Zika Virus and the Safety of Blood Supply in Brazil: A Retrospective Epidemiological Evaluation.

The potential for transfusion transmission of dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV) has raised concerns about the safety of the blood supply in endemic areas. In this study, nucleic acid testing (NAT) for ZIKV, DENV, and CHIKV RNA was performed in asymptomatic blood donor samples in the city of Campinas, located in the southeast region of Brazil (1962 in 2015 and 1775 in 2016). The prevalence of reactive NAT was 0.15% in 2015 and 0.62% in 2016 for dengue, 0.05% in 2015 and 0.17% in 2016 for Zika, and 0% in both years for chikungunya. These results demonstrate the weakness of the clinical interview in screening these blood donors. Furthermore, positivity for ZIKV was detected in March 2015, 1 year before the first reported cases in the region. These data attest the feasibility of using donor samples held in library as a tool for retrospective epidemiological evaluation, which is particularly interesting considering emerging pathogens, for which data on their spread and penetrance are initially scarce.