High incidence of maternal parvovirus B19 infection in a large unselected population-based pregnancy cohort in Norway.
BACKGROUND
Around 40% of pregnant women in Norway are parvovirus B19 (B19V) seronegative and thus at risk for B19 V infection. Studies on samples from women with symptomatic disease or known exposure have shown that nucleic acid amplification assays combined with serology increase the sensitivity and improves the diagnostic procedure.


OBJECTIVES
The aim was to investigate the seroprevalence of B19V infection, the occurrence of new infections and vertical transmission in a population-based pregnancy cohort, with special emphasis on the diagnostic methods.


STUDY DESIGN
We randomly selected 1350 pregnant women from the Norwegian Mother and Child Cohort Study (MoBa), using an algorithm for the detection of B19V infection, including both serology and PCR.


RESULTS
Maternal infection was confirmed in 50 subjects (3.7% of 1349 women), of which 35(70%) were viremic. Of the initially seronegative 33(6.8%) seroconverted. The estimated average annual seroconversion rate was 15.5%, with the highest estimated annual seroconversion rate of 31.6%. The rates of yearly seroconversion followed the pattern found in reports from Norwegian microbiology laboratories. Among all women, 31 (2.3%) had an inconclusive serological profile and 17 (54.8%) had detectable virus. Of the 16 women with virus detectable at gestational week 17-18, seven were still seronegative with absent seroconversion in the second sample taken at birth. All together 10 children were vertically infected.


CONCLUSIONS
High incidence of viremic B19V infections and high estimated annual seroconversion rates were found. Lack of seroconversion despite longstanding viremia emphasizes the importance of including PCR when testing for B19V infection during pregnancy.
['Barlinn|Regine|R|', 'Rollag|Halvor|H|', 'Trogstad|Lill|L|', 'Vainio|Kirsti|K|', 'Basset|Coraline|C|', 'Magnus|Per|P|', 'Dudman|Susanne G|SG|']
D000328:Adult D000465:Algorithms D000914:Antibodies, Viral D005260:Female D006801:Humans D007074:Immunoglobulin G D007075:Immunoglobulin M D015994:Incidence D009664:Norway D010322:Parvoviridae Infections D016732:Parvovirus B19, Human D011247:Pregnancy D016036:Seroepidemiologic Studies
Parvovirus B19 Pregnancy Seroprevalence The norwegian mother and child cohort study (MoBa) Seroconversion Based pregnancy cohort Population