Comparison of cytomegalovirus loads in plasma and leukocytes of patients with cytomegalovirus retinitis

Cytomegalovirus (CMV) DNA loads in paired leukocyte and plasma samples from 199 patient visits by 66 patients with CMV retinitis were determined. Leuk ocyte CMV load determinations had a greater range of values (mean, 24,587 c opies/10(6) leukocytes; maximum, 539,000) than did plasma CMV load determin ations (mean, 10,302 copies/ml; maximum, 386,000), and leukocyte viral load s were detectable in a greater proportion of patients at the time of diagno sis of CMV retinitis prior to initiation of anti-CMV therapy (82%) than wer e plasma viral loads (64%) (P = 0.0078). Agreement,vith CMV blood cultures was slightly better for plasma (kappa = 0.68) than for leukocytes (kappa = 0.53), due to a greater proportion of patients with detectable viral loads in leukocytes having negative blood cultures.