Most B19V infections are asymptomatic or are associated with only a mild nonspecific illness.

• Erythema infectiosum (fifth disease): The main manifestation of symptomatic B19V disease, erythema infectiosum presents as a low-grade fever ~7-10 days after exposure and a facial “slapped-cheek” rash (more common among children) a few days later. Two or three days after the facial rash develops, a lacy, reticular macular rash may spread to the extremities.
• Polyarthropathy syndrome: Arthralgias, typically symmetric and affecting the small joints of the hands and occasionally the ankles, knees, and wrists, occur in ~50% of adults (more commonly women). Most cases resolve in a few weeks, but some persist for months.
• Transient aplastic crisis (TAC): Pts with chronic hemolytic conditions (e.g., hemoglobinopathies, autoimmune hemolytic anemia) can develop aplastic crisis with B19V infection that can be life-threatening. Pts display symptoms associated with severe anemia.
• Pure red-cell aplasia/chronic anemia: Immunosuppressed pts can develop persistent anemia with reticulocytopenia, high levels of B19V DNA in serum, and absent or low levels of B19V IgG. B19V occasionally causes a hemophagocytic syndrome.
• Hydrops fetalis: B19V infection during pregnancy can lead to hydrops fetalis and/or fetal loss. The risk of transplacental fetal infection is ~30%, and the risk of fetal loss (which occurs predominantly early in the second trimester) is ~9%. The risk of congenital infection is <1%.