In terms of how the virus is transmitted, there is no evidence of any other route of transmission other than from mother to offspring through the placenta or vector borne routes such as that of the Culicoides obsoletus biting midge. EFSA noted that recent results have identified SBV where the biting midge Culicoides obsoletus group is found. Some research data suggest that the Culicoides obsoletus group is widespread in Europe; however more comprehensive, harmonised datasets are required.

The Authority reviewed those animal species most susceptible to the virus, noting that it has been detected in cattle, sheep, goats and a bison. SBV antibodies have been detected in deer but no other species are known to be affected. EFSA also reiterates that new studies support the initial assessment undertaken by the European Center for Disease Control and Prevention, indicating that it is very unlikely that SBV poses a risk to humans.

Prediction of spread in 2013

The probability of SBV surviving over the winter and subsequently spreading in 2012 and manifesting itself in late 2012 / early 2013 is difficult to assess because of a lack of data. Should the virus survive the winter, EFSA’s geographical spread model predicts that SBV is most likely to re-emerge between mid-April and the end of May and that any outbreak of SBV is likely to be of a similar size to the one that occurred in 2011. It is likely to affect regions previously unaffected (assuming immunity of animals in previously affected regions). Based on the model developed by EFSA to predict possible geographical spread of SBV over time, the areas most likely to be affected -- should the virus manifest itself again later this year or early in 2013 — would be in regions to the south and east of the previously-affected areas. This assessment on the impact of SBV should be interpreted with caution since the reported levels depend on national rules in place regarding the obligation to notify the disease upon its detection, the level of awareness of different stakeholders and the diagnostic capability in the Member States. No data are currently available on the impact of SBV on individual farms.

In its conclusions, EFSA puts forward a number of research recommendations to fill the knowledge gaps that have been identified through the Authority’s extensive analysis based on its data collection and liaison with the Member States.

The Authority will continue to monitor and analyse the epidemiological data collected from the Member States and provide further reports to the European Commission and Member States as needed.

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