Transmission
It is not known how this virus is transmitted. It is known, however, that the virus is spread from person to person, and not from an animal source. It has been suggested that this virus may be transmitted through respiratory fluids or urine, since infected individuals periodically excrete virus in the urine. A survey of 400 healthy blood donors was reported as showing that 82% were positive for BK virus.
Read more about this topic: BK Virus