Prevalence, incidence, and residual risk of human immunodeficiency virus among community and replacement first-time blood donors in Sao Paulo, Brazil

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Abstract
Concerted efforts have been directed toward recruitment of community rather than replacement donors in Brazil. Time trends and demographic correlates of human immunodeficiency (HIV) prevalence and incidence among first-time (FT) donors in Brazil were examined by donation type. HIV residual risk from FT-donor transfusions, and projected yield of p24 antigen and nucleic acid test (NAT) screening were estimated. HIV prevalence data and seroreactive specimens were obtained at Fundação Pró-Sangue/Hemocentro-de-São Paulo from 1995 to 2001. To estimate incidence, confirmed-positive samples from July 1998 through December 2001 were tested with a less-sensitive (detuned) enzyme immunoassay to detect recent seroconversions. Incidence data were used to estimate residual risk and p24 and NAT yield based on published window periods (WPs). HIV prevalence was 22 percent higher among the FT community donors than replacement donors (19.6 vs. 16.1 per 10,000; p < 0.01) and 48 percent higher among men than women (19.1 vs. 12.9; p < 0.01). In the multivariable logistic regression, both variables remained significant predictors of HIV prevalence. HIV prevalence decreased from 20.4 (1995) to 13.1 per 10,000 FT donations (2001). HIV incidence was 2.7 per 10,000 person-years. The estimated rate of infected antibody-negative donations was 14.9 per 1,000,000 units (95% confidence interval, 9.8-20.0). It was estimated that addition of p24 antigen, minipool NAT, and individual-donation NAT assays would detect 3.9 (2.0-5.8), 8.3 (5.3-11.3), and 10.8 (7.1-14.5) WP units per 1,000,000 FT donations, respectively. HIV incidence and residual transfusion risk estimates are approximately 10 times higher in Brazil FT donors compared to US and European FT donors. Community FT donors had higher HIV prevalence than replacement FT donors. The yield of p24 antigen or RNA screening will be low in Brazilian donors, but substantially higher than in US donors.