High incidence of maternal parvovirus B19 infection in a large unselected population-based pregnancy cohort in Norway

Human parvovirus B19 infection in a pregnant patient resulting in severe hydrops, foetal death and persistent infection

Human parvovirus B19 (B19V) is the aetiological agent of erythema infectiosum. Primary infection during pregnancy can be transmitted to the foetus and cause foetal abnormalities related to depletion of erythrocyte progenitor cells, including congenital anaemia, hydrops, and foetal death. In this paper we report the detection of B19V infection in a pregnant patient, which onset occurred without appreciable signs and symptoms until she developed inappropriate contractions for gestational age and fluid loss. B19V infection resulted in severe hydrops fetalis with a fatal course for the foetus, while persisted in the mother at least 12 months after foetal death. The objective of this report is to highlight the importance of optimizing B19V diagnosis through early suspicion and testing during pregnancy. Knowing the mother’s immune status before or at the beginning of gestation can contribute, together with early diagnosis, to improve the management of patients at risk.

Parvovirus B19 DNAemia in pregnant women in relation to perinatal death: A nested case-control study within a large population-based pregnancy cohort

INTRODUCTION

Parvovirus B19 (B19V) is the infectious cause of exanthema infectiosum. In Europe around 40% of pregnant women are susceptible to infection. Having small children at home is the main risk factor for contracting an infection during pregnancy. The association between B19V-infection and perinatal death is not yet settled. The aims of the study were to estimate the association between maternal parvovirus B19 infection in pregnancy and perinatal death, and to assess the significance of a positive B19V PCR in pregnancy.

MATERIAL AND METHODS

The study population consists of women included in the Norwegian Mother and Child Cohort Study, a prospective population-based pregnancy cohort of nearly 100 000 women. Blood samples were obtained during weeks 17-18 in pregnancy (M1), at birth, and in umbilical cord blood. Within participants in the pregnancy cohort, 138 cases of perinatal death and 1350 controls with live-born children were included in a nested case-control study. Samples were analyzed with B19V serology and B19V PCR according to a predefined test algorithm. For cases, medical records and laboratory results from hospitals were combined with the results of B19V serology and PCR. The reported causes of perinatal death were categorized using the classification system: Causes Of Death and Associated Conditions (CODAC).

RESULTS

The B19V seroconversion rates were 9.8% for cases and 6.8% for control mothers. The odds ratio for maternal B19V infection in cases compared with controls was 1.28 (95% CI 0.35-4.70), adjusted for age, parity, body mass index and tobacco use. B19V-PCR-positive samples were detected at weeks 17-18 of gestation in both cases and controls. The proportion of positive samples was similar in cases and controls, 24% and 28.2%, respectively. Mothers with PCR-positive M1 samples transmitted B19V vertically in 9.1% of cases and in 11.9% of the controls. Of all perinatal deaths, 53% were attributed to placental pathology or unknown causes.

CONCLUSIONS

B19V PCR positivity was high and similar in both cases and controls. In our study B19V DNAemia was not seen to be associated with fatal outcome of pregnancy. The clinical significance of B19V DNA detection during pregnancy is uncertain. Caution is needed when diagnosing a B19V infection based only on B19V DNAemia.

Immunity to varicella zoster virus among pregnant women in the Norwegian Mother and Child Cohort Study

Introduction

Infection with varicella zoster virus (VZV) in pregnancy may lead to serious outcomes both for the mother and the newborn. Targeted screening and vaccination of non-immune women during reproductive age could prevent varicella infection in pregnancy. Currently, no universal varicella screening of pregnant women is implemented in Norway, but serological testing in pregnancy is recommended in particular situations. We examined seroprevalence of VZV in a national pregnancy cohort in order to help assess a need for VZV screening of women during reproductive age.

Methods

We determined the susceptibility to VZV and the reliability of self-reported history of VZV infection in the Norwegian obstetric population by using a random sample of 1,184 pregnant women from the Norwegian Mother and Child Cohort study (MoBa). The MoBa study included approximately 95,200 pregnant women in Norway between 1998 and 2009. Blood samples taken at gestational week 17–18 were analysed using a commercial enzyme immunoassay for specific IgG antibodies to Varicella-Zoster virus. Second sample taken at birth was tested if the first sample result was negative or equivocal.

Results

Of the 1,184 pregnant women, 98.6% (n = 1,167) were seropositive, 0.83% (n = 10) remained seronegative, and four women (0.34%) seroconverted during their pregnancy. No significant associations were found between serological status and women’s age at birth, gestational age, women’s country of birth and year of child’s birth. One woman reported prior history of varicella, whereas 143 (12.1%) women reported a household exposure to childhood diseases with fever and rash, of which 25 reported exposure to varicella, of which all were seropositive.

Conclusions

The findings support antenatal screening recommendations in Norway advising testing for VZV in pregnant women with unknown immunity to VZV. Further studies are however needed to better identify target groups for screening and vaccination.

Preventing vertical virus infections: the role of serologic screening of pregnant women

Several virus infections affect the pregnancy itself as well as the foetal development (rubella, PVB19, VZV, HSV, HCMV, HBV, HIV). Prevention can be established by vaccination or an assessment of the immunity status as well as by chemotherapy. The following review provides an update to current aspects focusing on the role of serologic screening.