Preventing congenital varicella syndrome with immunization

Diagnosis, antiviral therapy, and prophylaxis of varicella-zoster virus infections

Varicella-zoster virus (VZV), an important member of the Herpesviridae family, is the etiological agent of varicella as primary infection and zoster as recurrence. An outstanding feature is the lifelong viral latency in dorsal root and cranial nerve ganglia. Both varicella and zoster are worldwide widespread diseases that may be associated with significant complications. However, there is a broad spectrum of laboratory methods to diagnose VZV infections. In contrast to many other viral infections, antiviral treatment of VZV infections and their prevention by vaccination or passive immunoprophylaxis are well established in medical practice. The present manuscript provides an overview about the basic knowledge of VZV infections, their laboratory diagnosis, antiviral therapy, and the prevention procedures, especially in Germany.

Management of varicella-zoster virus primary infection during pregnancy: A national survey of practice

BACKGROUND

Varicella (VZV) infection in pregnancy can result in serious outcomes: maternal pneumoniae irrespective of the term of pregnancy, and lead to congenital varicella syndrome before 18 weeks of gestation and neonatal varicella. There are between 350 and 500 cases a year in France. Until now, there have been no scientific obstetrical guidelines for clinical practice in France for VZV infection during pregnancy.

OBJECTIVES

To evaluate health care providers' knowledge and practices concerning varicella infection during pregnancy in France.

STUDY DESIGN

An anonymous survey on VZV infection was sent by e-mail to gynecologists-obstetricians and midwives. We evaluated their knowledge and practices concerning VZV transmission, maternal varicella, congenital varicella syndrome, neonatal varicella and prevention.

RESULTS

The survey was completed by 271 professionals: gynecologists (161/271; 60%) and midwives (110/271; 40%). Among 20 items, 5 were multiple choice questions. 29 correct answers were expected. Scores ranged from 6/29 to 28/29 (mean score: 17.44/29).

CONCLUSIONS

The consequences of VZV primary infection in pregnancy are poorly known. We reveal a diversity of management among practitioners in our study population, not always in accordance with the international scientific literature or with the guidelines of other countries. Health care providers should update their knowledge of varicella infection during pregnancy. The publication of national guidelines could help to achieve this objective.

[Vaccination and pregnancy]

Vaccination against influenza is recommended during the vaccination period in pregnant women regardless of trimester. In contrast, administration of live vaccines, such as the vaccine against varicella, MMR (measles-mumps-rubella) is contraindicated in pregnant women. Vaccinations against hepatitis B, diphtheria, tetanus, poliomyelitis, hepatitis A can be made as indicated. Vaccination against yellow fever may be considered in pregnant women travelling to endemic countries. In post-partum period, live vaccines may be administered if necessary, especially vaccination against whooping cough for women not to date with their vaccinations. Vaccination against yellow fever is contraindicated in case of breast feeding. Prevention of pertussis in newborns is based in France on vaccination of the mothers in the post-partum period, and the close contacts of the newborn during the pregnancy ("cocooning").

The role of VariZIG in pregnancy

Varicella infection during pregnancy is associated with serious maternal and fetal complications such as congenital varicella syndrome, maternal pneumonia and neonatal varicella. Pregnant women are ineligible to receive the varicella vaccination, thus women who lack evidence of immunity to varicella are at an increased risk for developing a varicella infection if exposed to a contagious individual. Presently, post-exposure prophylaxis involves the administration of a varicella zoster immunoglobulin (VariZIG™) to prevent or reduce the severity of an infection. The US FDA recently approved VariZIG for licensure and recommend that it be administered as soon as possible following VZV exposure, ideally within 96 h for greatest effectiveness. The following review critically examines the role of VariZIG in post-exposure prophylaxis of varicella during pregnancy.

Advances in the treatment of varicella-zoster virus infections

Varicella-zoster virus (VZV) causes two distinct diseases, varicella (chickenpox) and shingles (herpes zoster). Chickenpox occurs subsequent to primary infection, while herpes zoster (usually associated with aging and immunosuppression) appears as a consequence of reactivation of latent virus. The major complication of shingles is postherpetic neuralgia. Vaccination strategies to prevent varicella or shingles and the current status of antivirals against VZV will be discussed in this chapter. Varivax®, a live-attenuated vaccine, is available for pediatric varicella. Zostavax® is used to boost VZV-specific cell-mediated immunity in adults older than 50 years, which results in a decrease in the burden of herpes zoster and pain related to postherpetic neuralgia. Regardless of the availability of a vaccine, new antiviral agents are necessary for treatment of VZV infections. Current drugs approved for therapy of VZV infections include nucleoside analogues that target the viral DNA polymerase and depend on the viral thymidine kinase for their activation. Novel anti-VZV drugs have recently been evaluated in clinical trials, including the bicyclic nucleoside analogue FV-100, the helicase-primase inhibitor ASP2151, and valomaciclovir (prodrug of the acyclic guanosine derivative H2G). Different candidate VZV drugs have been described in recent years. New anti-VZV drugs should be as safe as and more effective than current gold standards for the treatment of VZV, that is, acyclovir and its prodrug valacyclovir.

[Seroprevalence of antibodies against infectious pathogens relevant to pregnancy among healthcare workers]

Healthcare workers (HCWs) are exposed to infectious diseases throughout the course of their work. The concerns of pregnant HCWs are considerable because certain otherwise mild infections may affect fetal development. We studied 424 pregnant HCWs at the University Hospital Frankfurt between March 2007 and July 2011. Serological tests were carried out for varicella zoster virus (VZV), measles, mumps, rubella (MMR), cytomegalovirus (CMV) and parvovirus B19. Our overall seroprevalence data with regard to VZV, MMR, CMV and parvovirus B 19 corresponded to the general population. However, physicians demonstrated lower seroprevalence towards the two non-vaccine-preventable diseases (CMV: 37.5% [KI 27.4-48.5]; parvovirus B19: 69.3% [KI 58.6-78.7]) compared with nurses (CMV: 53.4% [KI 46.1-60.6], parvovirus B19: 75.1% [68.4-81.1]). It was striking that, only one in five of the study population showed IgG antibodies against all of the six pregnant-relevant viral diseases tested, of the physicians as few as one in six. A routine exclusion from the workplace due to non-immunity would mean that it would not be possible to employ the majority of pregnant staff in healthcare and childcare.

Fetal varicella - diagnosis, management, and outcome

Fetal varicella syndrome (FVS) is due to transplacental infection by the Varicella zoster virus following maternal infection. The risks for the fetus and neonate depend on the timing. When varicella occurs around delivery, it often leads to disseminated neonatal varicella. When varicella occurs during pregnancy, transmission can occur, but is usually asymptomatic; some infants develop zoster postnatally and a few have FVS. Before 20 weeks' gestation, FVS can occur, with an incidence of about 1%. The lesions can affect the skin, limbs, central and autonomous nervous systems, eyes, cause calcifications, and growth retardation; mortality is high. Lesions typically follow one or several nerve territories, suggesting that damage results from in utero zoster following primary fetal infection. There has been little study of prenatal diagnosis of FVS. Serial ultrasound examination can detect various anomalies, magnetic resonance imaging can be of use to investigate for microphthamia and cerebral lesions, and amniocentesis can diagnose viral transmission. Prevention strategies include vaccination and post-exposure prophylaxis with immune globulin and/or antivirals. Perspectives for treating infected fetuses in utero require further research.