To the Editor: In 2011, Schmallenberg virus, a novel orthobunyavirus of the Simbu serogroup, emerged in Germany and the Netherlands and spread rapidly over large parts of central and western Europe (1–5). The infection primarily affects ruminants but affects camelids as well (1,6). So far, evidence has not shown that humans are susceptible to Schmallenberg virus infection (7). Although the infection in adult animals causes only mild symptoms (1) or remains clinically inapparent, in pregnant animals, transplacental transmission during a limited period can lead to the birth of severely malformed progeny (1,2). Acute infections of adult ruminants or malformed Schmallenberg virus–positive offspring have been detected on >5,000 farms in Austria, Belgium, Denmark, Finland, France, Ireland, Germany, Italy, Luxembourg, Norway, Poland, Spain, Sweden, Switzerland, the Netherlands, and the United Kingdom. Also, a high proportion of adult ruminants were seropositive for antigens of the virus in the core region affected by Schmallenberg virus in the Netherlands, Germany, and Belgium (2,4,5). Schmallenberg virus caused the first known outbreak of an infection with a virus of the Simbu serogroup in Europe. Schmallenberg virus infections are notifiable in Germany. Biting midges seem to play a key role in the transmission of the infection (8), and this transmission led to seasonal spread of the infection in summer and autumn 2011.