A DNA virus most famously associated with a childhood viral disorder, so-called “fifth disease.” Parvo can also cause a complete lack of production of all blood cells (“aplastic crisis”) in adults, especially in immunocompromised adults, pregnant women, and their fetuses. Blood bankers most encounter parvovirus in the setting of plasma-derived products, where the usual heat and/or solvent-detergent treatment methods don’t work to get rid of the virus (S/D treatment does not work because parvovirus is not contained within a lipid envelope; i.e., it is non-enveloped). The FDA published a guidance in July 2009 requiring nucleic acid testing for parvovirus B19 on units of source plasma and recovered plasma sent for further manufacture into plasma derivatives.