Two outbreaks of Schmallenberg virus (SBV) infection that coincided with the introduction of two bulls imported from France into two herds located in West Pomerania and Silesia provinces in Poland are described in detail. The first SBV real-time RT-PCR-positive result was obtained during routine testing of one of the imported bulls. The second bull and the affected farms were tracked by further investigation. Transmission of SBV into Polish cattle herds where the bulls were imported was confirmed by viral RNA detection in real-time RT-PCR, virus isolation followed by immunoperoxidase (IPX) staining and seroconversion. SBV RNA was detected also in Culicoides obsoletus pools caught in a trap located 5 km from one of the outbreaks. Testing nearly 900 samples collected prior to the two outbreaks from the same areas or provinces neighbouring with Germany where SBV cases had previously been detected gave negative results for the presence of SBV or specific antibodies. These cases are the first ones detected in cattle in Poland and provide evidence of recent transmission of the pathogen into the country and involvement of midge vectors.
Schmallenberg virus (SBV), an emerging arbovirus in Europe, is an important pathogen in domestic ruminants; however, its impact on free-ranging wild ruminants is not well studied. Three hundred and forty-seven serum samples collected between 2011 and 2016 from 302 European bison ( Bison bonasus) from 12 different sites in Poland were tested for the presence of SBV antibodies. In addition, 86 sera were collected between 2013 and 2016 from three species of cervids for testing for SBV antibodies. After the first detection of the virus in Poland in October 2012, the proportion of SBV-seropositive European bison reached 81% (95% confidence interval [CI]: 77.1-85.8%), whereas in cervids seroprevalence was 34% (95% CI: 23.5-43.9%). There was an increase in seroprevalence in European bison from 2012 to 2014. Biting midges ( Culicoides spp.), the primary vectors of SBV, were monitored entomologically for the identification of the biting midge populations and virologically for SBV infections in the Białowieża Forest region, which contains the world's largest European bison population. We detected SBV by PCR in 3% of Culicoides pools from 2015. In addition, seven fetal brain samples from European bison or cervids were tested and were negative for SBV RNA. Our results indicate a high seroprevalence with reduced transmission of SBV in subsequent years in the European bison populations and lower seroprevalence in cervids.
The aim of the study was to estimate and compare the distribution of Culicoides biting midges species at farms with different main hosts - cattle and horse. Culicoides spp. are known vectors of arboviruses including African horse sickness virus (AHSV), bluetongue virus (BTV) and Schmallenberg virus (SBV). The latter two have been already reported in Polish ruminants recently, while AHSV remains absent, however the risk of its emergence has been increasing in the recent years. In order to establish the activity of potential AHSV vector at vicinity of horses, an OVI midge trap has been placed at the horse stables in the southeastern Poland. Another trap has been placed 7 km away at the cattle farm. The collections were carried over the midge activity season from April until November 2016. The midge abundances at both sites were comparable with the total numbers of insects trapped of 43,153 and 34,829 at the cattle and horse farm, respectively. Midges belonging to C. obsoletus/scoticus complex were the dominant ones at both locations. The other most abundant species were C. punctatus and C. pulicaris, while the other ten species identified (C. chiopterus, C. deltus, C. dewulfi, C. fagineus, C. impunctatus, C. newsteadi, C. nubeculosus, C. parroti, C. riethi, C. stigma) accounted for less than 0.5%. The study has shown that the Orbivirus vectors are present at a high abundance at the Polish horse farm, what may be a helpful tool in the AHS risk assessment in the nonendemic part of Europe.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.