Parvovirus B19 infection: association with third-trimester intrauterine fetal death

Revised clinical presentation of parvovirus B19-associated intrauterine fetal death

Adverse pregnancy outcome due to human parvovirus B19 (hereafter referred to as "parvovirus B19") has been characterized, in numerous reports, as an event that occurs during the first and second trimesters and is strongly associated with symptoms of fetal hydrops. Recent findings have indicated that parvovirus B19-associated intrauterine fetal death (IUFD) is also a problem in late gestation, although its clinical presentation is aberrant, lacking signs of fetal hydrops. We outlined the clinical presentation and assessed the frequency of parvovirus B19 infection in a retrospective analysis of 92 unselected cases of IUFD that occurred during or after gestational week 22. By polymerase chain reaction, parvovirus B19 DNA was detected in 13 (14%) of the 92 cases. Only 2 of the parvovirus B19 DNA-positive cases were hydropic, both representing early IUFDs. This finding indicates that parvovirus B19-associated IUFD in late gestation is a common finding and that hydropic presentation is rare. This knowledge may contribute to a reduction in the number of unexplained cases of IUFD.

Human parvovirus B19 infection in pregnancy: should screening be offered to the low-risk population?

Human parvovirus B19 infection during pregnancy can result in fetal hydrops and death. Intra-uterine transfusion in hydropic fetuses affected by the virus can reduce perinatal deaths. Up to 33% of women with this infection are asymptomatic. In view of the significant adverse outcomes, the role of routine screening among low-risk pregnant women is discussed.

Human parvovirus B19

Parvovirus B19 (B19) was discovered in 1974 and is the only member of the family Parvoviridae known to be pathogenic in humans. Despite the inability to propagate the virus in cell cultures, much has been learned about the pathophysiology of this virus, including the identification of the cellular receptor (P antigen), and the control of the virus by the immune system. B19 is widespread, and manifestations of infection vary with the immunologic and hematologic status of the host. In healthy immunocompetent individuals B19 is the cause of erythema infectiosum and, particularly in adults, acute symmetric polyarthropathy. Due to the tropism of B19 to erythroid progenitor cells, infection in individuals with an underlying hemolytic disorder causes transient aplastic crisis. In the immunocompromised host persistent B19 infection is manifested as pure red cell aplasia and chronic anemia. Likewise, the immature immune response of the fetus may render it susceptible to infection, leading to fetal death in utero, hydrops fetalis, or development of congenital anemia. B19 has also been suggested as the causative agent in a variety of clinical syndromes, but given the common nature, causality is often difficult to infer. Diagnosis is primarily based on detection of specific antibodies by enzyme-linked immunosorbent assay or detection of viral DNA by dot blot hybridization or PCR. Treatment of persistent infection with immunoglobulin reduces the viral load and results in a marked resolution of anemia. Vaccine phase I trials show promising results.

Diagnostic evaluation of intrauterine fetal deaths in Stockholm 1998-99

BACKGROUND

To evaluate the diagnostic methods and to elucidate the etiology of intrauterine fetal death.

MATERIAL AND METHODS

A prospective study was conducted on all intrauterine fetal deaths occurring in Stockholm County in 1998-99. During a 24-month period, 188 cases of intrauterine fetal death with gestational ages of > or = 22 weeks were investigated in accordance with structured test protocol. All information from antenatal and delivery records as well as all test results were entered in to an Internet-based database for continuous evaluation.

RESULTS

A presumptive explanation to the stillbirth was established in 91% of the cases. The most common factors associated with intrauterine fetal death could be identified as infections (24%), placental insufficiency/intrauterine growth restriction (22%), placental abruption (19%), intercurrent maternal conditions (12%), congenital malformations (10%), and umbilical cord complications (9%).

CONCLUSIONS

A relevant test protocol in cases of intrauterine fetal death reduces the number of unexplained cases to a minimum. An Internet-based register on test results of fetal deaths may enable a continuous evaluation of the diagnostic tools and etiologic factors in an ever-changing panorama. The results from the present study can serve as a base for a case-control study in Sweden.

Seropositivity of cytomegalovirus, parvovirus and rubella in pregnant women and recurrent aborters in Leningrad County, Russia

BACKGROUND

The objectives of this paper were to assess the prevalence of different viral infections in relation to late abortions, stillbirths, and congenital malformations in sera from Russian pregnant women and recurrent aborters in order to establish basic knowledge for future pregnancy care.

METHODS

Patients were recruited at the Women's Clinic, Leningrad Regional Hospital during the period March-June 1995. One group of normally pregnant women (Group 1; n=182) and one group of recurrent aborters (Group 2; n=127) were evaluated, including demographic, medical, clinical, and serological data.

RESULTS AND CONCLUSIONS

The mean age of the two groups was 27.1 and 28.2 years, respectively. The mean number of deliveries was low (0.4 and 0.5, respectively). Thirty-one point six percent of Group 1 and 41.9% of Group 2 were daily smokers. The group of normally pregnant women had a significantly increased frequency of induced abortions compared to the recurrent aborters, while the recurrent aborters reported more genital infections. There was little difference in total antibodies to cytomegalovirus (CMV) (78.0% and 81.1%, respectively) or B19 IgG (75.3% and 66.9%, respectively) between the groups, while the normal pregnant women had a significantly higher prevalence of rubella antibodies (77.5% and 59.8%, respectively). Our results indicate that less women remain susceptible to primary CMV infection in pregnancy in Russia compared to western Europe and North America. The prevalence of B19 IgG was slightly lower than data from Sweden. Natural immunization against rubella virus was lower than in other, unvaccinated female populations. Vaccination strategies for rubella are now initiated in the Russian Federation. Results from this study are utilized in a federally supported, comprehensive pregnancy care project of North-West Russia.

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.

Frequency of human parvovirus B19 infection in intrauterine fetal death

BACKGROUND

Parvovirus B19 is known to cause fetal death in the second trimester, mainly in combination with hydrops fetalis. However, the frequency of parvovirus-B19-associated non-hydropic fetal loss in the late second and third trimester has not been thoroughly investigated. We aimed to investigate the frequency of parvovirus B19 infection in unselected cases of intrauterine fetal death and to assess the sensitivity of different diagnostic procedures.

METHODS

Of 14147 deliveries in three hospitals in the major Stockholm area of Sweden, all cases of intrauterine fetal death (>22 gestational weeks) that occurred between January, 1998, and May, 1999 (n=47), referred cases of miscarriage (<22 gestational weeks, n=37), and induced abortions (n=29), were included in the study. Placental and fetal tissues were examined by means of parvovirus-B19-specific PCR, histopathology, and immunohistochemistry. Placental tissues from 53 normal pregnancies at term were also examined.

FINDINGS

Significantly more cases of intrauterine fetal death were positive for parvovirus B19 DNA (seven [15%]) than were normal pregnancies at term (zero, p=0.049). Furthermore, parvovirus B19 DNA was found in two (5%) of the miscarriages but not in any of the cases of induced abortion. Only three of nine DNA-positive cases had parvovirus-B19-associated inclusions and stained positive for viral proteins. All but one of the DNA-positive cases of intrauterine fetal death were non-hydropic.

INTERPRETATION

The presence of parvovirus B19 DNA in cases of late second-trimester and third-trimester fetal death is common, and most are non-hydropic. The sensitivity of conventional diagnostic procedures for intrauterine fetal death could be greatly improved by addition of parvovirus B19 PCR.

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.