Erythema infectiosum (also known as fifth disease) is usually a benign childhood condition characterized by a classic slapped-cheek appearance and lacy exanthem.  It results from infection with human parvovirus (PV) B19, anhrerytovirus. . Human PV-B19 also is associated with other hematologic, rheumatologic, and neurologic conditions, including polyarthropathy, aplastic anemia, and hydrops fetalis. In erythema infectiosum, a classic 3-phased cutaneous eruption follows a rarely noticed prodrome. In most cases, this is such a mild illness that no medicine is necessary.