1. Introduction
Intrapartum transmission of pathogens to newborns can occur by exposure of genital secretions to newborns or by hematogenous infection. Group B streptococci (GBS), herpes simplex virus (HSV), human papilloma virus (HPV), Chlamydia trachomatis, Neisseria gonorrhea, and cytomegalovirus (CMV) can be transmitted by newborns’ exposure to genital secretions. Indeed, culture of GBS and polymerase chain reaction (PCR) tests for the detection of Chlamydia trachomatis in the genital secretions are widely used as maternal screening tools to prevent intrapartum mother-to-infant transmission of these pathogens. In previous studies, it was reported that the presence of viral DNA, including hepatitis B virus, human immunodeficiency virus (HIV), and HPV, in the maternal uterine cervical secretion or vaginal secretion may be a risk factor for mother-to-child transmission of viruses [Citation1–Citation3]. However, there have been no studies that evaluate the usability of PCR tests for CMV-DNA in the uterine cervical secretion as a tool for predicting congenital CMV infection before birth.
Human CMV is the most common cause of congenital viral infection in humans. Ten to fifteen percent of infected fetuses have the clinical symptoms of congenital CMV infection, including fetal growth restriction, and central nervous system and multiple organ involvement, at birth. Approximately 90% of the surviving infants who have obvious symptoms of congenital CMV infection have severe long-term neurological sequelae. In addition, even in the infants who have no obvious symptoms of congenital CMV infection at birth, 10–15% of them develop long-term sequelae, including progressive or late-onset sensorineural hearing difficulty. On the other hand, it has been suggested that early diagnosis using PCR assay for CMV-DNA in newborn urine samples and early antiviral therapy may improve neurological outcomes of infants with symptomatic congenital CMV infection [Citation4–Citation7]. Therefore, the prenatal detection of mothers and newborns at high risk for congenital CMV infection is important. However, universal screening of newborns for congenital CMV infection is still not recommended.
Hence, we tried to determine noninvasive methods for predicting congenital CMV infection, including PCR tests for CMV-DNA in the uterine cervical secretion, among high-risk pregnant women [Citation8].
2. Commonly used methods for prenatal detection of fetuses at high risk for congenital CMV infection
It is well known that approximately 40% of fetuses whose mothers have primary CMV infection during pregnancy will be infected. Therefore, maternal serological tests for detecting pregnant women with primary CMV infection, including maternal blood tests of CMV-specific Immunoglobulin (Ig) G and CMV-specific IgM, were widely used. Especially, testing for maternal serum CMV IgM is commonly used to identify primary CMV infection. However, it is known that CMV IgM positivity yielded 20–25% sensitivity [Citation9], 15–20% false-positive rate [Citation10] for detecting primary CMV infection, because of a prolonged IgM response which may persist for 6–9 months following primary CMV infection or a nonspecific reaction caused by auto-immune disease.
The serum CMV IgG avidity measurement is also used to determine primary CMV infection during pregnancy. CMV IgG avidity index (AI) reflects the binding affinities of CMV IgG to viral antigen; a low AI indicates a recent primary infection within the previous 3 months. The previous study suggested that a CMV IgG AI may be useful for predicting congenital CMV infection [Citation11,Citation12].
It is well known that ultrasound fetal abnormalities, including ventriculomegaly, microcephaly, intracranial calcification, fetal growth restriction, and hepatosplenomegaly are closely associated with fetal CMV infection.
On the other hand, PCR assay for CMV-DNA in the amniotic fluid are highly sensitive and specific for fetal CMV infection, although amniocentesis is essentially an invasive procedure with a risk of rupture of the membranes. Therefore, it is not realistic that all pregnant women suspected of having primary CMV infection, including CMV IgM-positive pregnant women, receive CMV-DNA PCR analyses of the amniotic fluid.
3. The presence of CMV-DNA in the uterine cervical secretion was predictive of congenital CMV infection among high-risk pregnant women
We conducted a prospective cohort study to determine maternal clinical, laboratory, and ultrasound findings that effectively and noninvasively predict the occurrence of congenital CMV infection among CMV IgM-positive pregnant women, who are at high risk for congenital CMV infection [Citation8]. The maternal clinical and laboratory findings, including CMV IgG AI, antigenemia assay (C7-HRP), PCR for the detection of CMV-DNA in the maternal serum, urine, and uterine cervical secretion (SRL, Tokyo, Japan) (positive, ≥1.0 × 102 copies/ml), and prenatal ultrasound findings, were evaluated. In 22 of the 300 pregnant women who tested positive for CMV IgM, congenital CMV infection was confirmed by positive PCR results for CMV-DNA in newborn urine. A stepwise approach using univariate and multivariate logistic regression analyses revealed that the presence of ultrasound fetal abnormalities (OR 31.9, 95% CI 8.5–120.3; p = 3.1 × 10–7) and positive PCR results in the uterine cervical secretion (OR 16.4, 95% CI 5.0–54.1; p = 4.3 × 10–6) were independent predictive factors of congenital CMV infection in CMV IgM-positive pregnant women. The positive CMV-DNA PCR results in the uterine cervical secretion yielded 50.0% sensitivity, 94.2% specificity, 40.7% positive predictive value, and 96.0% negative predictive value for the prediction of congenital CMV infection.
4. CMV-DNA PCR test of uterine cervical secretion may be a novel method for predicting congenital CMV infection before birth
Until now, PCR tests for uterine cervical secretion have been generally used for diagnosis of chlamydial cervicitis or gonorrheal cervicitis. Additionally, in previous studies, cervical specimens were tested by real-time PCR for HPV, HSV, CMV, Epstein-Barr virus, and HIV. The investigators mainly discussed from the viewpoint of the etiology of sexual transmitted diseases, uterine cervical cancer, or vertical transmission of these viruses from mothers to their infants following ascending infection or birth canal infection [Citation13,Citation14]. In our study, the percentage of positive PCR results for the cervical secretion in pregnant women with congenital CMV infection was 50% but only 5.8% in women without congenital CMV infection [Citation8]. It is known that CMV shedding in the genital secretions may be prolonged after primary infection [Citation15] and could also represent reactivation of latent virus [Citation16]. In addition, it was reported that 7.7% of healthy pregnant women tested positive for CMV-DNA in the vaginal secretion during the first trimester [Citation17]. The percentage of patients with positive CMV-DNA PCR results for the cervical secretion in pregnant women with congenital CMV infection was much higher than that in women without congenital CMV infection or that in healthy pregnant women. One obvious hypothesis to explain these differences could be a persistent CMV shedding in vaginal secretions because of maternal primary or secondary infection. Another hypothesis could be that CMV-DNA in the amniotic fluid might leak into the genital tract. Further studies are needed to better understand the physiopathology of this association. On the other hand, vertical transmission by birth canal infection or breast-feeding could not occur in this study, because the presence of congenital infection was determined by a positive PCR result for CMV-DNA in the urine of newborns within 1 week of age.
In addition, we have recently encountered a case which had a clinical course as follows. A 29-year-old primigravida pregnant woman was found to have elevated liver enzyme levels and found that serum CMV IgM and IgG levels measured by using enzyme immunoassay kits (Denka Seiken, Tokyo, Japan) were 5.11 index (negative, <0.8; borderline, 0.8–1.2; positive, ≥1.2) and 2.5 (negative, <2.0; borderline, 2.0–3.9; positive, ≥4.0) at 21 weeks and 1 day of gestation, respectively. She was referred to Kobe University Hospital at 23 weeks and 5 days of gestation, and the laboratory findings were as follows: CMV IgM 10.96 index, CMV IgG 9.4, CMV IgG AI (Aisenkai Nichinan Hospital, Miyazaki, Japan) 1.1% (low, ≤35%; high, >35%), and negative CMV-DNA PCR results for the uterine cervical secretion (SRL, Tokyo, Japan) (positive, ≥1.0 × 102 copies/ml). The amniocentesis followed by PCR analysis for the amniotic fluid (SRL, Tokyo, Japan) (positive, ≥1.0 × 102 copies/ml) was performed at 30 weeks and 0 day of gestation, and it was revealed that she had a positive CMV-DNA PCR result for the amniotic fluid (1.2 × 106 copies/ml). At 30 weeks and 5 days of gestation, she had a positive CMV-DNA PCR result for the uterine cervical secretion (1.4×104 copies/ml). These results suggested that CMV-DNA PCR tests for the uterine cervical secretion should be repeatedly performed to predict the occurrence of congenital CMV infection more accurately (unpublished data).
Our study may provide a new concept in the prenatal diagnosis of congenital CMV infection. In clinical practice, the clients can get information that can be provided by performing noninvasive procedure before they give consent for invasive procedures. Furthermore, neonatologists can identify high risk neonates who need workup for congenital CMV infection. The early assessment and detection may lead to accurate diagnosis as well as early antiviral therapy.
The sensitivity (50.0%) and positive predictive value (40.7%) of the CMV-DNA PCR test for the uterine cervical secretion for predicting congenital infection were not so high. However, the effective methodology of universal screening for fetal CMV infection has not been established, the results of our study suggest that PCR assays for CMV-DNA in the cervical secretion and ultrasound examinations only for CMV IgM-positive women may be useful in determining pregnancies with higher risks of congenital CMV infection. Although, it is unclear whether these results are applicable to pregnant women at normal or low risk of congenital CMV infection. Further studies are necessary to resolve these questions.
Declaration of interest
H. Yamada has received financial support by Grants-in-Aid from the Ministry of Health, Labour and Welfare of Japan (grant nos. H23-Jisedai-Ippan-001 and H25-Jisedai-Shitei-003). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
Additional information
Funding
References
- Zhang SL, Yue YF, Bai GQ, et al. Mechanism of intrauterine infection of hepatitis B virus. World J Gastroenterol. 2004;10(3):437–438.
- Clemetson DB, Moss GB, Willerford DM, et al. Detection of HIV DNA in cervical and vaginal secretions. Prevalence and correlates among women in Nairobi, Kenya. JAMA. 1993;269(22):2860–2864.
- Tseng CJ, Liang CC, Soong YK, et al. Perinatal transmission of human papillomavirus in infants: relationship between infection rate and mode of delivery. Obstet Gynecol. 1998;91(1):92–96.
- Kimberlin DW, Lin CY, Sanchez PJ, et al. Effect of ganciclovir therapy on hearing in symptomatic congenital cytomegalovirus disease involving the central nervous system: a randomized, controlled trial. J Pediatr. 2003;143(1):16–25.
- Nishida K, Morioka I, Nakamachi Y, et al. Neurological outcomes in symptomatic congenital cytomegalovirus-infected infants after introduction of newborn urine screening and antiviral treatment. Brain Dev. 2016;38(2):209–216.
- Oliver SE, Cloud GA, Sanchez PJ, et al. Neurodevelopmental outcomes following ganciclovir therapy in symptomatic congenital cytomegalovirus infections involving the central nervous system. J Clin Virol. 2009;46(Suppl 4):S22–26.
- Kimberlin DW, Jester PM, Sanchez PJ, et al. Valganciclovir for symptomatic congenital cytomegalovirus disease. N Engl J Med. 2015;372(10):933–943.
- Tanimura K, Tairaku S, Ebina Y, et al. Prediction of congenital cytomegalovirus infection in high-risk pregnant women. Clin Infect Dis. 2017;64(2):159–165.
- Revello MG, Fabbri E, Furione M, et al. Role of prenatal diagnosis and counseling in the management of 735 pregnancies complicated by primary human cytomegalovirus infection: a 20-year experience. J Clin Virol. 2011;50(4):303–307.
- Griffiths PD, Stagno S, Pass RF, et al. Infection with cytomegalovirus during pregnancy: specific IgM antibodies as a marker of recent primary infection. J Infect Dis. 1982;145(5):647–653.
- Sonoyama A, Ebina Y, Morioka I, et al. Low IgG avidity and ultrasound fetal abnormality predict congenital cytomegalovirus infection. J Med Virol. 2012;84(12):1928–1933.
- Ebina Y, Minematsu T, Sonoyama A, et al. The IgG avidity value for the prediction of congenital cytomegalovirus infection in a prospective cohort study. J Perinat Med. 2014;42(6):755–759.
- Staykova J, Belovska T, Murad A, et al. Cervical viral infections among asymptomatic bulgarian women. Cent Eur J Public Health. 2016;24(3):176–179.
- Berntsson M, Dubicanac L, Tunback P, et al. Frequent detection of cytomegalovirus and Epstein-Barr virus in cervical secretions from healthy young women. Acta Obstet Gynecol Scand. 2013;92(6):706–710.
- Cannon MJ, Hyde TB, Schmid DS. Review of cytomegalovirus shedding in bodily fluids and relevance to congenital cytomegalovirus infection. Rev Med Virol. 2011;21(4):240–255.
- Shen CY, Chang SF, Chao MF, et al. Cytomegalovirus recurrence in seropositive pregnant women attending obstetric clinics. J Med Virol. 1993;41(1):24–29.
- Tanaka K, Yamada H, Minami M, et al. Screening for vaginal shedding of cytomegalovirus in healthy pregnant women using real-time PCR: correlation of CMV in the vagina and adverse outcome of pregnancy. J Med Virol. 2006;78(6):757–759.