The correlation of maternal cytomegalovirus infection during varying stages in gestation with neonatal involvement

The "silent" global burden of congenital cytomegalovirus

Human cytomegalovirus (CMV) is a leading cause of congenital infections worldwide. In the developed world, following the virtual elimination of circulating rubella, it is the commonest nongenetic cause of childhood hearing loss and an important cause of neurodevelopmental delay. The seroprevalence of CMV in adults and the incidence of congenital CMV infection are highest in developing countries (1 to 5% of births) and are most likely driven by nonprimary maternal infections. However, reliable estimates of prevalence and outcome from developing countries are not available. This is largely due to the dogma that maternal preexisting seroimmunity virtually eliminates the risk for sequelae. However, recent data demonstrating similar rates of sequelae, especially hearing loss, following primary and nonprimary maternal infection have underscored the importance of congenital CMV infection in resource-poor settings. Although a significant proportion of congenital CMV infections are attributable to maternal primary infection in well-resourced settings, the absence of specific interventions for seronegative mothers and uncertainty about fetal prognosis have discouraged routine maternal antibody screening. Despite these challenges, encouraging results from prototype vaccines have been reported, and the first randomized phase III trials of prenatal interventions and prolonged postnatal antiviral therapy are under way. Successful implementation of strategies to prevent or reduce the burden of congenital CMV infection will require heightened global awareness among clinicians and the general population. In this review, we highlight the global epidemiology of congenital CMV and the implications of growing knowledge in areas of prevention, diagnosis, prognosis, and management for both low (50 to 70%)- and high (>70%)-seroprevalence settings.

Perinatal risk factors as predictors of developmental functioning

This study examined the relationship between perinatal risk factors and developmental functioning for a referred population of 216 children. A canonical correlation analysis indicated that 31% of the variability in developmental information could be predicted from perinatal events. The results were interpreted as lending support to a multivariate link between perinatal complications and developmental functioning for referred children.

Can cytomegalovirus cause brachydactyly? A case report and review of the literature

A child with the diagnosis of CMV infection associated with brachydactyly is presented. The case is interesting as, to our knowledge, no similar case has been reported up to the present. In our case, apart from CMV, no teratogenic factor which may cause brachydactyly could be detected.

Systemic viral infections and their retinal and choroidal manifestations

Viruses are one of the most common causes of infections involving the posterior segment of the eye. Such infections can occur either on a congenital or an acquired basis, and may affect primarily the retina or the choroid. Congenital cytomegalovirus (CMV) and rubella infections may result in retinitis. CMV retinitis is also the most common cause of acquired viral retinitis, primarily because of the acquired immunodeficiency syndrome (AIDS). Other types of viral retinitis, such as those caused by herpes simplex or herpes zoster, can occur in immunocompromised or immunocompetent individuals. Retinitis or choroiditis caused by viruses such as measles, influenza, Epstein-Barr virus, and Rift Valley fever virus, typically occurs subsequent to an acute viral systemic illness. The systemic and ocular manifestations, as well as the histopathology, laboratory tests, differential diagnoses, and treatment regimens for each of the individual viruses are discussed in detail.

Progressive hearing loss in children with congenital cytomegalovirus

Case studies of five children with congenital cytomegalovirus (CMV) who were referred for audiological evaluation are presented. Significant deterioration of hearing was noted in all cases within the first 4 years of life. It is essential that neonates with congenital CMV be referred for hearing assessment and that the child's hearing be monitored on a long-term basis. Early intervention is vital for the speech and language development of the hearing-impaired child.

Lissencephaly-pachygyria associated with congenital cytomegalovirus infection

We report the presence of major cerebral migrational defects in five severely, multiply handicapped children with congenital cytomegalovirus (CMV) infection. These patients had both computed tomographic (CT) scan and magnetic resonance imaging (MRI) evidence of marked migrational central nervous system defects consistent anatomically with the spectrum of lissencephaly-pachygyria, a disorder commonly idiopathic or associated with chromosomal abnormalities or with unknown early gestational insults. Neuroradiologic features included broad, flat gyri, shallow sulci, incomplete opercularization, ventriculomegaly, periventricular calcifications, and white-matter hypodensity on CT scans or increased signal intensity on long-TR MRI scans. Evidence for congenital CMV infection included prenatal onset of microcephaly, periventricular calcifications, neonatal jaundice, hepatomegaly, elevated CMV-specific immunoglobulin M, or viral isolation from urine. Previous reports of the neurologic sequelae of CMV have emphasized varying degrees of psychomotor retardation, cerebral palsy and epilepsy due to polymicrogyria, periventricular calcification, microcephaly, or rarely, hydrocephalus. Our patients appear to represent extremely severe examples of the effects of CMV on neurologic growth, maturation, and development. Recognition of these severe migrational abnormalities was improved by use of MRI, a technique that affords superior definition of the nature and extent of gyral and white-matter abnormalities. We suggest that these abnormalities may be more common than has previously been recognized.

Relation of maternal CMV viremia and antibody response to the rate of congenital infection and intrauterine growth retardation

Pregnancy outcome after maternal primary CMV infection initiated at different times during gestation was investigated by using the inbred Strain-2 guinea pig model of congenital CMV infection. The highest vertical transmission rates occurred in pups from dams that were initially viremic in late gestation presumably because delivery occurred prior to detectable maternal CMV-specific immune response. In contrast, conceptus loss was highest with maternal CMV infection initiated at conception. Intrauterine resorptions, intrauterine growth retardation, and disseminated neonatal CMV infection with CNS involvement were more frequent in pups born to mothers that were initially viremic prior to rather than after midgestation. Maternal viremia was prolonged and antibody responses were delayed after CMV inoculation in early gestation compared to late gestation. Prolonged maternal viremia plus early gestational virus exposure/infection of the fetus appeared to be associated with the most severe outcome. These findings suggest that the timing of initial maternal viremia and immune responses, the stage of fetal development, and the length of in utero exposure to CMV are important factors in subsequent disease expression and rates of congenital infection.

Infection control considerations for in vitro fertilization and embryo transfer programs

In vitro fertilization and embryo transfer (IVF-ET) is a process in which human ova are obtained by laparoscopic ovarian follicular puncture, fertilized in vitro by capacitated donor sperm, and introduced transcervically into the uterus. The prospective mother's ovarian cycle is usually stimulated with either clomiphene citrate, human menopausal gonadotropin, or both, so that multiple aspiratable follicles are produced. Follicular development is monitored by ultrasound and by serial serum or urine estrogen determinations. When adequate follicular development has been achieved, a pre-ovulatory dose of human chorionic gonadotropin is administered.

An early marker of fetal infection after primary cytomegalovirus infection in pregnancy

Fourteen patients with primary cytomegalovirus infection diagnosed by serological screening at antenatal attendances were examined for their responses in the lymphocyte transformation test against cytomegalovirus. Tests were done during pregnancy, shortly after the diagnosis of primary infection. Eight women showed positive lymphocyte transformation responses and gave birth to uninfected babies. Six showed negative responses and four of the babies were born congenitally infected. Cellular immunity therefore plays a part in preventing intrauterine transmission of cytomegalovirus, and its depression after primary infection in the mother during pregnancy may be used as an early marker of fetal infection.

The effects of maternal murine cytomegalovirus infection on the mouse conceptus at different gestational stages

The effects of murine cytomegalovirus (MCMV) on the prenatal development of the CD-1 mouse were investigated. Two sets of experiments were performed. In the first, mice were inoculated with different doses of MCMV on gestational day 7, and in the second, pregnant animals were inoculated with a subacute injection dose at different gestational stages. The effects of maternal infection on pregnancy in terms of maternal sickness, embryo lethality, date of parturition, litter size, postnatal death, and pups' body weight on d 1 and d 3 postpartum were investigated. High-dose MCMV infection on d 7 of pregnancy resulted in a significant increase in early embryo resorption and also in a reduction of the neonatal body weight of surviving pups. Two gestational stages were identified as being especially susceptible to MCMV infection. Most embryonic death as indicated by resorption rates was found after treatment on d 9, whereas perinatal death was most frequent when treatment was done on d 13 of gestation. Still births and neonatal death within 24 h of birth were found commonly in this latter group, which also showed the most pronounced growth retardation. The phenomenon of delay in time of parturition was noted and found to be most significant in groups of animals that were inoculated on d 3 or d 13. This investigation suggests that the effects of MCMV on the CD-1 mouse vary greatly with the age of the embryo and the course of the infection.

Immunoglobulin M antibodies detected by enzyme-linked immunosorbent assay and radioimmunoassay in the diagnosis of cytomegalovirus infections in pregnant women and newborn infants

Immunoglobulin M (IgM) antibodies were detected by a commercially available enzyme-Linked Immunosorbent Assay (ELISA) in 36 of 49 (73%) pregnant women with primary cytomegalovirus (CMV) infection. A positive ELISA-IgM result occurred in 10 of 13 patients (77%) assessed within 8 weeks of seroconversion. The sensitivity of the radioimmunoassay (RIA) to identify primary infection in pregnant women was comparable, 78% in general and 86% for women tested within 16 weeks of seroconversion. Of the 36 women with primary infection who had detectable IgM antibodies by ELISA, 25 (69%) were delivered of congenitally infected infants, whereas of the 13 with undetectable IgM antibodies, 7 (54%) transmitted the infection in utero. IgM antibodies were detected by ELISA in only 5 of 43 (11%) women who experienced a recurrence of CMV which either did or did not result in congenital infection. RIA was less likely to measure CMV-specific IgM in recurrent infection, inasmuch as 1 of 19 (5.2%) women with proven recurrent infection had detectable IgM antibody, giving RIA a better specificity for primary infection. Specific IgM antibodies were detected by ELISA in 42 of 61 (69%) babies congenitally infected with CMV and in 4 of 70 (5.7%) uninfected control newborn infants. The RIA was superior for diagnosis of congenital CMV infection, with a sensitivity of 89% and a specificity of 100%. The lower sensitivity of the ELISA-IgM occurred in the category of congenitally infected infants born to mothers with recurrent infection (43%), a group that is at the lowest risk of disease or to develop sequelae. This commercially available ELISA-IgM could be used in combination with a CMV-specific IgG test for monitoring women during pregnancy for primary infection.

Congenital cytomegalovirus infection and disease in Sweden and the relative importance of primary and secondary maternal infections. Preliminary findings from a prospective study

In a prospective Swedish study started in 1977 and still in progress 10 328 newborn infants in an urban district were investigated for cytomegalovirus (CMV) excretion in the urine by the virus isolation test. Congenital infection was found in 50 cases (0.5%). Of 47 infected infants with known clinical status at birth 9 (19%) had hepatomegaly, splenomegaly, jaundice and/or petechiae. The symptoms were moderate or mild. Of the infants followed up, 2 (25%) of 8 neonatally symptomatic ones and 3 (9%) of 35 asymptomatic ones developed neurologic sequelae. Altogether 5 (12%) of 43 had permanent neurologic symptoms corresponding to 0.06% in the general population. The children ranged in age from 6 months to 4 yr at the last examination. 21 mothers of the 47 infants with known status at birth had a confirmed or presumed primary infection, 15 a confirmed or presumed secondary infection and 11 an undetermined type of infection. Of the 5 infants with neurologic sequelae, 1 with a grave psychomotor retardation and deafness was born to a mother with a primary infection in the 1st trimester; 1 infant with a moderate retardation and 3 deaf infants were all exposed to confirmed or presumed secondary maternal infections. Prospective serological studies of maternal sera in early pregnancy would have suspected only the gravely retarded infant to be at risk.

Congenital cytomegalovirus infection: on the relation between type and time of maternal infection and infant's symptoms

Maternal sera from 45 live-born infants with congenital cytomegalovirus (CMV) infection and 4 cases of legal abortion were analysed for CMV IgG and IgM. The investigation included cases from routine work and prospective studies of unselected infants. The purpose was to elucidate the relation between the maternal type and time of infection and the signs and symptoms of the offspring at birth and follow-up. Serological patterns compatible with primary maternal infection during trimesters I and II, but also with secondary infection (in at least 1 case), were associated with infant sequelae or death. Asymptomatic infant infection was found after primary infection in trimesters II and III and after secondary infection. Virus could not be isolated from some of the fetuses legally aborted due to primary maternal infection in trimester I. Attempts to demonstrate CMV IgM activity as a marker of active infection in sera from early pregnancy (period of legal abortion) were successful in only half of the 10 cases with infant sequelae or death. Symptoms at birth were prognostically serious, but the further course was sometimes uneventful even in infants with neonatal signs of cerebral infection. A few children without initial symptoms developed sequelae (impairment of hearing).

Recommendations for pregnant employee interaction with patients having communicable infectious diseases

The transmission of communicable infectious diseases from hospitalized patients to health care providers is a well-documented phenomenon. This occurrence is of particular concern when the health care worker is a pregnant female and there is worry about the development of a congenital infection or transmission of infection at the time of delivery. Infection control practitioners and Employee Health Service personnel are often consulted by pregnant hospital employees who are concerned about interacting with patients having communicable infectious diseases, and appropriate advice is sought. Since it has often been necessary in the past to consult numerous resources in order to respond to these issues, we have compiled recommendations that can serve as a reference to help ICPs and Employee Health Service personnel deal with these situations.

Histological study of congenital and acquired cytomegalovirus infection

Of 180 autopsied cases in children, of which 85 infants were less than one month of age, seven cases of cytomegalovirus infection are described here. Two patients died of congenital cytomegalovirus infection with generalized cytomegalic inclusion disease and one of them was associated with leukemoid mononucleosis. Five cases, 2.8 per cent of 180 cases, were acquired cytomegalovirus infection with localized lesions of cytomegalic cells in the lungs, incidentally found at postmortem examination. The youngest case of acquired cytomegalovirus infection was one month of age. These spontaneous pulmonary infectious changes early in life, associated occasionally with cytomegalic cells in the vascular wall, may suggest that the lung is one of the initial sites of the acquired cytomegalovirus infection preceeding viruria or elevation of antibody titer at later period of life.

Experimental primary cytomegalovirus infection in pregnancy: timing and fetal outcome

In contrast to intrauterine rubella infection, the relationship between timing of maternal cytomegalovirus (CMV) infection and fetal outcome has not been clearly defined. In order to investigate this relationship, a guinea pig model was utilized to assess the fetal consequences of maternal CMV infection during the first, second, or third trimester of pregnancy. Congenital infection occurred in 24 of 35 newborn guinea pigs (69%) delivered to mothers infected during the third trimester, with localization of virus to salivary gland in 17 of the 24 infected newborn guinea pigs. In contrast, only one of 28 (5%) progeny sacrificed following first-trimester maternal infection was congenitally infected (p less than 0.01). Second-trimester maternal infection was associated with an intermediate risk of intrauterine infection with transmission of virus to 17 of 54 progeny (33%) (p less than 0.01). Eight of the 10 fetuses delivered after second-trimester infection had virus in multiple organs including the brain. These data suggest that timing of maternal CMV infection is an important variable affecting fetal outcome, with increased risk of intrauterine infection when maternal infection occurs late in pregnancy. However, if fetal infection occurs earlier in pregnancy, it appears to present a greater threat to the fetus, with the potential for dissemination of virus in multiple fetal tissues, including the brain.

Congenital cytomegalovirus infection: The relative importance of primary and recurrent maternal infection

We studied the incidence of primary and recurrent cytomegalovirus infection in 3712 pregnant women--2698 of middle to high income and 1014 of low income--to determine whether there were differences in the effects on the fetus. In the higher-income group, 1203 women (45 per cent) did not have antibodies to cytomegalovirus and were therefore susceptible to primary infection, as compared with 179 women (18 per cent) of low income. Congenital infection occurred more often (1.6 vs. 0.6 per cent) in infants in the low-income group. In this group it was associated with recurrent maternal infection more often (in 82 per cent) than with primary maternal infection, whereas in the upper-income group, it was associated with primary maternal infection in half the cases. Altogether, there were 32 cases of congenital cytomegalovirus infection - 16 in each group. Whereas primary maternal infection resulted in fetal infection in only half the cases, it was more likely to ge associated with clinically apparent disease than was recurrent infection. When these cases were combined with 28 cases of congenital infection retrospectively identified at other prenatal clinics, five of 33 infected infants born after primary maternal infection had clinically apparent disease, as compared with none of 27 born after recurrent maternal infection. We conclude that congenital cytomegalovirus infection resulting from primary maternal infection is more likely to be serious than that resulting from recurrent infection, and is more likely to occur in upper socioeconomic groups.

Primary and secondary maternal cytomegalovirus infections and their relation to congenital infection. Analysis of maternal sera

4 382 new mothers were examined retrospectively with the enzyme-linked immunosorbent assay (ELISA) for IgG activity to cytomegalovirus (CMV) during pregnancy. Some of them were also studied with the indirect immunofluorescence (IIF) test for CMV-IgM antibodies. All the infants had been studied for CMV excretion within the first week of life. Nineteen of them had been shown to be congenitally infected with CMV. 1 218 (28%) women lacked CMV-IgG activity at their first antenatal visit (usually in months III-IV). Fourteen of them seroconverted before parturition (primary infection). Thirteen of the seroconverters were shown to develop CMV-IgM activity. In 6 (43%) cases the primary infection was transmitted to the offspring. The remaining 13 congenitally infected infants were born to mothers with a positive IgM-test at their first antenatal control. Only one of these mothers had a clearly positive IgM-test. She was shown to lack CMV-antibodies before conception (primary infection during the first trimester). Preconceptional sera were obtained from further 4 of the 13 seropositive mothers of congenitally infected infants; all 4 had CMV antibodies before pregnancy (secondary infection during pregnancy). The combined studies of the mothers and infants revealed that 21-63% of the congenital infections could have been caused by secondary maternal infections. Prospectively performed, the study would only have disclosed one of the three fetal CMV infections that resulted in neurological sequelae.

Risk of cytomegalovirus infection in nurses and congenital infection in their offspring

The risk of contracting cytomegalovirus (CMV) infection in nursing of infants and of congenital CMV infection in infants born to such nursing personnel were investigated. The investigation comprised 292 women working in paediatric clinics or day nurseries and a control group of 163 women who had no professional contact with infants. Among the women younger than 25, those who had tended infants for more than six months were significantly (p less than 0.001) more often seropositive for CMV than were those--mainly student nurses--with less than six months' infant nursing service, but ot more often than control women. At ages above 25 there was no demonstrable difference between the groups. In a separate study the occupation of 36 mothers of infants with congenital CMV infection was investigated. Compared to a control group no overrepresentation of nurses was found. All six congenitally infected infants born to nurses developed normally.

The presumptive diagnosis of primary cytomegalovirus infection in early pregnancy by means of a radioimmunoassay for specific-IgM antibodies

During a 30 month investigation 3633 women were studied when the booked for antenatal care. Complement fixing antibodies against cytomegalovirus (CMV) were detected in 2078 (57 per cent) of the women and these sera were further tested for the presence of specific IgM antibodies by means of a solid-phase radioimmunoassay. Since specific IgM antibodies have previously been shown to persist for up to four months after primary CMV infection, their presence in a booking serum sample (mean gestation 15 weeks) was taken as presumptive evidence of a first trimester primary CMV infection. From theoretical considerations, 11.6 positive CMV-IgM reactions were predicted in these women and 11 were observed. A highly significant (p less than 0.001) excess of fetal death was seen in the infected women since three pregnancies ended in missed abortion (15 weeks), intrauterine death (29 weeks) and spontaneous abortion (24 weeks) whilst the remaining 8 women gave birth to apparently normal babies. Cord sera were available from 5 of the surviving babies and only one contained specific IgM antibodies, showing that transplacental spread of the maternal infections had not occurred in 4 of the 5 survivors.

Prevention of transfusion-acquired cytomegalovirus infections in newborn infants

Transfusion-acquired cytomegalovirus infections occurred in 13.5% of 74 infants of seronegative mothers who were exposed to one or more blood donors who had a CMV indirect hemagglutination titer of 1:8 or higher. None of 90 infants of seronegative mothers exposed only to donors with CMV IHA titers of less than 1:8 became infected. Ten of 41 (24%) infants of seronegative mothers who received more than 50 ml of packed red blood cells and who were exposed to at least one seropositive donor became infected. None of 23 infants of seronegative mothers who received this amount of blood but who were exposed only to seronegative donors became infected. Fatal or serious symptoms developed in 50% of the infected infants of seronegative mothers and in none of the 32 infected infants of seropositive mothers. Acquired CMV infections occurred in 15% of infants of seropositive mothers who were exposed to the red blood cells of seropositive donors and in 17.6% of infants of seropositive mothers exposed only to seronegative donors. Use of seronegative donors reduced the prevalence of excretion of CMV among hospitalized infants who were 4 weeks of age or older from 12.5 to 1.8% and eliminated acquired CMV infections in infants of seronegative mothers.

Persistence of high titre antibodies to the early antigens of cytomegalovirus in pregnant women

Serial serum samples were obtained from 45 pregnant women who had been shown to possess complement fixing (CF) antibodies to cytomegalovirus (CMV) during a previous pregnancy. The serial samples were tested for antibodies against the early antigens (EA) and complement fixing antigens of CMV. All of the 45 women still possessed CF antibodies at the commencement of their next pregnancy. Six of the 45 women (13 per cent) lacked detectable IFA-EA antibodies whilst 19/45 (42 per cent) women possessed only low titres (less than or equal to 64) of these antibodies. However, 20/45 (44 per cent) women possessed high titre (greater than or equal to 128) antibodies despite having experienced their primary CMV infection many months previously. It is concluded that antibodies to the EA OF CMV are not as transitory as has been suggested and that their presence, even at high titre, in a serum sample from a pregnant woman cannot be taken as presumptive evidence of recent primary infection with this virus.

Clinical anophthalmia associated with congenital cytomegalovirus infection

Three cases of congenital clinical anophthalmia associated with congenital cytomegalovirus infection were diagnosed by positive viral cultures and immunologic studies. Ultrasonography in one infant with clinically detected anophthalmia showed the presence of severe microphthalmia with cyst. These findings suggest that maternal infection occurred within the first trimester of gestation.

A prospective study of primary cytomegalovirus infection in pregnant women

During a four year study, sera were obtained from 5575 women attending for antenatal care and 3188 (57.2 per cent) were shown to possess complement fixing antibodies to cytomegalovirus (CMV). A total of 1608 seronegative women were followed to term and 14 (0.87 per cent) primary CMV infections occurred in either the second or third trimester. Transplacental spread of CMV occurred in 3 out of 12 (25 per cent) of the 14 babies born to infected mothers. All 14 babies were apparently normal at birth but short term clinical follow-up has already revealed that one child has impaired hearing whilst another is microcephalic. The women were also monitored serologically throughout pregnancy for evidence of rubella infections. Only 12 infections were detected and 7 of these occurred during the large rubella epidemic of 1978. Of the 10 pregnancies which were allowed to proceed to term, transplacental spread of rubella virus occurred in 1 out of 7 (14 per cent). During this study period, CMV infections occurred as frequently as did rubella infections. We therefore conclude that, apart from those years when extensive epidemics occur, many more pregnant women are infected with CMV than with rubella virus.

Teratoepidemiology

A review of the field of human teratoepidemiology—the epidemiology of congenital malformations—is presented here along with a discussion of the importance of international collaboration in monitoring congenital malformations. Studies implicating various environmental teratogens such as drugs, industrial and agricultural chemicals, intrauterine infections, radiation and nutritional factors are discussed at some length as well as problems encountered in detecting human teratogenic agents.

A prospective study on the incidence and significance of congenital cytomegalovirus infection

Screening of 3060 neonates for congenital cytomegalovirus (CMV) infection by virus excretion in the urine showed an overall incidence of 0.4%. The incidence was about 1% for mothers between 16 and 25 years and only 0.2% for mothers between 25 and 35. No mothers over 35 years of age gave birth to congenitally infected infants. The percentage of women in the child-bearing age susceptible to CMV infection was estimated by the absence of CMV complement-fixing antibodies in cord sera and ranged from 48% to 33% with increasing age. None of the infected infants showed obvious signs of congenital CMV infection at birth. At follow-up, two infants showed slight, but transient symptoms compatible with a foetal infection; a pair of premature twins exhibited retarded physical and psychomotor development, but this could just as well be ascribed to the prematurity itself. None of the infants had detectable CMV--IgM antibodies in cord sera, but a trend towards elevated total IgM concentration in cord sera and elevated virus excretion titres appeared in the infants with symptoms. With the very low incidence and no signs of sensomotor sequelae the preliminary conclusion is that foetal CMV infection in our population by no means has a significance to deserve screening or a vaccination programme.

Epidemiology of cytomegalovirus infections during pregnancy and infancy. A prospective study

The occurrence and possible consequences of cytomegalovirus (CMV) infections were studied in 200 mothers and their children by means of immunofluorescent antibody assays in serum, virus isolation from urine and regular clinical and neurological examinations. The prospective study covered the time from early pregnancy to 1 year post partum. The frequency of intrauterine infections was 2%, while 30% of the children became perinatally infected as indicated by the onset of virus excretion and an antibody response at the age of 2--4 months. Later on the occurrence of CMV infections declined sharply. 23 mothers had no CMV antibodies and none of their children contracted CMV during the first year of life. Maternal antibodies seemed unable to protect the child from CMV infections or to delay the onset of virus excretion in perinatally infected children. Intrauterine infections did not correlate with significant increases in the antibodiy titres of the mothers or the presence of IgM antibodies either in the mother's sera or in the cord sera. Perinatal infections were often associated with the presence of IgM antibodies both in the child and in the mother and in these mothers significant increases in CMV antibody titres were frequently seen, probably indicating an activated latent infection. Immunofluorescent antibody assay correlated well with virus isolations and was more sensitive than complement-fixing antibody assay.

Cytomegalovirus infection in the neonate and its prevention

About 0.5% of infants are infected in utero with cytomegalovirus (CMV). As many as 20% become mentally retarded and a further substantial proportion suffer lesser degrees of brain damage. The need for a vaccine is greater than in the case of rubella. A live, tissue culture-adapted strain of CMV has been shown to produce neutralizing antibody in volunteers without significant side effects or detectable virus excretion. The problems of developing such a vaccine for use in man, namely, attenuation, antigenic differences among virus strains, reactivation of latent infection and oncogenicity, are briefly discussed.

Congenital cytomegalovirus infection

The overall prevalence of congenital cytomegalovirus infection among the offspring of a highly immune young female population was 2.4 per cent (23 of 939). To ascertain whether the presence of anticytomegalovirus antibodies protects the developing fetus, we examined the offspring of 239 prospectively studied women. Despite substantial levels of preconceptional antibodies, intrauterine cytomegalovirus infection occured in seven of 208 (3.4 per cent) seroimmune women. Three neonates with congenital infection were born to 31 initially seronegative women. All the congenitally infected infants had subclinical involvement. Maternal humoral immunity may not protect the fetus against congenital cytomegalovirus infection. Neutralization kinetics and restriction enzyme analysis with endonucleases (EcoR-1 and HinD 111) demonstrated antigenic and genetic homology between viral strains isolated from two siblings consecutively infected in utero, indicating that repeat maternal infection with the same virus is transmissible to sequential products of conception.

Prospective study of cytomegalovirus infection in pregnancy

In a prospective study of cytomegalovirus infection in 1,040 pregnant women in London 319 (42%) of the white Englishwomen but only 28 (10%) of the immigrant Asian women were without antibodies at the onset of pregnancy. Out of 254 susceptible white women and 16 susceptible Asian women 8 (3%) and 3 (16%) respectively experienced primary infection during the course of pregnancy. The overall incidence of fetal infection after primary infection in the mother was almost 50%, and was higher in early pregnancy. One out of the five infected infants was found to be mentally retarded.Reactivation of latent infection was recognized in 0.7-2.9% of pregnant women; this occurred without involving the fetus.