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

BACKGROUND: 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. STUDY DESIGN AND METHODS: 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. RESULTS: Three of 384 samples from 192 seroconverting donors had low levels of plasma CMV DNA (4001600 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. CONCLUSIONS: 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.