How does BTV-8 overwinter?
Vertical transmission of a female to her egg has recently been claimed in the USA but has not been found to be the case hitherto. Different viruses and midge vectors make any work on one not necessarily applicable to another. Young female obsoletus midges have been recorded all through the winter at a very low rate in the Netherlands at the monitoring sites in and around animal housing. Older virus positive females were not found. However the infection emerged again in ruminants at multiple sites throughout the previous extent of infection early in the summer. The longevity of infectiousness of a ruminant is rather variable- not all ruminants infected experimentally are infectious to midges anyway, of those that are some may be infectious for 60 – 90 days though most are infectious to midges for up to 21 days. As so many animals are infected those few at the far end of the bell shaped curve with infectious periods of longer than 60 days are likely to be significant in number and span t
