Table 1. The different grades of CMV infection.

CMV infection status	Description
Not infected	Not infected with the virus; negative IgG and IgM antibodies against CMV
Latent infection	Carrier of the CMV genome without active replication
Active infection	Detectable viral replication in peripheral blood or organs or a significant rise in IgM antibodies against CMV
Disease	Clinical expression of active infection, that is, active CMV infection with end-organ involvement