[Parvovirus B-19 infections in pregnant women in day care facilities: health economic analysis of prohibition to employ seronegative women]

Are Daycare Workers at a Higher Risk of Parvovirus B19 Infection? A Systematic Review and Meta-Analysis

Objective: In this systematic review, we aimed to summarize the evidence on the association between being a daycare educator working with children and the possible increased risk of parvovirus B19 infection compared to the general population. Methods: The Medline and Embase databases were searched using a defined search to find studies published since 2000. Two reviewers evaluated the search hits using predefined inclusion and exclusion criteria. The resulting studies were extracted and were assessed in eight domains of bias. A pooled relative risk (RR) of parvovirus infection for daycare workers compared to the general population was calculated. Results: After evaluating the 7781 search hits and manual search, four methodologically-adequate studies were identified: three cross-sectional studies and one retrospective cohort study. Of the three studies investigating the risk of infection, one evaluated parvovirus B19 seroconversion rates for daycare workers. There was an indication for an increased risk for daycare workers compared to the unexposed population (RR = 1.12, 95% CI 0.98-1.27) using prevalence estimators. Furthermore, daycare workers had a higher seroconversion rate compared to the unexposed population (RR = 2.63, 95% 1.27-5.45) in the low risk of bias study. Conclusions: Our findings suggest a higher risk of parvovirus B19 infection for daycare workers compared to an unexposed comparison population, which necessitate preventative efforts. Considering the underestimation of the occupational seroconversion risk by prevalence-based estimators, parvovirus B19 infections among daycare workers might mostly be occupationally acquired.

The lack of routine surveillance of Parvovirus B19 infection in pregnancy prevents an accurate understanding of this regular cause of fetal loss and the risks posed by occupational exposure

In Europe, fetal loss due to Parvovirus B19 (B19V) is under-reported and a poorly addressed occupational risk to pregnant women. This is exemplified internationally, where it was unmentioned in the last two European Centre for Disease Prevention and Control (ECDC) annual surveillance reports or its 2009 special report on infections in pregnancy. To assess this potential for underestimating B19V fetal loss in pregnancy, we undertook a systematic review of practice in Northern Ireland in the management and reporting of B19V infections over a 12-month period of heightened transmission, one of six observed in a span of 9 years. Pregnant and non-pregnant women presented with symptomatic infection in 24 and 93 % of confirmed B19V infections, respectively, with no difference in viral loads. There was underinvestigation of viral causes of fetal loss, with only 143/2739 (5 %) tested for B19V, and a failure to follow up most non-immune women tested following rash contact. Occupational exposure was recorded in 31/60 (51.6 %) of pregnancies audited following rash exposure, the majority teachers or day care workers. Against a background seroprevalence of 66.5 % immunity in women of child-bearing years, two patterns of infection were identified. Firstly, pregnant women investigated for a rash or exposure to slapped cheek syndrome, where an infection incidence of 18 % was observed, resulted in 42 confirmed infections, all proceeding to healthy term deliveries. Secondly, pregnant women with unsuspected infection had six cases of confirmed B19V fetal loss, including four of 22 (18 %) diagnosed at autopsy, of which three were non-hydropic. While many studies have reported B19V fetal loss in pregnancy, there are no robust public health surveillance figures to draw on. That all six confirmed fetal losses came from the small number of miscarriages/stillbirths investigated, 143 out of 2739, suggests inadequate follow-up of those pregnancies where B19V-related fetal loss may be most common, and supports the need for enhanced surveillance pilots to address this significant gap in public health knowledge.

[Seroprevalence of antibodies against infectious pathogens relevant to pregnancy among healthcare workers]

Healthcare workers (HCWs) are exposed to infectious diseases throughout the course of their work. The concerns of pregnant HCWs are considerable because certain otherwise mild infections may affect fetal development. We studied 424 pregnant HCWs at the University Hospital Frankfurt between March 2007 and July 2011. Serological tests were carried out for varicella zoster virus (VZV), measles, mumps, rubella (MMR), cytomegalovirus (CMV) and parvovirus B19. Our overall seroprevalence data with regard to VZV, MMR, CMV and parvovirus B 19 corresponded to the general population. However, physicians demonstrated lower seroprevalence towards the two non-vaccine-preventable diseases (CMV: 37.5% [KI 27.4-48.5]; parvovirus B19: 69.3% [KI 58.6-78.7]) compared with nurses (CMV: 53.4% [KI 46.1-60.6], parvovirus B19: 75.1% [68.4-81.1]). It was striking that, only one in five of the study population showed IgG antibodies against all of the six pregnant-relevant viral diseases tested, of the physicians as few as one in six. A routine exclusion from the workplace due to non-immunity would mean that it would not be possible to employ the majority of pregnant staff in healthcare and childcare.

Diagnosis, management and possibilities to prevent parvovirus B19 infection in pregnancy

Human parvovirus B19 (B19V) infection in pregnancy can cause severe fetal anemia and nonimmune hydrops fetalis, which may be associated with spontaneous abortion and fetal death. Approximately 30–40% of women of child-bearing age are not immune to B19V infection. The risk to fetal life is particularly high if maternal infection occurs during the first 20 weeks of gestation. In this article we intend to give an overview on the molecular biology, epidemiology and management of B19V infection during pregnancy. These data will be combined with an assessment of the clinical situation of the infected fetus and the possibilities for avoiding and/or preventing B19V infection in pregnant women. Currently B19V infection is the causative agent of one of the most frequently occurring infectious complications in pregnancy that endangers fetal life, and so the necessity to develop a preventive vaccine is discussed.