Schmallenberg Virus Recurrence, Germany, 2014 - Volume 21, Number 7—July 2015 - Emerging Infectious Disease journal - CDC
Volume 21, Number 7—July 2015
Schmallenberg Virus Recurrence, Germany, 2014
Schmallenberg virus (SBV), an insect-transmitted orthobunyavirus with a negative-stranded tripartite RNA genome, causes no or only mild nonspecific clinical signs for a few days in adult ruminants (1). However, infection of immunologically naive animals during a vulnerable period of pregnancy can cause premature birth, stillbirth, or severe malformations in the offspring (2).
SBV was first detected in autumn 2011 in the blood of an acutely infected cow in North Rhine-Westphalia, Germany (1). In early 2012, a large number of malformed lambs and calves, which tested positive for SBV, were born in central Europe (2). The malformations resulted from infection of the dams in summer or autumn 2011 and transplacental transmission. Within this first vector season, the virus spread rapidly within and between the animal holdings. In the center of the epidemic in northwestern Germany, the Netherlands, and Belgium, >90% of tested cattle became seropositive (3). During the following year, SBV circulated again in Germany (4) but at a much lower level and predominantly at the margin of the initially most affected area because susceptible animals had remained there.
During the 2013 vector season and the following winter, SBV cases were detected only sporadically (only SBV genome detections without successful virus isolation) (5). For example, only 7 cases of viral genome detection were reported to the German Animal Disease Reporting System during January 1–March 24, 2014; these cases resulted from infection of the respective dams during summer or autumn 2013. The high seroprevalence of the ruminant population and the marked decline of births with SBV-associated malformations in newborns raised hopes that SBV had disappeared after the first epidemic, as occurred with the transient appearance of bluetongue virus serotype 8 in the same region of Europe (6).
Dr. Wernike is a veterinarian and scientist at the Friedrich-Loeffler-Institut, Institute of Diagnostic Virology. Her research interests are emerging animal viruses, molecular diagnostics, and pathogenesis.
We thank the German local diagnostic laboratories for providing the SBV-positive samples. We are grateful to Kristin Trippler for excellent technical assistance. We gratefully acknowledge Andrea Aebischer’s help with the animal experiment and the dedicated animal care by staff of the isolation unit of the Friedrich-Loeffler-Institut. We also thank Andreas Moss for providing SBV isolate D495/12-1.
This work was financially supported by Boehringer Ingelheim Vetmedica GmbH.
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Suggested citation for this article: Wernike K, Hoffmann B, Conraths FJ, Beer M. Schmallenberg virus recurrence, Germany, 2014. Emerg Infect Dis. 2015 Jul [date cited]. http://dx.doi.org/10.3201/eid2107.150180