Epidemiology Parvovirus B19 is a very common, ubiquitous disease that tends to produce spring epidemics in children 4-10 years of age. It is easily transmitted through respiratory secretions and close contact, and transmission is common in daycare centers and schools. The virus is transmitted from person to person during the incubation period, before a clinical rash actually appears. By the time the rash actually does appear, the infected individual is no longer capable of infecting others.
Transplacental transmission is also possible, but unlikely.
If fetal infection does occur, it is usually harmless. Transmission through blood transfusion is also possible. Pathogenesis Viremia reaches its peak one week after infection, at which point the virus is shed from the throat. Right after viremia ends, levels of specific IgM antibodies peak. Parvovirus B19 is selective for erythrocyte progenitors, infecting them and inhibiting their development into mature erythrocytes.