Borna disease (the name stem from a small village in Saxony, Germany where the disease became epidemic in 1895) is caused by atypical virus (Borna disease virus, BDV). BDV is prototypic virus of the family Bornaviridae, within the order Mononegavirales within which viruses of Ebola and Mahrburg, an Rhabdoviridae are also classified. Noteworthy, all attempts to isolate BDV with methods of classical virology failed and the virus was only molecularly cloned in the late eighties of the XX century. BDV occur epidemically in Germany, Switzerland, North America, Japan and Israel. It seems that, analogously to rabies virus, it may infect all the vertebrates including horses, primates, ships, lamas, hippos, cats and cattle but also birds (ostrich). The virus reservoir are probably small rodents. The problem of BDV infection in humans is still open to debate.