With growing concern about infectious diseases in donated organs, the Centers for Disease Control and Prevention is due to release next month draft guidelines for reducing transmission of hepatitis C and HIV through solid organ transplants. While the guidelines are still under review, they are widely expected to reflect the results of a new study led by CDC researchers that concludes the use of a rapid assay known as nucleic acid testing could significantly reduce the rate of undetected hepatitis C in deceased donors. The study calculated the prevalence of the two viruses in 13,667 potential donors managed by 17 organ procurement organizations over a five-year period. It estimated that a striking 18.2% of potential donors considered at high risk for hepatitis C and 3.45% of donors considered at normal risk could be infected with the virus. NAT can detect an infection acquired seven days before testing, while standard blood tests (known as serologic testing) measure antibodies to an infection that may take months to appear. Antibodies to hepatitis C, for example, may not be detected for as long as 70 days after exposure.