<prompt> About parvovirus B19 all are true except:Spread by respiratory routeHas affinity for erythrocyte progenitor cellsCauses transient aplastic crisisTransplacental transfer occurs in only 10 of cases  <response>: Ans. d i.e. Transplacental transfer occurs in only 10 of cases. Member of genus erythrovirus, exclusively infects humans Transmission occurs predominantly respiratory route, transfusion related transmission also seen. Pathogenesis - B19 replicates primarily in erythroid progenitors. This specifically is due to limited tissue distribution of B19 receptor, blood groups antigen globoside. Resulting in transient aplastic crisis. Other cells bearing B-19 receptor include megakaryocytes, endothelial cells, placenta, myocardium and liver. Transplacental infection is seen in 30 and the risk of fetal loss is 9. Risk of congenital infection is 1. 