IF the adage that the ‘retrospectoscope’ is a powerful tool is to be believed, it is useful to review the occurrence of the second epizootic viral vector borne disease to emerge in five years in Northern Europe: the emergence of Schmallenberg virus (SBV) illustrates a number of key principles in the control of such transboundary diseases. Globalisation and climate change are clearly drivers of changing patterns of vector borne disease (Saker and others 2004). Purse and others (2005) recognised the potential for bluetongue (BTV) to spread beyond its accustomed subtropical/Mediterranean distribution into more temperate climates, but the sudden occurrence of BTV-8 in 2006 and the speed and scale of its spread in Northern Europe was unprecedented. A similar pattern has been seen more recently with SBV. In the late summer of 2011, an unusual pattern of clinical disease (fever, milk drop and in some cases diarrhoea) was observed in dairy herds on both sides of the Dutch-German border (Promed 2011). The ability to recognise the occurence of something new and get an accurate picture of what is happening is the first step in disease control. Information on the emergence and spread of this, at first …