽  
L Bocian ◽  
A Barszcz ◽  
K Niemczuk ◽  
...  
Keyword(s):  
Wild Boar ◽  
Active Surveillance ◽  
African Swine Fever Virus ◽  
Winter Season ◽  
African Swine Fever ◽  
Disease Spread ◽  
Passive Surveillance ◽  
Wild Boar Population ◽  
Wild Boars ◽  
In The Wild

African swine fever (ASF) was first described in 1921 in Kenya. The latest epidemic of ASF started in 2007 in Georgia. The virus was introduced to Poland in 2014. Since the beginning of the epidemics, the National Veterinary Research Institute in Pulawy (NVRI) has been testing wild boar samples from restricted areas and other parts of Poland to conduct passive and active surveillance for ASFV in these groups of animals. The aim of this study was to summarise the last two years of the ASF epidemiological status in Poland and the attempt to find disease patterns in the wild boar population. The period between 2017 and 2018 brought a massive number of new ASF cases in Poland. The number of ASF-positive wild boars jumped from 91 in 2016 to 1 140 in 2017 (approximately a 12 × increase), and 2018 was even worse, with the disease affecting 4 083 animals (2 435 cases; one case could even be 10 animals or more if they are found in one place next to each other). The percentage of positive wild boars found dead (passive surveillance) in the restricted area increased in 2018 to 73.1% from 70.8% in 2017. The chance of obtaining positive results in this group was six times higher in December and 4.5 times higher in January than in August and September. The percentage of positive wild boars detected through active surveillance reached 1.5% in 2018. The data suggested that, not only in Poland, but also in other ASF-affected countries, during the epizootic stage of the disease spread the most important measure is an effective passive surveillance of dead wild boars especially, in the winter season rather than in the summer.

scholarly journals A Comparison of Perceptions of Estonian and Latvian Hunters With Regard to the Control of African Swine Fever

2021 ◽  
Vol 8 ◽  
Author(s):  
Nico Urner ◽  
Carola Sauter-Louis ◽  
Christoph Staubach ◽  
Franz Josef Conraths ◽  
Katja Schulz
Keyword(s):  
Wild Boar ◽  
Group Discussion ◽  
African Swine Fever ◽  
Control Measures ◽  
Disease Spread ◽  
Successful Implementation ◽  
Participatory Methods ◽  
The European Union ◽  
Passive Surveillance ◽  
Participatory Epidemiology

Since the first detected African swine fever (ASF) cases in Lithuanian wild boar in 2014, the virus has occurred in many other member states of the European Union (EU), most recently in Belgium in 2018 and in Germany in 2020. Passive surveillance and various control measures are implemented as part of the strategy to stop disease spread in the wild boar population. Within this framework, hunters perform important activities, such as the removal of carcasses, fencing or hunting. Therefore, the successful implementation of these measures largely depends on their acceptability by hunters. Methods of participatory epidemiology can be used to determine the acceptance of control measures. The use of participatory methods allows the involvement of key stakeholders in the design, the implementation and the analysis of control and surveillance activities. In the present study, two studies that had been conducted using participatory epidemiology with hunters in Estonia and Latvia were compared on the topics recruitment, participants, facilitators, focus group discussion (FGDs) and their contents. The aim was to evaluate similarities and differences in the two studies and to identify a broader spectrum of possibilities to increase the willingness of hunters supporting the fight against ASF. Evaluating all conducted FGDs in both countries showed primarily similarities in the perceptions and opinions of the hunters in Estonia and Latvia. One notable difference was that passive surveillance in Latvia was perceived mostly as topic of duty and ethics rather than an issue driven by incentives. Participatory methods have proven to be an effective tool in the evaluation of the acceptance of established ASF control systems. The results of this study point out further chances for improving the cooperation with hunters in the future. Nevertheless, the importance of gathering and analyzing the opinions of hunters in all ASF affected countries individually is highlighted.

scholarly journals African swine fever in the Lithuanian wild boar population in 2018: a snapshot

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Arnoldas Pautienius ◽  
Katja Schulz ◽  
Christoph Staubach ◽  
Juozas Grigas ◽  
Ruta Zagrabskaite ◽  
...  
Keyword(s):  
Wild Boar ◽  
Active Surveillance ◽  
African Swine Fever ◽  
Control Measures ◽  
Disease Spread ◽  
Passive Surveillance ◽  
Wild Boar Population ◽  
Prevalence Estimates ◽  
Risk Of Disease ◽  
Over Time

Abstract The first cases of African swine fever (ASF) were detected in the Lithuanian wild boar population in 2014. Since then, the disease spread slowly through the whole country, affecting both, wild boar and domestic pigs. In the other Baltic states, which both are also affected by ASF since 2014, the recent course of ASF prevalence suggests that the countries might be well under way of disease elimination. In contrast, in Lithuania the epidemic seems to be still in full progress. In the present study, we aimed to extend a previous prevalence study in Lithuania. Looking at ASF virus (ASFV) and seroprevalence estimates of wild boar in all months of 2018 and in all affected municipalities in Lithuania, the course of ASF was evaluated on a temporal and spatial scale. A non-spatial beta-binomial model was used to correct for under- or overestimation of the average prevalence estimates. Within 2018 no big differences between the prevalence estimates were seen over time. Despite of the lower sample size, highest ASFV prevalence estimates were found in dead wild boar, suggesting higher detection rates through passive surveillance than through active surveillance. Accordingly, with the maximum prevalence of 87.5% in May 2018, the ASFV prevalence estimates were very high in wild boar found dead. The number of samples originating from hunted animals (active surveillance) predominated clearly. However, the ASFV prevalence in those animals was lower with a maximum value of 2.1%, emphasizing the high value of passive surveillance. A slight increase of the seroprevalence in hunted wild boar could be seen over time. In the center of Lithuania, a cluster of municipalities with high ASFV and seroprevalence estimates was found. The results of the study indicate that ASFV is still circulating within the Lithuanian wild boar population, constituting a permanent risk of disease transmission into domestic pig holdings. However, additional, more recent data analyses are necessary to re-evaluate the course of ASF in Lithuania and thus, to be able to make a statement about the stage of the ASF epidemic in the country. This is of huge importance for Lithuania for evaluating control measures and their efficacy, but also for neighbouring countries to assess the risk of disease spread from Lithuania.

scholarly journals Predicting the Time to Detect Moderately Virulent African Swine Fever Virus in Finisher Swine Herds Using a Stochastic Disease Transmission Model

2021 ◽  
Author(s):  
Sasidhar Malladi ◽  
Amos Ssematimba ◽  
Peter J. Bonney ◽  
Kaitlyn M. St. Charles ◽  
Timothy Boyer ◽  
...  
Keyword(s):  
Disease Transmission ◽  
African Swine Fever Virus ◽  
Clinical Signs ◽  
African Swine Fever ◽  
The United States ◽  
Disease Spread ◽  
Transmission Model ◽  
Economic Losses ◽  
Parameter Estimates ◽  
Disease Transmission Model

Abstract Background: African swine fever (ASF) is a highly contagious and devastating pig disease that has caused extensive global economic losses. Understanding ASF virus (ASFV) transmission dynamics within a herd is necessary in order to prepare for and respond to an outbreak in the United States. Although the transmission parameters for the highly virulent ASF strains have been estimated in several articles, there are relatively few studies focused on moderately virulent strains. Using an approximate Bayesian computation algorithm in conjunction with Monte Carlo simulation, we have estimated the adequate contact rate for moderately virulent ASFV strains and determined the statistical distributions for the durations of mild and severe clinical signs using individual, pig-level data. A discrete individual based disease transmission model was then used to estimate the time to detect ASF infection based on increased mild clinical signs, severe clinical signs, or daily mortality. Results: Our results indicate that it may take two weeks or longer to detect ASF in a finisher swine herd via mild clinical signs or increased mortality beyond levels expected in routine production. A key factor contributing to the extended time to detect ASF in a herd is the fairly long latently infected period for an individual pig (mean 4.5, 95% P.I., 2.4 - 7.2 days). Conclusion: These transmission model parameter estimates and estimated time to detection via clinical signs provide valuable information that can be used not only to support emergency preparedness but also to inform other simulation models of evaluating regional disease spread.

scholarly journals Evaluation of the Presence of ASFV in Wolf Feces Collected from Areas in Poland with ASFV Persistence

Viruses ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2062
Author(s):  
Maciej Szewczyk ◽  
Krzysztof Łepek ◽  
Sabina Nowak ◽  
Małgorzata Witek ◽  
Anna Bajcarczyk ◽  
...  
Keyword(s):  
Wild Boar ◽  
Long Range ◽  
Disease Transmission ◽  
African Swine Fever ◽  
Movement Behavior ◽  
Dispersal Ability ◽  
Fecal Samples ◽  
Wild Boars ◽  
Daily Movement ◽  
Gps Collars

African swine fever (ASF), caused by a DNA virus (ASFV) belonging to genus Asfivirus of the Asfarviridae family, is one of the most threatening diseases of suids. During last few years, it has spread among populations of wild boars and pigs in countries of Eastern and Central Europe, causing huge economical losses. While local ASF occurrence is positively correlated with wild boar density, ecology of this species (social structure, movement behavior) constrains long-range disease transmission. Thus, it has been speculated that carnivores known for high daily movement and long-range dispersal ability, such as the wolf (Canis lupus), may be indirect ASFV vectors. To test this, we analyzed 62 wolf fecal samples for the presence of ASFV DNA, collected mostly in parts of Poland declared as ASF zones. This dataset included 20 samples confirmed to contain wild boar remains, 13 of which were collected near places where GPS-collared wolves fed on dead wild boars. All analyzed fecal samples were ASFV-negative. On the other hand, eight out of nine wild boar carcasses that were fed on by telemetrically studied wolves were positive. Thus, our results suggest that when wolves consume meat of ASFV-positive wild boars, the virus does not survive the passage through intestinal tract. Additionally, wolves may limit ASFV transmission by removing infectious carrion. We speculate that in areas where telemetric studies on large carnivores are performed, data from GPS collars could be used to enhance efficiency of carcass search, which is one of the main preventive measures to constrain ASF spread.

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