Parvovirus B19 infection.

Human parvovirus B19 (B19) is common in society. Among adults, more than 50% have contracted the infection and immunity is believed to last lifelong. Infection occurs in a few percent of pregnancies, and albeit rare it can then cause fetal anemia, non-immune fetal hydrops and fetal death. Among cases with fetal demise, B19 is found in significant numbers, especially in the second and third trimesters of pregnancy. There is no specific treatment or prophylaxis available against B19 infection, but counseling of non-immune mothers and active monitoring of confirmed maternal infections with intervention to correct fetal anemia is likely to decrease mortality. Passive immunization also has potential to resolve fetal complications, but needs further study.