Parvovirus B-19 in Pregnancy Parvovirus is a member of the family Parvoviridae. The virus contains a single-stranded DNA. It can only infect humans. 50% of all adults have been infected sometime during childhood or adolescence. Parvovirus B-19 in Pregnancy Epidemiology Congenital infection rates vary depending on the prevalence in the community. Approximately 50 to 75% of adult women are immune. 20% to 30% of susceptible adults in school settings will become infected. Day-care workers have a 20% to 50% risk of seroconversion. The risk of infection among susceptible adults following household exposure to an infected person is approximately 50%.