Serologic and virologic evidence for frequent intrauterine transmission of human parvovirus B19 with a primary maternal infection during pregnancy

Seroprevalence and geographical distribution of parvovirus B19 antibodies in pregnant women: A-meta analysis

Parvovirus B19 has been identified to infect pregnant women and cause anemia, spontaneous abortion, and fetal death. Given the significance of parvovirus B19 complications, this study aims to determine the seroprevalence and geographical distribution of parvovirus B19 antibodies in pregnant women to improve health control policies in the community. Online international databases and national Persian databases were used to define appropriate studies published between 2000 and January 2021. The quality of all papers was determined by a Newcastle-Ottawa Scale (NOS) checklist. The statistical analyses were performed using the Stata version 11 package (StataCorp, College Station, TX, USA) software. Heterogeneity among the primary studies was calculated using Cochran's Q-test and I2 index. The Egger test and the funnel plot chart with a significance level of less than 0.1 were used to evaluate the publishing bias. The seroprevalence of parvovirus B19 IgG antibodies among pregnant and non-pregnant women in Iran was assessed in 12 primary studies. Our finding showed that the seroprevalence of parvovirus B19 IgG antibodies among pregnant women varies from 21% to 76%. Combining the results of 5 primary studies based on the random effect model, the seroprevalence of parvovirus B19 IgG antibody among pregnant women in Iran was estimated to be 54% (95% CI:33-76). The seroprevalence of parvovirus B19 IgM antibodies has been reported in 9 studies. By combining the results of these studies using a random effect model, the seroprevalence of parvovirus B19 IgM antibody among pregnant women was estimated to be 3% (95% CI: 1-6). Generally, it is suggested that appropriate screening programs should be performed for the treatment and prevention of diseases. According to this point, the prevalence of parvovirus B19 is low among pregnant women, but it can cause serious manifestations such as hydrops fetalis and severe anemia, therefore, antibody determination using ELISA can be recommended for all pregnant women.

Serological detection of human parvovirus B19 infection and associated risk factors among pregnant women in Jigawa State, Nigeria

Human Parvovirus B19 (B19 V) infection is hyperendemic in Nigeria. Pregnant women are not classically immunocompromised but maybe physiologically immunosuppressed and susceptible to viral infection. However, there is a paucity of studies on the epidemiology of B19V in Jigawa State, Northwestern Nigeria. This study aims to determine the seroprevalence, sociodemographic, and risk factors of human B19V infection among present women attending antenatal clinics of Jahun General Hospital, Nigeria. Between 2 February and 30 June 2019, blood samples were collected from 200 consented pregnant women and analyzed for anti-B19V IgM and IgG using commercially available enzyme-linked immunosorbent assay (ELISA). Sociodemographic and risk factors of subjects were collated through pre-tested structured questionnaires. Data generated were statistically analyzed for the association of anti-B19V and subjects' variables studied. Overall, the seroprevalence of anti-B19V IgM and IgG among pregnant women attending antenatal clinics of Jahun General Hospital, Nigeria was 6.0% and 22.5%, respectively. There was no significant association between the seroprevalence of anti-B19V IgM and anti-B19V IgG with all the sociodemographic variables and risk factors of pregnant women (P ˃0.05). However, pregnant women with a history of blood transfusion had a significant risk associated with seroprevalence of B19V IgM (OR = 5.95; 95% CI: 1.96-22.76; P = .009). Findings from this study revealed that a high proportion of the pregnant women were susceptible to B19V infection and anti-B19V IgG immunity decreased with age. Given the incidence of acute B19V infection, it is clinically important to continuously monitor their erythrocytes indices and screen their neonates for B19V infection and fetal complications.

Diagnosis of intrauterine parvovirus B19 infection at birth - Value of DNA detection in neonatal blood and dried blood spots

BACKGROUND

Diagnosis of congenital viral infection at birth is generally attempted by direct detection of the virus by PCR in various neonatal materials. How to reliably diagnose intrauterine infection with parvovirus B19 (B19 V) at birth is unknown.

OBJECTIVES

To evaluate the performance of B19 V DNA detection in cord blood (CB) or neonatal dried blood spots (DBS) in diagnosing fetal infection.

STUDY DESIGN

Two cohorts of children diagnosed prenatally with an intrauterine B19 V infection were included in this study. CB samples of intrauterine B19 V infections that were sent to a reference laboratory for congenital infections in Stuttgart, Germany in the period 1995-2014 were tested in triplicate for B19 V DNA by quantitative PCR. DBS from children with intrauterine B19 V infection that underwent IUT at the LUMC, Leiden, the Netherlands in the period 2009-2014 were tested for B19 V DNA by quantitative B19 V PCR in triplicate.

RESULTS

Fourteen of twenty (70 %) CB samples tested positive for B19 V DNA. The positivity rate was 40 % (4/10) in those with a prenatal diagnosis <20 weeks gestation. When intrauterine B19 V infection was diagnosed thereafter, 100 % (10/10) samples were B19 V DNA positive. Of the thirteen available DBS, twelve (92 %) tested positive. Viral load in CB and DBS corresponded inversely with time from fetal diagnosis to birth.

CONCLUSION

B19 V DNA can be detected in neonatal blood samples of children following intrauterine B19 V infection, although the possibility of false-negatives, even in severe infections, should be considered. B19 V viral load at birth correlates with timing of infection.

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 risk of maternal parvovirus B19 infection during pregnancy on fetal loss and fetal hydrops: A systematic review and meta-analysis

BACKGROUND

Human parvovirus B19 (B19) is widespread infection in humans, yet the impact on adverse pregnancy outcomes is controversial.

OBJECTIVE

to evaluate the impact of B19 infection during pregnancy on adverse pregnancy outcome, and investigated the incidence of fetal loss and fetal hydrops after maternal B19 infection during pregnancy.

STUDY DESIGN

A systematic literature search was performed using Embase, Medline, PubMed, Web of science, and the Cochrane Library database for relevant publications up to 10^th August 2018. Cohort studies and case-control studies were included in analyses.

RESULTS

In total, 36 eligible studies were included. Of these, 18 studies reported the risk of maternal B19 infection during pregnancy on fetal loss and 20 studies reported the incidence of fetal loss or fetal hydrops after maternal B19 infection. Collectively, the results indicated that maternal B19 infection increased the risk of fetal loss, spontaneous abortion, and stillbirth with ORs of 2.68 (95% CI: 2.02-3.55), 2.42 (95% CI: 1.76-3.33), and 3.53 (95% CI: 1.91-6.54), respectively, when compared with uninfected pregnant women. In addition, the incidence of fetal loss and fetal hydrops in B19 infected pregnant women was 7.6% (95% CI: 5.5-9.5) and 9.3% (95% CI: 5.6-13.0), respectively.

CONCLUSIONS

maternal parvovirus B19 infection during pregnancy increased the risk of fetal loss, spontaneous abortion, and stillbirth. A high incidence of fetal loss and fetal hydrops was observed in pregnant women with parvovirus B19 infection.

Ultrasound Findings Associated With Antepartum Viral Infection

This article reviews the sonographic manifestations of fetal infection and the role of ultrasound in the evaluation of the fetus at risk for congenital infection. Several ultrasound findings have been associated with in utero fetal infections. For the patient with a known or suspected fetal infection, sonographic identification of characteristic abnormalities can provide useful information for counseling and perinatal management. Demonstration of such findings in the low-risk patient may serve to identify the fetus with a previously unsuspected infection. The clinician should understand the limitations of ultrasound in the prenatal diagnosis of congenital infection and discuss them with the patient.

Prevalence of Parvovirus B19 Infection by Serology and PCR in Pregnant Women Referring to Obstetrics and Gynecology Clinic

OBJECTIVE

Infection by Primate erythroparvovirus 1, generally known Parvovirus B19, is highly prevalent worldwide. Although infection by this virus will not be clinically problematic in most cases, new infections during pregnancy could result in serious repercussions in the fetus. Serologic and PCR-based methods are among the available approaches for diagnosis of Parvovirus B19 infection. In this regard, the present study is aimed to investigate the frequency of Parvovirus B19 infection by these two techniques in pregnant women of Zanjan.

MATERIALS AND METHODS

In this cross sectional-descriptive study, 110 pregnant women referring to Mousavi hospital in Zanjan during one year were evaluated in terms of serologic and Real-Time PCR test results in search for Parvovirus B19 infection. The rate of positive IgG and IgM were determined in women and the Real-Time PCR results were reported.

RESULTS

Overall, 18.2% of participants were above 35 years old and 4.5% of them were younger than 18 years old. 41 (44.1%) and 2 (1.8%) cases had positive anti-Parvovirus B19 IgG and IgM, respectively. Real-Time PCR results were negative in all the studied samples.

CONCLUSION

Based on the findings of this study, prevalence of acute Parvovirus B19 infection was 0 and 2% based on Real-Time PCR and IgM tests, respectively. About 40% of pregnant women had experienced infection with this virus before.

Parvovirus B19 infection during pregnancy and risks to the fetus

Parvovirus B19 infects 1 to 5% of pregnant women, generally with normal pregnancy outcomes. During epidemics, the rate of infection is higher. Major congenital anomalies among offspring of infected mothers are rare, as the virus does not appear to be a significant teratogen. However, parvovirus B19 infection may cause significant fetal damage, and in rare cases, brain anomalies and neurodevelopmental insults, especially if infection occurs in the first 20 weeks of pregnancy. Parvovirus B19 is also an important cause of fetal loss, especially in the second half of pregnancy when spontaneous fetal loss from other causes is relatively rare. Parvovirus B19 infection may affect many fetal organs and can cause severe anemia, following fetal erythroid progenitor cells infection and apoptosis, especially in fetuses, that have shortened half-life of erythrocytes. Severe anemia may cause high output cardiac failure and nonimmune hydrops fetalis. In addition, parvovirus B19 may directly infect myocardial cells and produce myocarditis that further aggravates the cardiac failure. Intrauterine fetal transfusion is commonly used for the treatment of severe fetal anemia with survival rates of 75 to 90% and significant reduction of fetal morbidity. Only 66 cases were evaluated neurodevelopmentally, of which 10 (16%) had slight or severe neurodevelopmental problems. Because parvovirus B19 infection can cause severe fetal morbidity and mortality, it should be part of the routine work-up of pregnant women who have been exposed to the virus or of pregnancies with suspected fetal hydrops. Assessment for maternal infection during pregnancy is especially important during epidemics, when sero-conversion rates are high. Birth Defects Research 109:311-323, 2017. © 2017 Wiley Periodicals, Inc.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Human parvovirus B19 antibodies induce altered membrane protein expression and apoptosis of BeWo trophoblasts

Human parvovirus B19 (B19) is harmful during pregnancy since it can be vertically transmitted to the developing fetus. In addition, the anti‑B19 antibodies induced by B19 infection are believed to have a cytopathic role in B19 transmission; however, knowledge regarding the effects of anti‑B19 antibodies during pregnancy is limited. To investigate the possible roles of anti‑B19 antibodies during pregnancy, the present study examined the effects of anti‑B19‑VP1 unique region (VP1u), anti‑B19‑VP2 and anti‑B19‑nonstructural protein 1 (NS1) immunoglobulin G (IgG) antibodies on BeWo trophoblasts. Briefly, BeWo trophoblasts were incubated with purified IgG against B19‑VP1u, B19‑VP2 and B19‑NS1. Subsequently, the expression of surface proteins and apoptotic molecules were assessed in BeWo trophoblasts using flow cytometry, ELISA and western blotting. The expression levels of human leukocyte antigen (HLA)‑G were significantly increased on BeWo trophoblasts treated with rabbit anti‑B19‑VP1u IgG, and were unchanged in those treated with rabbit anti‑B19‑NS1 and anti‑B19‑VP2 IgG, as compared with the control group. Furthermore, the expression levels of globoside (P blood group antigen) and cluster of differentiation (CD)29 (β1 integrin) were significantly increased in BeWo trophoblasts treated with rabbit anti‑B19‑NS1 and anti‑B19‑VP2 IgG, whereas only CD29 was also significantly increased in cells treated with anti‑B19‑VP1u IgG. In addition, the number of cells at sub‑G1 phase; caspase‑3 activity; and the expression of intrinsic and extrinsic apoptotic molecules, including Fas‑associated death domain protein, activated caspase‑8, activated caspase‑3, B‑cell lymphoma 2‑associated X protein, cytochrome c, apoptotic peptidase activating factor 1 and activated caspase‑9, were significantly increased in BeWo trophoblasts treated with anti‑B19‑VP1u and anti‑B19‑NS1 IgG. In conclusion, the present study demonstrated that antibodies against B19 may have a crucial role in pathological processes during pregnancy. These findings may help to elucidate the mechanisms underlying transmission of the B19 virus during pregnancy.

Infection-Related Focal Segmental Glomerulosclerosis in Children

Focal segmental glomerulosclerosis (FSGS) is the most common cause of steroid resistant nephrotic syndrome in children. It describes a unique histological picture of glomerular damage resulting from several causes. In the majority of patients the causing agent is still unknown, but in some cases viral association is evident. In adults, the most established FSGS causing virus is the human immune-deficiency virus, which is related to a collapsing variant of FSGS. Nevertheless, other viruses are also suspected for causing a collapsing or noncollapsing variant, for example, hepatitis B virus, parvovirus B19, and Cytomegalovirus. Although the systemic infection mechanism is different for these viruses, there are similarities in the pathomechanism for the induction of FSGS. As the podocyte is the key structure in the pathogenesis of FSGS, a direct infection of these cells or immediate damage through the virus or viral components has to be considered. Although viral infections are a very rare cause for FSGS in children, the treating pediatric nephrologist has to be aware of a possible underlying infection, as this has a relevant impact on therapy and prognosis.

Evidence for Vertical Transmission of Novel Duck-Origin Goose Parvovirus-Related Parvovirus

In 2015, novel duck-origin goose parvovirus-related parvovirus (N-GPV) infection progressively appeared in commercial Cherry Valley duck flocks in North China. Diseased ducks were observed to have beak atrophy and dwarfism syndrome (BADS). A previous study showed that a high seropositive rate for N-GPV indicated a latent infection in most breeder duck flocks. To investigate this possibility in hatching eggs collected from N-GPV-infected breeder ducks, 120 eggs were collected at various stages of embryonic development for viral DNA detection and an N-GPV-specific antibody test. N-GPV DNA was present in nine hatching eggs, eleven duck embryo and eight newly hatched ducklings. Of the newly hatched ducklings, 58.33% (21/36) were seropositive. Further, two isolates were obtained from a 12-day-old duck embryo and a newly hatched duckling. N-GPV infection did not reduce the fertilization rate and hatchability. These results indicate possible vertical transmission of N-GPV and suggest that it may be transmitted from breeder ducks to ducklings in ovo.

Induction of an embryonic mouse innate immune response following inoculation in utero with minute virus of mice

We used an embryonic-infection model system to show that MVMp, the prototypic minute virus of mice (MVM) serotype and a member of the genus Protoparvovirus, triggers a comprehensive innate immune response in the developing mouse embryo. Direct inoculation of the midtrimester embryo in utero with MVMp results in a widespread, productive infection. During a 96-h infection course, embryonic beta interferon (IFN-β) and IFN-γ transcription were induced 90- and 60-fold, respectively. IFN-β levels correlated with the embryo viral burden, while IFN-γ levels first increased and then decreased. Production of proinflammatory cytokines, interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-α), also increased, but by smaller amounts, approximately 7-fold each. We observed increased levels of downstream antiviral effector molecules, PKR and phosphorylated STAT2. Finally, we showed that there is an immune cell response to the virus infection. Infected tissues in the embryo exhibited an increased density of mature leukocytes compared to the same tissues in uninfected embryos. The responses we observed were almost completely restricted to the infected embryos. Uninfected littermates routinely exhibited small increases in innate immune components that rarely reached statistical significance compared to negative controls. Similarly, the placentae of infected embryos did not show any significant increase in transcription of innate immune cytokines. Since the placenta has both embryonic and maternal components, we suggest there is minimal involvement of the dam in the response to infection.

IMPORTANCE

Interaction between the small single-stranded vertebrate DNA viruses, the protoparvoviruses, and the host innate immune system has been unclear. The issue is important practically given the potential use of these viruses as oncotherapeutic agents. The data reported here stand in contrast to studies of innate immune response during protoparvovirus infection of adult hosts, which invariably reported no or minimal and sporadic induction of an interferon response during infection. We conclude that under conditions of robust and productive MVM infection, a normal murine host is able to mount a significant and broad innate immune response.

Increased risk of human parvovirus B19 infection in day-care employees: a cohort study among pregnant workers during an epidemic in Finland

BACKGROUND

Human parvovirus B19 (B19V) infection during early pregnancy increases the risk of miscarriage. Studies have inconsistently shown an elevated risk of infection among women with occupational contacts with children. Methodological differences, particularly in defining occupational exposure and in the type of reference group, may explain the conflicting findings.

METHODS

This cohort study compared B19V infections in pregnant day-care employees and healthcare professionals during a B19V epidemic in Finland. Women were identified from the files of nationwide trade unions and the National Supervisory Authority for Welfare and Health. Early-pregnancy maternal B19V IgG was analysed in 3710 women, and infections were defined as seroconversions after analysing in parallel the available umbilical cord blood samples of the 847 seronegative mothers. Independently of the serological status, the actual employment during pregnancy was assessed using registered information on employment history.

RESULTS

B19V infections were more common among day-care employees (22/331, 6.6%), than among those working in healthcare (12/326, 3.7%). The adjusted HRs of B19V infection, using proportional hazard regression, was 2.63 (95% CI 1.27 to 5.46) among all women and 5.59 (95% CI 1.40 to 22.4) among nulliparous women.

CONCLUSIONS

Day-care employees are at an increased risk of B19V infection, which warrants preventive measures.

Intrauterine infection with parvovirus B19 and CMV: implications in early and late gestation fetal demise

In utero viral infections have been associated with an adverse pregnancy outcome and may have a causative role in the unexplained fetal death file. Parvovirus B19 and cytomegalovirus are among the most common pathogens implicated in fetal loss cases. Parvovirus B19 has been reported to account for cases of spontaneous abortions, intrauterine fetal death and nonimmune hydrops fetalis, whereas cytomegalovirus accounts for nonimmune hydrops fetalis, intrauterine growth retardation and congenital anomalies. This review aims to summarize the current literature in an attempt to underline the need for routine screening, close follow-up and prevention. A better understanding of the pathogenetic mechanisms of viral infections during the crucial time of organogenesis, along with early detection, may contribute to the reduction in stillbirth rate.

Parvovirus B19 in pregnancy: possible consequences of vertical transmission

OBJECTIVE

The aim was to determine the outcome of pregnancies complicated by maternal Parvovirus B19 (B19) infection.

METHOD

Among 175 pregnant women referred to our clinic because of suspicion of a B19 infection, 63 with confirmed laboratory diagnosis of acute/recent B19 infection were followed up by ultrasound and Doppler measurement of the middle cerebral artery peak systolic velocity.

RESULTS

The vertical transmission rate was 31.7% (20/63). Of the 20 infected, 8 had hydrops, 1 had signs suggestive of meconium peritonitis and 1 had an isolated hydrothorax. Three fetuses presenting with hydrops were treated with intrauterine blood transfusion. Two of them died while the last showed resolution of anemia. Among the five untreated hydropic fetuses, one presented with mild signs that resolved spontaneously, two died at 16 and 17 weeks of gestation and two had also cardiomegaly and the parents opted for elective termination of pregnancy. All the anemic fetuses had middle cerebral artery peak systolic velocity values more than 1.8 multiples of the median. No stillbirth occurred.

CONCLUSIONS

The outcome of uncomplicated cases with B19 infection is good. In the presence of hydrops prognosis was very poor. It seems therefore logical to attempt to pick up this ominous signs early.

Parvovirus B19 infection in pregnancy: new insights and management

In this article, we review the virology, pathology, epidemiology and clinical spectrum of intrauterine human parvovirus B19 (B19V) infection, including intrauterine fetal death, non-immune hydrops fetalis, thrombocytopenia and neurological manifestations such as pediatric stroke and perivascular calcifications. In addition, we discuss the new insights into the neurodevelopmental outcome of intrauterine B19V infection. Current diagnosis and management of B19V infection is summarized, including a diagnostic and follow-up flowchart for practical clinical use.

Parvovirus B19 infection in human pregnancy

Human parvovirus B19 infection is widespread. Approximately 30-50% of pregnant women are nonimmune, and vertical transmission is common following maternal infection in pregnancy. Fetal infection may be associated with a normal outcome, but fetal death may also occur without ultrasound evidence of infectious sequelae. B19 infection should be considered in any case of nonimmune hydrops. Diagnosis is mainly through serology and polymerase chain reaction. Surveillance requires sequential ultrasound and Doppler screening for signs of fetal anaemia, heart failure and hydrops. Immunoglobulins, antiviral and vaccination are not yet available, but intrauterine transfusion in selected cases can be life saving.

Risk of fetal hydrops and non-hydropic late intrauterine fetal death after gestational parvovirus B19 infection

BACKGROUND

Risk assessment of parvovirus B19 (B19)-associated fetal complications following gestational B19 infection remains controversial.

OBJECTIVES

To determine the risk of fetal hydrops or non-hydropic late intrauterine fetal death following acute maternal B19 infection at defined gestational weeks.

STUDY DESIGN

Observational cohort study of pregnant women with serologic evidence of acute B19 infection. If available, fetal or neonatal tissue samples from cases complicated by fetal loss or hydrops were investigated for the presence of B19 DNA by polymerase chain reaction (PCR) and/or in situ hybridization (ISH).

RESULTS

Of 236 women with known pregnancy outcome, 228 had a live birth and 8 a fetal loss. The observed rate of fetal hydrops for all pregnant women was 4.2% (10/236) (95% confidence interval [CI], 2.1-7.7) and 10.6% (10/94) (95% CI, 5.2-18.7) for those infected between 9 and 20 weeks gestation. Tissue samples from 8 hydrops cases were investigated by PCR or ISH and all were B19 DNA positive. Fetal death occurring during or after gestational week 22 was only observed in one case which was associated with B19-derived fetal hydrops.

CONCLUSIONS

Our findings demonstrate that although adverse fetal outcome is a rare complication of gestational B19 infection, a relevant risk of fetal hydrops exists particularly for women infected between 9 and 20 weeks' gestation. Cases of B19-derived non-hydropic late intrauterine fetal death were not observed in the present study.

Maternal human parvovirus B19 infection and the risk of fetal death and low birthweight: a case-control study within 35 940 pregnant women

OBJECTIVES

To assess the association between maternal parvovirus B19 infection and fetal death, birthweight and length of gestation.

DESIGN

Case-control study.

SETTING

Population based.

POPULATION

Cases were all 281 women with fetal death within a cohort of 35 940 pregnant woxmen in Norway. The control group consisted of a random sample of 957 women with a live born child.

METHOD

Information on pregnancy outcome was obtained from the Medical Birth Registry of Norway. First trimester serum samples were tested for antibodies against parvovirus B19 (IgM and IgG). In seronegative women, further serum was analysed to detect seroconversion during pregnancy.

MAIN OUTCOME MEASURES

Fetal death, length of gestation and birthweight.

RESULTS

Two of 281 (0.7%) of the women who experienced fetal death and nine of 957 (0.9%) of the controls had presence of IgM antibodies, crude odds ratio 0.8; 95% CI (0.2-3.5). In initially, seronegative women, 3.1% (2/65) with fetal death and 2.6% (8/307) with a live birth seroconverted, crude odds ratio 1.2; 95% CI (0.2-5.7). Presence of maternal parvovirus-specific IgG or IgM antibodies in the first trimester, or seroconversion during pregnancy were not associated with lower birthweight or reduced length of gestation in live born children, but was associated with low birthweight in stillborn offspring.

CONCLUSION

Maternal parvovirus B19 infection was not associated with fetal death in our study. Very few cases of fetal death may be attributed to maternal parvovirus B19 infection.

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

German protective legislation during pregnancy and maternity prohibit employing pregnant women if occupational activities endanger the health of either the mother-to-be or the fetus. This applies for parvovirus B19 seronegative women caring for children <6 years. Here we present a cost-effectiveness analysis from the view of the society for the prohibition to employ B19-seronegative women in day care. Prohibition of employment starting at the first day of pregnancy may prevent 1.4 cases of fetal death (mortality) and 1.7 cases of hydrops fetalis (morbidity) per year resulting in costs of 30 million <euro> (22 million <euro>/live birth). The incidence of B19 infection, the elevated occupational risk and the fetal death rate were varied in sensitivity analyses. This resulted in 0.2-3.1 fetal deaths prevented per year and costs between 10 million <euro> and 150 million <euro> per live birth. Indeed, the protective effect is assumed to be even lower since 30% of fetal deaths occur after infection during the first 8 weeks of pregnancy. During that time prohibition of employment is often unrealistic since the majority of women are not aware of pregnancy. In conclusion a small number of fetal lives can be saved by prohibiting employment in contrast to the extremely high costs. The regulations for maternal protection should be revised.

Parvovirus B19 infection in pregnancy

Parvovirus B19 is a small single-stranded DNA virus and a potent inhibitor of erythropoiesis, due to its cytotoxicity to erythroid progenitor cells. Infection with parvovirus B19 during pregnancy can cause several serious complications in the fetus, such as fetal anemia, neurological anomalies, hydrops fetalis, and fetal death. Early diagnosis and treatment of intrauterine parvovirus B19 infection is essential in preventing these fetal complications. Testing maternal serum for IgM antibodies against parvovirus B19 and DNA detection by PCR can confirm maternal infection. If maternal infection has occurred, ultrasound investigation of the fetus and measurement of the peak systolic flow velocity of the middle cerebral artery are sensitive non-invasive procedures to diagnose fetal anemia and hydrops. Intrauterine transfusion is currently the only effective treatment to alleviate fetal anemia, but if the fetus is (near) term, induction of delivery should be considered. Most maternal infections with parvovirus B19 occur through contact with infected children at home. Individual counseling of susceptible pregnant women will reduce unnecessary fetal deaths.

Non-hydropic intrauterine fetal death more than 5 months after primary parvovirus B19 infection

AIMS

Clinical follow-up of possible fetal complications associated with maternal parvovirus B19 infection is usually recommended during the 2-3 months after primary infection.

RESULTS

A case of late intrauterine fetal death associated with at least 5 months of maternal parvovirus B19 viremia and in the presence of B19 IgG and IgM is described.

CONCLUSIONS

The time of clinical and laboratory follow-up after maternal parvovirus B19 infection may need to be revised if prolonged viremia is more common than previously described.

Detection of parvovirus B19, cytomegalovirus and enterovirus infections in cases of intrauterine fetal death

AIMS

Maternal infections with parvovirus B19, cytomegalovirus (CMV) and enterovirus have been associated with intrauterine fetal death (IUFD), but the incidence of these infections is not clear. This prospective study was conducted to estimate this incidence.

METHODS

A prospective study of 38 months was conducted on cases of IUFD referred to Huddinge University Hospital, Stockholm, Sweden. Placental biopsies, fetal blood and amniotic fluid were collected from cases of IUFD (n=52). Placental biopsies from normal pregnancies at term (n=53) were used as controls. These tissues were examined for parvovirus B19 DNA, CMV DNA and enterovirus RNA using polymerase chain reaction (PCR). Maternal viral serology was measured in 46 cases and virus isolation for enterovirus in maternal stool samples was performed in 31 cases.

RESULTS

Viral nucleic acid was recovered in at least one tissue sample from six cases of fetal death (parvovirus B19 in two cases, CMV in three and enterovirus in one), while all placental biopsies from controls were found negative. Serological signs of primary maternal infection were found in two of the cases, and virus isolation for enterovirus was negative in all samples examined.

CONCLUSION

Parvovirus B19, CMV and enterovirus may be considered as etiologic agents in cases of fetal death. PCR on placental and/or fetal tissue improves diagnostic accuracy for these infections.

Pre- and periconceptional primary cytomegalovirus infection: risk of vertical transmission and congenital disease

OBJECTIVE

To estimate the risk of congenital cytomegalovirus infection and disease following primary maternal infection around the time of conception compared with the risk during later stages of pregnancy.

DESIGN

Cohort study between 1990 and 2003.

SETTING

Germany.

PARTICIPANTS

One hundred and sixty-six pregnant women with serologically confirmed primary cytomegalovirus infection and known outcome.

METHODS

Timing of primary cytomegalovirus infection by analysing the kinetics of cytomegalovirus-specific IgG and IgM antibodies, the IgG avidity index and neutralising antibodies.

MAIN OUTCOME MEASURE

Onset of maternal primary infection in relation to congenital infection and disease.

RESULTS

Preconceptional (between eight and two weeks before onset of the last menstrual period) was determined in three women and did not lead to congenital infection. Periconceptional infection (between one week before and five weeks after last menstrual period) occurred in 20 women with congenital infection in nine cases (45%). Timing was less precise (between eight weeks before and five weeks after last menstrual period) in an additional 10 women, three cases of which resulted in congenital infection. Of the 12 pregnancies in which congenital infection occurred, seven were terminated, six before the 12th week of gestation (WG 12) and one at WG 19 due to fetal hyperechogenic bowel. One of the five infected live-born infants delivered to a mother with periconceptional infection showed dystrophy and mild microcephaly at birth, but had a rather normal development at two years of age. Primary infections occurring between WG 6-20 and WG 20-38 resulted in transmission rates of 30% (27/89) and 58% (18/31), respectively.

CONCLUSIONS

Counselling of women with periconceptional primary cytomegalovirus infection should be adjusted to offer prenatal diagnosis and high-level ultrasound controls due to the considerable risk for fetal infection and uncertainty of clinical outcome and disease.

The prognostic virtue of inflammatory markers during late-onset sepsis in preterm infants

AIM

Late-onset sepsis (occurring after the first three days of life) is a serious complication in preterm infants. In order to assess the possible prognostic virtues of the acute phase inflammatory response in the disease, we compared the inflammatory response of preterm infants who died within 72 hours (h) (fulminant sepsis) to infants who recovered from the disease (non-fulminant sepsis).

METHODS

Of 42 preterm infants that were evaluated: 10 had fulminant sepsis and 32 non-fulminant sepsis. Acute phase inflammatory response markers-C-reactive protein (CRP), serum amyloid A (SAA), interleukin (IL)-6 levels and white blood cell (WBC) counts were measured at the first suspicion of LOS and after 8, 24 and 48 h.

RESULTS

Small for gestational age (SGA) infants who were treated with fewer days of antibiotics characterized the fulminant sepsis group. The initial high levels of inflammatory markers were similar in both groups, but as early as 8 h after onset significantly lower levels of SAA, CRP and WBC counts were documented in the fulminant sepsis group. The inflammatory response remained low at 24 and 48 h in the fulminant sepsis group, while in the survivors, significantly increased inflammatory markers were measured. Decreases in the levels of the inflammatory markers preceded episodes of metabolic acidosis and arterial hypotension that were more common in the fulminant sepsis group. Infant mortality correlated inversely with SAA levels at 8 h and with CRP and WBC counts at 24 h after onset.

CONCLUSION

SAA, CRP and WBC counts can be used as prognostic markers in LOS in preterm infants, with SAA being the earliest prognostic marker.

Human parvovirus B19 DNA is not detected in Guthrie cards from children who have developed acute lymphoblastic leukemia

BACKGROUND

There has been much speculation about the cause of childhood acute lymphoblastic leukemia (ALL). It has been suggested, on the basis of findings in epidemiological studies, that ALL may be initiated by an in utero infection of the fetus. The human parvovirus B19 (B19) is etiologically related to human diseases, including erythema infectiosum and aplastic crisis, but it has not yet been considered to be involved in the development of ALL. Therefore, the aim of this study was to investigate, whether prenatal B19 infection could still be indirectly correlated with the development of childhood ALL.

PROCEDURES

Fifty-four Guthrie cards, collected at 3-5 days of age, from Swedish children who subsequently developed ALL, as well as from 50 healthy controls, were investigated by nested PCR for the presence of B19 DNA.

RESULTS

B19 DNA was not detected in any of the Guthrie cards from ALL patients or from healthy controls, although all tested samples had amplifiable cellular DNA as confirmed by an HLA DQ specific PCR.

CONCLUSION

B19 DNA was not found in any of the Guthrie cards from children who later developed ALL or in the healthy controls. These findings suggest that it is less likely that childhood ALL is associated with an in utero in fection with B19.

Long term follow up of serostatus after maternofetal parvovirus B19 infection

BACKGROUND

Maternofetal parvovirus B19 infection may result in fetal hydrops or abortion. Chronic infection has been associated with long term complications (polyarthritis, persistent aplastic anaemia, hepatitis). In pregnancy maternal immunosuppression caused by a TH2 dominant response to viral antigens has been observed. There is little information on long term reactivity to intrauterine infection.

AIMS

To assess the serological status in children and their mothers after maternofetal parvovirus B19 infection and development of fetal hydrops.

METHODS

A total of 18 children and their mothers, and 54 age matched control infants were studied. Main outcome measures were parvovirus B19 DNA, specific IgM and IgG against the virus proteins VP1/VP2, and NS-1 in venous blood.

RESULTS

Parvovirus B19 DNA and antiparvovirus B19 (IgM) were undetectable in all sera. A significant larger proportion of maternal sera compared to study children's sera contained IgG against the non-structural protein NS-1. Mean levels of VP1/VP2 IgG antibodies were significantly lower in the children than in their mothers (48 (36) v 197 (95) IU/ml). There was no history of chronic arthritis in mothers and children. Five women had subsequent acute but transient arthritis postpartum, which was not correlated with antibodies against NS-1.

CONCLUSIONS

Serological evidence of persistent infection after maternofetal parvovirus B19 disease could not be detected. Increased maternal prevalence of anti NS-1 (IgG) and increased levels of antiparvovirus B19 (IgG) may reflect prolonged viraemia compared to fetal disease.

Human fetal infection with parvovirus B19: maternal infection time in gestation, viral persistence and fetal prognosis

OBJECTIVE

To clarify the relation between the time of parvovirus B19 (B19) infection in pregnancy and fetal outcome, including the viral persistence in the fetus.

METHODS

Among 57 pairs showing serologic and/or virologic evidence of maternal and fetal B19 infection between 1986 and 1999 in Japan, 13 maternal-fetal pairs with the time of maternal B19 infection documented were retrospectively evaluated for fetal outcome and viral persistence.

RESULTS

Nonimmune hydrops occurred at 23, 21 and 26 gestational weeks (gw) in three fetuses as a result of their mothers' symptomatic infection (erythema infectiosum) at 3, 16 and 19 gw, respectively. Spontaneous abortion without hydrops and intrauterine growth retardation resulting in small-for-gestational age (SGA) classification occurred in two fetuses whose mothers had developed erythema infectiosum at 5 and 16 gw, respectively. Eight fetuses were asymptomatic as a result of their mothers' infection at 6, 9, 12, 15, 18, 23, 23 and 33 gw, respectively. B19 DNA was detected in neonatal serum in all nine cases tested.

CONCLUSION

Maternal B19 infection throughout gestation including the early stage after fertilization caused fetal infection that persisted until intrauterine fetal death with or without nonimmune hydrops or until the neonatal period after birth.

Fifth (human parvovirus) and sixth (herpesvirus 6) diseases

Fifth (erythema infectiosum) and sixth (roseola infantum) diseases are common rash illnesses of childhood that have long been recognized in clinical medicine. The discovery of the viruses that cause these illnesses has revealed relationships with other syndromes. Primary infection with the agent of erythema infectiosum, human parvovirus B19, is associated with transient aplastic crisis in hemolytic anemia, arthropathy in adults, chronic anemia in immunocompromised patients, and nonimmune fetal hydrops in pregnant women. The only documented illness associated with primary infection with human herpesvirus 6 is roseola or exanthema subitum in young children. However, reactivated infections in adults and immunocompromised patients may be associated with serious illness such as encephalitis/encephalopathy, and bone marrow suppression leading to transplant failure or graft-versus-host disease. Diagnostic studies for both viruses have been limited, although reliable serologic tests for human parvovirus B19 have recently become available. Diagnosis of human herpesvirus 6 remains problematic, because current tests cannot differentiate primary from reactivated disease. This is more of an issue for the putative relationship of these viruses to more chronic conditions, such as rheumatologic disease for human parvovirus B19 and multiple sclerosis for human herpesvirus 6. The relationship between the viruses and these conditions remains controversial, and better diagnostic tests and further information on viral pathogenesis for both viruses are required in order to make a reliable judgment in this regard.

Placental cellular immune response in women infected with human parvovirus B19 during pregnancy

Human parvovirus B19 can cause congenital infection with variable morbidity and mortality in the fetus and neonate. Although much information exists on the B19-specific antibody response in pregnant women, little information is available describing the cell-mediated immune (CMI) response at the maternal-fetal interface. The focus of this study was to characterize the CMI response within placentas from women who seroconverted to B19 during their pregnancies and compare it to controls. Immunohistochemical techniques were used to identify the various immune cells and the inflammatory cytokine present within placental tissue sections. Group 1 consisted of placentas from 25 women whose pregnancies were complicated by B19 infection; 6 women with good outcome (near-term or term delivery), and 19 with poor outcome (spontaneous abortion, nonimmune hydrops fetalis, or fetal death). Group 2 consisted of placentas from 20 women whose pregnancies were complicated with nonimmune hydrops fetalis of known, noninfectious etiology. Group 3 consisted of placentas from eight women whose pregnancies ended in either term delivery or elective abortion. The results of the study revealed a statistically significant increase in the number of CD3-positive T cells present within placentas from group 1 compared to group 2 or 3 (13.3 versus 2 and 1, respectively) (P < 0.001). In addition, the inflammatory cytokine interleukin 2 was detected in every placenta within group 1 but was absent from all placentas evaluated from groups 2 and 3. Together, these findings demonstrate evidence for an inflammation-mediated cellular immune response within placentas from women whose pregnancies are complicated with B19 infection.

Human parvovirus B19 infection in infancy associated with acute and chronic lymphocytic myocarditis and high cytokine levels: report of 3 cases and review

Human parvovirus B19 infection is occasionally associated with acute lymphocytic myocarditis (ALM). Three infants with B19 virus-associated ALM were followed up clinically, histologically, and immunovirologically. Each infant had B19 virus DNA in the blood or B19 virus-specific IgM antibodies. Two infants with postnatal infection recovered after immunosuppressive therapy. The third infant with possible prenatal infection developed chronic persistent myocarditis associated with persistent B19 virus DNA in the blood. All 3 infants had increased levels of interferon-gamma, tumor necrosis factor-alpha, and interleukins -6 and -8. Four newborns with congenital B19 virus infection and 4 infants and children who had postnatally acquired B19 virus infection without myocarditis all had normal levels of these cytokines. These observations suggest that B19 virus infection in infancy causes ALM in some infants and children.

Prenatal diagnosis of parvovirus B19-induced hydrops fetalis by chemiluminescence in situ hybridization

Parvovirus B19 can be transmitted transplacentally from the infected mother to the fetus during pregnancy, and hydrops fetalis, abortion, or stillbirth can result. In our study we explored the use of chemiluminescence in situ hybridization to detect B19 DNA on cord blood cells, amniotic fluid cells, and pleuric fluid cells from several cases of hydrops fetalis. B19 DNA was detected by using digoxigenin-labeled probes immunoenzymatically visualized with the chemiluminescent adamantil-1,2-dioxetane phenyl phosphate substrate for alkaline phosphatase. The luminescent signal emitted from the hybridized probes was detected, analyzed, and measured with a high-performance, low-light-level imaging luminograph connected to an optical microscope and to a personal computer for the quantification and localization of the chemiluminescent emission inside individual cells.