Since 2006 bluetongue disease is rapidly spreading across Europe and reached Switzerland in October 2007. In the present article a short overview about the disease and the virus is given, and the first three clinical bluetongue disease cases in cattle, and the respective laboratory findings are presented.
Neospora caninum has gained considerable attention through its role in the aetiology of bovine abortion. Due to its close phylogenetic relationship with Toxoplasma gondii, respective unequivocal differential diagnosis deserves special consideration. In order to evaluate the diagnostic performance of molecular and immunodiagnostic techniques and to provide insights into the epidemiological significance of bovine neosporosis in Switzerland, we conducted a study on 83 cases of bovine abortion: of these, 24 (29%) foetal brains were positive by Neospora-PCR, six of these foetuses were simultaneously seropositive in Neospora-IFAT and/or somatic antigen-ELISA. Conversely, four (5%) foetal brains were considered positive by Toxoplasma-PCR, two of which were also seropositive in the Toxoplasma-P30-ELISA and/or direct agglutination test. The seroprevalence in 1689 cattle sera obtained from 113 diary farms was 11.5% (95% confidence interval: 9.2-13.8) by Neospora-somatic antigen-ELISA were and 10.7% (95% confidence interval: 8.3-12.6) by Toxoplasma-P30-ELISA. From the same samples, 1.1%, less than statistically expected, were positive in both ELISA. Within selected groups of cow-calf farms, the seroprevalence determined using the Neospora-somatic antigen-ELISA was 14% (95% confidence interval 5.0-23.0) for dams and 15% (95% confidence interval: 3.0-28.0) for offspring calves. Seroprevalences determined by Toxoplasma-P30-ELISA were 8% (95% confidence interval: 4.0-12.0) for dams and 3% (95% confidence interval: 0.3-6.0) for calves. None of the sera gave a positive reaction in both ELISA. Our data indicated that prenatal neosporosis appears as an important cause of bovine abortion in Switzerland.
The risk of transmission of pathogens from free-ranging wild boars (Sus scrofa scrofa) to outdoor domestic pigs (S. scrofa domesticus) is of increasing concern in many European countries. We assess this risk, using Switzerland as an example. We estimated 1) the prevalence of important pathogens in wild boars and 2) the risk of interactions between wild boars and outdoor pigs. First, we tested 252 wild boars from selected areas between 2008 and 2010 for infection with Brucella spp. Bacterial prevalence was estimated to 28.8% (confidence interval [CI] 23.0-34.0) when using bacterial culture (B. suis Biovar 2) and real-time polymerase chain reaction. Antibody prevalence was 35.8% (CI 30.0-42.0), which was significantly higher than in previous studies in Switzerland. We also tested 233 wild boars for porcine reproductive and respiratory syndrome virus (PRRSV). Antibody prevalence was 0.43% (CI 0.01-2.4) for EU-PRRSV and real-time reverse transcription polymerase chain reaction results were negative. These findings suggest that B. suis is increasingly widespread in wild boars and PRRSV is currently not of concern. Second, we documented the spatial overlap between free-ranging wild boars and outdoor piggeries by mapping data on their respective occurrence. Wild boars are most widespread in the mountain range along the western and northern Swiss borders, while most piggeries are located in central lowlands. A risk of interaction is mainly expected at the junction between these two bioregions. This risk may increase if wild boars expand eastward and southward beyond anthropogenic barriers believed to limit their range. Therefore, we evaluated the potential of expansion of the wild boar population. Population trends suggest a continuous increase of wild boars for the past 15 yr. Surveillance of selected wildlife passages using cameras on highways and main roads indicates that these barriers are permeable (average of up to 13 wild boar crossings per 100 days). Thus an increase of wild boar range should be considered. There may be a risk of B. suis spillover from wild boars in Switzerland, which could increase in the future. Data on the occurrence of interactions between pigs and wild boars are needed to assess this risk.
During two survey rounds of a national surveillance system for infectious diseases in wild boar in Switzerland, each lasting four months from November to February, between 2001 and 2003, 1949 blood samples and 62 tissue samples from the spleen and 50 from the reproductive organs were collected from hunted wild boar. The survey was designed so that freedom from infection could be detected with a probability of 95 per cent at a threshold prevalence of less than 1 per cent for classical swine fever and Aujeszky's disease and less than 1.5 per cent for brucellosis. There was no serological evidence of classical swine fever or Aujeszky's disease, but brucellosis due to Brucella suis biovar 2 was confirmed serologically and by bacterial isolation.
The large abundance of free-ranging wild boars (Sus scrofa) and a trend towards animal friendly outdoor management of domestic pigs lead to an increasing probability of disease transmission between those animal populations. In 2001, an active monitoring was started for classical swine fever (CSF), Aujeszky's disease (AD) and porcine brucellosis (PB) in wild boars in Switzerland. The objective of this programme was to document the serological status of wild boars regarding the selected pathogens. To continue this serosurveillance, 1,060 wild boar samples were collected during two regular hunting seasons in [2004][2005]. Furthermore, in a pilot study, 61 outdoor pigs from 14 farms located in areas with high wild boar densities were sampled in 2004 and serologically tested for AD and PB. All wild boar samples were negative for CSF. Seroprevalence for AD was 2.83% (95% CI 1.91-4.02%). Seroprevalence for PB was 13.5% (95% CI 10.7-16.7%) for the Rose Bengal test and 11.05% (95% CI 8.82-13.61%) for the indirect ELISA. There was no serological evidence for AD in domestic pigs. All tested animals from 13 piggeries were seronegative for PB, but three pigs from the same farm showed doubtful results. Further investigations on the farm did not indicate the presence of PB in the herd. These findings urge the need for better diagnostic tools to obtain reliable results concerning PB prevalence. Since contact and following transmission of infectious agents between infected wild boars and outdoor pigs might occur in the future, it is advisable to include outdoor pigs in areas at risk in routine surveillance programmes.
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