Parvovirus B19 (“fifth disease”) is a common childhood infection caused by a small, non-enveloped DNA virus. It infects rapidly dividing cells, and effects the precursors of erythrocytes or red blood cells. Thirty to sixty percent of adults have prior exposure to parvovirus.
Parvovirus is diagnosed clinically with antibody testing. Viremia, or the presence of virus in the blood, begins approximately one week after exposure and lasts for one week. IgM antibodies can be detected 10 days after exposure and can last for several months. IgG antibodies are found as soon as a few days after IgM antibodies develop and can persist for years.
Parvovirus in Pregnancy
Although parvovirus typically only causes mild, flu-like symptoms in the mother, the risk to the fetus is greater. This is because it may infect the fetus and result in fetal anemia, fetal hydrops, and still birth. The rapidly expanding red cell volume, a shorter half-life of red blood cells, and an immature immune system make the fetus particularly susceptible to the effects of parvovirus B19 on red blood cells.
Fetal Infection with Parvovirus
Fortunately, in the majority of cases of maternal exposure and infection, parvovirus is not transmitted to the fetus. The risk of fetal infection from maternal infection appears to be approximately 25-33%. Furthermore, adverse effects such as fetal anemia are seen only a small portion of those fetuses infected. Therefore, overall, for women infected with parvovirus, the risk of fetal anemia requiring treatment is only 5%.
Management of Parvovirus in Pregnancy
For women with documented infections, diagnostic ultrasound is used to detect the development of fetal anemia, which usually occurs up to 10 weeks after infection. Once evidence of severe anemia develops, management involves intrauterine transfusion. Despite several reports of spontaneous resolution of fetal hydrops, intrauterine fetal transfusion is still considered the optimal management in parvovirus fetal anemia cases.
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Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!