Frequency and duration of plasma CMV viremia in seroconverting blood donors and recipients

Both CMV-seronegative blood and unscreened, filtered blood carry a low but definite risk of transmitting CMV infection. To explain this residual risk, evidence of cell-free viremia was sought in seroconverting and seroprevalent blood donors and seroconverting transfusion recipients by means of a plasma-based assay for CMV DNA.

A CMV DNA PCR assay (COBAS Amplicor CMV Monitor, Roche) was used to detect CMV DNA in 384 paired plasma samples from 192 donors who seroconverted to anti-CMV, 488 anti-CMV EIA-positive samples from 60 seroprevalent donors, and 113 serial samples from 11 seroconverting recipients with posttransfusion CMV hepatitis.

Three of 384 samples from 192 seroconverting donors had low levels of plasma CMV DNA (400-1600 copies/mL); one donor was positive before seroconversion, and the other two, after seroconversion. None of the 488 serial samples from 60 anti-CMV- positive donors contained CMV DNA in plasma. Three of 11 recipients demonstrated transient plasma viremia that temporally coincided with seroconversion.

Plasma CMV DNA was detected in a small percentage of seroconverting blood donors and a larger percentage of recipients but was undetectable in seroprevalent donors. Plasma viremia in seroconverting donors may partially explain the low residual risk of CMV transmission by both CMV-seronegative and WBC-reduced seropositive blood.