Perinatal Parvovirus B19 Infection

Abstract

After completing this article, readers should be able to: 1. Understand the epidemiology of parvovirus B19 infection. 2. Describe the clinical and hematologic features of B19 infection. 3. List the virologic and serologic tests used to diagnose B19 infection. 4. Describe the fetal consequences of maternal B19 infection. Parvovirus B19 infection in pregnancy may result in fetal infection with complications that include nonimmune hydrops and fetal death. Early case reports beginning in 1984 highlighted fetal adverse outcomes; subsequent prospective studies indicate a risk of adverse pregnancy outcomes considerably lower than initially appreciated. Nonetheless, the occurrence of severe nonimmune hydrops or stillbirths in even a small percentage of parvovirus B19-infected pregnant women is a concern. Human parvovirus was discovered in 1975. These small, single-stranded DNA viruses are distributed widely among mammals. B19 is the only human parvovirus identified to date. The virus is structurally simple; the genome consists of approximately 5,600 base pairs and three viral-coded proteins. Two proteins, designated VP1 and VP2, form the viral capsid; the third known protein is nonstructural (NS1) and is associated with viral replication and cytotoxicity. Viral replication occurs only in rapidly dividing cells, which partially explains the proclivity of the virus for fetal tissues and rapidly dividing erythrocyte precursors. B19 infection is common in childhood, with serologic evidence of previous infection seen in approximately 50% of adults. Following an incubation of about 10 days, symptoms, including fever and a flulike illness, may occur. This first phase of infection is accompanied by viremia. In 7 to 10 days, a second phase is characterized by immune-mediated symptoms such as rash and arthralgia. Viremia has ceased by the time the second phase of illness occurs, and virus no longer can be detected in respiratory secretions. The previous description of illness characterizes erythema infectiosum (fifth disease). The spectrum of symptoms includes asymptomatic …