Regine Barlinn1, Halvor Rollag2, Lill Trogstad3, Kirsti Vainio3, Coraline Basset3, Per Magnus4, Susanne G Dudman3. 1. Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway. Electronic address: regine.barlinn@fhi.no. 2. Department of Medical Microbiology, Oslo University hospital, Norway. 3. Division for Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway. 4. Division for Health Data and Digitalization, Norwegian Institute of Public Health, Oslo, Norway.
Abstract
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.
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.
Keywords:
Based pregnancy cohort; Parvovirus B19; Population; Pregnancy; Seroconversion; Seroprevalence; The norwegian mother and child cohort study (MoBa)