Recent outbreaks of erythema infectiosum (fifth disease) have caused consternation among pregnant women and their physicians, because of the risk of spontaneous abortion caused by this viral infection. This statement contains information concerning the infection and recommendations regarding control of exposure.
The agent of erythema infectiosum is a single-stranded DNA virus called parvovirus B19, which infects humans only.1,2 Parvovirus B19 is principally transmitted by respiratory secretions,3 and a primary site of replication is the red blood cell precursors found in the bone marrow.4 After an incubation period of approximately 1 week's duration, the virus produces a febrile illness accompanied by reticulocytopenia, which lasts approximately 7 days.5 The normal person recovers without evident anemia and, in some cases, within another week, a distinctive rash, consisting of a slapped cheek appearance and an erythematous, lacy rash on the trunk and extremities, will develop. Atypical maculopapular rashes also occur.6 In adult patients, particularly women, arthralgia or arthritis may develop at this stage7,8; children infrequently experience joint involvement. Asymptomatic infection without rash may occur more frequently than illness with typical rash.
Infection with parvovirus B19 can also cause aplastic crisis in patients with red blood cell abnormalities leading to shortened red blood cell halflives (such as sickle cell disease and autoimmune hemolytic anemia). The aplastic crises develop approximately 1 week after onset of the acute illness due to parvovirus B19.9 Patients with aplastic crisis appear to be contagious from the onset or before the onset of acute illness and through the subsequent week or so.
Erythema Infectiosum
