Human parvovirus B19 infection during pregnancy--value of modern molecular and serological diagnostics.
BACKGROUND
Over 95% of fetal complications (fetal hydrops and death) occur within 12 weeks following acute parvovirus B19 (B19) infection in pregnancy. Therefore, weekly fetal ultrasound monitoring is generally recommended for this time period. However, in the majority of women, typical symptoms of acute infection (rash or arthropathy) are absent, and during epidemics, B19 infection may be diagnosed incidentally by antibody screening of women at risk.


OBJECTIVE
To assess the diagnostic value of currently available molecular and serological methods for reliable diagnosis of primary B19 infection in pregnancy.


METHODS
Large panels of well-characterized acute-phase or convalescent sera were used to investigate the ability of a VP2 IgM EIA, a Light-Cycler-based B19-DNA PCR, a VP1-IgG avidity EIA and two VP2-IgG epitope-type specificity [ETS] EIAs to pinpoint the time of primary B19 infection in pregnancy.


RESULTS
The duration of low-level IgM positivity varied greatly (range 4-26 weeks). Samples collected within the first 2 weeks of infection showed high-level viremia (mean 1.75 x 10(8) geq/ml). During follow-up, low-level DNAemia (mean 9.7 x 10(4)geq/ml) persisted for at least 18 weeks in 91% (20/22) of patients. Considering the first 12 weeks after onset of disease the window of greatest risk for fetal complications, the "acute" phase was extended to cover this full period. In this case, performing the avidity and ETS-EIA sequentially, the positive predictive value was 100% in patients showing concordant avidity and ETS-EIA results.


CONCLUSIONS
In the presence of low IgM titres and/or low-level DNAemia the use of supplementary serological assays such as VP1-IgG avidity EIA and VP2-ETS-EIA is advisable for restriction or avoidance of unnecessary fetal ultrasound examinations or invasive diagnostics; and in general for strengthening the reliability of B19 serodiagnosis of pregnant women.
Enders
Martin
M
Labor Enders und Partner, Institut für Virologie, Infektiologie und Epidemiologie e.V., Stuttgart, Germany. menders@labor-enders.de
Schalasta
Gunnar
G
Baisch
Carola
C
Weidner
Andrea
A
Pukkila
Laura
L
Kaikkonen
Leena
L
Lankinen
Hilkka
H
Hedman
Lea
L
Söderlund-Venermo
Maria
M
Hedman
Klaus
K
D000914:Antibodies, Viral / Q000097:blood*; D000915:Antibody Affinity; D036022:Capsid Proteins / Q000276:immunology; D004279:DNA, Viral / Q000032:analysis / Q000097:blood*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D010322:Parvoviridae Infections / Q000175:diagnosis* / Q000821:virology; D016732:Parvovirus B19, Human / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis* / Q000821:virology; D017422:Sequence Analysis, DNA
D000914:Antibodies, Viral; D036022:Capsid Proteins; D004279:DNA, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C095547:capsid protein VP1, parvovirus B19; C095548:capsid protein VP2, parvovirus B19