Skip to main content

Lack of evidence for the presence of Schmallenberg virus in mosquitoes in Germany, 2011



In 2011, a novel orthobunyavirus of the Simbu serogroup was discovered near the German-Dutch border and named Schmallenberg virus (SBV). So far, SBV genome has been detected in various field-collected Culicoides species; however, other members of the Simbu serogroup are also transmitted by mosquitoes.


In the present study, approximately 50,000 mosquitoes of various species were collected during summer and early autumn 2011 in Germany. None of them tested positive in an SBV-specific real-time PCR.


The absence of SBV in mosquitoes caught in 2011 in Germany suggests that they play no or only a negligible role in the spread of the disease.



Schmallenberg virus (SBV), the first European member of the Simbu serogroup, genus Orthobunyavirus, emerged in summer 2011 near the German/Dutch border [1]. Since then, the virus has spread very rapidly over large parts of the continent. Affected adult ruminants show either no or non-specific, mild clinical signs for only a few days, but fetal infection may lead to severe malformation, stillbirth or premature birth [2].

Simbu serogroup viruses have been frequently isolated from Culicoides midges, but also from mosquitoes [3, 4]. So far, SBV has been detected in various Culicoides species such as C. obsoletus s.s., C. scoticus, C. chiopterus, C. dewulfii, C. pulicaris, or C. nubeculosus collected during summer and early autumn 2011 in Belgium, the Netherlands or Denmark [57]. Of head pools from Culicoides midges collected in the Netherlands throughout September and early October 2011 2.3% tested positive by real-time RT-PCR [5], and an infection rate of approximately 3.6% was estimated for Culicoides caught in the region of Antwerp (Belgium) in September 2011 [6].

However, in hibernating mosquitoes SBV was not detected which suggests that mosquitoes are not important for the persistence of SBV during winter [8]. However, their role in SBV-transmission during the period of high virus circulation is unknown.


In the present study, female mosquitoes were collected in summer and early autumn 2011 at 17 sites in Germany (Figure 1). The mosquitoes were either trapped with CO2-baited encephalitis vector surveillance (EVS) traps (BioQuip, Compton, CA) or gravid traps (GT) designed according to the CDC gravid trap model 1712 (John W. Hock Company, Gainesville, FL). Collected mosquitoes were deep-frozen transported to the laboratory and subsequently identified on chill tables according to species and sex using morphological characteristics [9]. Mosquitoes were pooled (up to 25 specimens) according to species and trapping site, placed in sterile 2-ml cryovials, and then maintained at −70°C until being tested for virus RNA. The homogenization of mosquitoes was done according to Jöst et al.[10]. Total RNA was extracted using the QIAamp viral RNA mini kit (Qiagen, Hilden, Germany) according to manufacturer’s recommendation, and tested by an SBV S-segment specific real-time RT-PCR [11] which has been previously used for SBV-detection in pools of midges (up to 50 midges per pool) [5, 6, 12].

Figure 1
figure 1

legend: Location of the trapping sites.

Results and discussion

Between May and September 2011, a total of 50,708 mosquitoes were collected. The most abundant species trapped were Culex pipiens/torrentium (62%) and Aedes vexans (24%). The number of individuals and the species are listed in Table 1 individually for each trapping site. Most of the individuals collected in GT are gravid females, which had already taken a blood meal, making them more suitable for arbovirus surveillance. All mosquitoes collected in summer and early autumn 2011 in Germany tested negative in the SBV-specific real-time PCR. During this period, an unidentified disease, which was later identified as an infection with SBV was reported in German and Dutch dairy cattle herds [1]. From August onwards, SBV-specific antibodies were detected in domestic ruminants [13] suggesting a circulation of virus during the trapping period. After the 2011 epizootic, the seroprevalence in cattle reached nearly 100% in the focus of the affected area, and the virus had spread very rapidly over large parts of Europe [14, 15]. SBV was even detected in Culicoides midges caught in Denmark in October or in Italy between September and November 2011 (reviewed in [14]). In the German federal state Rhineland-Palatinate, the seroprevalence in cattle was approximately 80% (95% confidence interval (CI) 67.67 - 89.22%) after the 2011 epizootic, and in Baden-Wuerttemberg it was about 32% (95% CI 22.23 - 44.10%) [14], the trapping sites 9 to 17, where more than half of the mosquitoes were collected, are located in the border region of both federal states. Despite this very high prevalence in the ruminant hosts and the thereby presumably considerable virus circulation, none of the mosquitoes collected in the present study tested positive by the SBV-specific real-time RT-PCR. However, approximately one third of the tested mosquitoes were caught in Mecklenburg-Pomerania (trapping site 7), a region with a seroprevalence of only about 2% (95% CI 0.06 – 12.29%) in cattle [14].

Table 1 Trapping sites, dates, and number of mosquitoes per species collected during the study period

In Australia, Asia or Africa, Simbu viruses can be isolated from local mosquitoes [3, 4]. Since SBV is the first European member of the Simbu serogroup, species potentially involved in transmission in Europe cannot be deduced from closely related viruses. However, several mosquito-borne mammal-associated orthobunyaviruses of other serogroups such as Ťahyňa virus, Inkoo virus (both California serogroup) or Batai virus (Bunyamwera group) have been documented in various western European countries [17]. Of these, Ťahyňa virus is most often isolated from Aedes vexans, which was the second most common species trapped in the present study, but also from other culicine mosquitoes. The principal vector for Batai virus in Europe are zoophilic mosquitoes such as Anopheles maculipennis s.l., Anopheles claviger, Ochlerotatus punctor and Ochlerotatus communis, among others [18]. All of these species were collected in the present study and tested for the presence of SBV.

Despite reported symptoms of the disease in susceptible animals during the trapping period and a high seroprevalence after the first vector season, none of the collected mosquitoes tested positive in the SBV-specific real-time RT-PCR. Considering the detection of viral RNA in biting midges in regions with a much lower seroprevalence in ruminants, in Denmark even before clinical signs were observed or virus was detected in domestic animals [19], mosquitoes most likely play only a negligible, if any, role in SBV transmission.



Schmallenberg virus


Encephalitis vector surveillance


Gravid trap.


  1. Hoffmann B, Scheuch M, Höper D, Jungblut R, Holsteg M, Schirrmeier H, Eschbaumer M, Goller KV, Wernike K, Fischer M, Breithaupt A, Mettenleiter T, Beer M: Novel orthobunyavirus in cattle, Europe, 2011. Emerg Infect Dis. 2012, 18 (3): 469-472. 10.3201/eid1803.111905.

    Article  PubMed Central  PubMed  Google Scholar 

  2. Beer M, Conraths FJ, van der Poel WH: 'Schmallenberg virus' - a novel orthobunyavirus emerging in Europe. Epidemiol Infect. 2013, 141 (1): 1-8. 10.1017/S0950268812002245.

    Article  CAS  PubMed  Google Scholar 

  3. Elliott RM, Blakqori G: Molecular biology of orthobunyaviruses. Bunyaviridae: Molecular and Cellular Biology. Edited by: Plyusnin A, Elliott RM. 2011, Norfolk, UK: Caister Academic Press, 1-39.

    Google Scholar 

  4. Saeed MF, Li L, Wang H, Weaver SC, Barrett AD: Phylogeny of the Simbu serogroup of the genus Bunyavirus. J Gen Virol. 2001, 82 (Pt 9): 2173-2181.

    Article  CAS  PubMed  Google Scholar 

  5. Elbers AR, Meiswinkel R, van Weezep E, van Oldruitenborgh-Oosterbaan MM S, Kooi EA: Schmallenberg Virus in Culicoides spp. Biting Midges, the Netherlands, 2011. Emerg Infect Dis. 2013, 19 (1): 106-109. 10.3201/eid1901.121054.

    Article  PubMed Central  PubMed  Google Scholar 

  6. De Regge N, Deblauwe I, De Deken R, Vantieghem P, Madder M, Geysen D, Smeets F, Losson B, van den Berg T, Cay AB: Detection of Schmallenberg virus in different Culicoides spp. by real-time RT-PCR. Transboundary and emerging diseases. 2012, 59 (6): 471-475. 10.1111/tbed.12000.

    Article  CAS  PubMed  Google Scholar 

  7. Rasmussen LD, Kristensen B, Kirkeby C, Rasmussen TB, Belsham GJ, Bodker R, Bøtner A: Culicoids as vectors of schmallenberg virus. Emerg Infect Dis. 2012, 18 (7): 1204-1206.

    PubMed Central  CAS  PubMed  Google Scholar 

  8. Scholte EJ, Mars MH, Braks M, DENH W, Ibanez-Justicia A, Koopmans M, Koenraadt JC ADEV, Reusken C: No evidence for the persistence of Schmallenberg virus in overwintering mosquitoes. Med Vet Entomol. 2013, 28 (1): 110-115.

    Article  PubMed  Google Scholar 

  9. Becker N, Petric D, Zgomba M, Boase C, Dahl C, Lane J, Kaiser A: Mosquitoes and their control. 2003, New York, NY: Kluwer, 1

    Book  Google Scholar 

  10. Jöst H, Bialonski A, Storch V, Gunther S, Becker N, Schmidt-Chanasit J: Isolation and phylogenetic analysis of Sindbis viruses from mosquitoes in Germany. J Clin Microbiol. 2010, 48 (5): 1900-1903. 10.1128/JCM.00037-10.

    Article  PubMed Central  PubMed  Google Scholar 

  11. Bilk S, Schulze C, Fischer M, Beer M, Hlinak A, Hoffmann B: Organ distribution of Schmallenberg virus RNA in malformed newborns. Vet Microbiol. 2012, 159 (1–2): 236-238.

    Article  CAS  PubMed  Google Scholar 

  12. Elbers AR, Meiswinkel R, van Weezep E, Kooi EA, van der Poel WH: Schmallenberg Virus in Culicoides Biting Midges in the Netherlands in 2012. Transboundary and emerging diseases. 2014, doi:10.1111/tbed.12128

    Google Scholar 

  13. Veldhuis AM, van Schaik G, Vellema P, Elbers AR, Bouwstra R, van der Heijden HM, Mars MH: Schmallenberg virus epidemic in the Netherlands: Spatiotemporal introduction in 2011 and seroprevalence in ruminants. Prev Vet Med. 2013, 112 (1-2): 35-47. 10.1016/j.prevetmed.2013.06.010.

    Article  CAS  PubMed  Google Scholar 

  14. Wernike K, Conraths F, Zanella G, Granzow H, Gache K, Schirrmeier H, Valas S, Staubach C, Marianneau P, Kraatz F, Höreth-Böntgen D, Reimann I, Zientara S, Beer M: Schmallenberg virus-Two years of experiences. Prev Vet Med. 2014, doi:10.1016/j

    Google Scholar 

  15. EFSA: "Schmallenberg" virus: analysis of the epidemiological data (May 2013). EFSA Supporting Publications 2013 EN-3429,; accessed 15/07/2013 2013

  16. Becker N, Kruger A, Kuhn C, Plenge-Bonig A, Thomas SM, Schmidt-Chanasit J, Tannich E: [Mosquitoes as vectors for exotic pathogens in Germany]. Bundesgesundhbl. Gesundheitsforsch. Gesundheitsschutz. 2014, 57 (5): 531-540. 10.1007/s00103-013-1918-8.

    Article  CAS  Google Scholar 

  17. Lundström JO: Mosquito-borne viruses in western Europe: a review. Journal of vector ecology: journal of the Society for Vector Ecology. 1999, 24 (1): 1-39.

    Google Scholar 

  18. Hubalek Z: Mosquito-borne viruses in Europe. Parasitol Res. 2008, 103 (Suppl 1): S29-S43.

    Article  PubMed  Google Scholar 

  19. Rasmussen LD, Kirkeby C, Bodker R, Kristensen B, Rasmussen TB, Belsham GJ, Bøtner A: Rapid spread of Schmallenberg Virus-infected Biting Midges (Culicoides spp.) across Denmark in 2012. Transboundary and Emerging Diseases. 2014, 61 (1): 12-16. 10.1111/tbed.12189.

    Article  CAS  PubMed  Google Scholar 

Download references


Alexandra Bialonski provided excellent technical assistance and Christina Czajka's help during the trapping of the mosquitoes is gratefully acknowledged.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Martin Beer.

Additional information

Competing interests

The authors have no financial, personal, or professional interests that inappropriately influenced this paper.

Authors' contributions

Conceived and designed the experiments: NB, JS, MB. Performed the experiments: HJ. Analyzed the data: KW HJ. Drafted the manuscript: KW JH. All authors read and approved the final manuscript.

Kerstin Wernike, Hanna Jöst contributed equally to this work.

Authors’ original submitted files for images

Below are the links to the authors’ original submitted files for images.

Authors’ original file for figure 1

Rights and permissions

Open Access  This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit

The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wernike, K., Jöst, H., Becker, N. et al. Lack of evidence for the presence of Schmallenberg virus in mosquitoes in Germany, 2011. Parasites Vectors 7, 402 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: