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![Geographical distribution of hunted wild boars in Sweden during the hunting seasons of 2009/2010 and 2010/2011. Based on data provided by the Swedish Association for Hunting and Wildlife Management, Wildlife Monitoring [9]. Colour scale represents number of animals hunted in each county (white areas represent no wild boars hunted). Regions (Nomenclature of Territorial Units for Statistics level 2) are drawn with black borders and black numbers on the map indicate percentage difference between proportion of hunted animals and proportion of sampled animals in each region. For example, South Sweden is underrepresented in our sample compared to the proportion of wild boars hunted in this region.](publication/267874930/figure/fig1/AS:601698213056542@1520467441331/Geographical-distribution-of-hunted-wild-boars-in-Sweden-during-the-hunting-seasons-of.png)
Geographical distribution of hunted wild boars in Sweden during the hunting seasons of 2009/2010 and 2010/2011. Based on data provided by the Swedish Association for Hunting and Wildlife Management, Wildlife Monitoring [9]. Colour scale represents number of animals hunted in each county (white areas represent no wild boars hunted). Regions (Nomenclature of Territorial Units for Statistics level 2) are drawn with black borders and black numbers on the map indicate percentage difference between proportion of hunted animals and proportion of sampled animals in each region. For example, South Sweden is underrepresented in our sample compared to the proportion of wild boars hunted in this region.
Source publication
Toxoplasma gondii
is a zoonotic protozoan parasite, infecting a wide range of warm-blooded animals. The Swedish wild boar population is expanding and increased hunting provides its meat to a growing group of consumers. We performed a spatio-temporal investigation of
T. gondii
seroprevalence in Swedish wild boars. An ELISA was set up and evaluated a...
Contexts in source publication
Context 1
... wild boar population in Sweden increased to more than 100 000 wild boars by 2010/2011 (July-June) compared to ∼40 000 animals in 2005/ 2006 [9]. The geographical distribution of wild boars has expanded during the study period from the south- ern area to include the middle-eastern parts of the country. The population distribution for 2009/2010 and 2010/2011 is shown in Figure 1. The material used in this study is a subset of samples from a national surveillance programme for absent diseases in Swedish wild boars [17]. This programme has been on-going since 2000 and is based on hunters sub- mitting wild boar serum samples to the National Veterinary Institute (SVA) in Uppsala, Sweden. Information on geographical origin is available for most samples, and for samples collected in 2010 and onwards, information on age group based on pheno- type (colour and size) is also registered. In this study the age groups were 412 months and >12 ...
Context 2
... strategy was to randomly select 250 samples from each year. This sample size was based on a population size of 100 000-150 000 wild boars, a maximum expected seroprevalence of 25% [10][11][12] and an aim to detect a 10% change in seroprevalence with 95% confi- dence level and 80% power (Win Episcope 2·0 [18]). Between 10% and 30% of the samples were excluded due to poor quality; moreover, only a limited number of samples were available from 2005 and 2009. Finally, 1328 samples were included in the study and these represented six regions in Sweden (Nomenclature of Territorial Units for Statistics (NUTS) system, level 2 [19]) (Fig. 1). Information on animal age was available for 480 samples. The distribution of samples per year, age group and region, is shown in Table ...
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Citations
... We decided to use meat juice for detection of T. gondii antibodies in raccoons because this material is more easily accessible from raccoon carcasses than blood and, therefore, more suitable in respect of meat inspection as already discussed for other animals (Berger-Schoch et al. 2011). Although it is generally known that antibody concentration in meat juice is lower than in serum, both matrices were shown to correlate well in serological analyses (Wingstrand et al. 1997 (Halos et al. 2010;Nöckler et al. 2005;Wallander et al. 2015). The manufacturer's instruction of the applied ID Screen ELISA test on the one hand advices to use a fivefold lower dilution of meat juice samples (1:2 rather than 1:10 as for serum) and on the other hand also contains an adjusted evaluation scheme for result interpretation from meat juice. ...
Toxoplasma gondii seroprevalence was determined in meat juice samples of 820 free-living raccoons from Germany. The animals were collected between December 2017 and April 2021. Using a commercial enzyme linked immunosorbent assay (ELISA), the overall seroprevalence was found to be 48.5%. Statistical analysis revealed significant seroprevalence differences between seasons, sex, and weight of analysed raccoons. The prevalence in late winter/spring (57.7%) was significantly higher than in autumn (38.4%) (p < 0.0003). Male raccoons (50.5%) were more often seropositive than females (41.0%) (p = 0.028). Increasing animal weight had a significant impact on the relative probability of a positive serostatus (odds ratio: 1.783, p < 0.0001). Furthermore, we found regional differences in seroprevalence, but there was no statistically significant difference resulting from animal age, degree of habitat urbanization and hunting year. Meat juice is a suitable medium for serological surveys for T. gondii in meat producing animals, as sampling is even possible after slaughter or during meat inspection when blood is no longer available. The observed high seroprevalence indicates that T. gondii infection is widespread among the German raccoon population providing a potentially relevant source of T. gondii transmission to humans upon consumption or handling of animal products.
... All the positives were adult wild boars (four adult males and eight adult females), and all 36 juveniles were negative. Kobayashi et al. and other studies have reported that the prevalence of anti-toxoplasma antibodies is low in young animals [3,5,17,24], and this 855-859, 2022 tendency was also observed in this study. A survey of anti-toxoplasma antibodies in wild boars in neighboring prefectures, found that 6.3% were positive in Gunma Prefecture (east of Nagano Prefecture) [7] and 22.7% were positive in Gifu Prefecture (west of Nagano Prefecture) [20]. ...
Wild boars (Sus scrofa) captured or found dead in Nagano Prefecture were surveyed for antibodies to Aujeszky's disease virus (ADV), Erysipelothrix rhusiopathiae, porcine reproductive and respiratory syndrome virus (PRRSV), and Toxoplasma gondii. While all 168 samples tested were negative for anti-ADV antibodies and all 140 samples tested were negative for anti-PRRSV antibodies, all 190 samples tested were positive for anti-E. rhusiopathiae antibodies and 12 of 180 samples were positive for anti-toxoplasma antibodies. These results suggest that since E. rhusiopathiae and T. gondii cause zoonotic diseases, in addition to wild boars being a potential source of infection for domestic pigs, caution should be taken when handling wild boars or eating wild boar meat because of the possibility of human infection.
... Although the seroprevalence of T. gondii in the European wild boar population is estimated at 26%, as noted by Rostami et al. [17], there are countries with a similarly high prevalence as in our study. Romania and Sweden have a T. gondii seroprevalence in wild boar of 57% and 50%, respectively [19,26]. In Spain, France, the Czech Republic, and the Slovak Republic, the prevalence is around 40% [22,[27][28][29][30]. ...
Toxoplasma gondii is a zoonotic parasite of great public health concern. Wild boars could be considered an emerging source of toxoplasmosis in humans due to the popularity of venison and their increasing population. The aim of this study was to determine the seroprevalence of T. gondii in the Slovenian wild boar population and evaluate risk factors for human infection. Of 353 samples, 62% were positive for T. gondii using ELISA tests. This is the highest T. gondii seroprevalence reported to date in wild boar worldwide. The increase in prevalence with increasing age (p = 0.003) and weight (p = 0.002) were statistically significant, whereas gender was not (p = 0.781). Odds for being T. gondii-positive increased with age with the largest difference being between 2–3-year-old and 1–2-year-old animals (OR = 2.66, 95%CI: 1.03–6.85). Animals weighing 20–40 kg had a higher risk than animals weighing 0–20 kg (OR = 2.74, 95%CI: 1.21–6.20), whereas a further increase in the weight was not associated with increasing the odds. Due to the high Toxoplasma prevalence, the study concluded that the risk of exposure to T. gondii from handling raw or undercooked wild boar meat is high. Surveillance protocols should be established at the national level together with increased awareness within the hunting community.
... We observed a 9% seroprevalence of T. gondii infection in wild boar. A clearly higher seroprevalence (50%) was reported in Sweden (Wallander et al. 2015). One reason for this may be the higher wild boar density and more frequent contact with cat feces in Sweden compared to Finland. ...
The northern European wild boar population has increased during the last decade. Highest wild boar numbers in Finland have been reported in the southeastern part near the Russian border. Wild boars may be infected with several human and animal pathogens. In this study, we investigated the presence of important foodborne pathogens in wild boars hunted in 2016 in Finland using serology, PCR and culturing. Seroprevalence of Salmonella (38%) and Yersinia (56%) infections was high in wild boars. Antibodies to hepatitis E virus, Toxoplasma gondii and Brucella were found in 18%, 9% and 9% of the wild boars, respectively. Trichinella antibodies were detected in 1% of the animals. We recorded no differences in the seroprevalence between males and females. However, Yersinia and T. gondii antibodies were detected significantly more often in adults than in young individuals. Listeria monocytogenes (48%) and stx -positive Escherichia coli (33%) determinants were frequently detected in the visceral organs (spleen and kidneys) by PCR. Yersinia pseudotuberculosis O:1 and L. monocytogenes 2a and 4b were identified by culturing from the PCR-positive samples. Brucella suis biovar 2 was isolated from visceral organs. No African swine fever, classical swine fever or Aujeszky’s disease were detected in the wild boars. Our study shows that wild boars are important reservoirs of foodborne pathogens.
... Im ursprünglichen Verbreitungsgebiet des Waschbären in Nordamerika reichen die Prävalenzwerte von T. gondii-Antikörpern im Blutserum von 15 % bis 100 % (Hancock et al. 2005;Mitchell et al. 2006 Gamarra et al. 2008;Wallander et al. 2014). Im Gegensatz zu nordamerikanischen und europäischen Studien fanden sich bei lediglich 9,9 % -13,7 % der in Japan eingeführten und freilebenden Waschbären T. gondii-Antikörper (Matoba et al. 2002;Sato et al. 2011 (Burridge et al. 1979;Smith et al. 1992;Hill et al. 1998;Mitchell et al. 1999;Hwang et al. 2007;Sato et al. 2011;Heddergott et al. 2017 ...
Toxoplasma gondii is a protozoon that can
cause toxoplasmosis in warm-blooded animals.
Most mammals, including humans, can act as
intermediate hosts, which can lead to subclinical
infection or even death. So far, there is little
information available on the epidemiology of
T. gondii in wild animals from Germany. The
raccoon (Procyon lotor), one of the most widely
distributed and common invasive species in
Germany, is an omnivore and is therefore particularly
exposed to this parasite. Previous studies
on raccoons from different regions of Germany
show a relatively high prevalence of T.
gondii (26.0 %–53.3 %). Here we report on the
prevalence of T. gondii antibodies in the blood
serum of raccoons from an area of the Hessian
Rhön in Germany. Using an indirect modified
agglutination test (MAT), antibodies against T.
gondii were detected in 61 of the 93 (65.6 %;
95 % confidence interval: 27.3 % – 81.2 %) raccoons
examined. We found a strong influence
of weight on the presence of T. gondii antibodies,
but not of sex and age group. The results
confirm previous studies that infections with T.
gondii are widespread in German raccoons and
further it can be assumed that there is a high
degree of circulation of this parasite in the Rhön
ecosystem.
... bovis studies reported LCM as the statistical analysis method. 23,38,80,117 A cost-effec-tive ELISA for screening for brucellosis in African buffalo (Syncerus caffer) was developed with determination of cutoff value based on the use of a Bayesian LCM. 38 Similar methods were also applied in henipavirus assays in African bats. ...
Evaluation of the diagnostic sensitivity (DSe) and specificity (DSp) of tests for infectious diseases in wild animals is challenging, and some of the limitations may affect compliance with the OIE-recommended test validation pathway. We conducted a methodologic review of test validation studies for OIE-listed diseases in wild mammals published between 2008 and 2017 and focused on study design, statistical analysis, and reporting of results. Most published papers addressed Mycobacterium bovis infection in one or more wildlife species. Our review revealed limitations or missing information about sampled animals, identification criteria for positive and negative samples (case definition), representativeness of source and target populations, and species in the study, as well as information identifying animals sampled for calculations of DSe and DSp as naturally infected captive, free-ranging, or experimentally challenged animals. The deficiencies may have reflected omissions in reporting rather than design flaws, although lack of random sampling might have induced bias in estimates of DSe and DSp. We used case studies of validation of tests for hemorrhagic diseases in deer and white-nose syndrome in hibernating bats to demonstrate approaches for validation when new pathogen serotypes or genotypes are detected and diagnostic algorithms are changed, and how purposes of tests evolve together with the evolution of the pathogen after identification. We describe potential benefits of experimental challenge studies for obtaining DSe and DSp estimates, methods to maintain sample integrity, and Bayesian latent class models for statistical analysis. We make recommendations for improvements in future studies of detection test accuracy in wild mammals.
... In this study, observed seroprevalences of T. gondii in the investigated game species varied between 6.4% in red deer to 24.4% in wild boar. These results are in line with other European studies, where seroprevalences between seven and 60% in cervids and five and 57% in wild boar have been observed in the past (European Food Safety Authority, 2013; Heddergott et al., 2018;Jokelainen, Velstrom, & Lassen, 2015;Racka et al., 2015;Wallander, Frossling, Vagsholm, Uggla, & Lunden, 2015), further implying the endemic nature of T. gondii in European sylvatic environments. ...
... Seroprevalence for T. gondii in all studied game species increased with age as was seen in many other studies investigating wildlife and humans (Berger-Schoch, Bernet, Doherr, Gottstein, & Frey, 2011;Deksne & Kirjusina, 2013;Heddergott et al., 2018;Jokelainen, Näreaho, Hälli, Heinonen, & Sukura, 2012;Laforet et al., 2019;Rostami et al., 2017;Wallander et al., 2015;Wilking et al., 2016). However, we only found statistical significance for this observation for roe deer. ...
... Finland (Jokelainen et al., 2010), Sweden (Wallander et al., 2015) and Estonia (Remes et al., 2018). As game becomes a more and more popular meat source, an increase in the number of farmed game can be expected and should therefore also be included in the studies. ...
Consumption of game in Germany has increased during the past 10 years. Wild boar (Sus scrofa), roe deer (Capreolus capreolus) and red deer (Cervus elaphus) are the most frequently hunted and consumed game animals in Germany, yet information on the occurrence of zoonotic pathogens in these animal species is scarce. To better estimate the public health risk emanating from handling and consumption of game, this study investigated seroprevalences of Toxoplasma gondii in game hunted in the German federal state of Brandenburg during two hunting seasons from 2017 to 2019. Toxoplasma gondii‐specific antibodies were detected in 24.4% (44/180, 95% CI: 18.4%–31.4%) of wild boar, 12.8% (16/125, 95% CI: 7.5%–20%) of roe deer and 6.4% (3/47, 95% CI: 1.3%–17.5%) of red deer using a commercial ELISA kit. Seroprevalences were similar in the two hunting seasons. Correlation between sex and seropositivity could not be observed. A rise in seroprevalence was seen with increasing age in all studied game species. Observed seroprevalences suggest that T. gondii is endemic in the sylvatic environment in the German federal state of Brandenburg and imply that game could represent a relevant source for human T. gondii infection.
... A higher seroprevalence of T. gondii was observed in studies employing ELISA (enzymelinked immunosorbent assay) or MAT than in those which used LAT (latex agglutination test). Using ELISA, the highest prevalence of antibodies to T. gondii in Europe has been demonstrated in wild boars from Sweden (50%) and Romania (56.7%) [15,39]. A relatively high prevalence was reported using MAT in studies conducted by Richomme et al. [32] in France (40.4%) and in Spain (43.5%) [7]. ...
PurposeThe European wild boar (Sus scrofa) is a popular game animal species. Its meat, however, can represent a reservoir of dangerous foodborne diseases and can play an important role in the transmission of many pathogens, including Toxoplasma gondii, in humans and animals worldwide. The aim of the present study was to determine the presence of antibodies to T. gondii in the serum of hunted wild boars in Poland.Methods
Using the commercial direct agglutination test, 398 serum samples collected during the hunting season 2009/2010 were tested for the presence of T. gondii antibodies, and the titre of 40 was considered indicative of T. gondii infection in analysed samples.ResultsIt was found that nationwide, 37.7% were seropositive to T. gondii, although seroprevalence varied from 11.6 to 50% depending on the Voivodeship. Significant differences were observed between the Great Poland and Lubusz Voivodeships and between Great Poland and Warmian-Masurian.Conclusion
Serological test indicated widespread exposure to T. gondii by wild boar; therefore, consumption of raw or undercooked game meat of infected animals can carry a significant risk of T. gondii infection.
... The minimum needed sample size for estimating the seroprevalence was calculated to be 85-91 animals, based on the seroprevalence estimates of 33% and 50% from Finland and Sweden, respectively [12,13], a 80% confidence level, and a population size of 200 (estimated annual wild boar hunting bag in Denmark). The sample size available for the study was 101 wild boars, 38 (37.6%) of which were reported to be younger than 1 year old. ...
... The seroprevalence was significantly higher in the wild boars reported to be at least 1 year old than in those reported to be younger. This result is in line with the result from free-ranging wild boars from Sweden [13], and indicates that the infections are acquired: older wild boars have had longer time to encounter the parasite. Whether the antibodies persist lifelong in wild boars has been questioned [16]. ...
... A recent systematic review and meta-analysis on T. gondii in wild boars estimated the seroprevalence to be 23% globally and 26% in Europe [3]. Our overall estimate (27.7%) was thus of the expected magnitude, and did not differ significantly from those reported for farmed wild boars in Finland (33.0%) [12] and Latvia (20.3%) [18] nor from those reported for free-ranging wild boars in Latvia (35.1%) [18], Estonia (24.0%) [17], and Sweden (28.6%) [19], but it was lower (P-value < 0.001) than an earlier estimate for freeranging wild boars in Sweden (49.5%) [13]. It should be emphasized that the results of different studies are not directly comparable due to different farm management and game management, different sampling strategies, and different methods applied, but they illustrate that the parasite is common and endemic in the Nordic-Baltic region. ...
Toxoplasma gondii is a zoonotic parasite of worldwide importance. In this study, we estimated T. gondii seroprevalence in extensively farmed wild boars in Denmark, where little is known about T. gondii in animal hosts. Our study focused on wild boars because they are considered good indicator species for the presence of T. gondii, and wild boar meat is used for human consumption. Serum samples from 101 wild boars collected in 2016–2018 from five different locations from the continental part of Denmark, Jutland, were screened for anti-T. gondii antibodies. The samples were analysed using a commercial indirect enzyme-linked immunosorbent assay (ELISA). Samples from 28 (27.7%) of the 101 wild boars tested positive with the ELISA. The odds for a wild boar to test seropositive were higher if it was sampled during the hunting season 2017–2018 than during 2016–2017 and if it was reported to be at least 1 year old than if it was younger (logistic regression model with the two variables: odds ratios 17.5 and 3.9, respectively). A substantial proportion of the investigated extensively farmed wild boars had been exposed to T. gondii. Moreover, the parasite appeared widespread, at least in the continental part of Denmark, Jutland, as seropositive wild boars were found from all five sampled locations. Assuming seropositivity indicates hosting viable parasites, consumption of undercooked wild boar meat from Denmark is a potential source of T. gondii infections to other hosts, including humans.
... Comparison is challenging, as no reference method with 100% SE and SP is available. The MAT was used as a reference test, in the same manner as in other studies (Forbes et al., 2012;Steinparzer et al., 2015;Wallander, Frossling, Vagsholm, Uggla et al., 2015). It has been shown to work even for meat juice samples with low antibody levels (Forbes et al., 2012). ...
Salmonella spp., Yersinia enterocolitica, Toxoplasma gondii and Trichinella spp. are the most relevant biological hazards in the context of meat inspection of pigs in the European Union (EU). These zoonotic pathogens show no clinical symptoms or gross pathological lesions in pigs, and thus are not detectable with current meat inspection procedures, except Trichinella spp. by laboratory analysis. In this study, we analysed the serological prevalence of these pathogens in Finnish fattening pigs and evaluated serological monitoring as a control method.
In total, we studied 1353 meat juice samples and 1793 serum samples of fattening pigs using commercial ELISA kits. The seroprevalence of pathogenic Yersinia spp. was the highest of the studied pathogens, and Yersinia antibodies were detected in 57% and 66% of the meat juice and serum samples at the end of the fattening period, respectively. The seroprevalences of Salmonella spp. and T. gondii were low. Salmonella antibodies were detected in 3% of the meat juice samples and in 18% of the serum samples at the end of fattening. T. gondii antibodies were detected in 3% of meat juice samples and 1% of serum samples. Trichinella spp. antibodies were not detected. The seroprevalences at the end of the fattening or at slaughter were not associated with post-mortem findings of the current batch, which was expected. This indicates that we need new tools to control these public health hazards in pork.
Meat juice serology at slaughter was feasible and easy to perform. We observed huge differences between farms considering Salmonella spp., Yersinia spp. and T. gondii seroprevalences. This shows that farm-level serological data could be used as part of the food chain information (FCI) for risk-based decisions to improve food safety. Risk-based decisions include slaughtering arrangements, additional carcass processing, targeted sampling at the slaughterhouse and improved biosecurity measures at the farm. However, risk mitigation targets and procedures must be carefully adjusted for each pathogen. With targeted serological monitoring of T. gondii we could effectively target control measures and diminish the pathogen in pork. Serological monitoring of pathogenic Yersinia spp. could be the first step in the huge challenge of Y. enterocolitica in pigs, allowing for the possibility of slaughtering pigs from high-risk farms at the end of the day. Serological monitoring of Salmonella spp. would be beneficial, but would only have a limited positive impact on food safety, because the current situation is already excellent. Serosurveillance of Trichinella spp. would become meaningful, if current testing is to be diminished.
In addition to food safety issues, FCI could be useful for visual-only inspection, which should be the most common inspection method. We analysed authentic FCIs and meat inspection findings of 85 slaughter batches of fattening pigs. In addition, we analysed on-farm health status indicators, assessed by a veterinarian, and the meat inspection findings of another 57 slaughter batches. The partial carcass condemnation rate of the current batch was best predicted by the partial carcass condemnation rate of the pigs from the same farm within one year. Constant coughing and tail biting at a farm were associated with partial carcass condemnations. On-farm health indicators (such as the healed tail biting rate at the end of fattening and constant coughing during fattening) together with previous meat inspection results could be used as part of the FCI to make decisions regarding the meat inspection procedure: visual-only or additional inspections. However, farmers must be properly advised to carefully report this information.
