Editing Bluetongue disease (section)

===Overwintering===
A puzzling aspect of BTV is its survival between midge seasons in temperate regions. Adults of ''Culicoides'' are killed by cold winter temperatures, and BTV infections typically do not last for more than 60 days, which is not long enough for BTV to survive until the next spring. It is believed that the virus somehow survives in overwintering midges or animals. Multiple mechanisms have been proposed.  A few adult ''Culicoides'' midges infected with BTV may survive the mild winters of the temperate zone.  Some midges may even move indoors to avoid the cold temperature of the winter.  Additionally, BTV could cause a chronic or latent infection in some animals, providing another means for BTV to survive the winter.  BTV can also be transmitted from mother to fetus.  The outcome is abortion or stillbirth if fetal infection occurs early in gestation and survival if infection occurs late.  However infection at an intermediate stage, before the fetal immune system is fully developed, may result in a chronic infection that lingers until the first months after birth of the lamb. Midges then spread the pathogen from the calves to other animals, starting a new season of infection.<ref name=Wilson2008>{{cite journal | vauthors = Wilson A, Darpel K, Mellor PS | title = Where does bluetongue virus sleep in the winter? | journal = PLOS Biology | volume = 6 | issue = 8 | pages = e210 | date = August 2008 | pmid = 18752350 | pmc = 2525685 | doi = 10.1371/journal.pbio.0060210 | doi-access = free }}</ref>