Clinical and virological aspects of human parvovirus B19 Infection during Gestation.

Congenital Human Parvovirus B19 (B19V) infection can lead to life threatening fetal complications as hydrops, fetal demise or severe fetal anaemia and thrombocytopenia. Maternal symptoms frequently pass unnoticed at the time of maternal infection and there was little information on the mechanism and time course of vertical transmission of B19V during gestation. Treatment consists of intrauterine fetal red blood cell and/ or platelet transfusion (IUT). The indication for treatment with IUT is set by performing fetal ultrasound screening for fetal anaemia and signs of fetal hydrops. The fetal middle cerebral artery peak systolic flow correlates well with the severity of fetal anaemia. The first two chapters of this thesis give an overview of the existing literature concerning fetal hydrops and congenital B19V infection. In the ensuing chapters we describe the course of maternal and fetal B19V infection by the B19V viral load and maternal immune response. We did not find a correlation between the fetal or maternal B19V viral load and the severity of fetal anaemia or thrombocytopenia. Thrombocytopenia is frequently encountered in congenital B19V infection, but fetal bleeding complications are not. The use of fetal platelet transfusion is therefore a matter of debate. The long- term neurodevelopment of affected fetus can be significantly delayed at a later age despite a technically correct IUT procedure. The possibility of cerebral damage due to congenital B19V infection is discussed. Parents should be counselled of these risks before the IUT procedure and long term follow -up following congenital B19V infection is advise