scholarly journals Estimation of the Lethality Rate, Recovery Rate, and Case Fatality Ratio of Classical Swine Fever in Japanese Wild Boar: An Analysis of the Epidemics From September 2018 to March 2019

2021 ◽  
Vol 8 ◽  
Author(s):  
Ryota Matsuyama ◽  
Takehisa Yamamoto ◽  
Yoko Hayama ◽  
Ryosuke Omori
Keyword(s):  
Population Dynamics ◽  
Wild Boar ◽  
Recovery Rate ◽  
Case Fatality ◽  
Classical Swine Fever ◽  
Accurate Estimation ◽  
Detailed Data ◽  
Wild Boar Population ◽  
Case Fatality Ratio ◽  
In The Wild

Understanding the morbidity and lethality of diseases is necessary to evaluate the effectiveness of countermeasure against the epidemics (e.g., vaccination). To estimate them, detailed data on host population dynamics are required; however, estimating the population size for wildlife is often difficult. We aimed to elucidate the morbidity and lethality of classical swine fever (CSF) currently highly prevalent in the wild boar population in Japan. To this end, we estimated lethality rate, recovery rate, and case fatality ratio (CFR) of CSF without detailed data on the population estimates of wild boar. A mathematical model was constructed to describe the CSF dynamics and population dynamics of wild boar. We fitted the model to the (i) results of the reverse transcription polymerase chain reaction (RT-PCR) test for the CSFV gene and the (ii) results of the enzyme-linked immunosorbent assay (ELISA) test for the antibody against CSFV in sampled wild boar. In the 280 wild boar sampled from September 2018 to March 2019 in the major CSF-affected area in Japan, the lethality rate and recovery rate of CSF per week were estimated as 0.165 (95% confidence interval: 0.081–0.250) and 0.004 (0–0.009), respectively. While the estimate of lethality rate of CSF was similar with the estimates in previous studies, the recovery rate was lower than those reported previously. CFR was estimated as 0.959 (0.904–0.981) using our estimate of recovery rate. This study is the first to estimate lethality rate of CSF from the dynamics of CSF epidemics in the wild boar population. Since the value of CFR is sensitive to the value of recovery rate, the accuracy in the estimate of recovery rate is a key for the accurate estimation of CFR. A long-term transmission experiment of moderately virulent strains may lead to more accurate estimation of the recovery rate and CFR of CSF.

scholarly journals Epidemiological analysis of classical swine fever in wild boars in Japan

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Yumiko Shimizu ◽  
Yoko Hayama ◽  
Yoshinori Murato ◽  
Kotaro Sawai ◽  
Emi Yamaguchi ◽  
...  
Keyword(s):  
Wild Boar ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Classical Swine Fever ◽  
Disease Spread ◽  
Wild Boar Population ◽  
Wild Boars ◽  
First Case ◽  
Forest Continuity ◽  
In The Wild

Abstract Background Classical swine fever (CSF) is a contagious disease of pigs and wild boars that is transmitted through direct/indirect contact between animals or CSF virus-contaminated fomites. When the disease re-emerged in 2018 in Japan, a CSF-infected wild boar was reported shortly after the initial pig farm outbreak; subsequently, the disease spread widely. To control the disease spread among wild boars, intensive capturing, fencing, and oral bait vaccination were implemented with concomitant virological and serological surveillance. This study aimed to describe the disease spread in the wild boar population in Japan from September 2018, when the first case was reported, to March 2020, based on the surveillance data. We conducted statistical analyses using a generalized linear mixed model to identify factors associated with CSF infection among wild boars. Moreover, we descriptively assessed the effect of oral bait vaccination, which started in March 2019 in some municipalities in the affected areas. Results We observed a faster CSF infection spread in the wild boar population in Japan compared with the CSF epidemics in European countries. The infection probability was significantly higher in dead and adult animals. The influence of the multiple rounds of oral bait vaccination was not elucidated by the statistical modeling analyses. There was a decrease and increase in the proportion of infected and immune animals, respectively; however, the immunization in piglets remained insufficient after vaccination for 1 year. Conclusions Conditions regarding the wild boar habitat, including forest continuity, higher wild boar population density, and a larger proportion of susceptible piglets, were addressed to increase the infection risk in the wild boar population. These findings could improve the national control strategy against the CSF epidemic among wild boars.

scholarly journals Efficacy of Oral Vaccine against Classical Swine Fever in Wild Boar and Estimation of the Disease Dynamics in the Quantitative Approach

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 319
Author(s):  
Enkhbold Bazarragchaa ◽  
Norikazu Isoda ◽  
Taksoo Kim ◽  
Madoka Tetsuo ◽  
Satoshi Ito ◽  
...  
Keyword(s):  
Wild Boar ◽  
Oral Vaccine ◽  
Classical Swine Fever ◽  
Control Measures ◽  
Wild Boar Population ◽  
Oral Vaccination ◽  
Wild Boars ◽  
In The Wild ◽  
High Virus ◽  
Gifu Prefecture

Classical swine fever virus (CSFV) in the wild boar population has been spreading in Japan, alongside outbreaks on pigs, since classical swine fever (CSF) reemerged in September 2018. The vaccination using oral bait vaccine was initially implemented in Gifu prefecture in March 2019. In the present study, antibodies against CSFV in wild boar were assessed in 1443 captured and dead wild boars in Gifu prefecture. After the implementation of oral vaccination, the increase of the proportion of seropositive animals and their titer in wild boars were confirmed. Quantitative analysis of antigen and antibodies against CSFV in wild boar implies potential disease diversity in the wild boar population. Animals with status in high virus replication (Ct < 30) and non- or low-immune response were confirmed and were sustained at a certain level after initial oral vaccination. Through continuous vaccination periods, the increase of seroprevalence among wild boar and the decrease of CSFV-positive animals were observed. The epidemiological analysis based on the quantitative virological outcomes could provide more information on the efficacy of oral vaccination and dynamics of CSF in the wild boar population, which will help to improve the implementation of control measures for CSF in countries such as Japan and neighboring countries.

scholarly journals Prevalence and Antimicrobial Resistances of Salmonella spp. Isolated from Wild Boars in Liguria Region, Italy

Pathogens ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 568
Author(s):  
Elisabetta Razzuoli ◽  
Valeria Listorti ◽  
Isabella Martini ◽  
Laura Migone ◽  
Lucia Decastelli ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Wild Boar ◽  
Antimicrobial Susceptibility ◽  
Potential Risk ◽  
Salmonella Enterica ◽  
Intestinal Tract ◽  
Wild Boar Population ◽  
Salmonella Spp ◽  
Wild Boars ◽  
In The Wild

Salmonella spp. is an important zoonotic agent. Wild boars might host this pathogen in the intestinal tract and might represent a risk for Salmonella spp. transmission to humans. Wild boars are widely spread in Liguria, due to the environmental characteristics of the region. The aim of the study was the isolation, typing, and investigation of antimicrobial susceptibility of the isolated strains of Salmonella spp. During the 2013–2017 hunting seasons, 4335 livers of wild boars were collected and analyzed for the presence of Salmonella spp. A total of 260 strains of Salmonella spp. were isolated and characterized, with a prevalence of 6%. The isolated strains belonged to all six Salmonella enterica subspecies. Most of them were identified as Salmonella enterica subs. enterica of which 31 different serotypes were identified. The dominating serotype identified was S. Enteritidis. The antimicrobial resistance profiles of the isolated strains were analyzed against sixteen molecules. Of the isolated strains, 94.6% were resistant to at least one of the tested antimicrobials. This study showed the circulation of resistant Salmonella spp. strains in the wild boar population living in this area of Italy, underling the potential risk for these animals to disseminate this pathogen and its antimicrobial resistances.

scholarly journals Pets becoming established in the wild: free–living Vietnamese potbellied pigs in Spain

2013 ◽  
Vol 36 (2) ◽  
pp. 209-215
Author(s):  
M. Delibes–Mateos ◽  
◽  
A. Delibes ◽  
Keyword(s):  
Wild Boar ◽  
Sus Scrofa ◽  
Species Abundance ◽  
Crop Damage ◽  
Wild Boar Population ◽  
Natural Habitats ◽  
Free Living ◽  
In The Wild ◽  
Google Search ◽  
Adequate Management

Vietnamese potbellied (VPB) pigs (Sus scrofa) are a common pet in North America and Europe, but their recent decrease in popularity has increased their abandonment. Our main aim was to identify potential cases of free–living VPB pigs in Spain through an in–depth Google search. We identified 42 cases of free–living VPB pigs distributed throughout the country. The number of free–living VPB pigs reported increased by year but the species abundance still seems to be low. Signs of VPB pig reproduction and possible hybrids between VPB pigs and wild boar or feral pigs have been also reported. Free–living VPB pigs could erode the gene pool of the Spanish wild boar population and exacerbate the damage (e.g. crop damage or spread of diseases) already caused by wild board. Urgent evaluation and adequate management of wild VPB pig sightings is needed to prevent their establishment in natural habitats.

scholarly journals Does the infection with endoparasites influence the effect of oral vaccination against classical swine fever in wild boar?

2015 ◽  
Vol 84 (3) ◽  
pp. 225-230
Author(s):  
Anna Ondrejková ◽  
Ondrej Kiš ◽  
Juraj Ciberej ◽  
Katarína Oberhauserová ◽  
Róbert Ondrejka ◽  
...  
Keyword(s):  
Wild Boar ◽  
Classical Swine Fever ◽  
Viral Disease ◽  
Economic Losses ◽  
Parasitic Infections ◽  
Oral Vaccination ◽  
Specific Antibodies ◽  
Antibody Titres ◽  
In The Wild ◽  
Direct Elisa

Classical swine fever is a highly contagious viral disease that affects domestic and wild suids and could cause important economic losses. It is the most dangerous infectious disease of the wild boar that can cause severe death in densely populated areas. The aim of the study was to determine the effect of endoparasites on the oral vaccination against classical swine fever in wild boar. The study compared classical swine fever antibody titres in wild boar treated and untreated with antiparasitics. Fourteen six-month-old wild boar piglets were tested via direct ELISA to detect specific antibodies in blood serum after vaccination. Before the vaccination, one group of piglets was administered antiparasitic therapy; the other group of animals remained untreated. Twenty-eight days post vaccination, piglets from the first group (free of parasites) showed significantly (P = 0.0015) higher concentrations of specific antibodies than the infected animals. Obtained results proved that parasitic infections substantially influence the efficacy of oral vaccination against classical swine fever and may support the ability of the virus to produce infectious diseases and its transmission in the wild boar population. For that reason, antiparasitic therapy of wild boar populations before their vaccination is highly recommended in order to increase the vaccine’s efficacy.

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 Dynamics of Classical Swine Fever Spread in Wild Boar in 2018–2019, Japan

Pathogens ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 119 ◽  
Author(s):  
Norikazu Isoda ◽  
Kairi Baba ◽  
Satoshi Ito ◽  
Mitsugi Ito ◽  
Yoshihiro Sakoda ◽  
...  
Keyword(s):  
Wild Boar ◽  
Euclidean Distance ◽  
Classical Swine Fever ◽  
Control Measures ◽  
Anthropogenic Factors ◽  
Epidemiological Analysis ◽  
Period Prevalence ◽  
Positive Rate ◽  
In The Wild ◽  
Spatiotemporal Analyses

The prolongation of the classic swine fever (CSF) outbreak in Japan in 2018 was highly associated with the persistence and widespread of the CSF virus (CSFV) in the wild boar population. To investigate the dynamics of the CSF outbreak in wild boar, spatiotemporal analyses were performed. The positive rate of CSFV in wild boar fluctuated dramatically from March to June 2019, but finally stabilized at approximately 10%. The Euclidean distance from the initial CSF notified farm to the farthest infected wild boar of the day constantly increased over time since the initial outbreak except in the cases reported from Gunma and Saitama prefectures. The two-month-period prevalence, estimated using integrated nested Laplace approximation, reached >80% in half of the infected areas in March–April 2019. The area affected continued to expand despite the period prevalence decreasing up to October 2019. A large difference in the shapes of standard deviational ellipses and in the location of their centroids when including or excluding cases in Gunma and Saitama prefectures indicates that infections there were unlikely to have been caused simply by wild boar activities, and anthropogenic factors were likely involved. The emergence of concurrent space–time clusters in these areas after July 2019 indicated that CSF outbreaks were scattered by this point in time. The results of this epidemiological analysis help explain the dynamics of the spread of CSF and will aid in the implementation of control measures, including bait vaccination.

scholarly journals Epidemiological survey of swine influenza A virus in the wild boar population of two Italian provinces

2013 ◽  
Vol 7 ◽  
pp. 16-20 ◽  
Author(s):  
Emanuela Foni ◽  
Chiara Garbarino ◽  
Chiara Chiapponi ◽  
Laura Baioni ◽  
Irene Zanni ◽  
...  
Keyword(s):  
Wild Boar ◽  
Influenza A Virus ◽  
Influenza A ◽  
Swine Influenza ◽  
Epidemiological Survey ◽  
Wild Boar Population ◽  
Italian Provinces ◽  
In The Wild ◽  
Swine Influenza A Virus

A long-term serological survey on Aujeszky's disease virus infections in wild boar in East Germany

2011 ◽  
Vol 140 (2) ◽  
pp. 348-358 ◽  
Author(s):  
G. PANNWITZ ◽  
C. FREULING ◽  
N. DENZIN ◽  
U. SCHAARSCHMIDT ◽  
H. NIEPER ◽  
...  
Keyword(s):  
Wild Boar ◽  
Disease Virus ◽  
East Germany ◽  
Wild Boar Population ◽  
Entire Study ◽  
Domestic Pigs ◽  
Aujeszky's Disease ◽  
Aujeszky’S Disease ◽  
Aujeszky’S Disease Virus ◽  
In The Wild

SUMMARYBetween 1985 and 2008, a total of 102 387 wild boar sera originating from Eastern Germany covering an area of 108 589 km2 were tested for the presence of Aujeszky's disease virus (ADV)-specific antibodies. From 1985 until 1991 and from 1992 until 2008, wild boar sera were exclusively investigated using either conventional seroneutralization assays (n=39 621) or commercial gB and full antigen ELISAs (n=62 766), respectively. Spatial-temporal analysis revealed an increasing ADV seroprevalence from 0·4% to 15·9%, on average, during the 24-year observation period that went along with a continuous spread of the infection in a western direction. During 2006 and 2008, 18% of the 66 affected districts had ADV seroprevalences >30%. There was a significant correlation between ADV seroprevalence and the hunting index of population density (HIPD) of wild boar in the entire study area, although this did not hold true for some regions. Seroprevalences did not differ between sexes but were age-dependent. East Germany has been officially free of Aujeszky's disease (pseudorabies) in domestic pigs since 1985. Although a risk for domestic pigs cannot be completely ruled out, experience has shown that ADV in domestic pigs could be eliminated although the virus was present in the wild boar population. Despite increasing ADV seroprevalence in the East German wild boar population no spillover infections from wild boar to domestic pigs have been reported. To further trace ADV infections in the wild boar population in Germany, a nationwide serological monitoring programme should be implemented.

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