Quantitative herpes simplex virus concentrations in neonatal infection

Neonatal herpes simplex virus infection: From the maternal infection to the child outcome

This review examines the recent literature on the management of herpes simplex virus (HSV) infections in neonates. We summarized the three clinical categories of maternal HSV infection during pregnancy (primary first episode, nonprimary first episode, or recurrent episode) and the mechanisms of fetal damage. Considering when the transmission of the infection from the mother to the fetus/newborn occurs, three types of neonatal infection can be distinguished: intrauterine infection (5% of cases), postnatal infection (10% of cases), and perinatal infections (85% of cases). Neonatal presentation could range from a limited disease with skin, eye, and mouth disease to central nervous system disease or disseminated disease: the treatment with acyclovir should be tailored according to symptoms and signs of infection, and virological tests. These children need a multidisciplinary follow-up, to timely intercept any deviation from normal neurodevelopmental milestones. Prevention strategies remain a challenge, in the absence of an available vaccine against HSV.

Pregnancy and viral infections: Mechanisms of fetal damage, diagnosis and prevention of neonatal adverse outcomes from cytomegalovirus to SARS-CoV-2 and Zika virus

Some maternal infections, contracted before or during pregnancy, can be transmitted to the fetus, during gestation (congenital infection), during labor and childbirth (perinatal infection) and through breastfeeding (postnatal infection). The agents responsible for these infections can be viruses, bacteria, protozoa, fungi. Among the viruses most frequently responsible for congenital infections are Cytomegalovirus (CMV), Herpes simplex 1–2, Herpes virus 6, Varicella zoster. Moreover Hepatitis B and C virus, HIV, Parvovirus B19 and non-polio Enteroviruses when contracted during pregnancy may involve the fetus or newborn at birth. Recently, new viruses have emerged, SARS-Cov-2 and Zika virus, of which we do not yet fully know the characteristics and pathogenic power when contracted during pregnancy.

Viral infections in pregnancy can damage the fetus (spontaneous abortion, fetal death, intrauterine growth retardation) or the newborn (congenital anomalies, organ diseases with sequelae of different severity). Some risk factors specifically influence the incidence of transmission to the fetus: the timing of the infection in pregnancy, the order of the infection, primary or reinfection or chronic, the duration of membrane rupture, type of delivery, socio-economic conditions and breastfeeding. Frequently infected neonates, symptomatic at birth, have worse outcomes than asymptomatic. Many asymptomatic babies develop long term neurosensory outcomes.

The way in which the virus interacts with the maternal immune system, the maternal-fetal interface and the placenta explain these results and also the differences that are observed from time to time in the fetal‑neonatal outcomes of maternal infections. The maternal immune system undergoes functional adaptation during pregnancy, once thought as physiological immunosuppression. This adaptation, crucial for generating a balance between maternal immunity and fetus, is necessary to promote and support the pregnancy itself and the growth of the fetus. When this adaptation is upset by the viral infection, the balance is broken, and the infection can spread and lead to the adverse outcomes previously described. In this review we will describe the main viral harmful infections in pregnancy and the potential mechanisms of the damages on the fetus and newborn.

Postnatal Exposure to Herpes Simplex Virus: To Treat or Not to Treat?

Neonatal herpes simplex virus (HSV) infection carries significant morbidity and mortality. In contrast to perinatal exposure, there are no clear guidelines for the management of postnatal HSV exposure. This review focuses on the risk of HSV infection following postnatal exposure and suggests an approach to management. While many infants are protected by transplacentally transferred maternal anti-HSV antibodies, infants of seronegative mothers with significant postnatal HSV exposure may be at risk of severe disease. Individual risk assessment, appropriate investigations, and empiric acyclovir treatment should be considered in postnatally exposed newborns, even if asymptomatic. In all cases, close clinical follow-up is indicated, as well as education of families on the symptoms of neonatal HSV disease. Finally, measures to reduce the risk of postnatal HSV infection should be considered, such as discouraging individuals, particularly those with a history of recurrent cold sores, from kissing newborns.

Antiviral Approaches for the Treatment of Herpes Simplex Virus Infections in Newborn Infants

Herpes simplex virus (HSV) infections in newborns are associated with severe disease and death. Trials conducted by the Collaborative Antiviral Study Group have established the standard of care for the treatment of neonatal HSV disease with marked improvements in morbidity and mortality. We review the studies that have contributed to our understanding of the epidemiology and clinical course of neonatal HSV disease and discuss the landmark trials that have resulted in safe and effective treatment together with improved diagnostics. Although significant advances have been made, neonatal HSV disease continues to have an unacceptably high mortality rate with significant sequelae in survivors. Further research is urgently needed for prevention.

The Tail Wagging the Dog (or the Challenges Faced When the Financing of Medicine Gets Ahead of the Science of Medicine)

In their article in this issue of the Journal of Clinical Microbiology, S. R. Dominguez et al. (J Clin Microbiol 56:e00632-18, 2018, https://doi.org/10.1128/JCM.00632-18) describe the performance of PCR detection of herpes simplex virus (HSV) DNA versus viral culture in skin and mucosal samples from 7 neonates with HSV disease. This is a significant contribution to our understanding of the optimal diagnostic approach in babies being evaluated for neonatal HSV disease. Many diagnostic laboratories already have made the change to molecular diagnostics for skin and mucosal swab testing, however, in large part due to the labor costs associated with viral cultures. Thus, important studies such as this one are being conducted to support a decision that has already been made in many locations on mostly economic grounds. This small case series supports the decision to use molecular testing for samples from skin and mucosal sites, but larger studies are needed to more fully define the performance characteristics of PCR in this population. Since a false-positive result would commit a baby to months of management that would be unnecessary and have potential harm, it is critical to base diagnostic decision making on data that support the use of a specific test.

Neonatal herpes simplex virus infections

Neonatal herpes simplex virus (HSV) is an uncommon but devastating infection in the newborn, associated with significant morbidity and mortality. The use of PCR for identification of infected infants and acyclovir for treatment has significantly improved the prognosis for affected infants. The subsequent use of suppressive therapy with oral acyclovir following completion of parenteral treatment of acute disease has further enhanced the long-term prognosis for these infants. This review article will discuss the epidemiology, risk factors and routes of acquisition, clinical presentation, and evaluation of an infant suspected to have the infection, and treatment of proven neonatal HSV disease.

Neonatal Herpes Simplex Virus Infection

Herpes simplex virus (HSV) 1 and HSV-2 infections are highly prevalent worldwide and are characterized by establishing lifelong infection with periods of latency interspersed with periodic episodes of reactivation. Acquisition of HSV by an infant during the peripartum or postpartum period results in neonatal HSV disease, a rare but significant infection that can be associated with severe morbidity and mortality, especially if there is dissemination or central nervous system involvement. Diagnostic and therapeutic advances have led to improvements in mortality and, to a lesser extent, neurodevelopmental outcomes, but room exists for further improvement.

Herpes Simplex Virus DNAemia Preceding Neonatal Disease

Polymerase chain reaction testing of blood for herpes simplex virus (HSV) is recommended for newborns delivered to mothers with active genital HSV lesions at delivery. We report an infant who had a positive blood HSV polymerase chain reaction test before the onset of clinical signs of HSV disease.