The Panel said that, although no single mechanism has been found to be responsible for the survival of the bluetongue virus through winter, infected Culicoides midges still remain the most likely way.

Although recent data showed that in different geographical areas across Europe some Culicoides midges may remain active indoors through winter, the role of these insects in prolonging the transmission period of the virus is still not clear. The Panel concluded that in some geographical areas in Europe there may not be an absolute vector-free period.

The Panel added that more information is needed on the daylight and indoor winter activities of Culicoides and on their ability to spread the disease. Experts therefore recommended that Member States carry out in-depth analyses at regional level, since the life pattern of these insects may vary depending on location and season.

The opinion also reviewed data on the effectiveness of insecticides as one of the measures to protect animals against attacks from vectors. The Panel said insecticides may be used to limit the population of Culicoides and their biting rates, thereby reducing the risk of subsequent bluetongue virus transmission; however, they should not be used as a stand-alone measure to protect animals against Culicoides attacks.

By September 2008, the Panel will also deliver an additional opinion specifically on the risks linked to the transit of animals through bluetongue infected areas.