Parvovirus B19 infection during pregnancy and development of hydrops fetalis despite the evidence for pre-existing anti-B19 antibody: how reliable are serological results?

BACKGROUND

Primary infection with human parvovirus B19 during pregnancy can lead to fetal hydrops, abortion, or stillbirth. However, reinfection in the presence of pre-existing anti-B19 antibody is generally assumed to have no significant effect on the developing fetus.

OBJECTIVE

To describe a case of fetal loss at 28 weeks' gestation associated with parvovirus B19 infection which took place in a 26-year-old woman despite the evidence for pre-existing anti-B19 IgG antibodies.

METHODS

A nested-PCR assay for parvovirus B19 DNA was performed on maternal and fetal samples. Blood samples were tested by various enzyme immunoassays (EIA) for the presence of both anti-B19 IgM and IgG antibodies.

RESULTS

B19 DNA together with anti-B19 IgG antibody were detected in maternal blood at the time of intrauterine fetal demise. Amniotic fluid, chorionic villi and various fetal tissues also tested positive for viral DNA. In retrospect, presence of anti-B19 IgG antibody, but no viral DNA, was repeatedly demonstrated in maternal blood before infection took place. However, the serological results differed with the test system used.

CONCLUSIONS

Provided that the positive serological results are reliable, the presence of anti-B19 IgG in blood samples collected as early as four years before pregnancy neither protected the mother from reinfection not the fetus from transplacental infection with B19 virus. However, discrepant (negative) serological results were also obtained depending on the test system used. Therefore, and in the light of the possible severe consequences of B19-infection during pregnancy, the means for assessment of the significance of anti-B19 titers have to be urgently established by development of both qualitative and quantitative anti-B19 IgM and IgG standards.