Schmallenberg Virus beyond Latitude 65°N

• Published in: Transboundary and emerging diseases Vol. 62; no. 5; pp. e11 - e18
• Main Authors: Chenais, E., Ståhl, K., Frössling, J., Blomqvist, G., Näslund, K., Svensson, L., Renström, L., Mieziewska, K., Elvander, M., Valarcher, J. F.
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Science 01.10.2015; Blackwell Publishing Ltd; Hindawi Limited
• Subjects: Animal diseases; Animals; bulk milk; Bunyaviridae Infections - epidemiology; Bunyaviridae Infections - veterinary; Bunyaviridae Infections - virology; Cattle; Cattle Diseases - virology; emerging; Geography, Medical; Milk - virology; Orthobunyavirus - immunology; Orthobunyavirus - isolation & purification; Schmallenberg virus; Seasons; Seroepidemiologic Studies; Sheep; Sheep Diseases - virology; surveillance; Sweden; vectorborne infection; Viruses; Sweden; bulk milk; vectorborne infection; surveillance; Schmallenberg virus; emerging
• ISSN: 1865-1674; 1865-1682
• DOI: 10.1111/tbed.12195

Extensive and rapid spread of Schmallenberg virus (SBV) in Sweden was detected by consecutive serological bulk milk surveys conducted before and after the vector season of 2012. Whereas <0.2% of cattle herds tested positive in a first survey in spring 2012, SBV‐specific antibodies were detected in almost 75% of 723 bulk milk samples randomly collected all over the country 6 months later, beyond the 65th northern latitude, and with an observed spatial distribution suggesting multiple introductions of the virus. Circulation of virus was later confirmed by the detection of SBV in malformed lambs and calves starting from November 2012 and January 2013, respectively. These observations suggest SBV circulation starting from July 2012, with a peak in transmission between August and October. A local heterogeneity of within‐herd seroprevalence was found, indicating that SBV‐naïve animals remain also in highly infected areas enabling the re‐emergence of the infection in the coming vector season.