Current prevalence and incidence of infectious disease markers and estimated window-period risk in the American Red Cross blood donor population.

BACKGROUND There has been continuing progress in measures to reduce the risk of transfusion-transmitted infection, including introduction of serologic tests of increased sensitivity and the recent implementation of investigational NAT in small pools of samples. STUDY DESIGN AND METHODS Data relating to all blood donations to the American Red Cross have been consolidated into a single database. The prevalence of confirmed-positive test results for HBsAg, HCV, HIV, and HTLV were evaluated for each year for first-time donors from 1995 through 2001. Incidence rates for these infections were evaluated among repeat donors having at least two donations in a 2-year period. The frequencies of HIV-1 RNA- and HCV RNA-positive, seronegative donations were assessed for first-time and repeat donations. The relationship risk = (window period) x (incidence) was used to assess residual risk among repeat donations and to evaluate the incidence of HCV and HIV infection among first-time donors. RESULTS During the study period, prevalence rates for all markers declined significantly over time: in 2001, the rates per 100,000 were 75.6 for HBsAg, 299 for HCV, 9.7 for HIV, and 9.6 for HTLV; the corresponding incidence rates (/100,000 person-years) were 1.267, 1.889, 1.554, and 0.239, respectively. Estimates of residual risk in donations from repeat donors (after NAT) for HCV and HIV were 1 per 1,935,000 and 1 per 2,135,000, respectively. However, incidence rates for these agents are approximately two times greater among first-time donors. For both HCV and HIV, NAT yield was concordant with that predicted by current window-period models. CONCLUSION These data cover about half of all the whole blood collected in the United States. They suggest increasing improvement in transfusion safety and clearly define the benefit of pooled NAT.