Hello All,
CPV is the most common virus which effects  those hives with a high
investation of varroa. We had very little virus problems before varroa
although many viruses  were identified by Bailey aand others before varroa.
Most research was done in the U.K. looking for  a solution to tracheal
mites.
I suspect there is more to the story than 40% of the domestic hives dead
from viruses.
Sincerely,
Bob Harrison
Missouri
"Show me state"