Children with erythema infectiosum are unlikely to be infectious after the rash appears. Parvovirus B19 can cause transient red blood cell aplasia, which is related to lytic infection in erythrocyte precursors. The aplastic stage lasts about 7 to 10 days and is followed by increased reticulocytosis. 5 Bone marrow usually recovers within 2 to 3 weeks. The infection sometimes affects other cell lines, including the white cell line and the thrombocytes.
Mild anaemia is found in healthy older children and adults, but anemia can be severe in neonates.
Other organs, such as the heart, liver, and spleen, can be affected also. 6 Effects on the pregnancy and the fetus Despite earlier reports of high rates of vertical transmission and morbidity and mortality, more recent reports demonstrate that, in most cases, no adverse effects on the fetus are evident. The remaining 55 infected women delivered 56 healthy infants. In a prospective cohort study, Miller et al 10 investigated the risk of fetal loss and congenital abnormalities after maternal parvovirus B19 infection among 427 pregnant women with B19 infection and 367 surviving infants, of whom 129 were followed up at 7 to 10 years of age. Seven cases of fetal hydrops followed maternal infection between 9 and 20 weeks' gestation.